Morphometric analysis and water quality assessment in the Retiro Baixo Reservoir, Paraopeba River (Brazil)

Aim This study aims morphometric analysis and water quality assessment in the Retiro Baixo Reservoir, located in the mouth of Paraopeba River. Methods Morphometric parameters were investigated based on the governmental agencies, field works and geoprocessing software. Ninety water samples were collected in three points at three different depths between 02/2019 and 08/2022. Results The involvement factor (If) showed that the reservoir dilution capacity may be small compared to the large basin drainage area. During higher inflow periods, there was an increase in the total suspended sediment (TSS), copper (Cu), iron (Fe), nitrate (NO3-) and phosphate (PO43-) concentrations. The results also showed vertical variation in temperature and dissolved oxygen values, with the highest copper (Cu) concentrations measured at the deeper depths. In fact, 60% of the Cu values samples exceeded the limit established by Brazilian legislation, while most of the Fe and Mn samples analysed had low concentrations (91.1% Mn and 66.6% Fe), with a few exceptions. Conclusions This concentration is also strongly influenced by hydrodynamic seasonality and geochemical background.