One-dimensional Soil Water Movement under NegativeSupply Water Pressures

摘要

Supply water pressure was maintained at different negative values andvertical infiltration, capillary rise, and horizontal infiltration processes were observed.With decreasing supply water pressures, relative differences of vertical infiltration,capillary rise, and horizontal infiltration processes in infiltration rates and wetting frontmovement decreased. The wetted thickness at which infiltration rate is equal topotential evapo-transpiration rate is defined as critical wetted thickness, and criticalwetted thickness at different negative hydraulic heads were obtained for the studiedloamy soil by setting potential evapo-transporation rate at 5mm/d. Linear relationshipsbetween wetted thickness and cumulative infiltration for vertical infiltration, capillaryrise, and horizontal infiltration were validated. The slope of wettedthickness-cumulative infiltration, I.e., mean percentage of wetted soil volume occupiedby infiltrated moisture, was defined as wetting coefficient, and the relationshipsbetween wetting coefficient and supply hydraulic head were provided for the studiedloamy soil. A model describing soil moisture profile for vertical infiltration, capillary rise,and horizontal infiltration under negative supply water pressures was provided. Thereliance of wetting front water content on supply hydraulic head was alsodemonstrated.