Uso e ocupação do solo, qualidade da água e disponibilidade hídrica do médio curso do rio Piracicaba-MG

Abstract

Water resources are essential for the survival of living beings and for economic development. The forms of land use and occupation can affect the environment and water bodies, and trigger negative changes to these resources. The study area of this work encompasses the region of the middle course of the Piracicaba River, which has activities with high potential impact on the environment and water resources, being the Piracicaba River its main watercourse. The main objective of this research is to obtain a diagnosis of water quality, flow and precipitation behavior and land use and occupation of the middle course of the Piracicaba River-MG in the years 2011 and 2020. To this end, land use and occupation charts will be generated, the Water Quality Index-IQA will be calculated, water quality parameters will be evaluated, rainfall/fluviometric behavior will be analyzed using data from monitoring stations present in the study region, and the interrelationship between these factors will be verified. Most of the sub-basin is occupied by forest formation (45.11%). In second place are the pasture areas (31.23%), it is noteworthy that in the region there are localities with cattle breeding, which justifies the maintenance of pasture areas for agricultural production. The mosaic class of agriculture and pasture obtained 11.49%. The planted forest class makes up 8.07%, with eucalyptus reforestation areas in the region for the production of pulp and charcoal to supply steel mills. There was an increase in area between the periods studied of the mining, agriculture and pasture, forest formation, planted forest classes and there was a decrease in pastures and rivers and lakes classes. In most of the water quality stations and periods analyzed, the WQIs were classified as average. Comparing the 2011 and 2020 results, the WQI class remained the same or improved in practically all 2020 assessments, with the exception of RD034 (Mariana) which had all average WQIs in 2011 and, in 2020, obtained poor WQIs in the 1st quarter (rainy period). In general, analyzing the results of the water quality parameters, the oscillations of values referring to the WQI may be associated mainly with the high concentrations of Thermotolerant Coliforms, and also due to variations in pH, total phosphorus, turbidity and total solids. The Dissolved Oxygen and Biochemical Oxygen Demand values were satisfactory in the water quality analysis. There was a significant difference in the rainfall index in the periods studied and also variation in the average daily flows between some periods.