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ADVANCES IN MEASUREMENT TECHNOLOGY, DISASTER PREVENTION
AND MITIGATION
Advances in MeasurementTechnology, Disaster Prevention and Mitigationcollects papers resulting
from the conference on Measurement Technology, Disaster Prevention and Mitigation (MTDPM
2022), Zhengzhou, China, 27–29 May, 2022. The primary goal is to promote research and devel-
opmental activities in measurement, disaster prevention and mitigation, and another goal is to
promote scientific information interchange between scholars from the top universities, business
associations, research centers and high-tech enterprises working all around the world.
The conference conducts in-depth exchanges and discussions on relevant topics such as mea-
surement, disaster prevention and mitigation, aiming to provide an academic and technical
communication platform for scholars and engineers engaged in scientific research and engineering
practice in the field of measurement application, measurement in civil engineering and disaster
reduction. By sharing the research status of scientific research achievements and cutting-edge tech-
nologies, it helps scholars and engineers all over the world comprehend the academic development
trend and broaden research ideas. So as to strengthen international academic research, aca-
demic topics exchange and discussion, and promote the industrialization cooperation of academic
achievements.

PROCEEDINGS OF THE 3RD INTERNATIONAL CONFERENCE ON MEASUREMENT
TECHNOLOGY, DISASTER PREVENTION AND MITIGATION (MTDPM 2022),
ZHENGZHOU, CHINA, 27–29 MAY 2022
AdvancesinMeasurementTechnology,
DisasterPreventionandMitigation
Edited by
Zongming Li
North China University of Water Resources and Electric Power, China
Mohd Johari MohdYusof
Faculty of Design and Architecture, Universiti Putra Malaysia, Malaysia

First published 2023
by CRC Press/Balkema
4 Park Square, Milton Park / Abingdon, Oxon OX14 4RN / UK
e-mail: [email protected]
www.routledge.com – www.taylorandfrancis.com
CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business
© 2023 selection and editorial matter, Zongming Li and Mohd Johari Mohd Yusof;
individual chapters, the contributors
The right of Zongming Li and Mohd Johari Mohd Yusof to be identified as the authors of the
editorial material, and of the authors for their individual chapters, has been asserted in
accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this book may be reprinted or reproduced or utilised
in any form or by any electronic, mechanical, or other means, now known or
hereafter invented, including photocopying and recording, or in any information
storage or retrieval system, without permission in writing from the publishers.
Although all care is taken to ensure integrity and the quality of this publication and
the information herein, no responsibility is assumed by the publishers nor the author
for any damage to the property or persons as a result of operation or use of this
publication and/or the information contained herein.
Library of Congress Cataloging-in-Publication Data
A catalog record has been requested for this book
ISBN: 978-1-032-36087-4 (hbk)
ISBN: 978-1-032-36088-1 (pbk)
ISBN: 978-1-003-33017-2 (ebk)
DOI: 10.1201/9781003330172
Typeset in Times New Roman
by MPS Limited, Chennai, India

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Editor(s), ISBN: 978-1-032-36087-4
Table of contents
Preface xi
Committee members xiii
Keynote lectures
Construction and whole-process management for urban lifeline projects 3
Zongming Li
Research on WPC-based key technologies 4
Feiyan Meng
Measurement technology and data predictive risk assessment
Temporal and spatial characteristics of satellite remote sensing precipitation data in
Naqu, Tibet 7
Jiarui Hong, Jing Zhang & Yongyu Song
Design of a tension measuring instrument for cable structure 16
Yue Hua, Ting-Ting Liu, Tian Shi & Guo-Hui Chen
Practical application of radar wave testing technology in soil cavity damage detection 23
Liyang Wan
Analysis of passive flood inundation and assessment of ecosystem service value loss in
Chittagong 30
Panpan Zhang, Zhikun Zhang, Xin Teng & Mohammad Saydul Islam Sarkar
Application of single hole acoustic testing technology in blasting excavation of
reservoir dam foundation 39
Sen Ma
Displacement prediction method of cofferdam under condition of exceeding warning
value based on adaptive Kalman filter 46
Mingjie Chen & Pingjie Li
Glacierized and snow-cover area variation in O’Higgins lake area from 2000 to 2020 56
Jiantan Chen
Experimental research on performance of a novel differential pressure flowmeter:
Olive-shaped flowmeter (OSF) 65
Chen Gu, Guozeng Feng & Yuejiao Guo
Study on site selection evaluation of post-earthquake reconstruction in active fault
area—Taking Qingshuihe plain in Tongxin county of Ningxia as an example 72
Yunlin Liu & Chunfeng Li
Study on the site selection method of highway dumping field in Jiangxi mountainous
area based on GIS 81
Wukun Zou, Chunsheng Hu, Sangen Deng, Xuan Ding, Guangqing Yang,
Rongbin Zhang & Feng Xu
v

Study on long-term performance monitoring technology of loess tunnel based on
distributed optical fiber 87
Guang Yao
Research on permeability coefficient of fractured rock mass 93
Zhaowei Yu & Xiang Wang
Comprehensive safety risk assessment of foundation pit construction based on FAHP-SPA
coupling 98
Jian-feng Liu, Lu Yang, Kun-peng Wu, Jun-xing Luo, Hong-xing Zhou & Qing-chang Qiu
Urban flood risk analysis based on GIS and SWMM: A case study in Dujiangyan 104
Mingxia Lu, Ting Ni & Xuejin Ying
Analysis of monitoring results of spillway slope of Wacun hydropower station 110
Xiaochuang Ding
Study of land surface temperature in Beijing based on remote sensing technology 117
Shizheng Guan & Jing Zhang
Research on noise reduction method of slope monitoring data based on wavelet analysis 125
Dexin Liu, Wenqing Wang, Peng Liu & Feng Xu
Research on remote sensing technology application in water quality parameter inversion 132
Xin Cao & Jing Zhang
Application of air-coupled seismic waves to explosion yield estimation 140
Liangyong Zhang, Weiguo Xiao, Xiaolin Hu, Xin Li, Yanjun Ma, Ao Li & Qiang Lu
Rational evaluation of substation engineering cost based on fuzzy evaluation theory 148
Ye Ke, Minquan Ye, Huiying Wu, Wenqi Ou, Jiawei Lin, Cheng Xin & Jinpeng Liu
Research on substation engineering cost prediction method based on index theory 154
Zheng Chenhong
Identification and assessment of safety risks for coastal tunnel construction 159
Bao Yang
Risk assessment of valley debris flow based on the residual structure–Taking
Nujiang Lisu autonomous prefecture as an example 165
Fanshu Xu, Jun Han, Baoyun Wang & Kunxiang Liu
Analysis of construction safety risk coupling behavior based on the
EWM-DEMATEL model: A case study of the Xidian bay subsea tunnel project 174
Ping Wu, Guojun Lin, Hangcheng Zhang & Yuanxiao Ma
Evaluation of debris-flow risk in Xiaohongyan Gully of Baihetan hydropower
station on the Jinsha River 181
Zhi-gang Shan, Wei-da Ni, Hao Wu & Yi-huai Lou
Technical analysis of the Guangli canal from the perspective of harmony between
man and nature 190
Bo Zhou & Tianliang Li
Simulation of damage mode of RC bridge pier under contact explosion 197
Pingming Huang & Zerui Liu
A numerical simulation study of curtain grouting boreholes for Gravity Dams 203
Yapeng Zhang
vi

Disaster prevention and intelligent disaster reduction project
Construction and implementation of ontology model of dam break emergency plan 213
Dewei Yang, Shuai Liu, Jinbao Sheng, Xuehui Peng & Huiwen Wang
Research on the spatial distribution of natural disasters harmful to China’s inland channel 221
Baoying Mu, Lixin Lu & Yuchuan Wang
Application of super map technology to geological visualization in landslide monitoring 227
Jun Zhou, Xunsheng Bian & Qiong Liu
Comprehensive geological and geophysical exploration of loess landslides and
high-precision 3D geological interpretation 236
Jie Li, Pingsong Zhang & Yulin Xiao
Establishment and evaluation of urban disaster prevention and mitigation
model based on full-cycle monitoring 243
Yueyi Gao, Haibo He & Gangfeng He
Spatial pattern and interannual variation characteristics of rainstorms and
flood disasters in Southern Xinjiang 250
Kan Chen & Xi Wang
Research on the time distribution of natural disasters harmful to inland channel in China 257
Baoying Mu, Yuchuan Wang & Lixin Lu
Research on resilience and disaster resilience evaluation system for older
communities under hierarchical analysis and delphi method 262
CenSi Hu & Xin Zhou
Study on attenuation effect of buffer barrier on blast load in the soil 269
Zhao Zhang, Fei Liu, Yonghong Gao, Kai Xin, Minhua Yan, Xu Huang,
Yapeng Duan & Chaoyuan Huang
Supply and form of earthquake prevention and disaster reduction publicity and
education products for the public 276
Yunlin Liu
Yuzhou mine section of the main canal of south-to-north water diversion mid-route
phase i project deformation monitoring analysis 288
Xiaoying Liu
Installing air curtains for fire smoke control in long entrances and exits of
metro stations without intermediate vertical evacuation staircases 300
Lu Zhou, Hongshan Dong & Miaocheng Weng
Stability analysis of unsaturated soil slope under rainfall infiltration 307
Yiliang Zhou, Ming Li, Zhuoqun Chen & Fenghan He
The influence of the operation and management of the Cao’e River gate on the
flood control and drainage of the Hangyong Canal 315
Chengjie Tu, Weijin Chen, Yishan Chen, Mei Chen, Xiongwei Zhang,
Linjie Wang & Liya Zhu
Numerical simulation of slope retrogressive thaw slumps in the permafrost region 322
Bao Zhou, Zhongfu Wang, Liang Wu, Yongyan Zhang, Sailajia Wei & Wenfeng Zhu
Research on horizontal roadway passing through large hidden collapse column 329
Xianzhi Shi, Yongjin Tang, Yanmei Chen & Weifeng Huang
vii

Research on simulation pre-assembly method of bridge steel structure based on
characteristic space line under safety monitoring background 337
Yanyi Li & Mingfang Zhu
Taking the Longxian-Qishan-Mazhao fault as an example to analyze the
pseudo effect of normal/inverse fault caused by strike-slip movement 343
Chenyi Yang, Ji Ma, Xiaoni Li, Yifei Xu & Lina Su
Effect of unidirectional tension on permeability of sand-geotextile system 353
Jiabao Hu, Xiaolei Man, Hui Liu, Hanyue Wang & Mengyu Rong
Seismic response of 8 MW offshore wind turbines supported on the pile-bucket
composite foundation 362
Yanguo Sun, Chengshun Xu, Xiuli Du, Piguang Wang, Renqiang Xi & Yilong Sun
Seepage stability analysis of 3# reservoir for a ski park 369
Yanjing Shi, Wenlong Niu, Lingchao Meng & Linlin Jiang
Scenario construction and emergency rescue analysis of high altitude mine fire 375
Jun Hu & Rui Huang
Seismic performance analysis of concrete-filled steel tubular column-corrugated
steel plate composite pier 382
Ziqi Li, Yanyan Fan, Wang Li & Wenlong Zhang
Research on civil and hydraulic structure and geological characteristics
A comparative study on determination methods of effective area of natural smoke
and heat exhaust ventilator 391
Hang Yin & Longfei Tan
Research on the bearing capacity of box aluminum alloy joints using welded 398
Qiujun Ning, Jiawei Lu & Xiaosong Lu
Comprehensive evaluation of operation reliability of IWCDSS for large water
supply engineering based on cloud model 408
Xiaoying Liu, Heng Zhang & Guanghui Li
Study on self-healing properties of reactive powder concrete with nano SiO
2 418
Tao Xu, Xiaofeng Liu, Shujie Liu, Mengjun Han & Peibao Xu
In-place evaluation of resilient modulus of roadbed with iron tailings materials
using portable falling weight deflectometer 425
Zhibin Wang, Ting Li, Guangqing Yang & Yunfei Zhao
Research on application technology of in-situ loading test of cast-in-place concrete slab 431
Jianpeng Zhang & Jianyang Zhang
Study on vibration response characteristics of subgrade filled with granite residual soil 437
Junlong Hu, Yongjia Nong, Yao Xie, Jing Wang & Deyong Wang
Study on vertical deformation law of existing pipeline caused by tunnel construction 444
ShouJia Chen, HeXin Wei, YunPeng Fan, XiuJun Ai, ChaoLong Zhao & XinZhen Luan
Acoustic-to-seismic coupling characteristics of a specific poroelastic site 454
Liangyong Zhang, Xin Li, Weiguo Xiao, Xiaolin Hu, Shuai Cheng, Kaikai Li & Dezhi Zhang
The coupling effect of fluid and solid in the red rock slope of Yunnan Province 468
Jiachen Xu & Qingwen Zhang
viii

Analyzing the characteristics of the flow field and laws of tunnels at different
inclinations using CFD 473
Jie Xu & Qingwen Zhang
Review on the development of bridge health monitoring system 479
Beilin Han, Yansong Huang, Genghao Song, Lixuan Luo, Zhongheng Wu & Siyue Zhu
Analysis of reservoir damage and optimization on completion fluid system of
adjusting wells of Weizhou 12-1 oil field 486
Cheng Jian & Xingjin Xiang
Effect of cement ratio on work and bonding properties of styrene acrylic
emulsion-based cement composites 497
Yipeng Ning, Biao Ren, Zhihang Wang, Ao Yao, He Huang & Tengjiao Wang
The application status of red mud in building materials 503
Guilin Huang
Research on optimum design of reinforced concrete frame structure 509
Man Chen
Comparison of VVCM and marshall method for ATB-30 asphalt mixture design515
Mei Song, Sheng Li & Yu-hao Bao
Establishment and validation of finite element model for GFRP confined basalt
fiber reinforced concrete long columns under compression 522
Jingshan Jiang, Xin Huang, Zhihua Wang, Chao Zhang & Youxin Wei
Research and practice on gas control technology of long-distance adjacent strata
in large inclined coal mining face 529
Zhanjin Lu & Zunyu Xu
Study of the deformation characteristics of overlying surrounding rock in floor
roadway of Qujiang coal mine 535
Zhonghua Wang
Research on the law of pressure relief and permeability increase in overlying
coal seam of floor roadway 541
Zhonghua Wang
Analysis of hydration heat and pipe cooling of the mass concrete cap of the
main tower of a self-anchored suspension bridge 545
Zhaobing Wang, Fajiang Luo, Kui Huang, Peng Li, Hualong Li, Kun Guo, Jianning Li,
Zizhou Dai, Qinxiong Zhang, Leping Ren, Litao He & Jincheng Fan
The practice of optimal and fast drilling technology in complex formation
environment of tight reservoir 551
Wen Li, Dawei Zhao, Fu Tao, Ning Li, Zhuolin Lv, Xianlong Zhao, Hanlie Cheng,
Shiela Kitchen & Graciela Daniels
Research on Jiangxiyan irrigation system 557
Bo Zhou, Xiaoming Jiang, Yunpeng Li & Jun Deng
Study on internal relative humidity and hydration characteristics of early-age concrete 566
Xiaofei Zhang, Wenwei Zhang & Peipei Wei
Analysis of the causes of abnormal seepage in Hualiangting reservoir 575
Dewei Yang, Chengjun Xu & Huiwen Wang
ix

Laboratory experimental study on leakage of dams considering low-temperature
water leakage and composite geomembrane defects 582
Ke Li, Jie Ren & Lei Zhang
An experimental study on the effect of unidirectional tension on permeability of
geotextile sand covering systems 589
Chengbin Lu, Xiaolei Man, Hao Xiao, Ying Ge & Yingjie Wu
Three dimensional finite element analysis of a soft foundation sluice 599
Xiaona Li & Yuchen Li
Author index 605
x

