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Garden with Insight v1.0 Help: Soil patch next day functions: calculate potential soil evaporation

Potential soil evaporation can be calculated using any of four methods. The EPIC description says "The model offers four options for estimating potential evaporation: Hargreaves and Samani (1985), Penman (1948), Priestly-Taylor (1972), and Penman-Monteith (Monteith, 1965). The Penman and Penman-Monteith methods require solar radiation, air temperatue, wind speed, and relative humidity as input. If wind speed, relative humidity, and solar radiation data are not available, the Hargreaves or Priestley-Taylor methods provide options that give realistic results in most cases." We have included all these methods, but we have not tested any but the Penman-Monteith method.

Potential soil evaporation increases with higher solar radiation (because the radiation heats up the water at the surface of the soil), air temperature (because the water molecules move faster), and wind speed (because the water vapor is pulled away from the soil surface faster). High relative humidity tends to reduce evaporation because water from the soil enters the air slowly when the air already has a lot of water vapor in it.

calculation of actual soil evaporation
EPIC Evapotranspiration
Model contents

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Updated: May 4, 1998. Questions/comments on site to
Copyright © 1998 Paul D. Fernhout & Cynthia F. Kurtz.