Spectro-temporal analysis of anthropic interference in water production in the Guarani Aquifer

The Guarani Aquifer System is one of the largest freshwater reservoirs in the world and has been widely exploited due to the quantity and quality of the stored water. The outcropping areas are considered highly vulnerable, and anthropic interference can influence the recharge potential and cause changes in water quality. The purpose of this research was to spectrally and temporally analyze the anthropic interference in water production in the Guarani Aquifer in four distinct areas located in the outcrop and recharge areas located in the State of São Paulo, Brazil, from 2012 to 2018. Rainfall data were obtained using the CHIRPS dataset, and the actual evapotranspiration rate was obtained using the MODIS product. The lithology and piezometric level data were obtained through RIMAS of the Geological Service of Brazil. The piezometric level monitoring wells were used as a reference to delimit the study areas and the distance to eliminate overlapping spatial resolutions of the remote sensing products. The area bounded by the buffer is equivalent to 31,412 ha. The recharge was estimated with the ESPERE using the water table fluctuation method. The end classifications of land use were obtained using the normalized difference vegetation index through remote sensing data. The study area located in the municipality of Boa Esperança do Sul - SP had the largest area of exposed soil with a median of 2936 (ha) and the lowest recharge potential with a median of 338 mm/year. The study area located in the municipality of Bofete - SP had the smallest area of exposed soil with a median of 516 (ha) and the highest recharge potential with a median of 502 mm/year. The study area located in the municipality of Brotas - SP showed the lowest evapotranspiration rate, with a median of 639 mm/year. The municipality of São Simão - SP had the largest forest area, with a median of 18,009 ha. Although water resource policies have significantly influenced the valuation of groundwater, studies that assess changes in land use variables using time series analysis and evaluate how these changes influence water dynamics in the hydrological cycle are still lacking. The study aims to contribute technical support to the decision-making process of the National System of Water Resources Management (SINGREH) and State Law 9866/1997 to contribute to the sustainability of the Guarani Aquifer System.