Mesoscale Mapping of Sediment Source Hotspots for Dam Sediment Management in Data-Sparse Semi-Arid Catchments

Smetanová, Anna; Müller, Anne; Zargar, Morteza; Suleiman, Mohamed A.; Gholami, Faraz Rabei; Mousavi, Maryam

doi:10.3390/w12020396

Cited by 5 publications

(2 citation statements)

References 117 publications

(174 reference statements)

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“…Sustainable land management and water resource development in many developing countries [47] are susceptible to accelerated erosion and downstream sediment transport [48,49]. Siltation of reservoirs is of utmost concern in regions of semi-arid catchments where water is insufficient, and land degradation commonly leads to increased masses of sediments entering rivers and reservoirs [50]. The storage capacity of reservoirs in East Africa is being reduced by accelerated sedimentation, which jeopardizes food, water, and energy security [51][52][53][54].…”

Section: Changing Sediment Flux Dynamics In East African Riversmentioning

confidence: 99%

Drivers, Impacts and Mitigation of Increased Sedimentation in the Hydropower Reservoirs of East Africa

Amasi

Wynants

Blake

et al. 2021

Land

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Hydropower reservoirs are essential for the climate-neutral development of East Africa. Hydropower production, however, is threatened by human activities that lead to a decrease in water storage capacity of reservoirs. Land use/land cover and climatic changes are driving accelerated soil erosion in semi-arid East Africa, which ultimately increases reservoir sedimentation and decreases energy production. Sediment delivery dynamics at the catchment scale are complex, involving the interaction of multiple factors and processes on different spatial and temporal scales. A lack of understanding of these processes and their interactions may impede the efficiency of sediment mitigation and control strategies. A deep understanding of the processes of erosion and connectivity of the land to river channel, as well as storage of eroded material within hillslopes and floodplains, and sediment accumulation in the reservoirs supports selection of future dam locations and sustainable management of reservoirs. The sediment budget approach can provide such a holistic perspective by accounting for the various sediment sources, transport, sinks, and redistribution when the sediment is routed through that catchment. Constructing sediment budgets is challenging, but the potential for integrating a number of different techniques offers new opportunities to collect the required information. In East Africa, the spatial planning of dams is mainly dominated by political and financial motives, and impacts of land use and climate on the sediment transport dynamics are not adequately considered. Production of sediment budgets under different scenarios of land use and climate change should be an essential step when deciding the location and management strategies for dams. Selection of new hydroelectric reservoir sites must consider long-term scientific data on climate change, and the sediment budget components for sustainable land management planning, hydropower sustainability.

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Section: Changing Sediment Flux Dynamics In East African Riversmentioning

confidence: 99%

Drivers, Impacts and Mitigation of Increased Sedimentation in the Hydropower Reservoirs of East Africa

Amasi

Wynants

Blake

et al. 2021

Land

View full text Add to dashboard Cite

show abstract

“…Sustainable land management and water resource development in many developing countries (Francke, 2009) are susceptible to accelerated erosion and downstream sediment transport (Morris & Fan, 1998;Le Tamene et al, 2006). Siltation of reservoirs is an utmost concern in regions of semi-arid catchments where water is insufficient, and land degradation commonly leads to increased masses of sediments entering rivers and reservoirs (Smetanová et al, 2020).…”

Section: Hydropower Productionmentioning

confidence: 99%

Investigation of sediment source and delivery dynamics in an east African hydropower reservoir using sediment tracing technology

Amasi

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This study aimed to reconstruct the sedimentation rates over time and identify the changing sources of sediment in a major hydropower reservoir in Tanzania, the Nyumba ya Mungu (NYM). The study also aimed to evaluate the soil carbon as a proxy for erosion risk in the catchment. Fallout 210Pb measurements were used to estimate age of sediment deposits and broad changes in sedimentation rates were reconstructed. Sedimentation peaks were cross referenced to geochemical profiles of allogenic and autogenic elemental constituents of the sediment column to confirm a causal link. Finally, geochemical fingerprinting of the sediment cores and potential sources were compared using a Bayesian mixing model (MixSIAR) to attribute the dominant riverine and land use sources to the reservoir. Reservoir sedimentation generally increased from 0.1 g cm−2 yr−1 in the lower sediment column to 1.7 g cm−2 yr−1 in the most recent deposits. These results correlated to changes in allogenic and autogenic tracers. The model outputs revealed that the Kikuletwa River with 60.3%, was the dominant contributing tributary to the total reservoir sediment and the Ruvu River 39.7%. However, downcore unmixing results indicated that the latest increases in sedimentation is moistly driven by an increased contribution from the Ruvu River. Cultivated land (CU) was shown to be the main land use source of riverine sediment, accounting for 38.4% and 44.6% in Kikuletwa and Ruvu rivers respectively. The “soil slake test” method for soil aggregate stability in water (WSA) indicated a significant decrease in soil aggregate stability in cultivated land in comparison to other land use types which indicates that the unsustainable land use changes can thus potentially increase the susceptibility of soils to erosion by water when soil organic matter (SOM) is reduced. This study has explicitly demonstrated that the integration of sediment tracing and -dating tools can be used for quantifying the dominant source of sediment infilling in East African hydropower reservoirs. The results underscore the necessity for catchment-wide management plans that target to limit soil erosion and reduce further impact to rivers and reservoirs to maintain and enhance food, water and energy security in Eastern Africa.

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Reservoir sedimentation and spatiotemporal land use changes in their watersheds: the case of two sub-catchments of the White Volta Basin

Atulley

Kwaku

Gyamfi

et al. 2022

Environ Monit Assess

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Mesoscale Mapping of Sediment Source Hotspots for Dam Sediment Management in Data-Sparse Semi-Arid Catchments

Cited by 5 publications

References 117 publications

Drivers, Impacts and Mitigation of Increased Sedimentation in the Hydropower Reservoirs of East Africa

Drivers, Impacts and Mitigation of Increased Sedimentation in the Hydropower Reservoirs of East Africa

Investigation of sediment source and delivery dynamics in an east African hydropower reservoir using sediment tracing technology

Reservoir sedimentation and spatiotemporal land use changes in their watersheds: the case of two sub-catchments of the White Volta Basin

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