Hydrological regime, water availability and land use/land cover change impact on the water balance in a large agriculture basin in the Southern Brazilian Amazon

Abstract

The Southern Brazilian Amazon, in the North of Mato Grosso state, has experienced significant changes in land use and cover, which can cause major changes in its hydrological regime. Moreover, data availability and technical support are very scarce in the region, which has been causing serious problems and eminent water conflicts. This study assessed the hydrological regime, water availability, and the impact of land use/land cover (LULC) change in a large agriculture river basin in the Southern agricultural frontier of the Brazilian Amazon. The water balance components such as runoff potential, evapotranspiration, lateral flow and groundwater contribution of the Upper Teles Pires basin have been simulated under different LULC scenarios using the Soil and Water Assessment Tool (SWAT). Overall, the SWAT model performed well and was able to reproduce the flow regime adequately for the Upper Teles Pires basin, demonstrating robustness even within a data-sparse basin. The forest conversion to agriculture use has directly impacted the surface runoff and groundwater contribution of the Upper Teles Pires basin from 1986 to 2014, increasing by 30.8% and decreasing by 5.29%, respectively. From 1986 to 2006, a 5% forest change causes a 17% (9.2 mm) change in the runoff, which represented 6.5% of the total runoff in the basin from 1986 to 2006. The information provided in this study would help local authorities and decision-makers to plan water resources strategies in this basin of strategic importance for Brazilian agriculture.