Surface Seal Hydraulic Conductivity as Affected by Rainfall
ABSTRACT Anew method is presented for determining the effective hydraulic conductivity of a surface seal at the beginning of ponding. Experiments were conducted to measure soil-water pressure changes occurring during surface seal development caused by rainfall applied over a range of intensities. Soil-water pressure was measured at 1 cm and 5 cm depths beginning within 10 min after rainfall application began and continuing until ponding occurred. These measurements were used to compute hydraulic conductivity of the surface layer at the beginning of ponding. These computations were based on a 1 cm thick surface seal, determined by the placement of the first tensiometer. Soil stability factors were calculated for each of the soils analyzed. Equations were developed relating the decay of effective hydraulic conductivity of the surface seal at ponding to rainfall and soil characteristics. A relation predicting hydraulic conductivity of a 1 cm surface seal at ponding as a function of time to ponding and percent sand in the soil was developed and tested.