Crise hídrica no abastecimento de água em Campina Grande: análise de cenários futuros no volume de água do reservatório Epitácio Pessoa entre 2020 e 2030

Abstract

The water supply in Campina Grande has been suffering since 2012 with severe occurrences due to rain reduction, delineating a complex scenario of water scarcity. Thus, the objective of this study was to analyze future impacts on the Epitácio Pessoa reservoir volume, based on rainfall variability, population growth and recent changes in the land use and cover. This objective was based on the hypothesis that the water availability of the reservoir will not meet the demand of the population supplied by the reservoir, even with the transposition of the waters of the São Francisco river. In order to reach the objective of the study, several techniques of Geographic Information Systems, Remote Sensing and hydrological modeling were used, besides historical time series such as: (a) rainfall, (d) soil types, (c) land use and cover, d) land slope, and (e) demographic data. Several methodological procedures were performed: (a) non-parametric Mann-Kendall and Sen tests, (b) Pettitt's test, (c) simulation of land use and cover scenarios using the LCM algorithm, (d) simulation of future rainfall scenarios for the period from 2020 to 2030, (e) calibration and validation of the SWAT model for the period 1963 to 1991, and (f) prediction of reservoir volume. The results indicated that there were no significant rainfall trends in the study area, however, they showed a significant decrease in rainfall between 1963 and 1991. The SWAT calibration and validation results were considered satisfactory based on R², Nash, and PBIAS. As for the rainfall time series, a period of 10 years (1981 to 1991) was selected, in which reductions were applied in the monthly volumes (-40%, -45% and -50%). Then, the results were assumed as rainfall scenarios for the period from 2020 to 2030, together with the land use and cover scenario for 2030, including the estimated outflow for the transposition of the São Francisco river. The results confirm the veracity of the hypothesis in this study since in the three rainfall scenarios adopted, the reservoir reaches its critical volume in the first two years of the analyzed period, returning to increase the reservoir volume until 2024 and subsequently returns to critical volume, reaching the critical volume 2030.