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Editor(s), ISBN: 978-1-032-36087-4
Preface
The 2022 3rd International Conference on Measurement Technology, Disaster Prevention and Mit-
igation (MTDPM 2022) was planned to be held in Zhengzhou, China from May 27–29, 2022.
However, it is uncertain when the COVID-19 will end, so it remains unclear for postponement
time, while many scholars and researchers wanted to attend this long-waited conference and have
academic exchanges with their peers. Therefore, in order to actively respond the call of the govern-
ment, and meet author’s request, MTDPM 2022 was organized in a virtual mode. This approach
not only avoids people gathering, but also meets their communication needs.
This conference is mainly for experts, scholars and engineers from universities, research insti-
tutes, enterprises and institutions at home and abroad, providing an academic platform to share
scientific research results, explore cutting-edge engineering issues, discuss opportunities and chal-
lenges, promote cooperation and exchange, and promote the industrialization of scientific research
results.
This scientific event brings together more than 120 national and international researchers in
Measurement Technology, Disaster Prevention and Mitigation. On top of the local participants
coming from different national universities, international participants are also registered from dif-
ferent countries, namely Algeria, Turkey, Australia, Malaysia and India. During the conference, the
conference model was divided into three sessions, including oral presentations, keynote speeches,
and online Q&A discussion. In the first part, some scholars, whose submissions were selected as
the excellent papers, were given about 5–10 minutes to perform their oral presentations one by
one. Then in the second part, keynote speakers were each allocated 30–45 minutes to hold their
speeches.
We were greatly honor to have invited two distinguished experts as our keynote speakers. Pro-
fessorial Senior Engineer Zongming Li, North China University of Water Resources and Electric
Power was the first one to perform his thought-provoking speech. And then we had Senior Engi-
neer Feiyan Meng, Nanjing University of Science and Technology. Their insightful speeches had
triggered heated discussion in the third session of the conference. The online discussion lasted for
about 30 minutes. Every participant praised this conference for disseminating useful and insightful
knowledge.
We are glad to share with you that we received lots of submissions from the conference and
we selected a bunch of high-quality papers and compiled them into the proceedings after rigor-
ously reviewed them. These papers feature following topics but are not limited to: Measurement
Technology, Application and Modern Detection Technology, Measurement Technology in Civil
Engineering, Measurement Applications in Construction Engineering, Hydraulic Engineering and
Surveying Applications, Intelligent Disaster Reduction and Protection Engineering, etc. All the
papers have been through rigorous review and process to meet the requirements of international
publication standard.
Lastly, we would like to warmly thank all the authors who, with their presentations and papers,
generously contributed to the lively exchange of scientific information that is so vital to the
endurance of scientific conferences of this kind.
The Committee of MTDPM 2022
xi

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Editor(s), ISBN: 978-1-032-36087-4
Committee members
Conference Chair
Professorial Senior Engineer Zongming Li,North China University ofWater Resources and Electric
Power, China
Program (Academic) Committee Chair
Assoc. Prof. Mohammad Russel,School of Ocean Science and Technology, Dalian University of
Technology, Bangladesh
Program (Academic) Committee Member
Prof. Bachir Achour,University of Biskra, Algeria
Prof. Behnam,University of Tabriz, Iran
Prof. Haluk Akgün,Middle East Technical University, Turkey
Prof. Fauziah Ahmad,Universiti Sains Malaysia, Malaysia
Senior Engineer Feiyan Meng,National Quality Supervision and Inspection Centre for Building
Decoration and Decoration Materials, China
Dr. Xingbo Han,University of New South Wales, Australia
Dr. R. S. AJIN,Idukki District Disaster Management Authority (DDMA) Collectorate, India
Organizing Committee Chair
Assoc. Jianjun Ma,Henan University Of Science And Technology, China
Organizing Committee Member
Prof. Keren Dai,Chengdu University of Technology, China
Prof. Tetsuya HIRAISHI,Kyoto University, Japan
Assoc. Prof. Mohammadreza Vafaei,Universiti Teknologi Malaysia, Iranian
Dr. Zhe Yang,Hainan Tropical Ocean University, China
Dr. Sadegh Rezaei,Shargh-e Golestan Institute of Higher Education, Iran
Publication Chair
Prof. Sudip Basack,MAKA University of Technology, Kolkata, India
Professorial Senior Engineer Zongming Li,North China University ofWater Resources and Electric
Power, China
Assoc. Prof. Ts. Gs. Dr. Mohd Johari Mohd Yusof,Universiti Putra Malaysia, Malaysia
Assoc. Prof. Ziyan Zhang,Hainan Tropical Ocean University, China
xiii

Keynote lectures

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Author(s), ISBN: 978-1-032-36087-4
Construction and whole-process management for urban lifeline projects
Zongming Li
North China University of Water Resources and Electric Power
ABSTRACT: Urban lifeline projects mainly include urban pipeline networks, road traffic, electric
power, communications, gas, heat, water supply and drainage. Due to rapid economic development,
most modern urban infrastructures are overloaded, and the performance of materials and structures
is fatigued or degraded due to aging, corrosion, and repeated loading. Besides, the scarcity of
primary data could also lead to vulnerability of these infrastructures under disaster conditions.
DOI 10.1201/9781003330172-1 3

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Author(s), ISBN: 978-1-032-36087-4
Research on WPC-based key technologies
Feiyan Meng
Nanjing University of Science and Technology
ABSTRACT: WPCs have beautiful appearance of wood products, with advantageous features
such as antibacterial effect, anti-corrosion, and recyclability, making them an optimal choice in
manufacturing. We believe that through studying key technologies of advanced processing and
manufacturing processes, our project will achieve a breakthrough in high performance and cost
performance of WPC products. This could help us establish a technology platform to support
the development of WPC industry, as well as its related industries, including building materials,
automobile manufacturing, logistics and transportation, and furniture manufacturing. This project
could also generate substantial economic benefits for WPC manufacturers. It can, for instance,
effectively utilize natural wood fiber and improve reasonable utilization of wood resources. In
addition, it can also reduce environmental pollution, contributing to the coordination of man and
nature, and to the national economy as well as to sustainable social development.
4 DOI 10.1201/9781003330172-2

Measurement technology and
data predictive risk assessment

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Author(s), ISBN: 978-1-032-36087-4
Temporal and spatial characteristics of satellite remote sensing
precipitation data in Naqu, Tibet
Jiarui Hong, Jing Zhang
∗
& Yongyu Song
Beijing Laboratory of Water Resources Security, Beijing, China
Key Laboratory of 3D Information Acquisition and Application of Ministry of Education, Capital Normal
University, Beijing, China
ABSTRACT: Due to the special geographical and topographic conditions of mountainous alpine
areas, the hydro-meteorological monitoring stations are scarce, which makes the measured data
less representative. In order to study the hydrological patterns in the plateau region where data
are severely scarce, this paper compares and evaluates the consistency, detection capability and
spatial and temporal characteristics of the measured precipitation and the multi-source precipi-
tation datasets using the Naqu watershed on the Qinghai-Tibet Plateau, China as the study area.
The results show that Multi-Source Weather (MSWX) and the China Meteorological Assimila-
tion Driving Datasets (CMADS) are better than Global Precipitation Climatology (GPCP) and the
Precipitation-PERSIANN Climate Data Record (PERSIANN-CDR), among which MSWX is the
best. On the whole, MSWX shows better precipitation inversion accuracy in the Naqu Basin and
has certain applicability. The distribution of precipitation in the Naqu Basin is relatively uneven
among months, and the spatial distribution of annual precipitation in the multi-source precipitation
datasets varies greatly.
1 INTRODUCTION
The watershed area of Naqu is 16822 km
2
, which is the source area of the Nujiang River. Runoff is
mainly derived from precipitation, and the inter-annual variation and regional distribution of runoff
are quite closely related to the variation of precipitation (Gong 2019). However, there is only one
meteorological station in the basin, and there is a lack of long-series precipitation information. The
local livestock industry is the mainstay of development, and the economic level is backward, so
water management needs to improve pasture production to promote economic development. The
scarcity of hydrological information alone to measure precipitation in the area is inadequate to
support water resource management.
Since the accuracy of multi-source precipitation datasets can vary significantly in different
regions due to multiple factors such as topography, climate, estimation algorithms, and the number
of actual measurement stations (Ma 2021). Luo et al. (2011) compared and analyzed the appli-
cability of TRMM-3B42 with station information in the region of China and concluded that the
applicability is higher in the eastern region. Deng et al. (2018) evaluated the accuracy and relia-
bility of MSWE precipitation products in China and found that there is an overall overestimation
phenomenon, and the agreement between MSWEP and the measured data is the lowest in the
southwest region due to the influence of local factors such as topography. Sheng et al. (2021) used
GPM-IMERG to build and calibrate the down-scaling model, which can better reflect the precip-
itation characteristics in the humid region. Chen et al. (2022) selected five precipitation products
to evaluate the applicability to the Yuanjiang-Hongjiang River basin, and the study found that the
accuracy of most precipitation products was related to the elevation.
∗
Corresponding Author: [email protected]
DOI 10.1201/9781003330172-3 7

Therefore, based on the Naqu Basin with few stations, this paper will evaluate the multi-source
precipitation data set, avoid the calibration instability caused by the scarcity of stations and the large
random error of a single station, and further improve the precipitation estimation accuracy in the
area with few stations on the QinghaiTibet Plateau. It is hoped that it can provide scientific reference
for selecting appropriate precipitation data in areas lacking data and enhance the understanding of
the temporal and spatial distribution characteristics of precipitation in the basin.
2 STUDY AREA AND DATA COLLECTION
2.1Overview of the study area
In this study, the Naqu watershed in the upper reaches of the Nujiang River was selected as the
study area, which is located between 91
◦
∼92
◦
E, 30
◦
∼32
◦
, with an average elevation above
4500 m. The climate type in the basin mainly belongs to the highland sub-cool monsoonal semi-
humid climate zone. The annual precipitation distribution in the Naqu Basin is extremely uneven,
concentrated from June to September, accounting for 80% of the year, and its multi-year average
annual precipitation is about 550 mm (Liu 2017). The geographical location of the Naqu River
Basin is shown in Figure 1. It is a typical area with a serious lack of data, and the precipitation
observation data of the stations are extremely scarce, and there is only one Dasa-Naqu station in
the basin.
Figure 1. The geographical location of the Naqu River Basin.
2.2Data sources
In this paper, the data from the national conventional meteorological stations will be taken as the
benchmark for assessing and analyzing the quality of other precipitation numbers. There is only one
meteorological station in the Naqu Basin, although it can only represent the precipitation values
in a small area and is the most direct and reliable data source at present (Meng & Wang 2017;
8

Meng 2008). Four widely used multi-source precipitation datasets with high accuracy worldwide
are collected, their applicability in the Naqu Basin is compared and analyzed, and the characteristics
of each data set are shown in Table 1.
Table 1. Characteristics of multi-source precipitation datasets.
No Short Name Coverage Area spatial resolution Time-series
1 CMADS East Asia 1 /3
◦
2008–2019
2 GPCP Global 1
◦
1998–2018
3 MSWX Global 0 .1
◦
1984–2021
4 PERSIANN-CDR Global 0 .25
◦
1990–2021
2.3Methodology
Considering the differences between the time scales, spatial resolutions, sequences and accesses of
the four multi-source precipitation datasets, the study will preprocess the data and interpolate the
spatial resolutions using the inverse distance weighting (IDW) method to unify them to 0.1
◦
×0.1
◦
,
while selecting the period 2008–2017 as the study period. IDW is the most popular geometric
method, and due to its simple nature, it has been applied to different spatial and temporal scales
(Kurtzman et al. 2009).
W
i=
h
−p
i
∗
n
i=1
h
−p
i
(1)
h
i=
◦
(x−x i)
2
+(y−y
i)
2
(2)
Wi=
(
R−h
Rh
)
2
∗
n
j=1
(
R−hRh
)
2
(3)
pis the weight index, usuallyp=2;h
iis the distance from the discrete point to the interpolation
point; (x,y) is the coordinates of the interpolation point; (x
i,yi) is the coordinates of the discrete
point;Ris the distance from the interpolation point to the farthest discrete point;nis the number
of discrete points.
Four basic statistical indexes, root mean square error (RMSE), correlation coefficient (CC),
relative bias (bias) and mean error (me), are used to quantitatively evaluate the performance and
applicability of four multi-source precipitation data sets in the Naqu Basin. Three classified sta-
tistical indexes, probability of detection (POD), false alarm rate (far) and critical success index
(CSI), are used to measure the detection ability of precipitation data set for precipitation events of
moderate rain and above in Naqu Basin (Zeng & Yong 2021).
Table 2. Calculation index calculation formula.
Indicators Formula Optimum value
Basic statistical
indicators
RMSE=
∼
1
n
n
∗
i=1
(Si−Gi)
2
0
(contined)
9

Table 2. Calculation index calculation formula.
Indicators Formula Optimum value
CC=
∗
n
i=1
(Gi−
G)(Si−S)
√∗
n
i=1
(Gi−
G)
2
∗
√∗
n
i=1
(Si−
S)
2
1
BIAS=
∗
n
i=1
(Si−Gi)
∗
n
i=1
Gi
0
ME=
∗
n
i=1
(Si−Gi)
N
0
Classification statistics
index
POD=
H
H+M
1
FA R=
F
F+H
0
CSI=
H
F+H+M
1
Siis the precipitation of the multi-source data set;G iis the actual precipitation measured at the
weather station;nis the number of samples.
Hindicates the number of days when both weather stations and precipitation datasets monitored
moderate rain and above;Findicates the number of days when only precipitation datasets monitored
moderate rain and above;Mindicates the number of days when only weather stations monitored
moderate rain and above.
3 RESULTS AND DISCUSSION
3.1Consistency analysis of multi-source precipitation datasets
In this paper, the four multi-source precipitation datasets are compared with the meteorological
stations within the Naqu Basin as a benchmark for one-dimensional linear analysis. According to
Table 3, it can be found that the CC values of the four precipitation datasets are low, and there is no
obvious linear relationship. Comparing the RMSE, only GPCP has a value greater than 5 mm/d in
the four precipitation datasets, indicating its worst accuracy, and MSWX has a minimum RMSE of
2.897 mm/d, indicating its better accuracy. The BIAS of MSWX and CMADS datasets are smaller
at 4.5% and –5.1%, respectively, of which only CMADS has a negative BIAS value, indicating
that the daily-scale CMADS dataset is underestimated. ME is consistent with the indicator trend
and positive and negative cases of BIAS.
Table 3. Comparison of basic statistical indexes of multi-source precipi-
tation datasets.
Index GPCP PERSIANN-CDR CMADS MSWX
RMSE 5.149 4.033 3 .186 2.897
CC 0.265 0.364 0 .495 0.504
BIAS 0.541 0.464 −0.051 0.045
ME 0.712 0.610 −0.067 0.059
In summary, it can be seen that MSWX reflects the best indicator situation and has the highest
accuracy, followed by CMADS, which also has higher accuracy. The consistency of MSWX in
the Naqu region, where the stations are sparse, is higher than in the rest of the datasets, proving
a better representation. This is consistent with Peng Zhenhua’s study statistics found that MSWX
in the Tibetan Plateau region performed significantly better than other multi-source precipitation
datasets (Peng et al. 2019).
10

