Spatio-temporal dynamics of surface water quality of two large reservoirs of Brazilian hydroelectric plants

ABSTRACT

The use of water resources for energy generation, generally, involves the design of artificial dams and reservoirs. The construction of reservoirs may be associated with socio-environmental impacts. The use of statistical techniques and indexes to assess surface water quality data has been an efficient tool for understanding the spatial dynamics of these environments. The work aimed to evaluate the water quality in two large reservoirs and their main tributaries, the Emborcação and Nova Ponte hydroelectric power plants in Minas Gerais. Secondary data were evaluated using the Multivariate Statistical Technique of Cluster Analysis (CA), followed by non-parametric tests, also the Environment Water Quality Index (WQI) and the Trophic State Index (TSI). To support the discussion of the results, the types of land use and occupation in the study area were also analyzed. The results of the CA indicated the separation of the monitoring sites of each reservoir into groups, according to their locations and the type of environment in which they are inserted. The results of the statistical tests suggested a better water quality in the groups formed by stations located in the reservoir and close to it, which have been confirmed by WQI. The results of the WQI indicated the adequacy of the quality of these waters, in relation to the proposed uses for class 2 framing. About the TSI, there was the presence of intermediate primary productivity at acceptable levels. The predominance of land use for agriculture can partially justify the degradation conditions of the water quality watercourses’, especially about the parameters associated with solids and nutrients.

Keywords:
water quality; reservoir; hydroelectric power plants; multivariate statistics