The infiltration capacity of a catchment is represented by Horton's equation as f= 0.5+ 1.2e^-0.5t where f is in cm/hr and t is in hours. Assuming the infiltration to take place at capacity rates in a storm of 4 hours duration, estimate the average rate of infiltration for the duration of the storm.

For a certain catchment with an area of 1000000m2, the average precipitation was 7cm and infiltration was 4cm. The hydrograph values are 20, 60, 88, 105, 70, 57, 20, and 5 m3/s and the base flow has constant value of 10 m3/s, the peak unit hydrograph ordinate is equal to

A 40-year annual series of eak river discharges with the mean equal to 15,000 cfs and standard deviation equal to 7,500 cfs approximates a normal distribution. (1) Determine the discharge woth a return period of 10 years. (2) Determine the discharge with a return period of 20 years. (3) what is the return period rhay corresponds to a discharge of period of 20 years. (3) What is the return period that corresponds to discharge of 20,000 cfs? (4) What is the probability that a discharge equal to or greater than 20,000 cfs will occur during a 5-year period?

You are asked to design a rectangular clarifier for a wastewater treatment plant. The clarifier is designed to settle 2,000 m3/day with an overflow rate of 32m3/m2-day. If the tank is 2.4 m deep and 4.0 m wide, what should the length and detention time be?