Figure 2. Scatter comparison between multi-source precipitation data set and measured precipitation of
meteorological stations.
3.2Comparison of precipitation level detection performance
According to the classification standard of precipitation intensity level specified by the National
MeteorologicalAdministration, the daily precipitation is divided into five levels, as shown inTable 4
below. Statistical multi-source precipitation data sets in different precipitation intensity occurrence
frequency and frequency error are compared and analyzed to show the detection capability.
Table 4. Classification standard of precipitation intensity level.Precipitation intensity
(mm/d) No rain Light rain
Moderate
rain Heavy rain Rainstorm
Precipitation (mm) <0.1 0.1 ∼9.9 9.9∼24.9 24.9∼49.9 49.9∼100
Figure 3 shows the frequency distribution of occurrence of actual precipitation data from meteo-
rological stations and four multi-source precipitation data sets at different precipitation intensities.
According to Figure 3, it can be seen that all four precipitation data sets have different degrees
of underestimation for no rain prediction and different degrees of overestimation for light rain
prediction. For the occurrence frequency of moderate rainfall, GPCP and PERSIANN-CDR are
more frequent than the measured ones, and CMADS and MSWX are lower than the measured ones.
The frequency of GPCP is over-represented in the frequency of occurrence of heavy rainfall and
heavy rainfall, while the frequency of MSWX is zero in both, indicating that it underestimates the
frequency of occurrence of precipitation intensity at heavy rainfall and above.
Combined with the statistical indicators of the detection ability of medium rainfall and above in
Table 5, it can be seen that the difference of FAR of the four multi-source precipitation datasets is
11

not large, among which the FAR of CMADS is relatively small, which indicates that the probability
of the datasets being incorrectly predicted for the measured precipitation is small. The probability
of precipitation being correctly detected for medium rainfall and above is small, and the POD of
CMADS is the highest but only 0.33. CSI can reflect the comprehensive index of correct detection
ability, and similar to POD, CMADS has the best effect of 0.162.
Figure 3. Frequency distribution of multi-source precipitation data set under different precipitation intensity.
Table 5. Comparison of statistical indicators of detection abil-
ity of multi-source rainfall data set to detect moderate and above
precipitation.
FAR POD CSI
GPCP 0.880 0.120 0.083 PERSIANN-CDR 0.870 0.130 0.086 CMADS 0.670 0.330 0.162 MSWX 0.781 0.219 0.045 Optimum value 1 1
In summary, the combination of the three statistical indicators shows that the multi-source
datasets are not effective in detecting medium rainfall and above, and the daily precipitation in
the Naqu River basin has a significant mismatch with the daily precipitation in the four precip-
itation datasets, and the CMADS is relatively effective in comparison. This may be because the
precipitation datasets reflect regional averages, resulting in a regional “normalization” of heavy
precipitation, which is confirmed by the TRMM satellite (Li et al. 2012).
3.3Spatial-temporal characteristics
The inter-annual variation curves of the actual and multi-source precipitation datasets at the meteo-
rological stations are shown in Figure 4. According to Figure 4, it can be seen that the trends of the
five curves are generally consistent, but there are some differences in the magnitude of the values.
The variability of the measured precipitation curves at the meteorological stations is greater than
that of the four multi-source precipitation datasets, with a slight jump in inter-annual variability in
2015. As seen in Figure 5, the distribution of inter-annual precipitation in the Naqu Basin is more
uneven each month, mainly concentrated in May-September, and its rainy season begins with the
12

shift of atmospheric circulation from winter to summer (Zou et al. 1995). The precipitation from
November to February is extremely low.
The spatial distribution of multi-year average precipitation in the Naqu Basin is shown in Figure 6.
As a whole, there are large differences in the spatial distribution of annual precipitation in the Naqu
Basin for each data set, with GPCP and PERSIANN-CDR gradually increasing from north to
south, and the southeast direction is the maximum precipitation area with annual precipitation
of 900∼1000 mm. the difference between the MSWX maximum value is smaller than that of
GPCP.
Figure 4. Inter-annual variation of measured precipitation and multi-source precipitation datasets.
Figure 5. Multi-year average precipitation by month in the Naqu Basin.
The CMADS precipitation distribution is more consistent with the glacier distribution (Liu et
al. 2017). In addition, topography and local circulation also become important factors affecting
precipitation (Li & Li 1992; Zhang & Liu 2018).
13

Figure 6. Spatial distribution of multi-year average precipitation in the Naqu Basin from multi-source
precipitation datasets.
4 CONCLUSION
In this paper, four multi-source precipitation datasets of the Naqu River basin from 1998-2017
are compared with the corresponding measured precipitation at meteorological stations. The sta-
tistical results show that MSWX and CMADS outperform GPCP and PERSIANN-CDR in each
precipitation class, and MSWX is more consistent than the remaining three multi-source datasets.
The detection ability to effectively identify real precipitation events is evaluated based on the three
statistical indicators. The multi-source datasets are not effective in detecting medium rainfall and
above. There is an obvious mismatch between the daily precipitation in the Naqu River basin and
the daily precipitation in the four precipitation datasets. CMADS is relatively better in compari-
son. According to the spatial and temporal distribution maps of the four multi-source precipitation
datasets, it can be seen that the inter-annual precipitation distribution is consistent with the per-
ception of flood and non-flood periods, but the distribution of precipitation in each month is more
uneven, mainly concentrated in May-September. From the overall perspective of the basin, the spa-
tial distribution of annual precipitation in the Naqu Basin from multi-source precipitation datasets
varies greatly due to the effects of topography, local circulation and glacier distribution.
In summary, based on the precipitation characteristics and accuracy performance of the datasets,
it is concluded that MSWX is more consistent with the remaining three multi-source datasets and
shows better inverse precipitation accuracy and applicability. In future studies, the precipitation
characteristics and precipitation phase identification in highland areas can be further analyzed to
calibrate the multi-source datasets. Coupled with the driven distributed hydrological model coupled
with the snow-melt module to simulate and predict the runoff in the Naqu Basin, it is beneficial to
understand the hydrological cycle in the Naqu Basin to support water resources management and
economic development.
ACKNOWLEDGMENTS
This research was funded by the National Key R&D Program of China (2017YFC0406004) and
the NSFC (41271004).
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model for water balance computations in Xinjiang catchment, Poyang lake basin[J].Journal of Hydrology,
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change[D].China Institute of Water Resources and Hydropower Research.
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Ma X. (2021) Accuracy evaluation of different types of precipitation products in different subdivisions of
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SWAT Model (CMADS) of East Asia.Water. 9(10), 765.
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15

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Author(s), ISBN: 978-1-032-36087-4
Design of a tension measuring instrument for cable structure
Yue Hua
∗
, Ting-Ting Liu
∗
, Tian Shi
∗
& Guo-Hui Chen
∗
Xi’an Institute of Space Radio Technology, Xi’an, China
ABSTRACT: In order to accurately obtain the tension of flexible cable net structure on Space-
borne mesh antenna with high precision, a tension measuring instrument is designed. The
instrument eliminates the influence of the three-point bending of the rope on the measurement
results through two actions and realizes the determination of the tension value of the fixed pre-
tension rope at both ends. By building a laboratory prototype, the tension measurement system is
designed, and the application test is carried out, which has a certain application value.
1 INTRODUCTION
Spaceborne mesh antenna reflector has the characteristics of lightweight, easy folding, high storage
ratio and large aperture, which provides an important solution for the demand for spaceborne large
aperture antenna.
According to the different support forms and deployment driving modes of the flexible reflection
network, it can be divided into the annular reflector, umbrella reflector, frame reflector and so on.
Its core is to form a stable support structure through the deployment and locking of the deployment
mechanism with high stiffness, and the rope connected to its connection point forms a rope grid.
By designing the rope grid, the reflective surface grid meeting the use accuracy is realized. The
reflective network is fixed to the node of the rope grid or the middle position of the rope system,
and finally, the surface accuracy is guaranteed through the accuracy of the rope grid.
The accuracy of the rope grid is determined by the material characteristics of the rope and the
tension characteristics after installation. The core of reflector profile accuracy lies in the design
and realization of rope tension. In order to realize the preset tension in engineering, Chen Lu et al.
studied the principle and method of cable tension measurement in cable structure (Chen et al. 2006)
and mainly determined the tension of cable through vibration method, three-point bending method
and elastic magnetism method. Li Zhao et al. studied the static tension measurement method of
anchor lifting and dropping streamer applied to the marine operation and adopted the working
principle of maintaining the balance between brake force and cable tension (Li & Chen 2017). Xie
Xin et al. studied the analysis process and measurement method of the tension of precision flexible
cable transmission. The measurement principle is the improved three-point bending method. Its
core is to invert the real-time tension on the flexible cable through the measurement of the bending
stiffness of the flexible cable, which greatly improves the measurement accuracy of the tension in
the cable (Xie et al. 2018).
In this paper, a tension measuring instrument is proposed. The equipment adopts the three-point
bending method. Through the operation of two measuring straight lines, the problem that it is diffi-
cult to eliminate the additional deformation caused by the substitution of the instrument in the one-
time three-point bending method is eliminated, and the equipment has high measurement accuracy.
∗
Corresponding Authors: [email protected]; [email protected]; [email protected] and
[email protected]
16 DOI 10.1201/9781003330172-4

2 PRINCIPLE OF CABLE TENSION MEASUREMENT WITH QUASI RIGID
CONSTRAINTS AT BOTH ENDS
The test principles are shown in Figures 1 and 2.
Figure 1. Test principle (step 1).
In the figure,T 0is the initial tension of tension wire rope. F is the load exerted by the main
measuring point on the tension mesh rope. F
1is the vertical component of the load applied by the
auxiliary measuring point to the tension net rope. T is the tension of the tension net rope when
the instrument is operating in the established state. L is the projection distance between the main
measuring point and the auxiliary measuring point. L
1is the projection distance between the rope
restraint point and auxiliary measuring equipment. L
ρ
1
is the distance between the rope restraint
point and auxiliary measuring equipment.
Mechanical conditions:
F
1=sinθ
ρ
·T=
X
L
ρ
1
·T (1)
F
1is the vertical component of the load exerted by the auxiliary measuring point on the tension
net rope (N);θ
ρ
is the included angle between the position after the tension net rope is offset and
the position before it is not offset during measurement (
◦
). T is the tension of the tension net rope
when the measuring instrument is in the established state of operation (N).
Physical conditions:
T=
EA·◦L
ρ
(2L1+2L−◦L 0)
(2)
In the formula, E is the elastic modulus of tension net rope (
N
√
m
2), A is the cross-sectional area
of the rope (m
2
).◦L
ρ
is the total elongation of the rope when the test instrument is established.◦L 0
is the pre-elongation of the rope before measurement.
The elongation of the rope factor test instrument when it is in the established state is:
◦L
ρ
=◦L 0+◦L C (3)
Geometric deformation conditions:
◦L
C=2
ρ
L
ρ
1
−L1
≤
(4)
Geometric conditions:
L
2
1
+X
2
=
ρ
L
ρ
1
≤
2
(5)
In the formula,◦L
cis the additional elongation generated by the instrument when the test
instrument is in the established state.
The first step of the measurement process belongs to the construction state of the tension mea-
suring instrument. The measuring instrument is in contact with the measured object, resulting in
the rope offset x, but the x value is difficult to determine. At this time, we fix the measuring
instrument, start the measuring operation, and move the main measuring point forward DX.
17

Figure 2. Test principle (step 2).
In the figure, Tcis the tension of the tension net rope when the main tension measuring point is
in the working state; L
ρ
is the distance between the main measuring point and auxiliary measuring
point;θ
ρ
is the included angle between the position of the tension net rope after offset and before
offset during measurement;θis the angle between the line formed by the rope in the working state of
the main tension measuring point and the contact point between the auxiliary measuring point and
the tension net rope and the two auxiliary measuring points when the test instrument is established
after the measurement operation is started.
Step 2 of the measurement method is the formal measurement operation.◦L
ρρ
refers to the total
elongation of the measured object after starting the measurement operation;◦L
ρ
C
is the additional
elongation during the measurement operation of the test instrument; X is the offset distance of the
rope caused by the measuring device when the influence of the established state operation of the
measuring instrument is caused;DXrefers to the distance that the main measurement point moves
forward after the measurement operation is started.
According to the mechanical conditions:
F=sinθ·T
c=
DX
L
·T
c (6)
Physical conditions:
T
C=EA·◦L
ρρ
(7)
The elongation of the rope due to the measurement operation is:
◦L
ρρ
=◦L
ρ
+◦L
ρ
C
(8)
Geometric deformation conditions:
◦L
ρ
C
=2
ρ
L
ρ
−L
≤
(9)
Geometric conditions:
L
2
+(DX)
2
=
ρ
L
ρ
≤
2
(10)
Initial physical condition:
T
0=
EA·◦L
0
2L1+2L2−◦L 0
(11)
Combining formula (1), formula (2) and formula (5), we have:
X=
F
1·(2L 1+2L−◦L 0)·
◦
L
2
1
+X
2
EA·◦L
ρ
(12)
Combining formula (3), formula (4) and formula (5), we have:
◦L
0=◦L
ρ
−2
≈∈
L
2
1
+X
2
−L1

(13)
18

From formula (6) to formula (10), we have:
◦L
ρ
=
L
DX·EA
·F−2
≈∈
(L)
2
+(DX)
2
−L

(14)
Substitute formula (14) into formula (12) to obtain:
X=
F
1.(2L1+2L−◦L 0)·
∈
L
2
1
+X
2
EA

L
DX·EA
·F−2
◦
L
2
+(DX)
2

−L
(15)
X can be obtained from formula (15). We bring formula (14) and x value into formula (13) to
obtain◦L
0, and substitute◦L 0into formula (11) to obtain the initial tension T0.
Where L, L
1,DX,F,F 1can be measured by the testing instrument.
3 DESIGN PRINCIPLE OF MEASURING EQUIPMENT
On the basis of theoretical research, a corresponding instrument for measuring the pretension of
two-end restraint rope is developed. This design is different from the traditional three-point bending
rope measuring instrument. It will not lead to excessive changes in the initial shape of the rope and
excessive additional stress in the test process.
The hardware design is divided into two parts: test instrument design and data processing instru-
ment. The structure of the measuring equipment is shown in Figure 3. Three measuring contacts
of equal length are designed. Among them, the auxiliary measuring contacts on both sides have
high axial and radial stiffness. The radial deformation generated in the test process is small, which
has little impact on the calculation of the geometric deformation of the rope and can be ignored.
A force sensor along the axial direction is arranged inside the contacts at both ends, which can
directly measure the axial load.
The middle main measuring point is a combined measurement, which can measure the linear
displacement and axial load at the same time.
Figure 3. Structure diagram of test equipment.
During the test, the test equipment must have high stiffness support to reduce its own deformation
in the test process, so as to reduce the error caused by the overall deformation or translation of the
test system.
The hardware system design block diagram of the data acquisition and processing end of the
measuring equipment is shown in Figure 4 (Zhang et al. 2015).
When the test system works, the power to drive the main and auxiliary measuring heads to make
a linear motion is provided by the stepping motor, which is driven by the control system to complete
the forward or backward action as required. In order to reduce the measurement error caused by
the gap between the actuating link mechanism of the main and auxiliary measuring points, the
19

Figure 4. Hardware system design block diagram.
linear motion value here is given by the displacement sensor, and the linear displacement value
converted by the stepping motor only plays the role of controlling the motion. The force sensor at
the front end of the stepping motor obtains the force value generated by the measuring point on the
tension rope of the measured object and realizes its digital display and communication through the
transmitter. The measured signal of the displacement sensor and the force value signal of the force
sensor is summarized, and the tension value is calculated and displayed by using the program in
combination with equation (11), equations (13), (14) and (15).
4 MEASUREMENT TEST
Spaceborne high-precision mesh antenna is a prestressed system composed of a cable net and
support structure with high rope tension requirements. During installation, the rope tension shall
be controlled by repeated measurement. In order to verify the accuracy of the measuring equipment,
a verification test is designed, as shown in Figure 5. By connecting the springs at both ends of
the tension rope in series, the spring shape variable is measured synchronously in the tension
measurement process. The two groups of test data are compared to verify the accuracy of the
measurement results of the measuring equipment.
At the beginning of the measurement, the tensiometer needs to be checked first. The probe length
of the three groups of main and auxiliary measuring points is consistent with the theoretical require-
ments. During measurement, the main measuring point will move axially. Before measurement,
zero and calibrate the measuring instrument, and adjust the three probes to the same plane. We
adjust the position and support of the measuring equipment so that there is a relatively good posi-
tion relationship between the measuring instrument and the measured object. The support needs to
have high overall stiffness, which can reduce the measurement error caused by stiffness. Then we
adjust the measuring equipment close to the measured part, place the measuring equipment within
2 mm from the measured rope and fix it so that the head of the measuring equipment has high
support stiffness. Generally speaking, the maximum deformation of the test equipment caused by
the reverse force applied by the tested object to the test equipment shall not exceed 1/10 of its own
deformation; otherwise, the measurement result error is large.
Figure 5. Verification of accuracy of Pre-tension cable net measurement system.
20

