Efeitos de fatores climáticos e uso do solo sobre o escoamento em uma região semiárida da Paraíba.

Abstract

The study of the variability of climatic factors and land use, and the possible impacts caused by them in the semi-arid region of the Northeast of Brazil, are of great importance since they directly affect the formation and generation of the runoff in the catchments of the region. The natural resources of the semi-arid zones, which are highly vulnerable to the variation of climate, tend to be scarce and are easily damaged by human action (land use) and also by the alterations in the evaporation and precipitation standards, with frequent occurrence of droughts and, as a result, reduction of water supply. In this research, the effects of the variability of the precipitation, evaporation and land use on the simulated water discharge of several catchments in the region of Alto Piranhas/PB are studied. The study is based on the application of the distributed model NAVMO, which was first validated for the region of the study and, after that, used to simulate different scenarios. The results show that, the model simulates the water flow reasonably well (1^-0.7 on average) which is mainly affected by the joint variability of precipitation, evaporation and land use. Separately, the precipitation has great effects on discharge, with mean variation (volumes and peaks in relation to the mean values) between 0.21 and 2.34 (volumes) and 0.3 and 1.83 (peaks), and the land use change with mean variation between 0.4 and 2.24 (volumes) and 0.58 and 1.44 (peaks). The evaporation has the least effects on the flow with mean variation between 0.92 and 1.11 (volumes) and 0.97 and 1.05 (peaks). Combining these factors, the effects on discharge are even greater with mean variation between 0.25 and 3.4 (volumes) and 0.33 and 2.44 (peaks).