The Prediction of Evaporation, Drainage, and Soil Water Storage for a Bare Soil

Abstract

Evaporation, drainage, and changes in storage for a bare Plainfield sand were measured with a lysimeter during June, July, and August 1967, under natural rainfall conditions. Cumulative evaporation at any stage was proportional to the square root of time following each heavy rainfall. The drainage rate was found to be an exponential function of water storage. Both relations can be predicted from flow theory with knowledge of soil capillary conductivity, diffusivity, and moisture retention characteristics. Using these two relations and daily rainfall data, the water storage in the top 150 cm was predicted over the season to within 0.3 cm.

Characterization of unsaturated hydraulic conductivity at the Hanford Site

“…Using a time-averaging approach, the integral, / B8/3t dz, of Equation (2.7) can be estimated by trapezoidal approximation for each depth interval, as described by Green, Ahuja, and Chong (1986 Green, Ahuja, and Chong (1986 Black, Gardner, and Thurtell (1969) studied drainage losses from lysimeters and noted that the "unit gradient" condition was often valid. Davidson et al .…”

Functional evaluation of a simplified scaling method for assessing the spatial variability of soil hydraulic properties at the hillslope scale

“…Thus, the potential evaporation is almost 45% of the potential evapotranspiration, during the entire simulation period. To calculate the actual evaporation rate, E a (cm d -1 ), we adopt Black's equation (Black et al 1969):…”

Physically-based modeling of topographic effects on spatial evapotranspiration and soil moisture patterns through radiation and wind

“…In the SWAP model, the actual soil evaporation (EA) is determined by the minimum value of EP, the restricted Darcy flux E max at the top soil layer (see Eq. 9) and/or the results from the empirical evaporation functions of Black et al (1969) or Boesten and Stroosnijder (1986).…”