CIV E 445 - APPLIED HYDROLOGY
SPRING 2014
HOMEWORK No. 7
Given the following 2-h unit hydrograph for a certain catchment, find the 3-h unit hydrograph.
Time
(h) | Flow
(m3/s) |
| 0 | 0 |
| 1 | 30 |
| 2 | 80 |
| 3 | 100 |
| 4 | 70 |
| 5 | 30 |
| 6 | 10 |
| 7 | 0 |
Using the 3-h unit hydrograph, calculate the 1-h unit hydrograph.
Verify using ONLINE S HYDROGRAPH.
The following 2-h unit hydrograph has been developed for a certain catchment:
Time
(h) | Flow
(ft3/s) |
| 0 | 0 |
| 2 | 100 |
| 4 | 200 |
| 6 | 70 |
| 8 | 50 |
| 10 | 30 |
| 12 | 0 |
A 6-h storm covers the entire catchment and is distributed in time as follows:
Time
(h) | Total rainfall
(in/h) |
| 0-2 | 1.0 |
| 2-4 | 2.0 |
| 4-6 | 1.5 |
Calculate the composite hydrograph for the effective storm pattern, assuming a runoff curve number CN = 84.
Verify using ONLINE CONVOLUTION.
A certain basin has the following 2-h unit hydrograph:
Time
(h) | Flow
(m3/s) |
| 0 | 0 |
| 1 | 5 |
| 2 | 20 |
| 3 | 35 |
| 4 | 65 |
| 5 | 90 |
| 6 | 70 |
| 7 | 55 |
| 8 | 40 |
| 9 | 20 |
| 10 | 10 |
| 11 | 0 |
Calculate the flood hydrograph for the following effective rainfall hyetograph:
Time
(h) | Effective rainfall
(cm/h) |
| 0-3 | 1.3 |
| 3-6 | 2.2 |
Calculate the 50-y peak flow by the TR-55 graphical method
for the following watershed data: (1) urban watershed, area A = 8.5 km2;
(2) surface flow is shallow concentrated, paved; hydraulic length L = 3350 m;
slope S = 0.01; (3) 48% of watershed is 1/3-ac lots, lawns with 85%
grass cover, 34% total impervious, soil group C; (4) 52% of the watershed is
1/3-ac lots, lawns with 95% grass cover, 24% total impervious, 25% of it
unconnected, soil group C; (5) Pacific Northwest region, 50-y 24-h rainfall P = 12 cm; 0.2% ponding.
Verify using ONLINE TR-55.
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