It turns on the test equipment and controls the computer. The purpose of clearing the sensing
quantity of the sensor is to eliminate the initial deviation. The difference between the left and right
measuring heads shall be less than 0.2 g. If the error exceeds this value, it is necessary to manually
adjust the placement angle between the measuring instrument and the measured object. Finally,
we input the constants of the test system, the distance between the auxiliary measuring heads, the
maximum value of the linear travel of the main measuring head, etc.
Figure 6. Terminal interface of measurement system.
Step1: Select the leveling of the auxiliary measuring head, and the leveling speed is≤1mm/s.
stop when the force value difference after the leveling of the auxiliary measuring head is≤0.05 N
and the force value is≤0.5 N.
Step2: Select the leveling of the main measuring head, the leveling speed is≤1 mm/s, the middle
measuring head presses the measured tension rope steadily forward, observe the measurement
reading of the main measuring head, and stop when the force value of the auxiliary measuring head
is≤1 n. After the measurement is completed, the tension value of the measured object displayed
on the measurement interface is the actual tension value.
Step3: Record the data, select the “reverse” option, start the motor and return the main measuring
head to the starting position. Repeat the measurement according to the above steps, take the average
value, save the data and exit the program.
5 CONCLUSION
Aiming at the difficult problem of tension measurement of pretension cable net structure of space-
borne high-precision mesh antenna, a tension measurement instrument for pretension cable is
developed in this paper. The measurement equipment is developed by establishing the measure-
ment principle of the measurement equipment, and the test verification of the test equipment is
carried out. The following conclusions can be drawn:
1) In the process of tension measurement of pretension rope, the smaller the additional tension
introduced by the measurement system, the higher the accuracy of tension measurement value;
2) Under the framework of the existing measurement principle, the measurement accuracy can be
improved by increasing the spacing between the sub-measuring heads;
3) The construction of a contact measurement system is complex, which is unsuitable for many
rapid measurement conditions. It can be used as an inspection measurement link of high-
precision and convenient measurement equipment in engineering.
21

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Method Based on Non-contact Measurement. 2015, 23(12): 3987–3989.
22

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Author(s), ISBN: 978-1-032-36087-4
Practical application of radar wave testing technology in soil cavity
damage detection
Liyang Wan
∗
First Water Conservancy Engineering Bureau of Henan Province, Zhengzhou, Henan, China
ABSTRACT: The existing buildings will be affected by rainstorms, floods and other disasters
during use. A large amount of rainwater scouring leads to the change in the current situation of the
structural soil, which also leads to the change in the service load of the buildings and the overpres-
sure failure of the waterproof structural layer of the soil adjacent structural surface. It will bring
irreversible damage to the safety performance and service performance of buildings in use. After
the flood, it is of great significance to find out the void of the surrounding soil to restore the safety
performance and normal use function of the building. The conventional soil core drilling method
is not only time-consuming and laborious, but also needs huge economic support and can only
detect the damage to soil point by point. At this time, the advantages of radar wave non-destructive
testing technology, which is mostly used for the detection of tunnel lining, highway pavement,
water conservancy anti-seepage walls and other projects, are prominent, and it has become the
main technical means to detect the damage of soil mass of flood building structure. This paper
introduces the relevant principles and achievement analysis methods of radar detection in detail,
and introduces the radar detection technology into the field of industrial and civil buildings, which
has guiding significance for the post-disaster maintenance and reinforcement of similar projects.
1 INTRODUCTION
The torrential rain disaster in Zhengzhou on July 20 has affected tens of millions of people and
countless buildings and structures, which has significantly impacted people’s life safety, economic
and social development and national security. After the disaster, many buildings suffered struc-
tural damage, their reliability was seriously reduced, and some even lost their use function. The
foundation of roads, bridges, and industrial and civil buildings is largely damaged, and the soil is
washed and soaked, resulting in internal looseness, cavity, ground subsidence, house inclination
and other phenomena from time to time. In order to restore production and life as soon as possible,
the damaged buildings must quickly find out the damage to formulate the recovery and reinforce-
ment plan in time. The timeliness of traditional detection methods is difficult to ensure, and the
advantages of radar wave non-destructive detection technology are prominent. It plays a great role
in the detection of foundation damage and saves a lot of time and cost for society in the evaluation
of the safety and use of the function of building structures.
2 RADAR WAVE TEST TECHNOLOGY
The radar wave test is commonly referred to as ground-penetrating radar. Ground-penetrating radar
uses the reflection of pulsed electromagnetic waves of different frequencies to detect target objects
and various geological phenomena (Zeng 2005). It emits electromagnetic waves down from the
surface of target objects to achieve the purpose of detection, so it is also called geological radar.
The ground-penetrating radar uses the characteristics of different frequencies of high-frequency
∗
Corresponding Author: [email protected]
DOI 10.1201/9781003330172-5 23

electromagnetic waves with different penetration and resolution to send them underground in the
form of broadband short-pulses from the ground through the transmitting antenna T, return to the
ground after being reflected by the stratum medium or target object, and be received by the receiving
antenna R (as shown in Figure 1) and the pulse wave travel timet=
√
4z
2
+x
2
/ν. When the wave
velocityV in the underground medium is known, it can be calculated according to the measured time
t. The depth z of the reflector can be calculated from the above formula. In the formula, the value of
X is fixed in profile detection, and the value of velocityV can be measured directly by the wide angle
method. When the conductivity of the medium is very low, it can also be calculated according to the
ν≈c/
√
εapproximation, where c is the speed of light (c = 0.3m / ns), andεis the relative permittivity
of the electromagnetic wave propagation medium (Shen 2017). The latter can be obtained using
the empirical data of similar media or direct measurement. According to this principle, the position
and depth of the change of the object interface of the measured target can be detected.
Figure 1. Principle of reflection detection.
In the process of electromagnetic wave propagation in the medium, due to the dispersive and
uneven nature of the medium, the electromagnetic wave will be absorbed or attenuated to varying
degrees. So, when the pulse electromagnetic wave is received by the receiving antenna, the elec-
tromagnetic wave energy is reduced, the wave amplitude is reduced, and the waveform changes
greatly. In addition, the interference of various circuit pipelines or vibration at the detection site
will also be received by the receiving antenna, resulting in the distortion of the measured waveform.
Therefore, the received signal must be properly processed to improve data quality. Radar data is
usually recorded in the form of a waveform when a pulse reflected wave is received. Reflected
waves are represented by white, gray or gray scales, respectively. In this way, the in-phase axis or
equal gray and equal color lines can intuitively show the position characteristics of the measured
medium interface (Zhong et al. 2010), as shown in Figure 2.
Figure 2. Typical radar profile.
24

The pulse radar wave propagates in the measured medium. As long as there is an electrical differ-
ence in the measured medium, the radar reflected wave corresponding to the electrical difference
interface could be found in the radar image section accumulated by the reflected wave group. The
curve formed by connecting the same phase of adjacent reflected waves in the reflected wave group
is the in-phase axis of the radar profile. In the process of radar measurement, the point distance
used for data acquisition is very small. Under the condition of no sudden change in the measured
medium, the characteristics of the two adjacent reflected wave groups will remain unchanged, and
the reflected waveforms will be similar. Therefore, the waveform, amplitude, period and envelope
of the reflected wave from the dielectric layer with similar electrical characteristics will form certain
characteristics.
The data of radar wave detection results are mainly reflected in the form of radar profiles. The
time profile reflected by the radar profile is the main data for analyzing the change in the dielectric
layer. During the detection process, in case of breakage, crack development and large change in
water content, the electrical characteristics of the medium will change, which is manifested in the
obvious dislocation of the phase axis of the radar reflected wave on the time profile. The greater
the change in electrical characteristics, the more obvious the in-phase axis dislocation is (Wang
et al. 2017), as shown in Figure 3.
Figure 3. Typical radar profile of in-phase axis staggering.
The development of cracks and the change of electrical characteristics in the measured soil
medium are often unbalanced, so the degree of absorption and attenuation of radar waves and
reflected waves is also different. The local absence of an in-phase axis in the radar profile is often
caused by the inconsistent effect of the change of electrical characteristics in different parts on the
absorption and attenuation of radar reflected waves, as shown in Figure 4.
Figure 4. Typical radar profile with partial loss of in-phase axis.
25

In the process of soil detection, the development of underground cracks and fissures, the content
of soil composition and salinity will change the electrical characteristics of the soil. Due to its
relaxation effect, absorption and attenuation of electromagnetic waves, it will sometimes cause
waveform distortion or frequency reduction of radar reflected waves. At this time, it is necessary to
comprehensively evaluate the reasons for the change in soil electrical characteristics in combination
with soil drilling data.
3 EXAMPLES OF RADAR WAVE DETECTION
3.1Project overview
The project is an underground civil air defense basement on the second floor, with a floor height of
5m. The foundation form is an integral raft foundation, the main structure form is a frame structure,
and the soil covering thickness above the structural roof is 4m. It is an underground shopping mall
in peacetime and a wartime shelter for civil air defense. Under the influence of a rainstorm, a
large amount of soil sediment around the structure washes out. In order to detect the cavity of
underground soil in time, with the consent of the project construction party, it is decided to use a
radar wave detection method to detect the cavity of soil around the building.
3.2Detection equipment, detection technology and analysis of measured data
SIR-20 radar produced by the American laurel company is used for this detection. The center
frequency of the radar antenna is 400 MHz and 80 MHz. According to the propagation speed
of electromagnetic waves in different media, we set the dielectric constant and propagation speed
after calibrating the parameters on site. The 400MHz antenna is measured by manual dragging. The
scanning rate is 100 scans/m, the time window length is 50 ns, the gain points are 5, the sampling
points are 512, and the detection depth is 2.5m∼3m. The 80MHz antenna is measured by point
measurement. The distance between measuring points is 0.2m, the length of the time window is
250ns, the number of gain points is 5, the number of sampling points is 512, and the detection
depth is 11m∼12m.
GPR data processing is divided into pre-processing and processing analysis, such as marking
stake numbers and adding title and identification. Its purpose is to suppress rules and eliminate
random interference, display reflected waves on the GPR image section with as high resolution
as possible, and highlight useful abnormal reflected signals to help interpretation. The ground-
penetrating radar receives reflected waves from different underground electrical interfaces, and its
correct analysis depends on factors such as reasonable selection of detection parameters, proper
data processing, simulation experiment analogy and map reading experience (Ma et al. 2011).
Figure 5. Detection mode.
26

According to the opinions of the construction parties and the actual situation of the site, a 400
MHz high-frequency antenna is used to detect horizontally from the outer wall of the basement,
and the detection depth is 2.5m–3.0 m, as shown in Figures 5 to Figure 8. An 80 MHz low-
frequency antenna is used to detect vertically from the ground downward, and the detection depth
is 11.0m–12.0m, as shown in Figures 9 and 10:
Typical radar profile analysis in the detection result data: the detection position is 4-7/Dofthe
outer wall of zone B on the second floor, 1.5m away from the bottom plate. The radar profile is
shown in Figure 6.
Figure 6. Radar profile at the height of 1.5m from the bottom plate of the outer wall 4-7 / D of zone B on
the second basement.
According to the measured radar profile, the grayscale of the reflected wave within the range of
0mm–500mm is obvious, clear and stable, indicating that the medium has good continuity and basi-
cally no electrical change. The field data show the grayscale display of reflected waves is obvious
in the range of 50mm–100mm, and the dielectric electrical property in this area has changed. Com-
pared with the red area, the reflected wave grayscale is obvious in the depth of 100mm–140mm,
proving that a large medium change has occurred at this interface. After comprehensive study and
judgment, the red circled area in the figure is a non-dense and void reflected signal. The green circle
area in the figure is the loose and water-rich reflection signal. Therefore, the depth of non-dense
and void parts in this area is 1.0m–1.3m. The depth of loose and water-rich parts is 0.5m-1.0m,
and the depth is 1.3m–2.5m. There are local loose and water-rich phenomena.
Figure 7. Exterior wall 33–36/Dofzone B on the second basement, 1.5m from the bottom plate.
27

Figure 8. Exterior wall 10-12 / A of zone B on the second basement, 1.5m from the bottom plate.
Based on this principle, the data analysis results in Figure 7 are as follows: the yellow triangle
area is a 500-mm reinforced concrete outer wall. The red circled area is the non-dense and void
reflection signal. The green circle area is a loose and water-rich reflection signal. The depth of
non-dense and vacant parts is 0.5m–0.8m. The depth of locally loose and water-rich parts is 0.8m–
2.5m. The data analysis results in Figure 8 are as follows: the yellow triangle area is a 500-mm
reinforced concrete outer wall. The red circled area is the non-dense and void reflection signal. The
green circle area is a loose and non-dense reflected signal. The position depth of non-dense and
void parts is 0.5m–1.2m. The depth of partially loose and non-dense parts is 1.2m–2.5m.
The typical profile of radar detection from the surface down is:
Figure 9. 13 / A-35 / A external soil mass of the exterior wall.
Figure 10. 38 / A-43 / A external soil mass of the exterior wall.
28

Comprehensive analysis and judgment on Figures 9 and 10: the red area 13 / A + 29560 on the
left side of Figure 9 is 4.0 m-11.5 m deep, hollow and not dense. Figure 10 red area 43 / A-9750
on the left, with a depth of 2.5 m-11.0 m, empty and not dense. The middle red area 41 / A-975-41
/ A-5850, with a depth of 2.5 m–5.5 m, is empty and not dense.
Through the comprehensive analysis of indoor detection data, the soil cavity results outside the
exterior wall of the basement are analyzed and judged. The soil within the range of 0.5m–1.5m
outside the exterior wall is loose and rich in water, and there are hollow and non-dense parts within
the range of 1.5 m–2.5 m outside the exterior wall. The water-rich part will form too high water
pressure on the outer wall of the basement, resulting in structural water leakage. During the field
investigation, it has been confirmed that there is a large amount of water leakage and local water
gushing at the construction joints of the outer wall. Through the analysis of the ground detection
results, there is water-rich, void and non-dense soil in the range of 3.0 m–12.0 m below the ground
outside the eastern exterior wall of the basement. Combined with the indoor detection results, it can
be determined that the range of 0.5 m–1.5 m outside the outer wall of the basement and the range
of 3.0 m–12.0 m below the surface are greatly affected by rainstorm scouring and there is soil loss.
Its development is very easy to cause pavement collapse and affect people’s life safety and social
and economic development. Special reinforcement measures should be taken for the soil within
this range to restore the prosperity and development of nearby businesses as soon as possible.
4 CONCLUSION
In recent years, the frequent occurrence of natural disasters has had a great adverse impact on
people’s production and life, and the building structure is also deeply affected. The rapid recovery
of the safety and use function of buildings after disasters has become the top priority of disaster
reduction. Compared with the traditional drilling technology, it will become the backbone of the
advanced, convenient and non-destructive detection technology.
REFERENCES
Ma Yan, Yang Yongguo, Wang Hu, et al. Application of geological radar in the detection of the cut-off wall [J]
Urban Survey, 2011 (3): 3
Shen Yaowei. Application of geological radar combined with seismic imaging in railway concealed karst
exploration [J]Chinese Sci-tech Journal Database (Abstract Edition) Engineering Technology: 00298–
00298, 2017
Wang Jiahui, Zhou Jianchun, XiongXuexiang. Application of comprehensive geophysical method in tunnel
geological prediction [J]Low-temperature Building Technology, 2017, 39 (2): 4
Zeng Yuzhen. Progress of FHWA GPR bridge deck non-destructive evaluation technology [J]Sino Foreign
Highway, 2005
Zhong Jinning, Hua Anzhong, Yang Yali, et al. Research on the application of geological radar to detect
underground cavities [C]Member Congress of Underground Pipeline of Professional Committee of China
Urban Planning Association, 2010
29

