Simulação hidrossedimentológica da bacia do riacho dos Namorados com modelo SWAT.

Abstract

In the regions where the monitoring network for runoff and erosion is deficient or inexistent, the use of hydrological models can provide reasonable estimates of surface runoff and soil loss, for watershed planning. This study deals with the application of the model SWAT (Soil Water Assessment Tool) in the "Riacho dos Namorados" Watershed and two of its sub-basins, 1 and 2 in the "Sao Joao do Cariri" Experimental Basin. The model, with the GIS interface ArcSWAT, requires the "Digital Elevation Model" (DEM) of the basin. The simulations were carried out using two different DEMs for the purpose of comparison: one was derived from the interpolation of field data and the other obtained through remote sensing. The model parameterization was done In the sub-basin 2 and the validation performed in sub-basin 1 T h e model performance was evaluated by the determination coefficient (R2) and of the efficiency factor of Nash-Sutcliffe. Riacho dos Namorados Watershed was simulated by the model under the present conditions of land use, by considering the presence of storage dams in one case and by ignoring them in another. These simulations permitted an evaluation of the influence of the dams. In order to evaluate the effects of changes of land use in the Riacho dos Namorados Watershed, four other scenarios in which the basin could be found were simulated in which the soil use considered were: (1) the native vegetation, (2) reforested with Mesquite (Prosopis Juliflora), (3) with the monoculture of corn, and (4) soil cleared bare. The influence of the dams in the basin simulated by the SWAT model was the attenuation of both surface flow and the sediment load. Among the simulated scenarios, reforestation with Mesquite protected the watershed against erosion better than the native vegetation "caatinga" and the cultivation of corn was just better than bare soil surface in terms of erosion. In conclusion, the SWAT model presented itself as a good tool for hydrosedimentological simulation in the region of Cariri in Paraiba.