Reuse of a dam as sediment trap and water reserve

ABSTRACT One of the dilemmas that characterizes the end of active service of small hydroelectric plants (SHPs) is regarding the destination of the dams. This is the case of the Pandeiros SHP, located in the state of Minas Gerais, Brazil. Several alternatives are being considered to make its decommissioning feasible, such as opening the bottom discharge gate and removing the reservoir containment dike. However, in a review of recent research in the basin, more than 200 active gullies were found upstream of the dam, contributing to the silting up of the reservoir and of the Pantanal Mineiro, an extensive wetland downstream of the SHP that is vital to the biodiversity of the region. Following a worldwide movement to reuse such structures, periodic dredging of part of the sediment retained in the reservoir is proposed, converting it into a trap to reduce the silting of the wetland by the upstream sediment, in addition to the creation of a reserve volume of water needed for agriculture and human consumption.