Unraveling the Impact of Human Activities on Water Quality of an Urban River in an Unplanned Zone of the Amazonian Coast

This study focuses on the Cereja River, a Permanent Preservation Area located in Amazon coast. The hypothesis tested was that the water quality of the Cereja River has worsened over recent years due to unplanned urban growth. To assess changes in the water quality, seven campaigns were undertaken with data being collected at six fixed points, during two distinct periods (2013–2014 and 2018–2019). High-resolution satellite images from GoogleEarth (2012 and 2019) were used to register unplanned occupation. The DPSWR (Driver-Pressure-State-Welfare-Response) socioecological framework was used to identify potential measures for the management of environmental and anthropogenic problems. The increase in the number of households found on the Cereja margins between 2012-2019 has contributed to the river’s intense trophic condition, low concentrations of dissolved oxygen, high concentrations of pathogenic bacteria, and loss of vegetation cover. The water of the Cereja River is inadequate for any human use, and its contamination is one of the principal factors determining the reduction of the water quality of the Caeté estuary. According to the obtained results, the DPSWR model proved to be an excellent analytical tool for the evaluation of specific local scenarios, through the integrated analysis of socio-environmental issues. The scenario observed can be extrapolated to other rivers located within urban areas in the Amazon region that have relatively unplanned growth.