Simulations of the climate change and its effect on water resources in the Palma River basin, Brazil

Anthropic and natural factors can affect the water availability in a basin, making necessary the use of tools that allow the simulation of future scenarios. Considering that future climate change can affect water resources, the objective of this study was to evaluate the sustainability of the Palma River basin, located in the Tocantins state, Brazil, throughout the century, under scenarios of climate change and increase in irrigated area. Future runoff was simulated using the SWAT model, considering the Eta/HadGEM2-ES and Eta/MIROC5 climate models and the RCPs 4.5 and 8.5 emission scenarios. The crop irrigation requirement was simulated using the AquaCrop model. A model was created in STELLA software, where the water supply and demand data in the basin were entered, and the sustainability index (SI) was calculated, whose results were statistically analysed through trend and correlation tests. HadGEM 8.5 was the most unsustainable scenario. MIROC 4.5 and MIROC 8.5 scenarios showed higher growth of unsustainable months over time. A trend of decreasing SI and increasing unsustainable months was observed in most scenarios. The results found can assist in the decision-making of water resource managers, to promote the mitigation of climate change effects in the basin.