Climate change and scenarios water uncertainty in the Upper Paraíba basin, Brazilian Semi-Arid

Abstract

Droughts and water scarcity are recurring phenomena in the Brazilian semi-arid region, historically associated with water, energy, and food insecurity. Recently, the longest drought on record was recorded, lasting from 2012 to 2017. In the state of Paraiba, this prolonged drought caused severe rationing of water supplies in Campina Grande and 22 other municipalities. This occurred because the Epitácio Pessoa reservoir, which supplies this region, reached a critical state, falling to its lowest historical level of 2.9%. Given this, this study aimed to analyze the impact of environmental and climate changes on the upper course of the Paraíba River basin, responsible for capturing and draining water for the Epitácio Pessoa reservoir. Changes in land use and land cover were assessed using the MAPBIOMAS database with a spatial resolution of 30 m per pixel, while current climatic conditions were analyzed using bioclimatic variables from 1970 to 2000 from WorldClim – Global Climate Data, and future scenario was projected using data from CMIP6 General Circulation Models (GCMs). Rainfall and reservoir volume data from AESA and livestock data from IBGE were used. The basin has lost about 1,400 km² of its Caatinga vegetation cover in the last 40 years, giving way to areas used for agriculture and livestock. With increased erosion, the reservoir has lost 13% of its capacity due to silting. Even though forecasts show that precipitation volumes will remain constant, an average temperature increase of 1.7 °C is anticipated, along with increased evapotranspiration and aridification, suggesting that water insecurity will persist in the upcoming decades.