Efeitos de escala na modelagem hidrossedimentológica na região semiárida da Paraíba.

Abstract

Representative basins are those that possess similar characteristics with a certain hydrologic region. Researches with hydrologic models in representative basins are very important because their results can, a priori, be expanded to regions of which these basins are representative. However, it is known that the scale of the watershed can affect the values of the parameters of a model used for simulating the hydrologic processes. Thus, the concept of representative basin needs to be reevaluated. In this study, two runoff-erosion models, distributed and event oriented, known as Kineros2 (Kinematic Runoff and Erosion Model) and WESP (Watershed Erosion Simulation Program), have been used to investigate the scale effect on their parameters, when they are applied to basins with scales varying between 100 m (plots) and 140 km . The Kineros2 model was applied to nine 100 m plots and four microbasins (0,5 - 1.0 ha) of the Experimental Basin of Sume (EBS) and to three sub-basins (10 - 140 km2) of the Representative Basin of Sume (RBS), located in the semiarid region of the State of Paraiba. The model WESP was only applied to the subbasins, since it had already been applied to the units of the EBS. The results show that the main parameters of the Kineros2 model, effective net capillary drive (G) of the Smith and Parlange infiltration equation and the parameter relative to the splash erosion, Cft suffer scale effect. It was also found out that the parameter N, of the Green and Ampt infiltration equation, used in WESP model, also varies with the watershed scale.