Three-dimensional numerical modeling of hydraulics and morphodynamics of the Schwarzenbach reservoir

Mouris, Kilian; Beckers, Felix; Haun, Stefan

doi:10.1051/e3sconf/20184003005

Cited by 6 publications

(4 citation statements)

References 8 publications

(7 reference statements)

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“…For the pumped-storage operation, an in-and outlet is based near the dam at ~5 m above ground. The contributions of the individual inputs are described in Mouris et al (2018).…”

Section: Study Sitementioning

confidence: 99%

Methane emissions due to reservoir flushing: a significant emission pathway?

Lessmann

Fernández

Martínez-Cruz

et al. 2023

Preprint

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Abstract. Reservoirs can emit substantial amounts of the greenhouse gas methane (CH4) via different emission pathways. In some reservoirs, reservoir flushing is employed as a sediment management strategy to counteract growing sediment deposits that threaten reservoir capacity. Reservoir flushing utilizes the eroding force of water currents during water level drawdown to mobilize and transport sediment deposits through the dam outlet into the downstream river. During this process, CH4 that is stored in the sediment can be released into the water and degas to the atmosphere resulting in CH4 emissions. Here, we assess the significance of this CH4 emission pathway and compare it to other CH4 emission pathways from reservoirs. We measured seasonal and spatial CH4 concentrations in the sediment of Schwarzenbach Reservoir, providing one of the largest datasets on CH4 pore water concentrations in freshwater systems. Based on this dataset we determined CH4 fluxes from the sediment and estimated potential CH4 emissions due to reservoir flushing. CH4 emissions due to one flushing operation can constitute 7–14 % of the typical annual CH4 emissions from Schwarzenbach Reservoir, whereby the amount of released CH4 depends on the timing of the flushing operation within the season. The larger the thickness of the sediment layer mobilized during the flushing operation the larger the average CH4 concentration per unit volume of flushed sediment. This suggests that regular flushing of smaller sediment layers releases less CH4 than removal of the same sediment volume in fewer flushing events of thicker sediment layers. In other reservoirs with higher sediment loadings than Schwarzenbach Reservoir, reservoir flushing could cause substantial CH4 emissions, especially when flushing operations are conducted frequently. Therefore, CH4 emissions due to reservoir flushing must be included in estimates of annual overall greenhouse gas emissions from reservoirs that are subject to regular flushing operations.

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“…For the pumped-storage operation, an in-and outlet is based near the dam at ~5 m above ground. The contributions of the individual inputs are described in Mouris et al (2018).…”

Section: Study Sitementioning

confidence: 99%

Methane emissions due to reservoir flushing: a significant emission pathway?

Lessmann

Fernández

Martínez-Cruz

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…For the pumped-storage operation, an inlet and outlet are based near the dam at ∼ 5 m above ground. The contributions of the individual inputs are described in Mouris et al (2018). Since the dam was completed in 1926, the reservoir has been completely emptied on three occasions, in 1935, 1952 and 1997.…”

Section: Study Sitementioning

confidence: 99%

Methane emissions due to reservoir flushing: a significant emission pathway?

