Application of indexes to assess the water quality of coastal basin of the Sapucaia in Sergipe

ABSTRACT

The reduction of quali-quantitative availability of water in the world is directly related to the forms of land use and occupation, the productive processes of agriculture and cattle raising, the process of urbanization and the generation of domestic and industrial effluents. Thus, it is important to evaluate hydrographic basins regarding the use and occupation of their land and water quality as a tool for water management. This study aimed to characterize and monitor the quality of water of the Sapucaia Coastal Basin in the state of Sergipe, Brazil. The collections were performed quarterly in eight points of the basin, from August 2014 to September 2015. In the assessment of water quality, the Water Quality Index (WQI) and the Trophic State Index (TSI) were used. The analyzes of the samples were carried out according to the procedures outlined in Standard Methods; the following parameters were analyzed: total and fecal coliforms, turbidity, pH, dissolved oxygen, total solids, total phosphorus, total nitrogen, temperature, conductivity, biochemical oxygen demand and chlorophyll. The results from the application of the WQI classified water bodies as acceptable (2.5%), good (92.5%) and very good (5.0%). The results of the TSI ranked the samples as ultraoligotrophic (67.5%), oligotrophic (20.0%), mesotrophic (2.5%), eutrophic (7.5%) and supereutrophic (2.5%). The results allow to affirm that Aningas and Sapucaia rivers and Lagoa Redonda pond, belonging to the Sapucaia Coastal Basin, in Sergipe, have a low degree of degradation, with lower conservation of the sample point located in Sapucaia river, within the Reserva Santa Isabel reserve, that being a widely visited area on weekends and holidays.

Keywords:
water resources; water quality; environment