Land use effects on water quality in the urban agglomeration of Cuiaba and Varzea Grande, Mato Grosso State, central Brazil

摘要

This study investigates the relationship between spatial patterns of water quality and land occupation in the cities of Cuiaba and Varzea Grande, Mato Grosso state, Brazil, applying Geographic Information System (GIS) techniques and Polynomial Redundancy Analysis. The results show a strong relationship between water quality and population density, urbanization rate and regionalized low water runoff. Higher treatment rates improve oxygenation levels, but do not reduce concentrations of total nitrogen, phosphorus and coliforms, indicating inefficiency of the sanitation infrastructure. The presence of more sophisticated treatment systems positively influenced catchment pollution levels. Sub-catchments which impact water quality of the Cuiaba River throughout the year typically deliver loads of mixed origin (impervious surfaces and untreated domestic wastewater). Monitoring stations downstream of the urban reach of the river show a trend of chemical and biological degradation.