Soil Hydraulic Parameters for Evaporation in Large Scale Heterogeneous Soils.

Effective soil hydraulic parameters at relatively large scales (e.g., remote sensing footprints and large climate model grids) are important for land–atmosphere interaction and general circulation models as well as other applications. This study investigates the use of effective soil hydraulic properties applicable to large scale evaporation problems in a landscape with heterogeneous soil hydraulic properties. The specific objectives are to investigate: 1) how the effective hydraulic parameters are sensitive to the heterogeneity of soil hydraulic properties, 2) how the evaporation time frame affects the effective hydraulic properties, and 3) which effective soil hydraulic property schemes are suitable to represent average behavior of large scale evaporation processes. Large scale average evaporation behavior in the heterogeneous soils is quantified through multiple simulations of local scale evaporation and aggregation. The effective hydraulic parameters are then calculated to minimize the difference between average cumulative evaporation and cumulative evaporation based on a single set of effective parameters. The effects of variances and correlations of local scale hydraulic parameters, and various other conditions such as surface boundary conditions on the effective hydraulic properties are extensively examined and discussed.