100 key questions to guide hydropeaking research and policy

Hayes, D.S.; Bruno, M.C.; Alp, M.; Boavida, I.; Batalla, R.J.; Bejarano, M.D.; Noack, M.; Vanzo, D.; Casas-Mulet, R.; Vericat, D.; Carolli, M.; Tonolla, D.; Halleraker, J.H.; Gosselin, M.-P.; Chiogna, G.; Zolezzi, G.; Venus, T.E.

doi:10.1016/j.rser.2023.113729

Cited by 11 publications

(2 citation statements)

References 140 publications

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“…In our experiments, we simulated single peak events to quantify larvae stranding. In hydropeaked rivers, however, artificial flow fluctuations can occur several times a day (Greimel et al, 2016), potentially causing long-term effects by repeated bank dewatering (Auer et al, in preparation;Halleraker et al, 2003;Hayes, Bruno, et al, 2023).…”

Section: Study Limitations and Advantagesmentioning

confidence: 99%

Variation in hydropeaking‐induced stranding of Barbus barbus L. and Chondrostoma nasus L. larvae: Assessing the impact of daytime and down‐ramping rates

Führer,

Auer,

Coudrais‐Duhamel

et al. 2024

Ecohydrology

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Unnatural changes in river flow patterns resulting from peak‐operating hydropower plants adversely impact freshwater ecosystems. In particular, the rapid dewatering of shoreline habitats during artificial flow down‐ramping puts early fish life stages at a high risk of becoming stranded if they fail to follow receding water levels in time. While extensive research has been conducted on the effects of hydropeaking on salmonid species, there is limited knowledge on the diverse cyprinid family, particularly on vulnerable early life stages. Hence, this study aims to compare the larval stranding of two cyprinid species, the common barbel (Barbus barbus L.) and common nase (Chondrostoma nasus L.), in response to bank dewatering. We conducted larvae experiments in near‐natural mesocosms, simulating single flow down‐ramping events with varying down‐ramping rates (0.3–1.8 cm·min−1) during the day and at night to quantify stranding rates, also including water temperature and fish development. Our results reveal distinct diurnal patterns for both species, with higher stranding rates during the night than during the day in all experimental scenarios. The data also show higher stranding rates at faster down‐ramping, with interaction effects between down‐ramping rates and time of day. The stranding rates between the two species are similar across most of the scenarios. Scenarios with colder water temperatures show that nase larvae tend to strand more frequently than with warmer temperatures. In conclusion, the study results contribute to the ongoing discourse on hydropeaking mitigation by providing new perspectives on flow‐reduction effects on early cyprinid life stages. Mitigation measures should prioritize the periods during early larval development and factor in prevailing water temperatures. Lowering down‐ramping rates, especially during nighttime, will help minimizing negative impacts on aquatic ecosystems, particularly when combining flow rules and habitat restoration measures.

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Section: Study Limitations and Advantagesmentioning

confidence: 99%

Variation in hydropeaking‐induced stranding of Barbus barbus L. and Chondrostoma nasus L. larvae: Assessing the impact of daytime and down‐ramping rates

Führer,

Auer,

Coudrais‐Duhamel

et al. 2024

Ecohydrology

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“…Subsequently, the loss of fish per drawdown event is a likely cause of diminished fish populations if occurring multiple times per season (Bauersfeld, 1978;Hayes et al, 2021;Sauterleute et al, 2016;Schmutz et al, 2015). Therefore, modifications of down-ramping rate are a key target when it comes to hydropeaking mitigation (Halleraker et al, 2022;Moreira et al, 2019), but also, diurnal or seasonal differences may need to be considered (Auer et al, 2017(Auer et al, , 2014Führer et al, 2022;Hayes, Auer, et al, 2023;Hayes, Bruno, et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

Fish stranding in relation to river bar morphology and baseflow magnitude: Combining field surveys and hydrodynamic–numerical modelling

Hayes,

Hauer,

Unfer

2024

Ecohydrology

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Hydropeaking mitigation based on down‐ramping thresholds is crucial to avoid stranding of fish and ensure sustainable hydropower production. However, the risk of stranding is influenced by several biotic and abiotic factors that interact with the ramping rate, including river morphology and baseflow magnitude. Also, at the river bar scale, the lateral or horizontal down‐ramping velocity may be of even greater importance than the vertical one as the prior integrates bar morphology. This study investigates the connection between ecologically relevant hydraulic parameters (vertical and lateral ramping velocity, dewatered river bar width) and the stranding of young‐of‐the‐year European grayling (Thymallus thymallus) due to down‐ramping, based on field observations of stranded fish at the hydropeaked Drava River in Austria combined with hydrodynamic–numerical modelling. We also examine the interplay between baseflow conditions and river topography in the dewatered areas. Stranding observations in spring and summer found a median rate of 90 individuals per 100 m, ranging from 50 to 500 fish per 100 m shoreline. Stranding rates were three times higher at night than during the day. Our data revealed a positive relationship between stranded fish and down‐ramping hydraulics, with higher intensity resulting in more stranded fish. This association was stronger for the lateral than the vertical ramping velocity, presumably because the former accounts for bar morphology, suggesting that the lateral dewatering velocity is a better indicator to assess fish stranding at the bar scale than the vertical velocity. We also found a negative relationship between the extent of the dewatered area and baseflow magnitude, indicating that the stranding risk is higher during down‐ramping at low flow conditions.

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Stream and river flows mediate adult lamprey spawning migrations: Considerations for management

Clemens,

Wagner

2024

River Research & Apps

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Organisms have adapted to dynamic river flows as part of the natural flow regime. However, climate change and humans' use of fresh water are associated with decreases in the quality and quantity of surface waters. In addition, river impoundments and water withdrawals for human use regulate and dampen the dynamism of flow in many rivers. These changes to the natural flow regime can impact the spawning migrations of lampreys (Petromyzontiformes). Here, our goal is to review the ecology of lamprey spawning migrations associated with river flows, with considerations for controlling invasive sea lamprey (Petromyzon marinus) and conserving native lampreys (including native, anadromous sea lamprey). We identify five common themes: (1) natural flow regimes provide a competitive edge to native fishes over non‐native fishes; (2) high flows (up to a threshold) attract adult lamprey and large streams attract large numbers of lamprey; (3) larval lamprey pheromones attract adult lampreys; (4) behavioral responses by adult lamprey to flow (including localized hydraulics) can inform dam passage and trapping methods; and (5) changes to rivers induced by climate change have been implicated in changing the phenology of run timing and spawning location. Controlling invasive sea lamprey and conserving native lampreys can be done with pheromones and flow management. Pheromones may be of more use under focused management efforts to control invasive sea lamprey, whereas flow management can provide a foundation for conservation of native lampreys.

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100 key questions to guide hydropeaking research and policy

Cited by 11 publications

References 140 publications

Variation in hydropeaking‐induced stranding of Barbus barbus L. and Chondrostoma nasus L. larvae: Assessing the impact of daytime and down‐ramping rates

Variation in hydropeaking‐induced stranding of Barbus barbus L. and Chondrostoma nasus L. larvae: Assessing the impact of daytime and down‐ramping rates

Fish stranding in relation to river bar morphology and baseflow magnitude: Combining field surveys and hydrodynamic–numerical modelling

Stream and river flows mediate adult lamprey spawning migrations: Considerations for management

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