Análise hidroclimática em bacias hidrográficas no semiárido brasileiro de acordo com projeções do CMIP6.

Abstract

The hydrographic sub-basins of SOBRADINHO, TRÊS MARIAS, and RETIRO BAIXO are located in the São Francisco River, which covers a large part of Northeast Brazil and plays a fundamental role in the production of biomass and quality water for the region, as well as being important for biodiversity conservation. Water resource management is essential to ensure effective water use. Climate change, driven by human activity, has significant impacts on the global hydrological cycle, including rising temperatures, glacier melting, changes in ocean currents and rainfall patterns, and a reduction in the amount of water stored in rivers and lakes. The Intergovernmental Panel on Climate Change (IPCC AR6) is an important report that assesses climate knowledge and describes how climate change affects various climatic elements. Understanding water flows is also crucial for planning measures to protect and recover the quality of water resources. The study aims to estimate the monthly water balance of the São Francisco River basin, focusing on the sub-basins of Retiro Baixo, Sobradinho, and Três Marias. For this purpose, the Thornthwaite method and the SMAP hydrological model were employed to understand variations in water resources over time and anticipate possible future climatic scenarios in the region.Climatology in the sub-basins under the historical period (1990-2014) differs from the SSP2-4.5 and SSP5-8.5 scenarios (2015-2035; 2045-2065; 2079-2100), revealing increases in temperatures and variations in precipitation. The water balance highlights pronounced deficits, especially in Três Marias and Sobradinho under SSP5-8.5 in the more distant time frames (2045-2065; 2079-2100), while the historical period (1990-2014) and the 2015-2035 range show similar deficits and surpluses.The use of SMAP to project flow shows good performance, but distinct patterns in calculated and observed flow highlight challenges in precise representation, especially in Sobradinho and Retiro Baixo during rainy periods and Três Marias in the dry period. In summary, model updates are crucial for accurate projections in the face of environmental changes, proving essential for sustainable water resource planning in the region.