10.7. The surface of a 2-ha catchment is characterized by a runoff coefficient of 0.5, a Manning's n for overland flow of 0.25, an average overland-flow length of 60 m, and an average slope of 0.5%.Calculate the time of concentration using the kinematic-wave equation. The drainage channel is to be sized for the peak runoff rate resulting from a 10-year rainfall event, and the 10-year IDF curve is given by i=150(t+8.96)0.78 cm/h where i is the average rainfall intensity in cm/h and t is the duration in minutes. The minimum time of concentration is 5 min. Determine the peak runoff rate.

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