Sediment transport below a small alpine reservoir desilted by controlled flushing: field assessment and one-dimensional numerical simulation

摘要: Sediment transport and riverbed sedimentation were investigated in an alpine stream below a small hydropower reservoir desilted by controlled sediment flushing (CSF) operation. The term “controlled” refers to the operational tasks implemented mitigate downstream environmental impact of experimental dataset acquired before, during, after CSF was also used carry out calibrate one-dimensional model monitored event. is located central Italian Alps, its original storage 160,000 m3, about 30% filled mixture sand silt/clay before CSF. Downstream concentration releasing clear water from upstream reservoirs regulating work earth-moving equipment emptied reservoir. A 3.6-km-long reach with average slope 0.015 monitored: grain size suspended measured during alteration evaluated volumetric sampling measurements deposits’ thickness. Sedimentation River Hydraulics—One Dimensional (SRH-1D) simulate Model parameters calibrated comparing computed observed amount deposited along study reach. carried October 2010 for 3 days. Ca. 16,000 m3 evacuated, representing approximately 70% sand. 2.4 Mm3 released reduce increase capacity downstream. About 3000 m3 CSF, maximum height up 0.2 m. Although simply set as mono-granular, calibrating parameters, good agreement achieved between depositional pattern SRH-1D one observed, both terms deposit thickness sediment. sensitivity analysis revealed major role controlling bed mixing processes affecting simulated deposition 0.1 mm diameter not detected river deposits flushing: effects on biota associated substrate clogging very fine therefore minimized. After proper calibration, 1-D modeling can effectively support planning operations: minimize effects, concurrently achieving acceptable efficiency, analyzed scenarios well outputs need be carefully multidisciplinary perspective.