Introduction to Environmental Indices.pptx

Environmental indices

1. Environmental Indices K Pavan Kumar Associate Professor SCALE, VIT University

2. Environmental Index - Definition An “environmental index” in its broadest concept is numerical or descriptive categorization of a large quantity of environmental data or information, with the primary purpose being to simplify such data and information so as to make it useful to decision makers and various public

3. In terms of EIA, environmental indices can be useful in accomplishing one or more of the following objectives: To summarize existing environmental data To communicate information on the quality of the effected (baseline) environment To evaluate the vulnerability and susceptibility of an environment category to pollution To focus attention on key environmental factors To serve as a basis for the expression of impact by forecasting the difference between the pertinent index with the project and the same index without the project

4. General Form of Indices Some of the commonly used environmental indices in EIA are :  

5. Environmental Media Index – Air Quality Indices of air pollution or air quality have been used for about 45 years Because of the wide diversity in air quality indices, a common pollutant standard index (PSI) was developed Ten criteria were delineated for the PSI; these criteria were that PSI should: Be easily understood by the public Include major pollutants and be capable of including future pollutants Relate to ambient air quality standards Relate to air pollution episode criteria Be calculated in simple manner using reasonable assumptions Be based on a reasonable scientific premise Be consistent with perceived air pollution levels Be spatially meaningful Exhibit day-to-day variation, and Enable forecasting a day in advance

6. Environmental Media Index – Water Quality Water Quality Index (WQI) developed by the U.S. National Sanitation Foundation (NSF) The WQI was based on Delphi approach Based on three questionnaires sent to various experts: Q No1 : 35 water-pollutant variables for possible inclusion in a water quality index. Also included was the pollutant significance to overall water quality on a scale of 1 (highest relative significance) to 5 (lowest relative significance) Q No2 : Each expert was asked to review their original ratings and to modify the response if desired From Q No2, the nine individual variables of greatest importance were identified as: DO, fecal coliform, pH, BOD 5 , NO 3 , PO 4 , temperature deviation, turbidity, and total solids

7. Q No3: The experts were asked to develop a rating curve for each of the included variables Levels of water quality from 0 to 100 were indicated on the ordinate of each graph, while various levels of the particular variables were arranged along the abscissa The resultant relationships are called “functional relationships” or “functional curves.” Variable Measurement I i W i I i ×W i Ii wi DO 60% 60 0.17 10.2 2.01 Fecal coliform 10000 20 0.15 3.0 1.57 pH 7 90 0.12 10.8 1.72 BOD 5 10 30 0.10 3.0 1.41 NO 3 10 50 0.10 5.0 1.48 PO 4 5 10 0.10 1.0 1.26 Temp deviation 5 40 0.10 4.0 1.45 Turbidity 40 JTU 44 0.08 3.5 1.35 Total solids (TS) 300 60 0.08 4.8 1.39 WQIa = 45.3 WQIm = 38.8

8. To calculate the aggregate WQI, either a weighted linear sum of the sub-indices ( WQIa ) or a weighted product aggregation function ( WQIm ) can be used These are expressed mathematically as: In summary the steps involved in the application of the WQI in an impact study are as follows: Assemble average and extreme data for each parameter Use functional curves to determine I i for average and extreme conditions Calculate WQI a and/or WQI m for average and extreme conditions and interpret the results as appropriate  

9. Descriptor words and colours suggested for reporting the example WQI Descriptor words Numerical range Colour Very bad 0 – 25 Red Bad 26 – 60 Orange Medium 51 – 70 Yellow Good 71 – 90 Green Excellent 91 - 100 Blue

10. Environmental Media Index - Noise Von Gierke et al. (1977) developed guidelines for addressing noise in EIA The guidelines cover the following: General audible noise environments Ultrasound and infrasound Environmental impact of structure borne vibrations A single-number noise-impact characterization should be used Should be based on level weighted population

11. Environmental Media Index – Ecological Sensitivity and Diversity Cooper and Zedler (1980) described an index method for evaluating the relative sensitivity to perturbations of the ecosystem in a region The ecological sensitivity of each area or ecosystem in a region to perturbations is assessed in terms of: Significance of the ecosystem both regionally and globally Rarity or abundance of the ecosystem relative to others in the region or elsewhere The resilience of the ecosystem “Ecosystem significance” represents a subjective valuation of the biological importance of species and of the ecosystem

12. Resilience is a measure of an ecosystem’s ability to absorb environmental stress without changing to a recognizably different ecological state Characteristics considered in determining the significance of species and ecosystems 1. Role of the local ecosystem in regional ecosystem function or importance of the species in ecosystem function 2. Uniqueness and isolation 3. Actual and potential aesthetic value 4. Actual and potential scientific value 5. Actual and potential economic value 6. Relative size or rarity 7. Prospects for continued persistence

13. Ecological responses to environmental stress considered in evaluating resilience of ecosystems or species populations Mortality 2. Changes in birth rates 3. Displacement (emigration or immigration) 4. Change in coverage, growth or vitality of individuals 5. Changes in behaviour 6. Disruption of ecosystem interrelationships (e.g., predator-prey interactions)

14. Four levels of ecological sensitivity were defined in the index approach by Cooper and Zedler (1980) Minimally sensitive areas – Areas which are already extensively disturbed by man, where additional human interference was not thought likely to induce much measurable ecological change Maximum sensitivity – was limited to areas where ecologically significant plants or animals are likely to be highly responsive even to slight intrusion by man and the consequences of this impact could probably not be reduced by any practical measure to a level generally regarded as acceptable The other two sensitivity levels (“major” and “moderate”) lie between the extremes