Impactos das mudanças climáticas e do uso e cobertura do solo na disponibilidade hídrica da bacia do rio Paraopeba

Abstract

The Paraopeba River basin, located in the state of Minas Gerais, Brazil, is strategic for public water supply, irrigation, and economic activities in the Metropolitan Region of Belo Horizonte. In recent years, the basin has undergone intense environmental changes resulting from climate change and significant transformations in land use and land cover, including deforestation, urban expansion, mining, and agricultural activities. In a context of water vulnerability, this study analyzed and quantified the impacts of climate change and anthropogenic activities on water availability in five sub-basins of the Paraopeba River Basin between 1986 and 2022. To this end, the Budyko curve decomposition method was adopted. This method, based on the relationship between precipitation, potential evapotranspiration, and actual evapotranspiration, allowed the decomposition of relative contributions from climate, through the aridity index, and from land use and land cover changes. The results showed an increasing trend in aridity in the region since 2014. All five analyzed sub-basins exhibited reductions in runoff, to varying magnitudes, due to both climatic and anthropogenic influences up to the end of 2022, with the most pronounced reduction observed in Sub-basin 5, reaching 57.31% relative to the mean runoff. In Sub-basins 2, 3, and 4, the negative effects of climate on runoff were partially offset by the opposing influence of anthropogenic activities; however, these effects were not sufficient to result in a positive total runoff balance. Sub-basin 5, corresponding to the most downstream accumulated area, presented the most critical scenario. In addition to climatic effects, land use also contributed to runoff reduction, indicating that extensive agricultural land use, marked by a strong presence of temporary crops, along with intensified water withdrawals especially for irrigation—may have played a significant role in reducing runoff. The results demonstrate that climate change and anthropogenic activities significantly affect water availability in the Paraopeba River Basin and may increase local vulnerability to drought events, which have become more frequent, severe, and intense in the basin.