SIMULATION OF PROFILE WATER STORAGE AS RELATED TO SOIL HYDRAULIC-PROPERTIES

The separate and combined processes of infiltration, drainage and evaporation as determined by hydraulic properties was simulated from a numerical model of soil-water dynamics. Three hypothetical soils were compared: sand, loam and clay. Typical soil moisture characteristic functions were assigned to each, and the respective hydraulic conductivity functions were calculated. Uniform profiles of these soils were then subjected to various sequences of rainstorms and dry periods. The sandy soil provided the least evaporation and the most rapid downward flow. This resulted in the most effective storage under a relatively dry regime. The situation was reversed in the case of the clay soil, which stored the most water under a relatively wet regime, while the loam exhibited intermediate behavior. Some consequences of affecting arid zone ecology are discussed.