Mudanças no uso do solo e comportamento hidrológico das bacias hidrográficas dos rios Peruípe, Itanhém e Jucuruçu, Bahia

Abstract

Land use activities, even in small proportions, are capable of causing interference in the hydrological behavior of river basins. Due to the fact that the substitution of native vegetation by anthropic activities is taking place on increasingly larger scales, it is necessary to analyze and understand its effects and consequences on the water availability of the basins. Therefore, this work sought to analyze the influence that changes in land use and occupation have on the hydrological behavior of the hydrographic basins of the Peruípe, Itanhém and Jucuruçu rivers, located in the identity territory of the Extreme South of Bahia. For this purpose, data from the historical series of the fluviometric stations located in the drainage areas of the studied watersheds, imported from the HidroWeb portal of the National Water and Sanitation Agency, were used. From these, the annual hydrological variables were obtained: maximum, average and minimum flows. The data related to the size of the area, extension and class delimitation were provided by the Forestry Forum of the Extreme South of Bahia. The data analysis was performed by comparing the maps of land use and occupation and the areas occupied by the 18 classes analyzed, thus verifying the changes that occurred in each period. Subsequently, the association of the data was made through quantitative analysis performed in the software SAS University Edition, where simple statistical correlations between the variables were obtained. The Itanhém and Jucuruçu river basins presented pastures as the predominant activity in their territory, occupying an area equivalent to 66.1% and 62.9%, respectively. The Peruípe river basin is currently occupied by pastures (32.4%) and eucalyptus (32.1%). The expansion of areas for livestock (Itanhém and Jucuruçu) occurred due to the suppression of areas of native vegetation, which suffered a significant decrease in these basins. It is believed that the fact that the basins are occupied predominantly by anthropic activities, is directly contributing to the reduction of these flows, since the correlation analysis has shown that the expansion of these areas has influenced the decrease in minimum flows. Therefore, it is necessary to balance economic objectives with the environmental damage that such cultures cause, through public policies that guarantee preventive planning and management, in order to guarantee security in the water availability of these basins