383477 - Slope wetting, infiltration, landslides, and erosion
Wednesday, June 6
4:00 PM - 5:30 PM
Location: Lake Superior B
J. Michael Johnson, Santa Barbara California – UCSB
A generalized Green-and-Ampt model is formulated to quantify infiltration on sloping terrain underlain by homogeneous soil wetted by surficial water application, such as rainfall or irrigation. This paper presents a theory for quantifying infiltration relying on the mathematical statement of the coupled partial differential equations (pdes) governing infiltration and runoff, which are solved employing an explicit finite-difference numerical method that calculates infiltration, the infiltration rate, the depth to the wetting front, the rate of runoff, and the depth of runoff everywhere on the slope during external wetting. Data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration, soil hydraulic characteristics. The paper develops and illustrates a method to predict the factor of safety against translational stability associated with an advancing wetting front caused by external slope wetting. Three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain. This paper resolves the effect that infiltration has on slope erosion. also.