Impact of Evaporation on Field Capacity during Water Drainage
Redistribution in a Soil
Abstract
To this day, field capacity (FC) is rarely defined in the context of
soil properties, and the use of non-physical simplistic models is the
common way to normalize water content at FC. In this study, the problem
of water drainage redistribution in a soil water column with and without
the presence of Evaporation (EV) was extensively studied. Analytical
solutions for Richard’s equation were established for the case of water
drainage redistribution through a deeply wetted soil column with and
without EV at Field Capacity (FC) conditions while water retention and
depth evolution curves were plotted first, using different EV values of
2 mm/day, 5 mm/day and 8 mm/day and second, for different drainage
redistribution durations of 1 day, 4 days and 6 days where EV was set to
zero for the case with no EV or to a fixed value of 5 mm/day for the
case with EV. The results suggest that EV plays a significant role in
soil water drainage suggesting that, in the presence of EV, the FC
drying front reaches much higher depths in the soil water profile than
if EV is turned off. It was also concluded that FC reaches deeper depths
faster the stronger EV is acting AT the surface of A soil water column.