On a particular day in 1990, there was a rainstorm event that produced the following rainfall and runoff on a 36-km2 drainage basin. Time (min) 0 15 30 45 60 75 90 105 120 Cumulative rainfall (mm) 0 10 50 75 90 100 Instantaneous runoff (m3 /s) 10 30 160 360 405 305 125 35 10 For the above rainstorm event, assume that the basefiow is 10 m3 /s. (a) Find the volume of direct runoff (in mm). (b) Assuming the initial loss is 10 mm, determine the value of f index (in mm/hr) and the corresponding effective rainfall intensity hyetograph (in mm/hr).

On a particular day in 1990, there was a rainstorm event that produced the following rainfall and runoff on a 36-km2 drainage basin. Time (min) 0 15 30 45 60 75 90 105 120 Cumulative rainfall (mm) 0 10 50 75 90 100 Instantaneous runoff (m3 /s) 10 30 160 360 405 305 125 35 10 For the above rainstorm event, assume that the basefiow is 10 m3 /s. (a) Find the volume of direct runoff (in mm). (b) Assuming the initial loss is 10 mm, determine the value of f index (in mm/hr) and the corresponding effective rainfall intensity hyetograph (in mm/hr).