Mudanças no uso e ocupação da terra e impacto no ciclo hidrológico: região de influência do rio Javaés

Abstract

Hydrological modeling has proven to be an effective tool for planning and managing water resources, allowing the assessment and prediction of anthropogenic impacts on the hydrology of a watershed. This study evaluated the relationship between land use and land cover changes and water availability in the region influenced by the Javaés River, Tocantins State, using the SWAT hydrological model and the Dinamica EGO spatial dynamics model. The research analyzed the impacts of agricultural activity between 2004 and 2023 and projected a future scenario for 2043. Land use and land cover, soil, slope, climatic, and streamflow data were processed. The calibration and validation of the SWAT model showed satisfactory performance. Between 2004 and 2023, native vegetation decreased by 8.24%, with a 21.03% reduction in Cerrado formations, alongside the expansion of pasture, rice, and soybean crops. These changes resulted in increased mean river flows (+0.27 m³/s at Barreira do Pequi and +0.32 m³/s at Fazenda COBRAPE), indicating reduced water retention capacity in the basin. The 2043 projection indicates continued agricultural expansion (rice to 3.64%, soybean to 1.60%, and pasture to 25.23%) and Cerrado reduction to 19.91%. This future scenario suggests an increase of approximately 0.6 m³/s in average monthly flows, with higher peaks during the rainy season and lower ones in the dry period, revealing a less resilient hydrological system. It is concluded that the conversion of native vegetation to agricultural uses affects the basin’s water dynamics, highlighting the need for integrated land-use planning that reconciles the region’s agricultural vocation with the sustainability of the Javaés River water resources.