AN INVESTIGATION OF THE SCALE EFFECTS IN RUNOFF-EROSION MODELING IN THE SEMIARID REGION OF BRAZIL

摘要

In this study, two runoff-erosion models, distributed and event oriented, Kineros2 (Kinematic Runoff and Erosion Model) and WESP (Watershed Erosion Simulation Program), have been used to investigate the scale effects on their parameters, when they applied to hydrologic basins varying in size from 100 m~2 of experimental erosion plots to a major sub-basin of 140 km~2. The Kineros2 model was applied to nine 100 m~2 plots and four microbasins (0,5 ha - 1.0 ha) of the Experimental Basin of Sume (BBS) and to three sub-basins 10 km~2 to 140 km~2 area of the Representative Basin of Sume (RBS), located in the semiarid region of the State of Paraiba, in the northeastern region of Brazil. The model WESP was applied only to the three sub-basins, since it had already been applied to the experimental units of the BBS in earlier studies. The results show that the main parameters of the Kineros2 model, the effective net capillary drive (G) of the Smith and Parlange infiltration equation and the parameter relative to the splash erosion, c_f, suffer scale effect. It was also found out that the parameter N_s of the Green and Ampt infiltration equation, used in the WESP model, also varies with the watershed size and hence subject to the effect of scale.