Application of indexes to evaluate the water quality of the Continguiba/Pindoba Irrigated Perimeter in Sergipe, Brazil

Irrigation makes food production viable, but the quality and quantity of water may be compromised as a result of inadequate management, which may lead to an increase in the concentration of nutrients, heavy metals and agrochemicals. This study aimed to characterize and monitor the water quality of the Continguiba/Pindoba Irrigated Perimeter in Sergipe, Brazil. Secondary data from the Water Quality Monitoring Program were used through the reports of monitoring campaigns carried out between 2013 and 2014. The Water Quality Index (WQI) and the Trophic State Index (TSI) were used in the water quality assessment. The results showed that there is an influence of seasonality, where the best indices were obtained in the rainy season, with the WQI characterized as regular to good, and the TSI characterized as oligotrophic. There was interference from the drainage of rice lots in the dry season, contributing to the increase of nutrients. There was no spatial influence for WQI, which may be related to the eclipse effect, which attenuated the negative impact of a certain variable given the aggregation of several variables. The TSI suffered spatial influence, the waters added to agricultural and fish lots were classified as oligotrophic or ultraoligotrophic, already in the drainage were found indexes of super-utrophic state