In: Civil Engineering
Time hr |
Discharge m3/s |
0 |
18 |
1 |
42 |
2 |
193 |
3 |
338 |
4 |
383 |
5 |
328 |
6 |
248 |
7 |
183 |
8 |
123 |
9 |
78 |
10 |
48 |
11 |
28 |
12 |
18 |
Lets say you want a 'Y' hour unit hydrograph then,
Area of catchment=81 Km2
= 81x10002 =81000000 m2
Area under DRH=1794 x (Y hour) x 60x60=6458400Y m3
DRH depth =
Rainfall excess = (6458400xY)/(81x1000x1000)
= 7.97333 x (Y) (centimetre )
Therefore, the ordinate of UH are obtained by dividing the ordinate of surface runoff hydrograph by rainfall excess 7.9733(Y) to get ordinates of UH.
Example- Obtaining unit hydrograph of 6Hr from this DRH
Y=6
Rainfall excess=7.97333x6=47.84
Data table-
6hr UH
similarily you can construct any hr duration UH