Análise da influência da precipitação pluviométrica e do uso do solo sobre a qualidade da água em microbacias hidrográficas no nordeste paraense: Amazônia Oriental

Abstract

When forest is removed, giving way to agricultural production systems, pastures and urbanization, not just the landscape is drastically changed but watercourses quality is modified. The multiple uses of water and human activities in a watershed may cause significant changes in water quality. This study aims to acquire better knowledge about the influence of rainfall and soil use on water quality of watersheds located in the Amazon biome. The field survey was developed in Praquiquara watershed, Castanhal city, Pará state, Brazil. GIS was used for the delineation and mapping of land use in Praquiquara watershed and 8 (eight) sub-basins corresponding to the water quality monitoring stations. Water quality monitoring occurred in 4 (four) field surveys, distributed during rainy and dry seasons. It was concluded that the use and occupation of land in the watershed have a great influence on several water quality parameters. Parameters showing the largest changes were: turbidity, total suspended solids, total solids, DO, BOD, Iron and thermotolerant coliforms. The parameters that showed violations of legal standards for water quality were: pH, Dissolved Oxygen, BOD and thermotolerant coliforms. The results of water monitoring also showed great influence of rainfall on water quality parameters. BOD, nitrate, and iron are among the parameters that have presented concentration reduction during the rainy season. Total Suspended Solids, Dissolved Oxygen, Ammonia Nitrogen, Ammonia and nitrite are among the parameters for which concentration increased during the rainy season