where i is the average rainfall intensity in mm/h and tis the rainfall duration in minutes. (a) Determine the peak runoff rate to a drainage structure located in a residential

area with single-family housing where the catchment area is 0.5 ha and the time of concentration is 10 min. (b) if the available soil storage on the site is 8 cm, determine the curve number and the volume of runoff (in m3) for a 10-yr 24-h rainfall event. 10.13. The 10-yr IDF curve for a 10-ha site in Cleveland, Ohio, is given by i=1209(t+8.86)0.79 mm/h