Estimation of Sediment Management Flushing Efficiency in the Valgrosina Reservoir

Sediment trapping by reservoir is a problem of global severity with associated environmental, social and economic repercussions. Reservoirs trap 100% of river bedload and a not negligible percentage of suspended load. The water storage is destinated for decreasing over the time, the aquatic habitat in the downstream channel is increasingly deprived of sediments and, in worst case scenarios, safety levels against dam stability and flood control may be weakened. Planning and operation of sustainable sediment management measures, as flushing, is essential to maintain reservoirs as renewable resources. This work analyses the real case of the Valgrosina reservoir, in the Northern Italy. Here, the managing Company A2A operated some flushing cycles in the recent past. The flushing parameters were evaluated through the REServoir CONservation (RESCON 2) tool. The consultation of site monitoring data aided in calibrating the model. Preliminary results showed that operational flushing efficiency criteria provided in the literature are not fulfilled due to geometrical constraints.