Effects of experimental floods in two rivers with contrasting valley morphologies

Kevic, Maja; Ortlepp, Johannes; Mürle, Uta; Robinson, Christopher T.

doi:10.1127/fal/2018/1177

Cited by 6 publications

(7 citation statements)

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“…In pre‐flood years, Robinson, Aebischer, and Uehlinger (2004) and Uehlinger et al (2003) reported high density of macroinvertebrates, moss, and periphyton in the river. Experimental floods were implemented initially (2000, 2001) with higher frequency, with peak flows ranging between 12 and 45 m 3 /s, while later floods were mostly released twice a year (Figure 1, Kevic et al, 2018). After an initial fluctuation, total secondary production steadily declined to values <10 g m −2 year −1 .…”

Section: Discussionmentioning

confidence: 99%

“…Robinson and Uehlinger (2008) attributed these changes to a period of non‐equilibrium during the early stages of the flood program, where all biotic parameters measured showed the largest increases in coefficient of variation, suggesting the passing of an ecological threshold towards the onset of an ecosystem shift. Due to a gap in biomass data, we could not make estimates between 2008 and 2013, the period when high‐magnitude floods were released (Kevic et al, 2018). However, Robinson (2012), Robinson et al (2018) reported that macroinvertebrate density was lowest in 2010, with a concomitant increase in taxa richness, a condition that persisted until 2015.…”

Section: Discussionmentioning

confidence: 99%

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Long‐term reconstruction of energy fluxes in an alpine river: Effects of flow regulation and restoration

Consoli

Siebers

Bruder

et al. 2023

River Research & Apps

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Flow regulation of montane and alpine headwater streams can fundamentally alter food web structure and energy flows through changes in productivity, resource availability, and community assembly. Dam flow‐release schemes can be used to mitigate the environmental impacts of flow regulation via environmental flows, which can increase discharge variability and other ecologically important hydrological properties. In particular, managed floods can reintroduce disturbance to the system and stimulate the reactivation of physical habitat dynamics. However, how managed floods might restore ecosystem processes is virtually unknown. In this study, we examined patterns in potential energy fluxes before, during and after a long‐term experimental flood program on the river Spöl, a regulated alpine River in southeast Switzerland. We used benthic samples collected during long‐term monitoring and stable isotope analysis (δ13C and δ15N) of macroinvertebrates and their potential food sources to reconstruct secondary production, and potential energy fluxes, over a 20‐year study period. The experimental floods did not alter the relative importance of basal resources but resulted in a considerable decline in secondary production, which remained low after the discontinuation of the floods. Our data suggest that a lack of recolonization by mosses following the discontinuation of the experimental flood program on the river Spöl may have driven patterns in energy fluxes by limiting macroinvertebrates using mosses for habitat. The effects of environmental flows on energy flows in this system thus depend on flood disturbance and the environmental context following the discontinuation of floods.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Long‐term reconstruction of energy fluxes in an alpine river: Effects of flow regulation and restoration

Consoli

Siebers

Bruder

et al. 2023

River Research & Apps

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“…According to observations of prior to dam construction, the maximum yearly discharge exceeded 40 m 3 /s at a further upstream location and thus is supposed to be even higher at the investigated river sites (Robinson et al, 2018). The largest artificial flood was released in 2009 with a peak discharge of 82 m 3 /s (Kevic et al, 2018). Discharge data from Groupe e (Sarine) and Engadiner Kraftwerke AG (Spöl).…”

Section: Artificial Floodsmentioning

confidence: 93%

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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“…As a result, the Engadine power company, Swiss National Park and state authorities began to implement artificial floods, predominately in the upper regulated part of the Spöl in 2000. Thirteen artificial floods have also been undertaken in the lower flow regulated section (2000–2017; Kevic, Ortlepp, Mürle, & Robinson, 2018). In September 2018 (the focus of this study), a controlled artificial flood was released in the lower flow regulated section, from the outlet of the Ova Spin reservoir over an 8‐hr period.…”

Section: Methodsmentioning

confidence: 99%

Patchiness in flow refugia use by macroinvertebrates following an artificial flood pulse

Mathers

Robinson

Weber

2022

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Flow refugia, locations that maintain substrate stability and low hydraulic stress during periods of high flow, can ensure riverine resilience in the face of increasing hydrological unpredictability. Despite their known importance, they have been overlooked in recent years with work on drought refugia currently seeing greater attention. Moreover, research on the role of flow refugia during artificial flood pulses in regulated rivers, where flood disturbances are no longer part of the hydrograph, is essentially absent. Here, we compared flow refugia for benthic macroinvertebrates among six habitats (main channel, side channel, riffle, margin, lentic including a floodplain pond, and inundated floodplain) within four different sites in response to an artificial flood pulse. We found that the grain‐size distribution and macroinvertebrate community composition changed at each site following the flood. Macroinvertebrate assemblages became longitudinally homogeneous, but within‐site beta diversity and taxa richness remained temporally stable following the flood pulse, suggesting the presence of flow refugia. In this respect, margin, inundated floodplain and lentic (a floodplain pond) habitats provided important flow refugia locations, particularly for the mobile mayfly Rhithrogena sp. In contrast, low substrate stability in riffle and side channels resulted in limited refugia potential for most taxa. Refuge use was however patchy with high levels of intra‐habitat variability being evident for Rhithrogena sp. and the amphipod Gammarus fossarum in margin and side channel habitats. Further work is required to advance our knowledge of flow refugia in rivers with differing flow regimes to enable their integration into management and restoration schemes.

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Effects of experimental floods in two rivers with contrasting valley morphologies

Cited by 6 publications

References 0 publications

Long‐term reconstruction of energy fluxes in an alpine river: Effects of flow regulation and restoration

Long‐term reconstruction of energy fluxes in an alpine river: Effects of flow regulation and restoration

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

Patchiness in flow refugia use by macroinvertebrates following an artificial flood pulse

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