53:119 Hydrology
Problem #10
Evaporation from the Land Surface (Energy Budget)

Evaporation from the land surface (i.e., evaporation from open water surfaces and transpiration through plants) depends on the soil moisture near the ground surface and the transport of water vapor (e.g., winds) away from the surface. For a (hypothetical) site, representative values of the Bowen's ratio are given below for various moisture states and weather conditions.

Conditions Dry Soils Wet Soils
Calm Day 1.5 0.8
Windy Day 0.6 0.2

If the net radiation on a given day is 300 W/m2, estimate the following for all four conditions:

  1. The energy (or power) (W/m2) used for evaporation (evaporative heat flux Qe)
  2. The energy (or power) (W/m2) used to heat the air above the ground (sensible heat flux Hs)
  3. The evaporation rate (mm/day) using the energy-budget method

Last changed on 09/05/12 by aab.