Advances in Measurement Technology, Disaster Prevention and
Mitigation – Li & Mohd Yusof (Eds)
© 2023 The Author(s), ISBN: 978-1-032-36087-4
Analysis of passive flood inundation and assessment of ecosystem
service value loss in Chittagong
Panpan Zhang
National Ocean Technology Center, Tianjin, China
Zhikun Zhang
∗
School of Civil and Architectural Engineering, Shandong University of Technology, Shandong, China
Xin Teng
National Ocean Technology Center, Tianjin, China
Mohammad Saydul Islam Sarkar
Department of Oceanography, University of Chittagong, Bangladesh
ABSTRACT: Chittagong city of Bangladesh has been seriously eroded by the flood disaster. The
evaluation of flood loss can provide a reference for Chittagong to guide life and production and
carry out post-disaster assessments. Taking Chittagong city as the research object, this paper, based
on DEM data and land-use dataset, extracts the scope of flood inundation by the passive inundation
analysis method and assesses the losses caused by floods to the city’s ecological environment. The
results show that: (1) The lands in Chittagong city were mainly used as farmlands and woodlands
with a quite high land use degree; (2) there existed a quadratic polynomial growth relationship
between the inundation area and the height of water level, and when the water level rose to 4m,
farmlands became the main land use type in each inundated area; (3) from the perspective of
ecological environment, the flood caused the greatest loss to wetlands. The relevant research results
can provide effective assistance for government departments in disaster prevention.
1 INTRODUCTION
With the rapid development of society and economy and the constant increase of population,
climate change has intensified the occurrence of natural disasters and brought great challenges
to the national economic development, so the rapid and accurate simulation and prediction of
disasters have become urgent demands for the current social development. Particularly, flood
inundation analysis and prediction have been emphasized by many scholars and have become
important research topics (Ansori et al. 2021; Azizian & Brocca 2020; Balogun et al. 2020).
Many scholars combine GIS (Geographic Information Science) spatial analysis technology with
hydrological analysis model to achieve rapid, accurate and scientific simulation and prediction of
flood inundation scope (Ding et al. 2013, 2004; Karamouz & Mahani 2021; Try et al. 2020). Liu et
al. (2015) classified flood inundation into “active inundation” and “passive inundation” according
to the causes, which has been widely used in flood analysis since then. On this basis, Cheng (2015),
in view of such defects as inefficiency and instability of active flood calculation, proposed a seed
spread algorithm for active flood inundation analysis based on the buffer stack in the inundated
area and then conducted relevant practice and verification. With the increasing maturity of GIS
technology, some scholars have designed a more comprehensive flood inundation model system for
comprehensive simulation and analysis of the whole inundated area. Luo et al. (2018) proposed a
∗
Corresponding Author: [email protected]
30 DOI 10.1201/9781003330172-6

calibrated flood inundation model to evaluate the impact of extreme rainfall events on the inundation
area in the center of Central Hanoi. Ao et al. (2018) achieved the macro dynamic monitoring of
inundation scope and depth in river basins without referential data by virtue of multi-source remote
sensing data. Sophal et al. (Try et al. 2018) proposed the rainfall-run-off inundation (RRI) model,
which can simultaneously simulate rainfall, runoff and flood inundation in the Mekong River Basin.
However, in reality, due to the influence of such factors as complex river geometry, large scale of
river basins and coarse resolution of topographic data, the flood inundation model may produce
various errors in the simulation of flood inundation scope. Borah et al. (2018), by synthetic aperture
radar (SAR) data, conducted flood monitoring in Kaziranga National Park during the monsoon
season in 2017, proving that the accuracy of the model adopted is improved through such data. The
studies above show that in flood prevention and control, GIS technology can simulate and predict
flood inundation and conduct loss assessments rapidly, accurately and scientifically.
According to the Global Risks Report 2015, Bangladesh has been identified as the sixth most
disaster-prone country in the world, with the number of losses caused by floods accounting for
23.23% of the total amount of disaster losses in the country (Bangladesh Bureau of Statistics.
Bangladesh Disaster-related Statistics 2015). Flood has become the most frequent and most serious
natural disaster in Bangladesh.
In view of the phenomenon above, this paper, taking Chittagong city as the research object,
adopts the passive inundation analysis method to rapidly and accurately analyze and predict the
scope of flood inundation in Chittagong City and, in combination with relevant land use data,
assesses the loss caused by flood to the ecological environment in the inundated area. This research
aims to provide data support for disaster loss reduction and assessment as well as production and
life guidance in Chittagong City by applying GIS-related technologies and models and providing
data guarantee for promoting regional economic development under such strategic opportunities
as the “Belt & Road Initiative,” “Maritime Silk Road,” and “Bangladesh-China-India-Myanmar
Economic Corridor.”
2 OVERVIEW OF THE RESEARCH OBJECT
Chittagong City is located in the hilly region of Southeastern Bangladesh, adjacent to the Bay of
Bengal, with latitude and longitude of 22
◦
18
ρ
N and 91
◦
48
ρ
E. The city is an important junction of the
“Silk Road Economic Belt” and the “21st Century Maritime Silk Road” that has the geographical
advantages of connecting the east and west, linking the south and north, and bridging the land and
sea. Chittagong city has a developed water system and a dense river network, with the Karnaphuli
River flowing from north to south into the Bay of Bengal from the east side of the city. As to climate,
Chittagong City is featured by warm and humid tropical monsoon climate with an average annual
temperature of roughly 25.9
◦
C. As to industrial distribution, the city’s commercial and port areas
are distributed in the southern and western parts, industrial areas in the southeastern, northeastern
and northwestern parts, and residential areas in the northern part. Chittagong City contributes 80%
of the volume of Bangladesh’s international trade and 40% of the country’s industrial output.
3 DATA SOURCES AND RESEARCH METHODS
3.1Data sources and processing
In this research, Landsat 5 TM images of Chittagong city in 2019 were selected as the data source,
and the data came from THE United States Geological Survey (http://glovis.usgs.gov/), with a
spatial resolution of 30m. On this basis, the method of artificial visual interpretation was adopted
to classify the land use types within the researched area into grassland, farmland, construction land,
woodland, unused land, wetland and waters in combination with the classification standards for
remote sensing interpretation and the land use characteristics of Chittagong City, and its overall
31

classification accuracy was verified to be above 90%, which can meet the study requirements (Liu
et al. 2014). The DEM data used in this research were obtained from the NASA Data Center with
a resolution of 10m.
3.2Land use degree analysis
The index of land use degree can quantitatively reveal the comprehensive level and changing trend
of land use in the researched area, reflecting not only the breadth and depth of land use but also the
comprehensive effects of human factors and the natural environment. Liu et al. (1992) classified
land use degree into four grades according to the natural balance state of the land natural complex
under the influence of social factors and assigned indices for different levels, respectively, as
shown in Table 1, thus providing the quantitative expression of land use degree. The formula for
the comprehensive index of land use degree is as follows:
L
a=100×
n

i=1
Bi×Ci (1)
wherein:L
aindicates the comprehensive index of land use degree;B iindicates the grading index
of gradiland use degree;C
iindicates the percentage of the grading area of gradiland use degree.
Table 1. Value assignment table for land use degree.
Grade 1 Grade 2 Grade 3 Grade 4
Land-use type Unused land Woodland, grassland and wetland Farmland Construction land
Graded index 1 2 3 4
3.3Flood inundation analysis
According to the causes of flood inundation, flood inundation can be divided into two categories:
passive inundation and active inundation (Guo & Long 2002). Passive inundation means that only
water level rise caused by precipitation is considered, that is, ensuring uniform precipitation within
the researched area without considering the inflow of surface runoff water. Active inundation
refers to flood inundation caused by river flow or reservoir burst. In the case of active inundation,
such complex problems as regional connectivity, depression merging and surface runoff should
be considered based on passive inundation. The two kinds of inundation analyses are both of
great significance in reality. Passive inundation is mostly applicable to areas where the terrain is
relatively flat, and the flood source is difficult to determine, while active inundation is mostly appli-
cable to mountainous and hilly areas (Jin & Xiao 2014). The complexity of the active inundation
model entails a relatively long calculation time, which is not conducive to rapid flood simulation.
Therefore, only passive inundation is selected for analysis in this paper.
When widespread precipitation occurs in the researched area, and the distribution of precipita-
tion amount is relatively uniform, it can be deemed that the researched area experiences passive
inundation. At this time, water logging disasters will occur in areas with low elevation points within
the researched area. Based on the DEM data and through the spatial analysis function of ArcGIS
software, this paper extracts inundated areas with elevation points lower than water level and, after
a series of processing, conducts overlay analysis in combination with the land-use dataset, finally
obtaining the information about various land-use types in each inundated area.
3.4Ecosystem service value assessment
Based on the table of ecological service equivalent per unit area improved by Xie (Xie et al.
2008), this paper draws on his research results—the economic value of each ecological service
32

value equivalent factor is equal to 1/7 of the economic value of food production service function
provided by farmland per unit area. According to the statistics released by the Bangladesh Bureau
of Statistics, the average grain yield in Bangladesh in 2018–2019 was 2,571 kg/ha, and the average
comprehensive grain price was $0.24 /kg. Therefore, it can be concluded that the economic value
of each ecosystem service value equivalent factor in Chittagong City was $88.15 /ha/yr. After
substituting this data into the improved table of ecological service equivalent per unit area, we
finally obtained the table of ecosystem service value coefficients for Chittagong City, as is shown
in Table 2.
Table 2. Table of ecosystem service value coefficients per unit area for each land use types in Chittagong.
City
Unit value ($/ha/yr)
Primary
classification
Secondary
classification Grassland Farmland
Construction
land Woodland
Unused
land Wetland
Supply
service
Food production 37.90 88.15 0 .00 29 .09 1 .76 31.73
Raw material
production 31 .73 34.38 0 .00 262 .69 3 .53 21.16
Regulation
service
Gas regulation 132.23 63.47 5 .29 380 .81 5 .29 212.44
Climate
regulation 137 .51 85.51 11 .46 358 .77 11.46 1194.43
Water
regulation 133 .99 67.88 0 .00 360 .53 6 .17 1184.74
Waste
treatment 116 .36 122.53 0 .00 151 .62 22.92 1269.36
Support
services
Soil
conservation
197.46 129.58 0 .00 354 .36 14.99 175.42
Biological
diversity
164.84 89.91 0 .00 397 .56 35.26 325.27
Cultural
services
Recreation 76 .69 14.99 183.35 183 .35 21.16 413.42
Total 1028.71 696 .39 200.10 2478.78 122 .53 4827.98
The total ecosystem service value can be calculated in combination with the table of ecosystem
service value coefficients and the area of each land-use type, and the calculation formula is as
follows:
ESV=
ηρ
A
p×Vc
≤
(2)
wherein:ESVindicates the total ecosystem service value;A
pindicates the area of land use type
p;V
cindicates the coefficient of ecosystem service value.
4 RESULTS AND ANALYSIS
4.1Analysis of land use distribution characteristics and land use degree in Chittagong city
This paper conducted statistical analysis on the land use dataset of Chittagong City, and finally
obtained the area and proportion of each land-use type in the research area, as shown in Table
3 and Figure 1. The chart shows that farmland was the largest land-use type in Chittagong City,
accounting for 39.30%, followed by woodland and construction land, accounting for 36.20% and
16.14%, respectively. In addition, based on the area statistics, the comprehensive land use index
of Chittagong City was calculated in combination with Formula (1), which was 271.43, indicating
that Chittagong City was highly developed and utilized by human beings.
33

Figure 1. Proportions of areas of various land-use types in Chittagong city.
To visualize the spatial distribution of various land-use types in Chittagong City, this paper
formulated the land use distribution map (Figure 2(a)) of Chittagong City. As shown in Figure 2, land
use types in Chittagong City are mainly farmland and woodland. Farmlands are mainly distributed
in low-altitude plain and hilly areas in an extensive way, making the land use index of farmland the
highest among all land use types in the city. The distribution of woodlands is relatively concentrated,
mainly in high-altitude mountainous areas in the eastern, northern and southern parts of the city.
The land use index of woodland is 72.44. Construction land is mainly concentrated in the estuary of
Karnaphuli River, where human activities are the most frequent and land use degree is the highest.
Wetlands are distributed in coastal areas in the form of marsh, and waters are dominated by the
Karnaphuli River and its tributaries. Grasslands and unused lands are relatively small in areas
without obvious distribution laws.
Table 3. Statistics of land use areas and the comprehensive index of land use degree in Chittagong city.
Grassland Farmland
Construction
land Woodland
Unused
land Wetland Waters Total
Area (km
2
)29 .79 1731 .02 710.99 1595 .38 7.65 165 .15 165.12 4405.09
Proportion (%) 0.68 39 .30 16.14 36 .22 0.17 3 .75 3.75 100.00
Land use index 1.36 117 .90 64.56 72 .44 0.17 7 .50 7.50 271.43
4.2Analysis of flood inundation in Chittagong city
According to the application scope of inundation analysis methods and the characteristics of the
research object, the passive inundation analysis method based on the water level was adopted to
analyze the flood inundation in Chittagong City in combination with the DEM data. Based on
the analysis of contour lines extracted from the DEM data and other relevant materials, it was
concluded that the water level in Chittagong City was roughly 0.5m at low tide and 4m at high tide.
Therefore, in this paper, the water level was set as 3m, 3.5m, 4m, 4.5m, 5m and 5.5m, respectively.
When the water level reaches the set value, all the pixels with elevation points below the water
level in the DEM grid will be extracted. In Figure 2, (a)–(f) respectively show the scope of flood
inundation when the water level rises from low to high.
By virtue of software tools, this paper had the inundation scope extracted and transformed into
vector data for overlay analysis in combination with the land-use dataset, based on which obtained
the relationship between the area of each land use type (excluding waters) in an inundated area and
the height of water level, as shown in Table 4. As can be seen from the table, when the water level is
lower than 4m, the wetland is the largest land-use type in each inundated area, while when the water
level exceeds 4m, farmland becomes the largest land-use type. Therefore, it can be concluded that
when the water level exceeds 4m, the continuous rise in flood level will cause greater damage to
the social economy. Figure 3 more intuitively shows the changing trend of the land-use area in each
inundated area with the height of the water level. It can be seen from the figure that the wetland area
34

shows slow linear growth with the rise of water level, and the proportion thereof keeps decreasing.
With the rise of water level, farmland area and its proportion both show increasingly high growth,
similar to construction land. The inundation area of woodland is not large because of the high-
altitude terrain. Grassland and unused land are less inundated because of small areas. Overall, the
growth trend of the total inundation area is similar to that of farmland. It can be seen from the
fitting function obtained through software calculation of the original data that the inundation area
and the height of the water level show a quadratic polynomial growth relationship. Using the fitting
function as a prediction function, the inundation area was calculated to be 869.05 km
2
when the
water level reached 6m, with an error of 5.43% compared with the true value. Therefore, it can be
concluded that this fitting function can well predict the changing trend of inundation areas with
the height of the water level.
Table 4. Statistics of land use area in each inundated area.
Water
level (m) Grassland Farmland
Construction
land Woodland
Unused
land Wetland Total
3
Area (km
2
) 0.38 22 .53 4 .57 0 .67 0.91 87 .18 58.13
Proportion (%) 0.44 25 .84 5 .24 0 .77 1.04 100 66 .68
3.5
Area (km
2
) 0.87 50 .42 9 .49 1 .72 1.08 134 .72 71.14
Proportion (%) 0.65 37 .42 7 .04 1 .28 0.80 100 52 .81
4
Area (km
2
) 1.67 104 .46 18 .89 4 .12 1.32 217 .03 86.56
Proportion (%) 0.77 48 .13 8 .70 1 .90 0.61 100 39 .89
4.5
Area (km
2
) 2.62 185 .71 34 .67 7 .75 1.71 332 .99 100.53
Proportion (%) 0.79 55 .77 10 .41 2 .33 0.51 100 30 .19
5
Area (km
2
) 3.58 293 .94 58 .42 13 .93 2.19 485 .70 113.64
Proportion (%) 0.74 60 .52 12 .03 2 .87 0.45 100 23 .40
5.5
Area (km
2
) 5.03 413 .74 88 .69 23 .60 2.68 655 .72 121.98
Proportion (%) 0.77 63 .10 13 .53 3 .60 0.41 100 18 .60
Figure 2. Inundation scope under different water levels.
35

