Processos hidrossedimentológicos na bacia do rio Taperoá

Abstract

The study of erosion processes generated by water action can be called runoff-erosion study. This work aims to analyzed the water and sediment yield at the Taperoá River basin, located in the semiarid region of Paraíba State, based on the runoff-erosion model named Soil and Water Assessment Tool (SWAT). In order to develop this study, rainfall, temperature and humidity data from 1970 to 1990, soil map, land cover map and digital elevation model with spatial resolution of 30 m were used. The data set was divided into two parts in order to compare the influence of land use with the behavior of runoff and sediment yield in the basin. The periods selected for modeling were: a) 19701980; and b) 19811990. The model was calibrated and validated by comparing simulated mean monthly runoff with observed longterm mean monthly runoff at Poço de Pedras gauge. The model was calibrated using the auto-calibration method SUFI-2 in order to obtain optimal settings for modeling. Statistical indices (Nash and R²) were used to evaluate the model performance to estimate the runoff and sediment yield in the basin. The results showed the effectiveness of the model for the analysis of runoff process with average observed runoff = 6.56 m³/s and average simulated runoff = 8.39 m³/s between 1970-1980, and average observed runoff = 3.48 m³/s and average simulated runoff = 3.67 m³/s between 1981-1990. The results show that the land cover change affected the basin hydrology, decreasing the sediment yield (1.33 t/ha/yr in 1970-1980 to 0.08 t/ha/yr in 1981-1990).