Environmental analysis in a hydrographic basin of Brazilian Cerrado: estimation of soil losses and water quality indicators

Abstract

The natural resources are fundamental elements for human development. Among the natural resources, water is the essential component for all forms of life on the planet. In spite of the importance of water resources, the quality and quantity of water are increasingly threatened by the disorderly use and occupation of hydrographic basins. In hydrographic basins where the use of natural resources are intensified by human actions, environmental monitoring and assessment become important tools for the planning and environmental management of water resources. In this sense, the application of different techniques as allow the evaluation of land use and cover conditions and identification of possible sources of pollution. In which the Universal Soil Loss Equation (USLE), multivariate statistics, water quality index (WQI) and trophic state index (TSI) stand out. In this context, the present study aimed to estimate soil losses and analyze the water quality of the hydrographic basin of the Verdinho River, located in the Brazilian Cerrado, identifying the factors that contribute to the erosion process and the indicators that influence the water quality of this important hydrographic basin. The greatest potential for erosion coincided with the rainy season (November-March). In terms of real erosion, the results ranged from 0 to 56,713.57 t ha-1 year-1, with the highest soil losses rates observed between the months of November and March. The land use and land cover categories with the highest soil losses are bare soil (48,369,623.73 t year-1), agriculture (35,617,228.52 t year-1) and pasture (20,509,860.52 t year-1). The principal component analysis (PCA) explained 73.69% of the variance among the 16 physical-chemical parameters. In the analysis, total solids, temperature, turbidity, alkalinity, biochemical oxygen demand, hardness, total phosphorus, nitrite, nitrate and ammonia showed strong correlations. The water quality was classified in the “good” category in the most of evaluations. The trophic state index presented conditions between mesotrophic and eutrophic. The indicators analyzed seasonally and spatially are associated with natural and anthropic factors. The future implementation of a catchment project 794.40 L s-1 of water from this hydrographic basin depends on environmental planning strategies to reduce the impacts of anthropic activities on the water quality of Verdinho River hydrographic basin.