For a given watershed you have an annual precipitation estim

For a given watershed, you have an annual precipitation estimate of 3 feet per year and an average discharge rate of 90 cubic feet per second. If the watershed is 100 mi2 (1 mile equals 5,280 feet) what is the annual rate of discharge in feet per year (assume that the system is in a steady state and round your answer to one digit)?

Solution

Q= 80 cubic feet per second

=80*365*24*60*60 ft3/year

=0.25*10¹⁰ft3/year

Precipitation= 3 feet/year

annual rate of discharge = 3*0.2788*10¹⁰ - 0.25*10¹⁰

=(0.5864*10¹⁰)/0.2788*10¹⁰

=2.1 ft

=25.24 inches.