Changing water availability in the São Francisco River Basin, Brazil: exploring the role of expanding agriculture and climate change

Abstract

Human activities, such as agriculture, not only depend on but can also substantially affect the availability of water. Therefore, it is a concern that water resources are quickly being depleted in regions which already experience drought, like the São Francisco River Basin in Brazil. This thesis explores how the growth of large-scale agriculture, in the face of climate change affects water availability at the São Francisco River Basin and its sub-basins the Alto, Submédio, Médio and Alto São Francisco. The work combines remote-sensing observations of land-use change, water surface area and center pivot irrigation by MapBiomas, GRACE observations of total water storage and GLDAS climate re-analysis data to quantify trends in agricultural land-use, climate patterns and decreased water resources. As part of the analysis, climate and land-use datasets are combined to estimate water used by center pivot irrigation systems. It is found across the basin that agricultural land-use is growing, air temperature is increasing, rainfall rate is decreasing, and water storage is decreasing. Through the sub-basin analysis, it is shown that depletion of water resources is most pronounced in the Médio and Alto São Francisco sub-basins where the largest growth in agriculture and center-pivot irrigation is also observed.