Sedimentation in reservoirs. Case study: the reservoir of the São Bartolomeu stream, Viçosa, Minas Gerais, Brazil

Abstract

Sedimentation in bodies of water is a worldwide problem that impairs its navigability and utilization, and, in reservoirs, this process reduces their partial or total storage capacity. Using single-beam bathymetric survey techniques, this study evaluates the silting process in a reservoir section at the Federal University of Viçosa (UFV), located in Viçosa, Minas Gerais, in the Southeast region of Brazil. An analysis of the charts showing the DEM (Digital Elevation Models) and the Elevation x Surface Area x Accumulated Volume for three surveys conducted in 2010, 2012, and 2016 provided the sedimentation rates between these years, as well as the accumulated volume of sediments in the area under analysis for each year. The information we collected shows sediments accumulated in the deepest part of the reservoir in the period between 2010 and 2012. From 2012 to 2016, however, the silting effect was concentrated in shallower depths, whereas the desilting was observed in the deepest parts. Moreover, the sedimentation rate in the analyzed area was linked to the total precipitation in the municipality during the concerning time frame, as well as to changes in land use that occurred over the past years throughout the watershed. This data indicates a call for management actions to reduce soil erosion in the watershed, as well as a need for desilting of the reservoirs in order to recover its storage capacity.