CIV E 634 - SURFACE WATER HYDROLOGY
FALL 2018
HOMEWORK 2:   EVAPORATION

  1. Use PENMAN to calculate the monthly ET for March for the given data: mean monthly air temperature 18°C, mean monthly net radiation 550 ca/cm2/day, relative humidity 70%, and wind velocity at 2-m depth 180 km/day.

  2. Use PENMAN-MONTEITH to calculate the evapotranspiration rate of the reference crop (clipped grass 0.12-m high) for the month of February, with the following atmospheric conditions: air temperature Ta = 23 oC; net radiation Qn = 600 cal/cm2/d; relative humidity RH = 75%; wind velocity v2 = 220 km/d; and atmospheric pressure = sea level (1013.2 mb).

  3. Use PENMAN-MONTEITH to study the sensitivity of the reference crop evapotranspiration to the relative humidity. Use the same data as in Problem 2. Vary relative humidity between 1% and 100% in increments of 20% (1, 20, 40, 60, 80, and 100) and report the results. What can you conclude from the results?

  4. Given the reference crop, with air temperature Ta = 16oC, net radiation Qn = 520 cal/cm2/d, and atmospheric pressure = 1005 mb. At what wind velocity during January will the reference crop PET at RH = 20% be double that at RH = 100%?