(a) The Horton's initial infiltration capacity for a catchment is 204 mm/h and the constant infiltration value at saturation is 60 mm/h. For a rainfall in excess of 204 mm/h maintained at this rate for 50 minutes, the infiltrated volume was observed to be 50.6 mm. Determine the value of k in Horton's equation.
(b) Soil infiltration characteristics (based on Horton's equation) and an observed 4-hr duration rainfall values for a 100 ha parkland catchment are given below:
fo = 15 mm/hr, fc = 5.0 mm/hr, k=0.6 hr-1
|
Duration
|
0 - 1 hr
|
1 - 2 hr
|
2 - 3 hr
|
3 - 4 hr
|
|
Rainfall
in mm
|
17.5
|
12.5
|
15
|
7.5
|
i. Calculate the total depth of infiltration
ii. What is the total volume of runoff in m3 for the observed rainfall
iii. Estimate f index of the catchment