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Reiterer, K; Gold, T; Habersack, H; Hauer, C; Sindelar, C.
(2020): Experimental Study at the Reservoir Head of Run-of-River Hydropower Plants in Gravel Bed Rivers. Part II: Effects of Reservoir Flushing on Delta Degradation
WATER-SUI. 2020; 12(11), 3038 FullText FullText_BOKU

Abstract:: Run-of-river hydropower plants (RoR HPPs) are capable of interrupting the sediment connectivity of many alpine rivers. Still, there is a lack of systematical investigations of possible sediment management strategies for small and medium sized RoR HPPs. This study deals with the headwater section of an impoundment and the approach of sediment remobilization during drawdown operations. Therefore, a typical medium sized gravel bed river having a width of 20 m, a mean bed slope of 0.005, a mean flow rate of 22 m(3)/s, and a 1-year flood flow of 104 m(3)/s is recreated by a 1:20 scaled physical model. Heterogenous sediment mixtures were used under mobile-bed conditions, representing a range of 14-120 mm in nature. During the experiments, the flow rate was set to be 70% of the 1-year flood (HQ(1)) regarding on the ability to mobilize all sediment fractions. The possibility to remobilize delta depositions by (partial) drawdown flushing within a reasonable period (approximate to 9 h in 1:1 scale) was shown by the results. The erosion of existing headwater delta deposition was found to be retrogressive and twice as fast as the preceding delta formation process. A spatiotemporal erosion scheme points out these findings. This supports the strategy of a reservoir drawdown at flood events of high reoccurrence rate.
Authors BOKU Wien:: Gold Thomas; Habersack Helmut; Hauer Christoph; Reiterer Kevin; Sindelar Christine
Find related publications in this database (Keywords): gravel bed rivers; run-of-river hydropower plants; sediment continuity; flushing events; delta formation; sediment management strategies; retrogressive erosion