DETERMINING THE SOIL MOISTURE-TENSION PARAMETER IN THE GREEN-AMPT INFILTRATION EQUATION FOR RUNOFF-EROSION MODELING

摘要

A method to determine the main parameters in the Green-Ampt infiltration equation is proposed based on indoor experiments carried out with two different samples of sand, and then the method is tested with field data collected in a semiarid region in Brazil. The results proved that the soil moisture content and suction could be aggregated in one parameter called moisture-tension parameter Ns, which showed to have a typical change according to the time variable. Thus, a relationship between the number of consecutive dry days and the parameter Ns was presented for a test field of a semiarid region in Brazil and a method was given to determine the parameter for the areas where measuring systems are not available on site.