ESTIMATION OF PARAMETER OF A HYDRODYNAMIC RUNOFF-EROSION MODEL WITH DATA FROM A SEMIARID REGION IN BRAZIL

摘要

Data from erosion plots and micro-basins installed in a semiarid region of Brazil were used to calibrate the main parameters of a physically based model called WESP. In order to estimate the soil moisture tension parameter of the Green and Ampt equation, used for modeling the infiltration process, it was related to the Kohler index, an antecedent precipitation index. The other parameters showed no such clear trend with any single physical factor, due to the interaction effect between the main parameters of the model. A relationship between the above soil moisture tension parameter and the parameter affecting the erosion process on overland flow planes was sought to verify the existence of such an interaction. This relationship was used to estimate the value the erosion parameter for each of the events. The validity of the relationship was tested by comparing the results obtained from using the calibrated and estimated parameters in an adjacent micro-basin. The results show that the model simulated the runoff satisfactorily, but the calculated erosion values varied in a wide range, in both the cases.