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Too much, however, has been made of this question both in
ancient and modern times. There is a stage of criticism in which all
works, whether of nature or of art, are referred to design. Now in
ancient writings, and indeed in literature generally, there remains
often a large element which was not comprehended in the original
design. For the plan grows under the author’s hand; new thoughts
occur to him in the act of writing; he has not worked out the
argument to the end before he begins. The reader who seeks to find
some one idea under which the whole may be conceived, must
necessarily seize on the vaguest and most general. Thus Stallbaum,
who is dissatisfied with the ordinary explanations of the argument of
the Republic, imagines himself to have found the true argument ‘in
the representation of human life in a State perfected by justice, and
governed according to the idea of good.’ There may be some use in
such general descriptions, but they can hardly be said to express the
design of the writer. The truth is, that we may as well speak of many
designs as of one; nor need anything be excluded from the plan of a
great work to which the mind is naturally led by the association of
ideas, and which does not interfere with the general purpose. What
kind or degree of viii unity is to be sought after in a building, in the
plastic arts, in poetry, in prose, is a problem which has to be
determined relatively to the subject-matter. To Plato himself, the
enquiry ‘what was the intention of the writer,’ or ‘what was the
principal argument of the Republic’ would have been hardly
intelligible, and therefore had better be at once dismissed (cp. the
Introduction to the Phaedrus, vol. i.).
Is not the Republic the vehicle of three or four great truths which,
to Plato’s own mind, are most naturally represented in the form of
the State? Just as in the Jewish prophets the reign of Messiah, or
‘the day of the Lord,’ or the suffering Servant or people of God, or
the ‘Sun of righteousness with healing in his wings’ only convey, to
us at least, their great spiritual ideals, so through the Greek State
Plato reveals to us his own thoughts about divine perfection, which
is the idea of good—like the sun in the visible world;—about human
perfection, which is justice—about education beginning in youth and
continuing in later years—about poets and sophists and tyrants who

are the false teachers and evil rulers of mankind—about ‘the world’
which is the embodiment of them—about a kingdom which exists
nowhere upon earth but is laid up in heaven to be the pattern and
rule of human life. No such inspired creation is at unity with itself,
any more than the clouds of heaven when the sun pierces through
them. Every shade of light and dark, of truth, and of fiction which is
the veil of truth, is allowable in a work of philosophical imagination.
It is not all on the same plane; it easily passes from ideas to myths
and fancies, from facts to figures of speech. It is not prose but
poetry, at least a great part of it, and ought not to be judged by the
rules of logic or the probabilities of history. The writer is not
fashioning his ideas into an artistic whole; they take possession of
him and are too much for him. We have no need therefore to discuss
whether a State such as Plato has conceived is practicable or not, or
whether the outward form or the inward life came first into the mind
of the writer. For the practicability of his ideas has nothing to do with
their truth (v. 472 D); and the highest thoughts to which he attains
may be truly said to bear the greatest ‘marks of design’—justice
more than the external frame-work of the State, the idea of good
more than justice. The great science of dialectic or the organisation
of ideas has no real content; but is only a type of the method or ix
spirit in which the higher knowledge is to be pursued by the
spectator of all time and all existence. It is in the fifth, sixth, and
seventh books that Plato reaches the ‘summit of speculation,’ and
these, although they fail to satisfy the requirements of a modern
thinker, may therefore be regarded as the most important, as they
are also the most original, portions of the work.
It is not necessary to discuss at length a minor question which has
been raised by Boeckh, respecting the imaginary date at which the
conversation was held (the year 411 B.C. which is proposed by him
will do as well as any other); for a writer of fiction, and especially a
writer who, like Plato, is notoriously careless of chronology (cp. Rep.
i. 336, Symp. 193 A, etc.), only aims at general probability. Whether
all the persons mentioned in the Republic could ever have met at
any one time is not a difficulty which would have occurred to an
Athenian reading the work forty years later, or to Plato himself at the

time of writing (any more than to Shakespeare respecting one of his
own dramas); and need not greatly trouble us now. Yet this may be
a question having no answer ‘which is still worth asking,’ because
the investigation shows that we cannot argue historically from the
dates in Plato; it would be useless therefore to waste time in
inventing far-fetched reconcilements of them in order to avoid
chronological difficulties, such, for example, as the conjecture of C.
F. Hermann, that Glaucon and Adeimantus are not the brothers but
the uncles of Plato (cp. Apol. 34 A), or the fancy of Stallbaum that
Plato intentionally left anachronisms indicating the dates at which
some of his Dialogues were written.

The principal characters in the Republic are Cephalus,
Polemarchus, Thrasymachus, Socrates, Glaucon, and Adeimantus.
Cephalus appears in the introduction only, Polemarchus drops at the
end of the first argument, and Thrasymachus is reduced to silence at
the close of the first book. The main discussion is carried on by
Socrates, Glaucon, and Adeimantus. Among the company are Lysias
(the orator) and Euthydemus, the sons of Cephalus and brothers of
Polemarchus, an unknown Charmantides—these are mute auditors;
also there is Cleitophon, who once interrupts (340 A), where, as in
the Dialogue which bears his name, he appears as the friend and
ally of Thrasymachus.
x Cephalus, the patriarch of the house, has been appropriately
engaged in offering a sacrifice. He is the pattern of an old man who
has almost done with life, and is at peace with himself and with all
mankind. He feels that he is drawing nearer to the world below, and
seems to linger around the memory of the past. He is eager that
Socrates should come to visit him, fond of the poetry of the last
generation, happy in the consciousness of a well-spent life, glad at
having escaped from the tyranny of youthful lusts. His love of
conversation, his affection, his indifference to riches, even his
garrulity, are interesting traits of character. He is not one of those
who have nothing to say, because their whole mind has been
absorbed in making money. Yet he acknowledges that riches have

the advantage of placing men above the temptation to dishonesty or
falsehood. The respectful attention shown to him by Socrates, whose
love of conversation, no less than the mission imposed upon him by
the Oracle, leads him to ask questions of all men, young and old
alike (cp. i. 328 A), should also be noted. Who better suited to raise
the question of justice than Cephalus, whose life might seem to be
the expression of it? The moderation with which old age is pictured
by Cephalus as a very tolerable portion of existence is characteristic,
not only of him, but of Greek feeling generally, and contrasts with
the exaggeration of Cicero in the De Senectute. The evening of life is
described by Plato in the most expressive manner, yet with the
fewest possible touches. As Cicero remarks (Ep. ad Attic. iv. 16), the
aged Cephalus would have been out of place in the discussion which
follows, and which he could neither have understood nor taken part
in without a violation of dramatic propriety (cp. Lysimachus in the
Laches, 89).
His ‘son and heir’ Polemarchus has the frankness and
impetuousness of youth; he is for detaining Socrates by force in the
opening scene, and will not ‘let him off’ (v. 449 B) on the subject of
women and children. Like Cephalus, he is limited in his point of view,
and represents the proverbial stage of morality which has rules of
life rather than principles; and he quotes Simonides (cp. Aristoph.
Clouds, 1355 ff.) as his father had quoted Pindar. But after this he
has no more to say; the answers which he makes are only elicited
from him by the dialectic of Socrates. He has not yet experienced
the influence of the Sophists like Glaucon and xi Adeimantus, nor is
he sensible of the necessity of refuting them; he belongs to the pre-
Socratic or pre-dialectical age. He is incapable of arguing, and is
bewildered by Socrates to such a degree that he does not know
what he is saying. He is made to admit that justice is a thief, and
that the virtues follow the analogy of the arts (i. 333 E). From his
brother Lysias (contra Eratosth. p. 121) we learn that he fell a victim
to the Thirty Tyrants, but no allusion is here made to his fate, nor to
the circumstance that Cephalus and his family were of Syracusan
origin, and had migrated from Thurii to Athens.

The ‘Chalcedonian giant,’ Thrasymachus, of whom we have
already heard in the Phaedrus (267 D), is the personification of the
Sophists, according to Plato’s conception of them, in some of their
worst characteristics. He is vain and blustering, refusing to discourse
unless he is paid, fond of making an oration, and hoping thereby to
escape the inevitable Socrates; but a mere child in argument, and
unable to foresee that the next ‘move’ (to use a Platonic expression)
will ‘shut him up’ (vi. 487 B). He has reached the stage of framing
general notions, and in this respect is in advance of Cephalus and
Polemarchus. But he is incapable of defending them in a discussion,
and vainly tries to cover his confusion with banter and insolence.
Whether such doctrines as are attributed to him by Plato were really
held either by him or by any other Sophist is uncertain; in the
infancy of philosophy serious errors about morality might easily grow
up—they are certainly put into the mouths of speakers in
Thucydides; but we are concerned at present with Plato’s description
of him, and not with the historical reality. The inequality of the
contest adds greatly to the humour of the scene. The pompous and
empty Sophist is utterly helpless in the hands of the great master of
dialectic, who knows how to touch all the springs of vanity and
weakness in him. He is greatly irritated by the irony of Socrates, but
his noisy and imbecile rage only lays him more and more open to the
thrusts of his assailant. His determination to cram down their
throats, or put ‘bodily into their souls’ his own words, elicits a cry of
horror from Socrates. The state of his temper is quite as worthy of
remark as the process of the argument. Nothing is more amusing
than his complete submission when he has been once thoroughly
beaten. At first he seems to continue xii the discussion with
reluctance, but soon with apparent good-will, and he even testifies
his interest at a later stage by one or two occasional remarks (v. 450
A, B). When attacked by Glaucon (vi. 489 C, D) he is humorously
protected by Socrates ‘as one who has never been his enemy and is
now his friend.’ From Cicero and Quintilian and from Aristotle’s
Rhetoric (iii. i. 7; ii. 23, 29) we learn that the Sophist whom Plato
has made so ridiculous was a man of note whose writings were
preserved in later ages. The play on his name which was made by

his contemporary Herodicus (Aris. Rhet. ii. 23, 29), ‘thou wast ever
bold in battle,’ seems to show that the description of him is not
devoid of verisimilitude.
When Thrasymachus has been silenced, the two principal
respondents, Glaucon and Adeimantus, appear on the scene: here,
as in Greek tragedy (cp. Introd. to Phaedo), three actors are
introduced. At first sight the two sons of Ariston may seem to wear a
family likeness, like the two friends Simmias and Cebes in the
Phaedo. But on a nearer examination of them the similarity vanishes,
and they are seen to be distinct characters. Glaucon is the
impetuous youth who can ‘just never have enough of fetching’ (cp.
the character of him in Xen. Mem. iii. 6); the man of pleasure who is
acquainted with the mysteries of love (v. 474 D); the ‘juvenis qui
gaudet canibus,’ and who improves the breed of animals (v. 459 A);
the lover of art and music (iii. 398 D, E) who has all the experiences
of youthful life. He is full of quickness and penetration, piercing
easily below the clumsy platitudes of Thrasymachus to the real
difficulty; he turns out to the light the seamy side of human life, and
yet does not lose faith in the just and true. It is Glaucon who seizes
what may be termed the ludicrous relation of the philosopher to the
world, to whom a state of simplicity is ‘a city of pigs,’ who is always
prepared with a jest (iii. 398 C, 407 A; v. 450, 451, 468 C; vi. 509 C;
ix. 586) when the argument offers him an opportunity, and who is
ever ready to second the humour of Socrates and to appreciate the
ridiculous, whether in the connoisseurs of music (vii. 531 A), or in
the lovers of theatricals (v. 475 D), or in the fantastic behaviour of
the citizens of democracy (viii. 557 foll.). His weaknesses are several
times alluded to by Socrates (iii. 402 E; v. 474 D, 475 E), who,
however, will not allow him to be attacked by his brother Adeimantus
(viii. 548 D, E). He is a soldier, and, like Adeimantus, has been xiii
distinguished at the battle of Megara (368 A, anno 456?)… The
character of Adeimantus is deeper and graver, and the profounder
objections are commonly put into his mouth. Glaucon is more
demonstrative, and generally opens the game. Adeimantus pursues
the argument further. Glaucon has more of the liveliness and quick

sympathy of youth; Adeimantus has the maturer judgment of a
grown-up man of the world. In the second book, when Glaucon
insists that justice and injustice shall be considered without regard to
their consequences, Adeimantus remarks that they are regarded by
mankind in general only for the sake of their consequences; and in a
similar vein of reflection he urges at the beginning of the fourth book
that Socrates fails in making his citizens happy, and is answered that
happiness is not the first but the second thing, not the direct aim but
the indirect consequence of the good government of a State. In the
discussion about religion and mythology, Adeimantus is the
respondent (iii. 376-398), but Glaucon breaks in with a slight jest,
and carries on the conversation in a lighter tone about music and
gymnastic to the end of the book. It is Adeimantus again who
volunteers the criticism of common sense on the Socratic method of
argument (vi. 487 B), and who refuses to let Socrates pass lightly
over the question of women and children (v. 449). It is Adeimantus
who is the respondent in the more argumentative, as Glaucon in the
lighter and more imaginative portions of the Dialogue. For example,
throughout the greater part of the sixth book, the causes of the
corruption of philosophy and the conception of the idea of good are
discussed with Adeimantus. At p. 506 C, Glaucon resumes his place
of principal respondent; but he has a difficulty in apprehending the
higher education of Socrates, and makes some false hits in the
course of the discussion (526 D, 527 D). Once more Adeimantus
returns (viii. 548) with the allusion to his brother Glaucon whom he
compares to the contentious State; in the next book (ix. 576) he is
again superseded, and Glaucon continues to the end (x. 621 B).
Thus in a succession of characters Plato represents the successive
stages of morality, beginning with the Athenian gentleman of the
olden time, who is followed by the practical man of that day
regulating his life by proverbs and saws; to him succeeds the wild
generalization of the Sophists, and lastly come the young disciples of
the great teacher, who know the sophistical arguments xiv but will
not be convinced by them, and desire to go deeper into the nature
of things. These too, like Cephalus, Polemarchus, Thrasymachus, are

clearly distinguished from one another. Neither in the Republic, nor
in any other Dialogue of Plato, is a single character repeated.
The delineation of Socrates in the Republic is not wholly
consistent. In the first book we have more of the real Socrates, such
as he is depicted in the Memorabilia of Xenophon, in the earliest
Dialogues of Plato, and in the Apology. He is ironical, provoking,
questioning, the old enemy of the Sophists, ready to put on the
mask of Silenus as well as to argue seriously. But in the sixth book
his enmity towards the Sophists abates; he acknowledges that they
are the representatives rather than the corrupters of the world (vi.
492 A). He also becomes more dogmatic and constructive, passing
beyond the range either of the political or the speculative ideas of
the real Socrates. In one passage (vi. 506 C) Plato himself seems to
intimate that the time had now come for Socrates, who had passed
his whole life in philosophy, to give his own opinion and not to be
always repeating the notions of other men. There is no evidence that
either the idea of good or the conception of a perfect state were
comprehended in the Socratic teaching, though he certainly dwelt on
the nature of the universal and of final causes (cp. Xen. Mem. i. 4;
Phaedo 97); and a deep thinker like him, in his thirty or forty years
of public teaching, could hardly have failed to touch on the nature of
family relations, for which there is also some positive evidence in the
Memorabilia (Mem. i. 2, 51 foll.). The Socratic method is nominally
retained; and every inference is either put into the mouth of the
respondent or represented as the common discovery of him and
Socrates. But any one can see that this is a mere form, of which the
affectation grows wearisome as the work advances. The method of
enquiry has passed into a method of teaching in which by the help
of interlocutors the same thesis is looked at from various points of
view. The nature of the process is truly characterized by Glaucon,
when he describes himself as a companion who is not good for much
in an investigation, but can see what he is shown (iv. 432 C), and
may, perhaps, give the answer to a question more fluently than
another (v. 474 A; cp. 389 A).

