Estudo do balanço hídrico da área de influência da zona de recarga do Sistema Aquífero Guarani (SAG) no estado de São Paulo

Abstract

The outcrop zone of the Guarani Aquifer System (GAS) in São Paulo has an area composed by sandstones of Botucatu and Pirambóia lands, with great potential for recharge. However, on the limits of this zone are the largest urban centers, such as: Ribeirão Preto, São Carlos and Araraquara, which uses water of the GAS to get water demand. This study, was based on a survey of weather data, the extracts of water balance about outcrop area of the GAS. Thus, the results obtained by the present study may help decisions about sustainable management of groundwater resources. For construction the extracts of water balance about outcrop areas of the GAS, was used the methodology created by Thornthwaite and Mather (1955). The application of this methodology, among the results, allows the best understanding of the hydrological cycle gains and losses, thus, the knowledge of the main factors related to water balance, as the potential and relative evapotranspiration, surplus and water stress. The northern region show extract of water balance with surplus between November to March for the historical period studied. Already the central region has averaged only between January to March. The southern region, shows an extract with water surplus throughout the historical average analyzed. The highest average deficit in the northern and central regions are found between August and September. In the southern region shows no significant mean deficit. With this analysis about the extracts of regions in the GAS, comparing different average historical periods, is concluded there was a negative trend in the water balance for the latest series (2002-2013), worsening of water stress.