HECRAS one dimensional modelling of River ganga at prayagraj.pptx

this presentation is about HEC RAS 1D modelling using HECRAS software which is used to determine flood variation and its characteristics in a stream.

1. Inundation modelling for Prayagraj Sangam using HEC-RAS 1D 1 Project presentation

2. Introduction 2

3. Objectives 3

4. Study Area 4

5. Methodology HEC-RAS 1 D model (Learn) Extracting the DEM (for preparing the geometry of the river reach) Data import from QGIS to HEC-RAS Assign attributes to the Cross section Hydraulic and Hydrologic modelling 5

6. Equations used Saint Venant’s Equation Z 2 + Y 2 + (α 2 V 2 2 ) ∕ 2g = Z 1 + Y 1 + (α 1 V 1 2 ) ∕2g + h e Y 1 , Y 2 = depth of water at cross sections; Z 1 , Z 2 = elevation of the main channel;V 1 , V 2 = average velocities (total discharge/total flow area); α 1 , α 2 = velocity weighting coefficients; g = gravitational acceleration; h e = energy head loss Manning’s Equation Q = (AR 2/3 ) ( S f ) ½ / n R = hydraulic radius (m); n = Manning roughness coefficient; K = conveyance (m 5/3 ), S f = average friction slope between adjacent cross-sections Continuity Equation Q = V 1 A 1 = V 2 A 2 Q = flow rate/discharge (m 3 /s); V n = average velocity at cross-section n (m/s); A n = area at cross-section n (m 2 ) 6

7. Variation of discharge along the length of river 7

8. Discharge variation 8 Last section Middle section First section

9. Critical depth variation 9 First section Last section

10. Energy Grade Variation 10 First section Middle section Last section

11. Water Surface Elevation variation 11

12. Depth at minimum and maximum discharge 12

13. Velocity variation at minimum and maximum discharge 13

14. Variation of D*V^2 14

15. Particle flow and velocity 15

16. Conclusion The overall results of this study indicate the usefulness of HEC-RAS software along with GIS tool to identify the flood extend zone and return period of food in the study area. This study is useful for local authority to minimize the flood risk in the area and enforce appropriate mitigation policies. The methodology utilized in the present study can also be used for other flood prone areas of the world for better management of flood in advance. 16

17. References Kumar, N., Kumar, M., Sherring , A., Suryavanshi , S., Ahmad, A., & Lal , D. (2020). Applicability of HEC-RAS 2D and GFMS for flood extent mapping: a case study of Sangam area, Prayagraj , India.  Modeling Earth Systems and Environment ,  6 (1), 397-405. Tate, E., & Maidment , D. (1999).  Floodplain mapping using HEC-RAS and ArcView GIS . University of Texas at Austin Center For Research in Water Resources. Opentopography.org Spatialreference.org 17

18. 18 Thank you