Neither can we be absolutely certain that Socrates himself xv
taught the immortality of the soul, which is unknown to his disciple
Glaucon in the Republic (x. 608 D; cp. vi. 498 D, E; Apol. 40, 41);
nor is there any reason to suppose that he used myths or revelations
of another world as a vehicle of instruction, or that he would have
banished poetry or have denounced the Greek mythology. His
favourite oath is retained, and a slight mention is made of the
daemonium, or internal sign, which is alluded to by Socrates as a
phenomenon peculiar to himself (vi. 496 C). A real element of
Socratic teaching, which is more prominent in the Republic than in
any of the other Dialogues of Plato, is the use of example and
illustration (τὰ φορτικὰ αὐτῷ προσφέροντες, iv. 442 E): ‘Let us apply
the test of common instances.’ ‘You,’ says Adeimantus, ironically, in
the sixth book, ‘are so unaccustomed to speak in images.’ And this
use of examples or images, though truly Socratic in origin, is
enlarged by the genius of Plato into the form of an allegory or
parable, which embodies in the concrete what has been already
described, or is about to be described, in the abstract. Thus the
figure of the cave in Book VII is a recapitulation of the divisions of
knowledge in Book VI. The composite animal in Book IX is an
allegory of the parts of the soul. The noble captain and the ship and
the true pilot in Book VI are a figure of the relation of the people to
the philosophers in the State which has been described. Other
figures, such as the dog (ii. 375 A, D; iii. 404 A, 416 A; v. 451 D), or
the marriage of the portionless maiden (vi. 495, 496), or the drones
and wasps in the eighth and ninth books, also form links of
connexion in long passages, or are used to recall previous
discussions.
Plato is most true to the character of his master when he
describes him as ‘not of this world.’ And with this representation of
him the ideal state and the other paradoxes of the Republic are quite
in accordance, though they cannot be shown to have been
speculations of Socrates. To him, as to other great teachers both
philosophical and religious, when they looked upward, the world
seemed to be the embodiment of error and evil. The common sense
of mankind has revolted against this view, or has only partially

admitted it. And even in Socrates himself the sterner judgement of
the multitude at times passes into a sort of ironical pity or love. Men
in general are incapable of philosophy, and are therefore at enmity
with the philosopher; but their misunderstanding of him xvi is
unavoidable (vi. 494 foll.; ix. 589 D): for they have never seen him
as he truly is in his own image; they are only acquainted with
artificial systems possessing no native force of truth—words which
admit of many applications. Their leaders have nothing to measure
with, and are therefore ignorant of their own stature. But they are to
be pitied or laughed at, not to be quarrelled with; they mean well
with their nostrums, if they could only learn that they are cutting off
a Hydra’s head (iv. 426 D, E). This moderation towards those who
are in error is one of the most characteristic features of Socrates in
the Republic (vi. 499–502). In all the different representations of
Socrates, whether of Xenophon or Plato, and amid the differences of
the earlier or later Dialogues, he always retains the character of the
unwearied and disinterested seeker after truth, without which he
would have ceased to be Socrates.

Leaving the characters we may now analyse the contents of the
Republic, and then proceed to consider (1) The general aspects of
this Hellenic ideal of the State, (2) The modern lights in which the
thoughts of Plato may be read.

Republic I.
ANALYSIS. BOOK I. The Republic opens with a truly Greek scene—a
festival in honour of the goddess Bendis which is held in the Piraeus;
to this is added the promise of an equestrian torch-race in the
evening. The whole work is supposed to be recited by Socrates on
the day after the festival to a small party, consisting of Critias,
Timaeus, Hermocrates, and another; this we learn from the first
words of the Timaeus.

When the rhetorical advantage of reciting the Dialogue has been
gained, the attention is not distracted by any reference to the
audience; nor is the reader further reminded of the extraordinary
length of the narrative. Of the numerous company, three only take
any serious part in the discussion; nor are we informed whether in
the evening they went to the torch-race, or talked, as in the
Symposium, through the night. The manner in which the
conversation has arisen is described as follows:—Stephanus
327Socrates and his companion Glaucon are about to leave the
festival when they are detained by a message from Polemarchus,
who speedily appears accompanied by Adeimantus, the brother of
Glaucon, and with playful violence compels them to remain,
promising them not only xvii the torch-race, 328but the pleasure of
conversation with the young, which to Socrates is a far greater
attraction. They return to the house of Cephalus, Polemarchus’
father, now in extreme old age, who is found sitting upon a
cushioned seat crowned for a sacrifice. ‘You should come to me
oftener, Socrates, for I am too old to go to you; and at my time of
life, having lost other pleasures, I care the more for conversation.’
329Socrates asks him what he thinks of age, to which the old man
replies, that the sorrows and discontents of age are to be attributed
to the tempers of men, and that age is a time of peace in which the
tyranny of the passions is no longer felt. Yes, replies Socrates, but
the world will say, Cephalus, that you are happy in old age because
you are rich. ‘And there is something in what they say, Socrates, but
not so much as they imagine—330as Themistocles replied to the
Seriphian, “Neither you, if you had been an Athenian, nor I, if I had
been a Seriphian, would ever have been famous,” I might in like
manner reply to you, Neither a good poor man can be happy in age,
nor yet a bad rich man.’ Socrates remarks that Cephalus appears not
to care about riches, a quality which he ascribes to his having
inherited, not acquired them, and would like to know what he
considers to be the chief advantage of them. Cephalus answers that
when you are old the belief in the world below grows upon you, and
then to have done justice and never to have been compelled to do
injustice through poverty, 331and never to have deceived anyone,

are felt to be unspeakable blessings. Socrates, who is evidently
preparing for an argument, next asks, What is the meaning of the
word ‘justice’? To tell the truth and pay your debts? No more than
this? Or must we admit exceptions? Ought I, for example, to put
back into the hands of my friend, who has gone mad, the sword
which I borrowed of him when he was in his right mind? ‘There must
be exceptions.’ ‘And yet,’ says Polemarchus, ‘the definition which has
been given has the authority of Simonides.’ Here Cephalus retires to
look after the sacrifices, and bequeaths, as Socrates facetiously
remarks, the possession of the argument to his heir, Polemarchus….
Republic I.
INTRODUCTION. The description of old age is finished, and Plato, as his
manner is, has touched the key-note of the whole work in asking for
the definition of justice, first suggesting the question which Glaucon
afterwards pursues respecting external goods, and preparing for xviii
the concluding mythus of the world below in the slight allusion of
Cephalus. The portrait of the just man is a natural frontispiece or
introduction to the long discourse which follows, and may perhaps
imply that in all our perplexity about the nature of justice, there is
no difficulty in discerning ‘who is a just man.’ The first explanation
has been supported by a saying of Simonides; and now Socrates has
a mind to show that the resolution of justice into two unconnected
precepts, which have no common principle, fails to satisfy the
demands of dialectic.
Republic I.
ANALYSIS. … 332He proceeds: What did Simonides mean by this
saying of his? Did he mean that I was to give back arms to a
madman? ‘No, not in that case, not if the parties are friends, and evil
would result. He meant that you were to do what was proper, good
to friends and harm to enemies.’ Every act does something to
somebody; and following this analogy, Socrates asks, What is this
due and proper thing which justice does, and to whom? He is
answered that justice does good to friends and harm to enemies.
But in what way good or harm? ‘In making alliances with the one,
and going to war with the other.’ Then in time of peace what is the

good of justice? 333The answer is that justice is of use in contracts,
and contracts are money partnerships. Yes; but how in such
partnerships is the just man of more use than any other man? ‘When
you want to have money safely kept and not used.’ Then justice will
be useful when money is useless. And there is another difficulty:
justice, like the art of war or any other art, must be of opposites,
334good at attack as well as at defence, at stealing as well as at
guarding. But then justice is a thief, though a hero notwithstanding,
like Autolycus, the Homeric hero, who was ‘excellent above all men
in theft and perjury’—to such a pass have you and Homer and
Simonides brought us; though I do not forget that the thieving must
be for the good of friends and the harm of enemies. And still there
arises another question: Are friends to be interpreted as real or
seeming; enemies as real or seeming? 335And are our friends to be
only the good, and our enemies to be the evil? The answer is, that
we must do good to our seeming and real good friends, and evil to
our seeming and real evil enemies—good to the good, evil to the
evil. But ought we to render evil for evil at all, when to do so will
only make men more evil? Can justice produce injustice any more
than the art of horsemanship xix can make bad horsemen, or heat
produce cold? The final conclusion is, that no sage or poet ever said
that the just return evil for evil; this was a maxim of some rich and
mighty man, 336Periander, Perdiccas, or Ismenias the Theban
(about B.C. 398-381)….

Republic I.
INTRODUCTION. Thus the first stage of aphoristic or unconscious morality
is shown to be inadequate to the wants of the age; the authority of
the poets is set aside, and through the winding mazes of dialectic we
make an approach to the Christian precept of forgiveness of injuries.
Similar words are applied by the Persian mystic poet to the Divine
being when the questioning spirit is stirred within him:—‘If because I
do evil, Thou punishest me by evil, what is the difference between
Thee and me?’ In this both Plato and Khèyam rise above the level of
many Christian (?) theologians. The first definition of justice easily

passes into the second; for the simple words ‘to speak the truth and
pay your debts’ is substituted the more abstract ‘to do good to your
friends and harm to your enemies.’ Either of these explanations gives
a sufficient rule of life for plain men, but they both fall short of the
precision of philosophy. We may note in passing the antiquity of
casuistry, which not only arises out of the conflict of established
principles in particular cases, but also out of the effort to attain
them, and is prior as well as posterior to our fundamental notions of
morality. The ‘interrogation’ of moral ideas; the appeal to the
authority of Homer; the conclusion that the maxim, ‘Do good to your
friends and harm to your enemies,’ being erroneous, could not have
been the word of any great man (cp. ii. 380 A, B), are all of them
very characteristic of the Platonic Socrates.

Republic I.
ANALYSIS. … Here Thrasymachus, who has made several attempts to
interrupt, but has hitherto been kept in order by the company, takes
advantage of a pause and rushes into the arena, beginning, like a
savage animal, with a roar. ‘Socrates,’ he says, ‘what folly is this?—
Why do you agree to be vanquished by one another in a pretended
argument?’ He then prohibits all the ordinary definitions of justice;
337to which Socrates replies that he cannot tell how many twelve
is, if he is forbidden to say 2 × 6, or 3 × 4, or 6 × 2, or 4 × 3. At
first Thrasymachus is reluctant to argue; but at length, 338with a
promise of payment on the part of xx the company and of praise
from Socrates, he is induced to open the game. ‘Listen,’ he says, ‘my
answer is that might is right, justice the interest of the stronger:
now praise me.’ Let me understand you first. Do you mean that
because Polydamas the wrestler, who is stronger than we are, finds
the eating of beef for his interest, the eating of beef is also for our
interest, who are not so strong? Thrasymachus is indignant at the
illustration, and in pompous words, apparently intended to restore
dignity to the argument, he explains his meaning to be that the
rulers make laws for their own interests. 339But suppose, says
Socrates, that the ruler or stronger makes a mistake—then the

interest of the stronger is not his interest. Thrasymachus is saved
from this speedy downfall by his disciple Cleitophon, who introduces
the word ‘thinks;’340—not the actual interest of the ruler, but what
he thinks or what seems to be his interest, is justice. The
contradiction is escaped by the unmeaning evasion: for though his
real and apparent interests may differ, what the ruler thinks to be his
interest will always remain what he thinks to be his interest.
Of course this was not the original assertion, nor is the new
interpretation accepted by Thrasymachus himself. But Socrates is not
disposed to quarrel about words, if, as he significantly insinuates, his
adversary has changed his mind. In what follows Thrasymachus
does in fact withdraw his admission that the ruler may make a
mistake, for he affirms that the ruler as a ruler is infallible.
341Socrates is quite ready to accept the new position, which he
equally turns against Thrasymachus by the help of the analogy of
the arts. 342Every art or science has an interest, but this interest is
to be distinguished from the accidental interest of the artist, and is
only concerned with the good of the things or persons which come
under the art. And justice has an interest which is the interest not of
the ruler or judge, but of those who come under his sway.
Thrasymachus is on the brink of the inevitable conclusion, when
he makes a bold diversion. 343‘Tell me, Socrates,’ he says, ‘have
you a nurse?’ What a question! Why do you ask? ‘Because, if you
have, she neglects you and lets you go about drivelling, and has not
even taught you to know the shepherd from the sheep. For you
fancy that shepherds and rulers never think of their own interest,
but only of their sheep or subjects, xxi whereas the truth is that they
fatten them for their use, sheep and subjects alike. And experience
proves that in every relation of life the just man is the loser and the
unjust the gainer, 344especially where injustice is on the grand
scale, which is quite another thing from the petty rogueries of
swindlers and burglars and robbers of temples. The language of men
proves this—our ‘gracious’ and ‘blessed’ tyrant and the like—all
which tends to show (1) that justice is the interest of the stronger;

and (2) that injustice is more profitable and also stronger than
justice.’
Thrasymachus, who is better at a speech than at a close
argument, having deluged the company with words, has a mind to
escape. 345But the others will not let him go, and Socrates adds a
humble but earnest request that he will not desert them at such a
crisis of their fate. ‘And what can I do more for you?’ he says; ‘would
you have me put the words bodily into your souls?’ God forbid!
replies Socrates; but we want you to be consistent in the use of
terms, and not to employ ‘physician’ in an exact sense, and then
again ‘shepherd’ or ‘ruler’ in an inexact,—if the words are strictly
taken, the ruler and the shepherd look only to the good of their
people or flocks and not to their own: whereas you insist that rulers
are solely actuated by love of office. ‘No doubt about it,’ replies
Thrasymachus. 346Then why are they paid? Is not the reason, that
their interest is not comprehended in their art, and is therefore the
concern of another art, the art of pay, which is common to the arts
in general, and therefore not identical with any one of them?
347Nor would any man be a ruler unless he were induced by the
hope of reward or the fear of punishment;—the reward is money or
honour, the punishment is the necessity of being ruled by a man
worse than himself. And if a State [or Church] were composed
entirely of good men, they would be affected by the last motive
only; and there would be as much ‘nolo episcopari’ as there is at
present of the opposite….
Republic I.
INTRODUCTION. The satire on existing governments is heightened by the
simple and apparently incidental manner in which the last remark is
introduced. There is a similar irony in the argument that the
governors of mankind do not like being in office, and that therefore
they demand pay.
Republic I.
ANALYSIS. … Enough of this: the other assertion of Thrasymachus is far
xxii more important—that the unjust life is more gainful than the just.

