Explain the utilization of HEC-RAS to two-dimensional simulation of flood wave propagation. also, show the application of ArcGis to draw flood risk maps.

1. Ahmed Adel Saleh
Using HEC-RAS 5.x to assess flash flood
risk in arid regions
National Water Research Center – Water Resources Research Institute
NorAhmed1@Gmail.com
FB| ahmed.a.saleh.965

2. Flood risk assessment studies

3. Goals / measurement
Repeat what was done
• Apply the solved example during/after this presentation
Find my faults, mistakes and shortages
• Write a short report/note
Fix my errors
• Propose solutions (a short report/note)
Upgrade my work
• Make a workshop

4. Contents
Overview on flash flood risk assessment
Overview on HEC-RAS 5.0
Main steps of flood risk assessment
Discussion
Quick application

5. Overview on flash flood risk assessment
• Assessing
• Mapping
Objectives
• Depth
• Velocity
Criteria

6. Approaches of flood risk assessment
0.00
0.50
1.00
1.50
2.00
2.50
3.00
Waterdepth∙floodvelocity
(m2/s)
Low
Moderate
High
Extreme
Thresholds of risk to life
Shabanikiya H,. Behavior of crossing flood on foot, associated risk factors and estimating a predictive model. Nat Hazards

7. Approaches of flood risk assessment
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 1 2 3 4 5 6 7 8
Depth(m)
Velocity (m/s)
Instabilityzone
Stabilityzone
Vehicles stability thresholds

8. Approaches of flood risk assessment
0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5 2 2.5 3
Waterdepth(m)
Water depth ∙ flood velocity (m2/s)
High
Moderate
Low
flood/ structures damaged relationship

9. Approaches of flood risk assessment
Flood vs. damage curves in complex land uses.

10. Flood Risk Assessment Using ArcGIS
Con("Water Depth x Water Velocity"< 0.75, 1, Con("Water Depth x Water Velocity"< 1.5, 2,Con("Water Depth x
Water Velocity"< 2.25, 3,4)))
Con((("depth" < 1.7282 - 0.2597 * "Velocity") | ("depth" > 5.0471 * "Velocity"- 7.8786)),1,Con((("depth" >
2.1049-0.2779 * "Velocity") | ("depth" < 3.4145 * "Velocity"- 6.3621)),3,2))
Con((("depth"<0.5) & ("Depth x Velocity"<0.5)),1,Con((("depth" > 2.0) | ("Depth x Velocity">2.0)),3,2))
Con(("Velocity">2.0),1,2)

11. Why 2D hydrodynamic modeling?

12. Solving Equations
Principals of conservation
Newton’s laws of motion
Navier-stokes equations
Full Saint Venant / Diffusion Wave Equations

13. Full Saint Venant or Diffusion Wave ?

14. 2D Saint Venant Equations
These equations are the conservative form of the Saint-Venant equations
. The first one is the mass conservations equation while the two others ar
e the momentum for the fluid:
x and y are the directions of the Cartesian Coordinate System used, qx and qy ar
e the flow rate in the x and y directions, respectively, t is the time, h is the water le
vel, H is the depth of the water column and Fx and Fy are the volume forces in th
e x and y directions, respectively.

15. Analytical  Numerical

16. Calculation points in HEC-RAS

17. HEC-RAS 5.x GU interface

18. HEC-RAS 5.x GU interface

19. HEC-RAS 5.x GU interface
Enter /Edit Geometry data
Enter /Edit
Flow data
Compute /Edit
Analysis parameters

20. HEC-RAS 5.x GU interface

21. Building a 2D simulation model using
HEC-RAS 5.x

22. Define Projection

23. Define Projection
All inserted layers should be
with the same projection

24. Define morphological data

25. Add Web data

26. Add terrain data

27. Add Land use data
Select a shp file

28. Define flow area

29. Define flow area

30. Define flow area

31. Define flow area
20m X 20m

32. Define flow area
Downstream Boundary
Condition
Upstream Boundary
Condition

33. Define flow area – Boundary conditions

34. Define flow area – Boundary conditions

35. Define flow data – Boundary conditions

36. Define flow data- Upstream Boundary Condition
OM_MERKA_07
Using HEC-HMS

37. Define flow data- Upstream Boundary Condition

38. Define flow data- Upstream Boundary Condition

39. Define flow data- Downstream Boundary Condition
Find Contour line of 0m a.s.l

40. Define flow data- Downstream Boundary Condition

41. Run the model

42. Run the model

43. Review Results

44. The whole story

46. • Control the results display
• Enhance the result accuracy
• Assis the risk using ArcGIS
• Representing the buildings