Experiments with sediment replenishment in a residual flow reach: Comparison of field datawith laboratory experiments

Stähly, Severin; Maître, Anthony; Franca, Mário J.; Robinson, Christopher T.; Schleiss, Anton

doi:10.1051/e3sconf/20184002022

Cited by 2 publications

(3 citation statements)

References 8 publications

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“…Of the 489 RFID-tagged stones placed in the artificial deposits, 277 were found and localized using the mobile antenna after the flood event (Stähly et al, 2018b). Out of these 277 stones, 166 were located in the river and 111 in the remaining part of the partially eroded artificial deposits.…”

Section: Sediment Trackingmentioning

confidence: 99%

Erosion, transport and deposition of a sediment replenishment under flood conditions

Stähly

Franca

Robinson

et al. 2020

Earth Surf Processes Landf

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River reaches downstream of dams with constant residual discharge often lack sediment supply and periodic high flows due to dam sediment retention and flow regulation, respectively. To test a novel multi-deposit methodology for defining environmental flows for activating the dynamics of the river morphology downstream of dams, a flood was released from Rossens Dam in Switzerland. This event was combined for the first time with a multi-deposit configuration of sediment replenishment consisting of four artificial deposits allocated as alternate bars along the riverbanks as a restoration measure. To validate the sediment transport behaviour observed in laboratory tests, stones were equipped with radiofrequency identification (RFID) passive integrated transponder (PIT) tags, a fixed antenna was installed at the river bed and a mobile antenna was used to enable the investigation of the erosion, transport and deposition of replenished sediments. The duration of the erosion period was determined for the tracked stones, and average transport velocities were found to be on the order of 10-3 m/s. To estimate the erosion efficiency of the flood, defined as the eroded tagged stones compared with the released water volume, the hydrograph was divided into different periods: rising limb, constant peak discharge, decreasing limb. During the rising limb of the flood, which lasted for 20% of the total flood duration, more than 40% of the PIT tags were transported. The defined erosion efficiency is a measure to support the hydrographic design of artificial flood releases from dams. The deposition of tagged stones resulted in a repeating cluster formation, as expected from previous laboratory experiments, creating an increase in hydraulic habitat diversity. Comparison of the results obtained in the field and from laboratory experiments confirmed the robustness of the multi-deposit sediment replenishment method. Combined with the knowledge gained on the erosion efficiency, these results could motivate further applications and research into multi-deposit sediment replenishment techniques as a habitat-oriented river restoration measure.

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Section: Sediment Trackingmentioning

confidence: 99%

Erosion, transport and deposition of a sediment replenishment under flood conditions

Stähly

Franca

Robinson

et al. 2020

Earth Surf Processes Landf

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“…Thus the sediment dynamics in the Sarine segments is highly limited. The artificial flood therefore was combined with sediment replenishment at different locations (Stähly et al, 2018). The sediment was excavated from the adjacent floodplain, allowing tracking of the replenished sediment based on 489 Passive Integrated Transponder (PIT) tags.…”

Section: Sediment Availabilitymentioning

confidence: 99%

“…To counteract these deficits, sediment replenishment combined with the release of artificial flood events have been widely studied (Arnaud et al, 2017;Battisacco et al, 2016;Gaeuman, 2012;Gaeuman et al, 2017;Heckmann et al, 2017;Robinson, 2012;Robinson et al, 2018;Staentzel et al, 2018;Stähly et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Artificial Floods in Residual Flow Reaches - How Do They Affect Hydraulic Habitats?

Stähly¹

2019

38th IAHR World Congress - "Water: Connecting the World"

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Floodplains in hydropower-controlled rivers, where a constant residual flow discharge is imposed, often lack sediment supply and periodic inundation due to the absence of natural flood events. In this study we compare two residual flow systems. The first river is the Spöl, located in the Swiss National Park close to the boarder with Italy. Since the year 2000, artificial floods are released from the Ova Spin Dam on a yearly bases, with the aim to restore river dynamics and habitats. The second river, is the Sarine in Western Switzerland where an artificial flood was released from the Rossens Dam for the first time. At one location this flood event was combined with sediment replenishment. In this study, an analysis of the two different systems before and after the event using the Hydro-Morphological Index of Diversity (HMID) is presented. The index is based on the variability of flow depth and flow velocity and represents the habitat diversity on a reach scale. Results reveal that a flood pulse can significantly increase hydraulic habitat diversity in a river reach and that sediment availability is crucial. Nevertheless, the change in habitats of a single flood event has a minor effect if artificial floods are periodically released. Under such conditions, the river has already reached an equilibrium condition considering habitat diversity.

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Experiments with sediment replenishment in a residual flow reach: Comparison of field datawith laboratory experiments

Cited by 2 publications

References 8 publications

Erosion, transport and deposition of a sediment replenishment under flood conditions

Erosion, transport and deposition of a sediment replenishment under flood conditions

Artificial Floods in Residual Flow Reaches - How Do They Affect Hydraulic Habitats?

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