Managing reservoir sedimentation by venting turbidity currents: A review

Chamoun, Sabine; Cesare, Giovanni De; Schleiss, Anton

doi:10.1016/j.ijsrc.2016.06.001

Cited by 51 publications

(23 citation statements)

References 32 publications

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“…1. seasons [6*, 16, 17, 18, 19] 2. response to climate change [3*, 20, 21] 3. changes in upstream impoundments [4*, 22, 23] 4. long run upstream land use changes [24,25,26] 5. changes in dam operating strategies [27,28,29] The degree of soil movement is further affected by the scale of economic activity, human population densities, and different forms of manufactured capital that are introduced into the system [30]. Fortunately, the changes in soil movements following various forms of human intervention are, by and large, measurable and these can and are being modelled to some extent [35].…”

Section: Modelling the Economic Lifespan Of A Dam: Backgroundmentioning

confidence: 99%

The impact of human behaviour and restoration on the economic lifespan of the proposed Ntabelanga and Laleni dams, South Africa: A system dynamics approach

Bester

Blignaut

Crookes³

2019

Water Resources and Economics

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The South African government intends to develop the Mzimvubu Water Project (MWP) which includes the construction of two dams (the Ntabelanga and Laleni dams) in the Tsitsa River, Eastern Cape province, South Africa. This investment is believed to be important to unlock the economic potential of this rural, poor and underdeveloped area. We consider a range of variables to ascertain what the realistic economic lifespan of each of the dams are, subject to uncertainty and complexity, as the Highlights:  Variability in soil erosion in a catchment cause a dam's actual and predicted economic lifespan to differ significantly.  When no mitigation is assumed the modelled Ntabelanga dam's lifespan declines from 55-68 years to 31-44 years. With mitigation, the anticipated lifespan is 50-65 years.  When no mitigation is assumed the modelled Laleni dam's lifespan declines from 26-33 years to 16-21 years. With mitigation, the anticipated lifespan is 24-30 years.  The state of the catchment has to be improved and maintained through restorative actions together with societal endorsement and behavioural change. Such behavioural change is to be informed by a catchment management plan and the proactive and careful implementation thereof.  The investment in social and natural capital to safeguard the lifespan of the manufactured capital (the dams) and thus the financial capital invested, is of high importance.

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Section: Modelling the Economic Lifespan Of A Dam: Backgroundmentioning

confidence: 99%

The impact of human behaviour and restoration on the economic lifespan of the proposed Ntabelanga and Laleni dams, South Africa: A system dynamics approach

Bester

Blignaut

Crookes³

2019

Water Resources and Economics

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“…Especially for reservoirs the continuous loss of possible storage volume is an extremely important question in connection with the sustainability of the HPP [16] and in extreme cases intake structures can be endangered, which would obviously hamper the function of water intakes such as head reace or bottom intake structures. Chamoun et al [17] summarised possible strategies to manage the inflowing sediments. Different aspects of this transport process in reservoirs are investigated experimentally [18][19][20][21] as well as numerically [22][23][24][25].…”

Section: Generalmentioning

confidence: 99%

“…The trash rack in the now mostly submerged lower sections could endure the pressure and the entrance of sediment in the structure itself is comparable small (Figure 1). Excavations of the sediment with airlift [17] were conducted as soon as possible but are generally restrained because of the limited accessibility due the alpine circumstances. The capacity of sediment extraction method in combination with a comparable high water level allows only a very small progress.…”

Section: Project-related Backgroundmentioning

confidence: 99%

Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

Gabl

Gems

Birkner

et al. 2018

Water

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An unexpected and massive redistribution of fine sediment in a large Alpine reservoir was triggered by a further lowering of the water level to conduct maintenance work. This caused the need of a total redesign of the existing head race intake for a high head power plant in the Austrian Alps. Two main geometry options for the trash rack support structure are compared with numerical simulations (ANSYS-CFX) as well as with a scale model test (scale 1:20). The laboratory experiment substantially benefited from the preliminary numerical investigation in respect of the location and implementation of the model boundaries. In return was the confidence in the numerics strengthened by the successful validation of the local head loss and the velocity distribution for the main operation cases. This allowed that the main inputs for the structural design and the further optimisation is conducted only with the 3D-numerical tool. The paper presents the interlaced concept as well as the main finding of the investigation, which lead to a successful adaptation of the intake structure.

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“…In the particular case of sedimentation due to turbidity currents, venting through bottom outlets or intakes is highly recommended (Chamoun et al, 2016a). This technique has both economic and environmental advantages because outflow discharges used during venting and the resulting sediment concentrations are relatively low.…”

Section: Introductionmentioning

confidence: 99%

“…Venting of turbidity currents is documented in numerous reservoirs worldwide (Chamoun et al, 2016a). Lee et al (2014) investigated venting operations in the Tsengwen reservoir in Taiwan through a hybrid numerical, theoretical and experimental approach leading to a formula used to predict sediment concentrations and venting efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Management of turbidity current venting in reservoirs under different bed slopes

Chamoun

Cesare

Schleiss

2017

Journal of Environmental Management

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a b s t r a c tThe lifetime and efficiency of dams is endangered by the process of sedimentation. To ensure the sustainable use of reservoirs, many sediment management techniques exist, among which venting of turbidity currents. Nevertheless, a number of practical questions remain unanswered due to a lack of systematic investigations. The present research introduces venting and evaluates its performance using an experimental model. In the latter, turbidity currents travel on a smooth bed towards the dam and venting is applied through a rectangular bottom outlet. The combined effect of outflow discharge and bed slopes on the sediment release efficiency of venting is studied based on different criteria. Several outflow discharges are tested using three different bed slopes (i.e., 0%, 2.4% and 5.0%). Steeper slopes yield higher venting efficiency. Additionally, the optimal outflow discharge leading to the largest venting efficiency with the lowest water loss increases when moving from the horizontal bed to the inclined positions.

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Managing reservoir sedimentation by venting turbidity currents: A review

Cited by 51 publications

References 32 publications

The impact of human behaviour and restoration on the economic lifespan of the proposed Ntabelanga and Laleni dams, South Africa: A system dynamics approach

The impact of human behaviour and restoration on the economic lifespan of the proposed Ntabelanga and Laleni dams, South Africa: A system dynamics approach

Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

Management of turbidity current venting in reservoirs under different bed slopes

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