Rainfall of magnitude 4.3 cm, followed by 3.7 cm, occurred on two consecutive 4 h durations on a catchment area of 25 km2 and there resulted a DRH (after isolation of base flow in the flood flow hydrograph) with the following ordinates starting from the beginning of the rainfall. (Adopt trapezoidal formula)
|
Time (hours) |
0 |
4 |
8 |
12 |
16 |
20 |
24 |
28 |
32 |
36 |
40 |
44 |
|
DRH (ordinate m3/sec) |
0 |
9 |
16 |
20 |
20 |
17.8 |
13.4 |
9.4 |
6.2 |
3.7 |
1.8 |
0 |
What is the ∅ index value?
1
0.149 cm/h
2
0.155 cm/h
3
0.161 cm/h
4
0.167 cm/h