Influence of land use on water in the São Gonçalo reservoir, Paraíba, Brazil

This study aimed to assess the influence of land and water use on the São Gonçalo reservoir in Paraíba. The survey of land use and occupation in the vicinity of the São Gonçalo reservoir in Paraíba was carried out using satellite images from the Landsat series (Land Remote Sensing Satellite), referring to the orbit/point provided by the National Institute for Space Research (INPE) and with the aid of Spring 5.1.8 software. The parameters pH, total alkalinity, electrical conductivity, probable residue, total dissolved solids, thermotolerant coliforms and Escherichia coli were analysed. The pH of the reservoir water ranged from 7.4 to 8.2 in August and May. The electrical conductivity of the water remained constant from June to August (0.25 dS m-1), differing only in May (0.23 dS m-1). The alkalinity mg L-1 in July was the highest average compared to the other months (118.2 mg L-1). Thermotolerant coliforms and E. coli were present in all samples analysed. Of the 172.8 km2 of the area, 7% is occupied by crops, 53% is preserved caatinga, 1% is water, 1% is exposed soil, and 38% is degraded caatinga.