1. CEVE 412/512 Dr. Phil Bedient Jan 2016
Hydrologic Analysis
Hydrology and Floodplain Analysis
Chapter 2
CEVE 412/512
Dr. Phil Bedient
Jan 2016

2. Applications of Unit Hydrographs
Hydrology and Floodplain Analysis, Chapter 2.4
Applications of Unit Hydrographs

3. UH Applications For complex watersheds:
Design storm hydrographs (10-yr, 25-yr,100-yr)
Historical rainfall events
Evaluate effects of land use changes, channelization, storage additions, and other variables
Simulate storm hydrographs (Ch. 4)
Analysis of flood control options (Ch. 4)

4. UH Applications
Design storm hydrographs (10-yr, 25-yr,100-yr)

5. Typical Design Rainfall Dist’n
Design storm hydrographs (10-yr, 25-yr,100-yr)
10 yr – 7.35 in
25 yr – 9.51 in
100 yr – in

6. UH Applications Design storm inches by duration (10-yr, 25-yr,100-yr)
Developed by the NWS for all urban areas
Duration 10 - yr yr 100 – yr
15 min
1 hr
3 hr
6 hr
12 hr
24 hr

7. UH Land Use Effects
Effects of land use changes, storage additions, and other variables – normally increase peak flows

8. UH Conversion to Storm Hydr
Create storm hydrograph from UH for each subbasin as function of rainfall
Combine hydrographs at each confluence
Flood route combined hydrographs downstream
Add in additional runoff from subbasins
Finally add together to get final storm hydrograph

9. Flood Routing – Reservoir & River Tends to shift hydrograph in time and reduce the flowQ S S Q
Reservoir Routing
River Routing

10. Hydrograph Watershed Analysis1 2 3 3

11. Hydrograph Combining/Routing
Subarea G + Subarea F = Combine PT1 1

12. Hydrograph Combining/Routing
Subarea G + Subarea F = Combine PT1
Subarea E + Route to 3 + Subarea C = Combine PT3 1 1 3

13. Hydrograph Combining/Routing
Subarea G + Subarea F = Combine PT1
Subarea E + Route to 3 + Subarea C = Combine PT3
Combine PT1 + Route to 2 + Subarea D = Combine PT2 2 3

14. Hydrograph Combining/Routing
Subarea G + Subarea F = Combine PT1
Subarea E + Route to 3 + Subarea C = Combine PT3
Combine PT1 + Route to 2 + Subarea D = Combine PT2
Combine PT2 + Route to 3 + Subarea B = Combine PT3 2 3 4

15. Hydrograph Combining/Routing
Combine PT Route to Subarea A = RESULTING HYDROG 2 3 Q 4 T

16. Linear and Kinematic Wave Models
Hydrology and Floodplain Analysis, Chapter 2.5
Linear and Kinematic Wave Models

17. Kinematic Wave
Used to develop stream hydrographs and compute overland flow
The Kinematic Wave is used because it assumes that the weight or gravity force is balanced by the resistive bed friction
Has been integrated into HEC-HMS and can be used for Storm Water Management Models

18. Kinematic Wave
Kinematic (kw) wave routing used to derive overland flow hydrographs
Can be added to produce collector or channel hydrographs
Then can be flood routed as channel or stream hydrographs.