348Now, as you and I, Glaucon, are not convinced by him, we must
reply to him; but if we try to compare their respective gains we shall
want a judge to decide for us; we had better therefore proceed by
making mutual admissions of the truth to one another.
Thrasymachus had asserted that perfect injustice was more
gainful than perfect justice, and after a little hesitation he is induced
by Socrates 349to admit the still greater paradox that injustice is
virtue and justice vice. Socrates praises his frankness, and assumes
the attitude of one whose only wish is to understand the meaning of
his opponents. At the same time he is weaving a net in which
Thrasymachus is finally enclosed. The admission is elicited from him
that the just man seeks to gain an advantage over the unjust only,
but not over the just, while the unjust would gain an advantage over
either. Socrates, in order to test this statement, employs once more
the favourite analogy of the arts. 350The musician, doctor, skilled
artist of any sort, does not seek to gain more than the skilled, but
only more than the unskilled (that is to say, he works up to a rule,
standard, law, and does not exceed it), whereas the unskilled makes
random efforts at excess. Thus the skilled falls on the side of the
good, and the unskilled on the side of the evil, and the just is the
skilled, and the unjust is the unskilled.
There was great difficulty in bringing Thrasymachus to the point;
the day was hot and he was streaming with perspiration, and for the
first time in his life he was seen to blush. But his other thesis that
injustice was stronger than justice has not yet been refuted, and
Socrates now proceeds to the consideration of this, which, with the
assistance of Thrasymachus, he hopes to clear up; the latter is at
first churlish, but in the judicious hands of Socrates is soon restored
to good humour: 351Is there not honour among thieves? Is not the
strength of injustice only a remnant of justice? Is not absolute
injustice absolute weakness also? 352A house that is divided
against itself cannot stand; two men who quarrel detract from one
another’s strength, and he who is at war with himself is the enemy
of himself and the gods. Not wickedness therefore, but semi-
wickedness flourishes in states,—a remnant of good is needed in

order to make union in action possible,—there is no kingdom of evil
in this world.
xxiii Another question has not been answered: Is the just or the
unjust the happier? To this we reply, that every art has an end and
an excellence or virtue by which the end is accomplished. And is not
the end of the soul happiness, and justice the excellence of the soul
by which happiness is attained? 354Justice and happiness being
thus shown to be inseparable, the question whether the just or the
unjust is the happier has disappeared.
Thrasymachus replies: ‘Let this be your entertainment, Socrates,
at the festival of Bendis.’ Yes; and a very good entertainment with
which your kindness has supplied me, now that you have left off
scolding. And yet not a good entertainment—but that was my own
fault, for I tasted of too many things. First of all the nature of justice
was the subject of our enquiry, and then whether justice is virtue
and wisdom, or evil and folly; and then the comparative advantages
of just and unjust: and the sum of all is that I know not what justice
is; how then shall I know whether the just is happy or not?…
Republic I.
INTRODUCTION. Thus the sophistical fabric has been demolished, chiefly
by appealing to the analogy of the arts. ‘Justice is like the arts (1) in
having no external interest, and (2) in not aiming at excess, and (3)
justice is to happiness what the implement of the workman is to his
work.’ At this the modern reader is apt to stumble, because he
forgets that Plato is writing in an age when the arts and the virtues,
like the moral and intellectual faculties, were still undistinguished.
Among early enquirers into the nature of human action the arts
helped to fill up the void of speculation; and at first the comparison
of the arts and the virtues was not perceived by them to be
fallacious. They only saw the points of agreement in them and not
the points of difference. Virtue, like art, must take means to an end;
good manners are both an art and a virtue; character is naturally
described under the image of a statue (ii. 361 D; vii. 540 C); and
there are many other figures of speech which are readily transferred

from art to morals. The next generation cleared up these
perplexities; or at least supplied after ages with a further analysis of
them. The contemporaries of Plato were in a state of transition, and
had not yet fully realized the common-sense distinction of Aristotle,
that ‘virtue is concerned with action, art with production’ (Nic. Eth.
vi. 4), or that ‘virtue implies intention and constancy of purpose,’ xxiv
whereas ‘art requires knowledge only’ (Nic. Eth. vi. 3). And yet in the
absurdities which follow from some uses of the analogy (cp. i. 333 E,
334 B), there seems to be an intimation conveyed that virtue is more
than art. This is implied in the reductio ad absurdum that ‘justice is a
thief,’ and in the dissatisfaction which Socrates expresses at the final
result.
The expression ‘an art of pay’ (i. 346 B) which is described as
‘common to all the arts’ is not in accordance with the ordinary use of
language. Nor is it employed elsewhere either by Plato or by any
other Greek writer. It is suggested by the argument, and seems to
extend the conception of art to doing as well as making. Another
flaw or inaccuracy of language may be noted in the words (i. 335 C)
‘men who are injured are made more unjust.’ For those who are
injured are not necessarily made worse, but only harmed or ill-
treated.
The second of the three arguments, ‘that the just does not aim at
excess,’ has a real meaning, though wrapped up in an enigmatical
form. That the good is of the nature of the finite is a peculiarly
Hellenic sentiment, which may be compared with the language of
those modern writers who speak of virtue as fitness, and of freedom
as obedience to law. The mathematical or logical notion of limit
easily passes into an ethical one, and even finds a mythological
expression in the conception of envy (φθόνος). Ideas of measure,
equality, order, unity, proportion, still linger in the writings of
moralists; and the true spirit of the fine arts is better conveyed by
such terms than by superlatives.

‘When workmen strive to do better than well,
They do confound their skill in covetousness.’
(King John, Act iv. Sc. 2.)
The harmony of the soul and body (iii. 402 D), and of the parts of
the soul with one another (iv. 442 C), a harmony ‘fairer than that of
musical notes,’ is the true Hellenic mode of conceiving the perfection
of human nature.
In what may be called the epilogue of the discussion with
Thrasymachus, Plato argues that evil is not a principle of strength,
but of discord and dissolution, just touching the question which has
been often treated in modern times by theologians and philosophers,
of the negative nature of evil (cp. on the other hand x. 610). In the
last argument we trace the germ of the xxv Aristotelian doctrine of
an end and a virtue directed towards the end, which again is
suggested by the arts. The final reconcilement of justice and
happiness and the identity of the individual and the State are also
intimated. Socrates reassumes the character of a ‘know-nothing;’ at
the same time he appears to be not wholly satisfied with the manner
in which the argument has been conducted. Nothing is concluded;
but the tendency of the dialectical process, here as always, is to
enlarge our conception of ideas, and to widen their application to
human life.

Republic II.
ANALYSIS. BOOK II. Thrasymachus is pacified, 357but the intrepid
Glaucon insists on continuing the argument. He is not satisfied with
the indirect manner in which, at the end of the last book, Socrates
had disposed of the question ‘Whether the just or the unjust is the
happier.’ He begins by dividing goods into three classes:—first, goods
desirable in themselves; secondly, goods desirable in themselves and
for their results; thirdly, goods desirable for their results only. He
then asks Socrates in which of the three classes he would place
justice. 358In the second class, replies Socrates, among goods

desirable for themselves and also for their results. ‘Then the world in
general are of another mind, for they say that justice belongs to the
troublesome class of goods which are desirable for their results only.’
Socrates answers that this is the doctrine of Thrasymachus which he
rejects. Glaucon thinks that Thrasymachus was too ready to listen to
the voice of the charmer, and proposes to consider the nature of
justice and injustice in themselves and apart from the results and
rewards of them which the world is always dinning in his ears. He
will first of all speak of the nature and origin of justice; secondly, of
the manner in which men view justice as a necessity and not a
good; and thirdly, he will prove the reasonableness of this view.
‘To do injustice is said to be a good; to suffer injustice an evil. As
the evil is discovered by experience to be greater than the good,
359the sufferers, who cannot also be doers, make a compact that
they will have neither, and this compact or mean is called justice, but
is really the impossibility of doing injustice. No one would observe
such a compact if he were not obliged. Let us suppose that the just
and unjust have two rings, like that of Gyges xxvi in the well-known
story, which make them invisible,360 and then no difference will
appear in them, for every one will do evil if he can. And he who
abstains will be regarded by the world as a fool for his pains. Men
may praise him in public out of fear for themselves, but they will
laugh at him in their hearts. (Cp. Gorgias, 483 B.)
‘And now let us frame an ideal of the just and unjust. Imagine the
unjust man to be master of his craft, seldom making mistakes and
easily correcting them; having gifts of money, speech, strength—
361the greatest villain bearing the highest character: and at his side
let us place the just in his nobleness and simplicity—being, not
seeming—without name or reward—clothed in his justice only—the
best of men who is thought to be the worst, and let him die as he
has lived. I might add (but I would rather put the rest into the
mouth of the panegyrists of injustice—they will tell you) that the just
man will be scourged, racked, bound, will have his eyes put out, and
will at last be crucified [literally impaled]—and all this because he
ought to have preferred seeming to being. 362How different is the

case of the unjust who clings to appearance as the true reality! His
high character makes him a ruler; he can marry where he likes,
trade where he likes, help his friends and hurt his enemies; having
got rich by dishonesty he can worship the gods better, and will
therefore be more loved by them than the just.’
I was thinking what to answer, when Adeimantus joined in the
already unequal fray. He considered that the most important point of
all had been omitted:—‘Men are taught to be just for the sake of
rewards; 363parents and guardians make reputation the incentive
to virtue. And other advantages are promised by them of a more
solid kind, such as wealthy marriages and high offices. There are the
pictures in Homer and Hesiod of fat sheep and heavy fleeces, rich
corn-fields and trees toppling with fruit, which the gods provide in
this life for the just. And the Orphic poets add a similar picture of
another. The heroes of Musaeus and Eumolpus lie on couches at a
festival, with garlands on their heads, enjoying as the meed of virtue
a paradise of immortal drunkenness. Some go further, and speak of
a fair posterity in the third and fourth generation. But the wicked
they bury in a slough and make them carry water in a sieve: and in
this life they xxvii attribute to them the infamy which Glaucon was
assuming to be the lot of the just who are supposed to be unjust.
‘364Take another kind of argument which is found both in poetry
and prose:—“Virtue,” as Hesiod says, “is honourable but difficult, vice
is easy and profitable.” You may often see the wicked in great
prosperity and the righteous afflicted by the will of heaven. And
mendicant prophets knock at rich men’s doors, promising to atone
for the sins of themselves or their fathers in an easy fashion with
sacrifices and festive games, or with charms and invocations to get
rid of an enemy good or bad by divine help and at a small charge;—
they appeal to books professing to be written by Musaeus and
Orpheus, and carry away the minds of whole cities, and promise to
“get souls out of purgatory;” and if we refuse to listen to them,
365no one knows what will happen to us.

‘When a lively-minded ingenuous youth hears all this, what will be
his conclusion? “Will he,” in the language of Pindar, “make justice his
high tower, or fortify himself with crooked deceit?” Justice, he
reflects, without the appearance of justice, is misery and ruin;
injustice has the promise of a glorious life. Appearance is master of
truth and lord of happiness. To appearance then I will turn,—I will
put on the show of virtue and trail behind me the fox of Archilochus.
I hear some one saying that “wickedness is not easily concealed,” to
which I reply that “nothing great is easy.” Union and force and
rhetoric will do much; and if men say that they cannot prevail over
the gods, still how do we know that there are gods? Only from the
poets, who acknowledge that they may be appeased by sacrifices.
366Then why not sin and pay for indulgences out of your sin? For if
the righteous are only unpunished, still they have no further reward,
while the wicked may be unpunished and have the pleasure of
sinning too. But what of the world below? Nay, says the argument,
there are atoning powers who will set that matter right, as the
poets, who are the sons of the gods, tell us; and this is confirmed by
the authority of the State.
‘How can we resist such arguments in favour of injustice? Add
good manners, and, as the wise tell us, we shall make the best of
both worlds. Who that is not a miserable caitiff will refrain from
smiling at the praises of justice? Even if a man knows the better part
he will not be angry with others; for he knows also that xxviii more
than human virtue is needed to save a man, and that he only praises
justice who is incapable of injustice.
‘The origin of the evil is that all men from the beginning, heroes,
poets, instructors of youth, have always asserted “the temporal
dispensation,” the honours and profits of justice. 367Had we been
taught in early youth the power of justice and injustice inherent in
the soul, and unseen by any human or divine eye, we should not
have needed others to be our guardians, but every one would have
been the guardian of himself. This is what I want you to show,
Socrates;—other men use arguments which rather tend to
strengthen the position of Thrasymachus that “might is right;” but

from you I expect better things. And please, as Glaucon said, to
exclude reputation; let the just be thought unjust and the unjust
just, and do you still prove to us the superiority of justice.’…
Republic II.
INTRODUCTION. The thesis, which for the sake of argument has been
maintained by Glaucon, is the converse of that of Thrasymachus—
not right is the interest of the stronger, but right is the necessity of
the weaker. Starting from the same premises he carries the analysis
of society a step further back;—might is still right, but the might is
the weakness of the many combined against the strength of the few.
There have been theories in modern as well as in ancient times
which have a family likeness to the speculations of Glaucon; e.g.
that power is the foundation of right; or that a monarch has a divine
right to govern well or ill; or that virtue is self-love or the love of
power; or that war is the natural state of man; or that private vices
are public benefits. All such theories have a kind of plausibility from
their partial agreement with experience. For human nature oscillates
between good and evil, and the motives of actions and the origin of
institutions may be explained to a certain extent on either hypothesis
according to the character or point of view of a particular thinker.
The obligation of maintaining authority under all circumstances and
sometimes by rather questionable means is felt strongly and has
become a sort of instinct among civilized men. The divine right of
kings, or more generally of governments, is one of the forms under
which this natural feeling is expressed. Nor again is there any evil
which has not some accompaniment of good or pleasure; nor any
good xxix which is free from some alloy of evil; nor any noble or
generous thought which may not be attended by a shadow or the
ghost of a shadow of self-interest or of self-love. We know that all
human actions are imperfect; but we do not therefore attribute them
to the worse rather than to the better motive or principle. Such a
philosophy is both foolish and false, like that opinion of the clever
rogue who assumes all other men to be like himself (iii. 409 C). And
theories of this sort do not represent the real nature of the State,
which is based on a vague sense of right gradually corrected and

enlarged by custom and law (although capable also of perversion),
any more than they describe the origin of society, which is to be
sought in the family and in the social and religious feelings of man.
Nor do they represent the average character of individuals, which
cannot be explained simply on a theory of evil, but has always a
counteracting element of good. And as men become better such
theories appear more and more untruthful to them, because they
are more conscious of their own disinterestedness. A little
experience may make a man a cynic; a great deal will bring him
back to a truer and kindlier view of the mixed nature of himself and
his fellow men.
The two brothers ask Socrates to prove to them that the just is
happy when they have taken from him all that in which happiness is
ordinarily supposed to consist. Not that there is (1) any absurdity in
the attempt to frame a notion of justice apart from circumstances.
For the ideal must always be a paradox when compared with the
ordinary conditions of human life. Neither the Stoical ideal nor the
Christian ideal is true as a fact, but they may serve as a basis of
education, and may exercise an ennobling influence. An ideal is none
the worse because ‘some one has made the discovery’ that no such
ideal was ever realized. (Cp. v. 472 D.) And in a few exceptional
individuals who are raised above the ordinary level of humanity, the
ideal of happiness may be realized in death and misery. This may be
the state which the reason deliberately approves, and which the
utilitarian as well as every other moralist may be bound in certain
cases to prefer.
Nor again, (2) must we forget that Plato, though he agrees
generally with the view implied in the argument of the two brothers,
is not expressing his own final conclusion, but rather xxx seeking to
dramatize one of the aspects of ethical truth. He is developing his
idea gradually in a series of positions or situations. He is exhibiting
Socrates for the first time undergoing the Socratic interrogation.
Lastly, (3) the word ‘happiness’ involves some degree of confusion
because associated in the language of modern philosophy with

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Advances In Measurement Technology Disaster Prevention And Mitigation Zongming Li

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