CE 4200 Chapter : Homework 7 2013 Fall
Document Summary
An asphalt pavement drains into a rectangular concrete channel. For an effective rainfall rate of 50 mm/h, the flowrate in the channel is estimated to be 0. 02 m3/s. Manning n for an asphalt surface is 0. 011 and for a concrete surface is 0. 013. Estimate the time of concentration of the catchment. [hint: use the kinematic-wave equation for overland flow and use the manning equation for channel flow. ] The surface of a 2-ha catchment is characterized by a runoff coefficient of 0. 5, a manning n for overland flow of 0. 25, an average overland flow length of 60 m, and an average slope of 0. 5%. The time of concentration can be calculated by the kinematic-wave equation. The drainage channel is to be sized for the peak runoff resulting from a 10-year rainfall event, and the 10-year. 0. 78 where i is the average rainfall intensity in cm/h and t is the duration in minutes. The minimum time of concentration is 5 minutes.
