CE 4200 Chapter : Homework 6 2013 Fall
Document Summary
Consider one-hour rainfall intensity below for an area. The area has a curve number cn = 70. 86. Before the storm comes, the area is in normal condition. Use the nrcs curve-number model to calculate total runoff at 60 min. Drainage facilities are to be designed for a rainfall of return period 10 years and duration 1 hour. 0. 73 where i is the average intensity in cm/h and t is the storm duration in minutes. The minimum infiltration rate is 10 mm/h, and the area to be drained is primarily residential with lot sizes on the order of 0. 2 ha (0. 5 ac). Use the nrcs method to estimate the total amount of runoff (in cm), assuming the soil is in normal condition at the beginning of the design storm. A proposed 20-ha development includes 5 ha of parking lots, 10 ha of buildings and, 5 ha of grassed areas.
