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Experiments on sediment trap efficiency in reservoirs
Author(s) -
Toniolo Horacio,
Schultz Jeremy
Publication year - 2005
Publication title -
lakes and reservoirs: research and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.296
H-Index - 39
eISSN - 1440-1770
pISSN - 1320-5331
DOI - 10.1111/j.1440-1770.2005.00256.x
Subject(s) - sediment , trap (plumbing) , geology , dredging , turbidity current , environmental science , hydrology (agriculture) , sediment trap , turbidity , geotechnical engineering , geomorphology , structural basin , environmental engineering , sedimentary depositional environment , oceanography
Sediment trap efficiency plays a key role in the effective operational life of reservoirs. This paper presents the results of five laboratory experiments on trap efficiency. An over‐spilling condition and four gaps located at the downstream end of a reservoir were analysed in this study. The experimental design assumed a river carrying two phases of sediment flowing into a one‐dimensional reservoir. The coarse sediment (sand) was deposited and formed a defined prograding delta. The fine sediment (mud) formed a dilute suspension of wash load in the river. As the river entered the reservoir, the muddy water plunged on the foreset, forming a turbidity current. The turbidity current deposits, in turn, formed a bottomset. Black coal slag and white glass beads were used to simulate sand and mud. Their specific densities were 2.6 and 2.5 for black coal and beads, respectively. The water surface elevation in the reservoir was approximately similar in all experiments. Neither the water nor sediment discharge conditions were changed during the experimental runs. Suspended sediment was sampled through seven siphons; six of these being components of a rake in which they were vertically stacked. The last siphon was positioned on the rake outlet. Sediment samples were taken three times, at approximately evenly spaced intervals in the experiments. Suspended sediment concentration and grain size distribution were calculated for each siphon. The bed sediment deposit was sampled after each experiment. Sediment trap efficiency in the reservoir was calculated. Experimental results show the maximum venting capacity (minimum trap efficiency) occurs under over‐spilling conditions.