What is it?
Evapotranspiration simulation reflects the effects of plant transpiration and direct evaporation in removing water from the saturated ground water regime. The approach is based on the following assumptions:(1) when the water table is at or above a specified elevation occuring at a constant depth below the aquifer top (land surface), evapotranspiration (EVT) loss from water table occurs at a maximum rate specified by the user;
(2) when water table is at a depth equal to or exceeding the extinction depth or cutoff depth (measured from the elevation at which maximum rate of water loss occurs), evapotranspiration loss from water table ceases; and
(3) between these limits, evapotranspiration loss from water table varies linearly with water table elevation. (see Figure below).
How to use it:
First, specifiy the maximum rate of water loss [L/T] due to evapotranspiration in the text field next to 'MAX ET:'Then specify:
i) the depth from the land surface at which the maximum rate of evapotranspiration occurs ('ET Depth'); and
ii) the depth at which evapotranspiration ceases ('Extinction depth'), measured from the elevation at which maximum rate of water loss occurs.
