Problem 3-1

Use the Penman method to calculate the evaporation rate for the following atmospheric conditions: air temperature, 20°C; net radiation, 525 cal/cm²/d; wind speed at 2-m above the surface, v₂ = 180 km/d; relative humidity, 30%.

Problem 3-2

Use the Thornthwaite method to calculate the potential evapotranspiration during the month of July for a geographic location at 40°N, with the following mean monthly temperatures, in degrees Celsius.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
10	12	14	16	18	20	21	19	17	15	13	10

Problem 3-3

The bottom of a certain 250-km reach of a river can be described by the following longitudinal profile:

in which y = elevation with reference to an arbitrary datum in meters; and x = horizontal distance measured from upstream end of reach in meters. Calculate the S₂ slope.

Problem 3-4

Calculate the peak discharge for a 650-mi² drainage area using the Creager formula (Eq. 2-73) with (a) C = 30 and (b) C = 100.