Evaluation of Biological and Sedimentological Issues Regarding a Bottom Discharge in the Paciência Small Hydro Power Plant - Brazil

The Paciência hydro power plant, located near the city of Juiz de Fora, Minas Gerais State - Brazil, was the scenario of many studies done in 2011-2012. These surveys were carried out in the scope of a project supported by CEMIG - electric utility responsible for the operation of the plant. The objective of this work is to present the results of the some studies conducted on the site, in particular those related to water quality and the existent benthic macroinvertebrate community, and the correlation of these parameters with the bottom discharge. The assessment of water quality showed the presence of critical levels of organic load in monitoring stations. The macrozoobenthic community found in the stations of the biomonitoring network reflected the conditions of water quality in this stretch of the Paraibuna River. The place was fairly poor in taxonomic variety and with excessive densities of a few taxonomic groups that are very resistant, characteristic of aquatic environments with high levels of organic load. The transport of fine sediment in suspension was quantitatively studied by labeling it with the radioactive tracer technetium 99, broadly used in nuclear medicine, in two campaigns, together with the application of a mathematical model. It was possible to verify that simulation of propagation of the suspended sediment concentration originating from bottom discharge in dry season, the most critical, showed that it decreased to a value of about 18% of the initial value of the bottom discharge