Projection of Land Use To 2030 and Its Impacts on Water Availability in a Brazilian Sub-Basin: a LCM and SWATAT App roach

Abstract

Changes in land use and land cover (LULC) can result in significant changes in a hydrographic basinflow regime. Future projections about LULC and its interference with water availability help toidentify extreme events in advance and help propose appropriate management measures. Thus, thisstudy aimed to make the LULC projection for the year 2030 for the Alto Rio Grande (ARG) subbasin,located in Southeastern Brazil. This region was chosen because of its intense water resourcesuse and for having recently faced water scarcity as result of prolonged droughts and inadequate waterresources management. To identify the LULC trend for the year 2030, the Land Change Modeler(LCM) was used, the map obtained was inserted in the Soil and Water Assessment Tool (SWAT)model previously calibrated and validated for the region’ environmental and climatic conditions.The ARG sub-basin was affected by heavy rains in 2011, which resulted in changes in the landscapedue to landslides. This particularity of the region contributed to the projection of LULC for theyear 2030 to present an increase in forest and pastures to the agricultural areas detriment. Whenevaluating the impacts of these changes in water availability, it was observed that the SWAT modelpresented, for the same rainfall conditions, a reduction in peak streamflows of up to 59% and areduction in the average monthly flow of up to 63% in 2030 in relation to the LULC observed in2017. Thus, this study provides an important contribution by identifying a considerable reductionin water availability. These results will help to formulate strategies for water resources managementand the adoption of measures to promote water security in the region.