Analysis of the response of the Epitácio Pessoa reservoir (Brazilian semiarid region) to potential future drought, water transfer and LULC scenarios

Abstract

The Brazilian semiarid region (BSAR) is affected by the high precipitation variability and severe drought events over time, promoting recurrent water scarcity. The water supply in the BSAR has suffered since 2012 from severe incidents of rainfall reduction, creating a complex scenario of water scarcity, for instance, in Campina Grande city, which is supplied by the Epitacio Pessoa reservoir (EPR). This study analyzed the future impacts on the volume of the EPR based on potential future droughts, water transfer from the Sao Francisco River, population growth and recent changes in land use and land cover (LULC). Several procedures were performed, including (a) simulation of LULC scenarios with the LCM algorithm, (b) simulation of future rainfall scenarios for the period from 2020 to 2030, (c) streamflow simulation using the Soil Water and Assessment Tool (SWAT) model and (d) prediction of water storage in the EPR for the period from 2020 to 2030 using three rainfall scenarios (− 40%, − 45% and − 50%). The results indicated that the SWAT calibration and validation results were considered satisfactory based on the R2, Nash, and PBIAS values. The results were assumed from the rainfall scenarios for the period from 2020 to 2030 together with the LULC scenario for 2030, including the estimated outflow of water transfer from the Sao Francisco River. The results showed, based on the three adopted rainfall scenarios, that the reservoir would reach its critical volume in the first two years of the analyzed period, and the reservoir volume would then increase until 2024 and subsequently return to decrease, reaching the critical volume in 2030.