Lessmann,

Encinas Fernández,

Martínez-Cruz

et al. 2023

Biogeosciences

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Abstract. Reservoirs represent a globally significant source of the greenhouse gas methane (CH4), which is emitted via different emission pathways. In some reservoirs, reservoir flushing is employed as a sediment management strategy to counteract growing sediment deposits that threaten reservoir capacity. Reservoir flushing utilizes the eroding force of water currents during water level drawdown to mobilize and transport sediment deposits through the dam outlet into the downstream river. During this process, CH4 that is stored in the sediment can be released into the water and degas to the atmosphere, resulting in CH4 emissions. Here, we assess the significance of this CH4 emission pathway and compare it to other CH4 emission pathways from reservoirs. We measured seasonal and spatial CH4 concentrations in the sediment of Schwarzenbach Reservoir, providing one of the largest datasets on CH4 pore water concentrations in freshwater systems. Based on this dataset we determined CH4 fluxes from the sediment and estimated potential CH4 emissions due to reservoir flushing. CH4 emissions due to one flushing operation can constitute 7 %–14 % of the typical annual CH4 emissions from Schwarzenbach Reservoir, whereby the amount of released CH4 depends on the seasonal timing of the flushing operation and can differ by a factor of 2. Larger flushing events that mobilize deeper sediment layers lead to non-linear increases in CH4 mobilization. This suggests that regular flushing of smaller sediment layers releases less CH4 than removal of the same sediment volume in fewer flushing events of thicker sediment layers. However, additional indirect CH4 emissions pathways contributing to the total CH4 emissions may vary with the flushing operation. In other reservoirs with higher sediment loadings than Schwarzenbach Reservoir, reservoir flushing could cause substantial CH4 emissions, especially when flushing operations are conducted frequently. Our study recognizes CH4 emissions due to reservoir flushing as an important pathway, identifies potential management strategies to mitigate these CH4 emissions and emphasizes the need for further research.

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“…Several parameters influence the quantity of settled sediments in the reservoir, such as catchment specific, reservoir specific and sedimentological parameters. Although the sedimentation process depends strongly on the above mentioned parameters, reservoir sedimentation itself follows generally a pre-defined pattern, where coarser sediments settle first and finer sediments are further transported into the reservoir [40][41][42]. Especially fine sediments with cohesive properties should be considered when it is intended to obtain a sustainable reservoir management.…”

Section: Sedimentsmentioning

confidence: 99%

“…In addition to guiding documents, containing empirical and analytical approaches, also physical models are employed to simulate management strategies. Recently, numerical models have been frequently employed to evaluate the success of sediment management strategies [40,48,64,[72][73][74][75][76]. Sediment management strategies to reduce reservoir sedimentation and maintain reservoir volume can be summarized under three main approaches [67]:…”

Section: Sedimentsmentioning

confidence: 99%

Interdisciplinary Reservoir Management—A Tool for Sustainable Water Resources Management

et al. 2021

Self Cite

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Reservoirs are a common way to store and retain water serving for a multitude of purposes like storage of drinking and irrigation water, recreation, flood protection, navigation, and hydropower production, and have been built since centuries. Today, few reservoirs serve only one purpose, which requires management of present demands and interests. Since each reservoir project will cause negative impacts alongside desired advantages both on a local, regional and global scale, it is even more urgent to develop a common management framework in an attempt to mitigate negative impacts, incorporate different demands and make them visible within the discourse in order to avoid conflicts from early on. The scientific publications on reservoirs are manifold, yet a comprehensive and integrative holistic tool about management of this infrastructure is not available. Therefore, a comprehensive and integrated conceptual tool was developed and proposed by the authors of this paper that can contribute to the sustainable management of existing reservoirs. The tool presented herein is based on the results from the interdisciplinary CHARM (CHAllenges of Reservoir Management) project as well as the condensed outcome of relevant literature to aid and enhance knowledge of reservoir management. The incorporated results are based on field, laboratory and empirical social research. The project CHARM focused on five different aspects related to existing reservoirs in southern Germany (Schwarzenbachtalsperre, Franconian Lake District), namely: sedimentation of reservoirs, biostabilisation of fine sediments, toxic cyanobacteria(l) (blooms), greenhouse gas emissions from reservoirs and social contestation, respectively consent. These five research foci contributed to the topics and setup of a conceptual tool, put together by the research consortium via delphi questioning, which can be found alongside this publication to provide insights for experts and laymen. Conceptualising and analysing the management in combination with quantitative and qualitative data in one descriptive tool presents a novelty for the case studies and area of research. The distribution within the scientific community and interested public will possibly make a positive contribution to the goal of sustainable water resources management in the future.

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Three-dimensional numerical modeling of hydraulics and morphodynamics of the Schwarzenbach reservoir

Cited by 6 publications

References 8 publications

Methane emissions due to reservoir flushing: a significant emission pathway?

Methane emissions due to reservoir flushing: a significant emission pathway?

Methane emissions due to reservoir flushing: a significant emission pathway?

Interdisciplinary Reservoir Management—A Tool for Sustainable Water Resources Management

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