Article

A computational tool for the characterisation of rapid fluctuations in flow and stage in rivers caused by hydropeaking

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Abstract

Power production by hydro-electric plants in response to short-term variations in the energy demand and market (hydropeaking) may lead to frequent and rapid fluctuations in flow and stage in rivers downstream of power plant outlets. We have developed a time series analysis tool designed to quantify these rapid fluctuations. They were identified by establishing river- and data-specific thresholds both for the rates of change in flow or stage, and for other peaking event parameters. In contrast to previous similar analyses, we separated peaking events into rapid increases and rapid decreases. We also analysed other parameters such as daylight conditions during peaking events, and calculated both mean and maximum rates of change in flow and stage. The results of such analysis in a Norwegian river were used to demonstrate outputs from the tool. Our tool may be useful with respect to environmental impact assessment and mitigation related to stream hydropeaking.

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... This lack of referencing is likely due to the hindrances in assessing the information, either because records of sub-daily flow fluctuations are inexistent or unavailable. However, the situation has changed in the last few years (Bejarano et al., 2017), with studies proposing flow metrics to quantify the magnitude, frequency and duration of flow fluctuations at sub-daily scales of 15 min (Sauterleute and Charmasson, 2014), 30 min (Zolezzi et al., 2011), and 1 h (Meile et al., 2010;Bevelhimer et al., 2015;Carolli et al., 2015;Chen et al., 2015;Alonso et al., 2017;Bejarano et al., 2017). Flow variability can be described by five components that depict spatio-temporal variations: magnitude, timing, frequency, duration, and rate of change of hydraulic parameters (Poff, 1997;Richter et al., 1996). ...
... Greimel et al., 2016), timing (daylight conditions) (e.g. Sauterleute and Charmasson, 2014), and frequency of peak flows (e.g. Bejarano et al., 2017). ...
... Although it is hard to find available information on finer sub-daily scales, these parameters can either be measured directly in the rivers or computed using hydrodynamic models. Sauterleute and Charmasson (2014) developed a computational tool for the characterization of rapid flow fluctuations, termed the COSH-Tool, which processes time series of discharge and water level, commonly designated as stage, to calculate a wide list of parameters. The authors based their approach on the method by Zolezzi et al. (2011), improving it by independently considering the increase (start of hydropower production) and decrease (shutdown of hydropower production) of flow. ...
Conference Paper
Hydropower plant (HPP) operations in response to variations in market energy demand and electricity production can generate rapid and frequent fluctuations of discharge in the river, downstream the HPP. The phenomenon, so-called hydropeaking, may result in a negative impact to fish populations. The present study aims to investigate the effects of hydropeaking in the Iberian barbel (Luciobarbus bocagei) habitat conditions. The River2D model was used to obtain the habitat suitability downstream of the hydropower plant. The influence of the environmental flow regime in the habitat conditions and in the flow fluctuations due to hydropeaking was assessed. The COSH-Tool was applied in order to quantify and characterize those rapid fluctuations (with and without the environmental flow), with the purpose of assessing the impacts in the fish habitat.
... COSH, a computational tool, was developed for hydropeaking time series analysis [20,21]. This tool accounts for the identification and quantification of rapid fluctuations in flow and stage in rivers. ...
... The interval of stage or flow observations is very important for the assessment of hydropeaking. According to [20], for accurate assessment of hydropeaking, fine intervals (10 min, 15 min, 1 h) of stage or discharge measurements are needed. For this study, measurements were carried out at intervals of 10-and 15 min. ...
... According to [44] the air temperature and light conditions have effect on fish stranding. As at low temperatures and during the dark period fish tend to stay closer to the riverbed, upramping and downramping during the twilight are most dangerous [20,44]. Therefore, in this study frequency of hydropeaking events during a 24-h period was assessed during low, average and high river channel water storage periods. ...
Article
Full-text available
This paper discusses rapid flow and stage fluctuations in a large lowland river downstream from a large hydropower plant (HPP) in Lithuania. The main problem arises when the HPP is operating in peak mode. Such operation of HPP causes rapid flow and stage fluctuations, which can have a certain impact on river ecosystems. The study analyzes general abiotic indicators such as upramping and downramping rates and stage fluctuations downstream of the HPP. The main idea was to assess recorded stage upramping and downramping rates along the river downstream of large HPP. To assess stage fluctuation statistics, COSH software was used. A maximum upramping rate of 1.04 m/h and maximum downramping rate of 0.88 m/h were identified using data from temporary and permanent gauging stations. Obtained results revealed that stage fluctuations exceed ecologically acceptable rates up to 20 km downstream of HPP. The effect of hydropeaking fades out only at a chainage of 45 km downstream of HPP. In mountainous regions, ecologically acceptable rates are reached at much smaller distances. The study shows that the traditional coefficient of variation of stage fluctuation data can be used to describe hydropeaking indicators. The main results of this study can be used for environmental impact assessment downstream from HPPs.
... pulse power generation) and the flow variations in rivers downstream the power plant outlets (e.g. rapid flow decreases) (Sauterleute & Charmasson 2014). Tools are now available to calculate hydro-peaking parameters based on time-series of discharge and water level (Sauterleute & Charmasson 2014;Carolli et al. 2015;Greimel et al. 2016). ...
... rapid flow decreases) (Sauterleute & Charmasson 2014). Tools are now available to calculate hydro-peaking parameters based on time-series of discharge and water level (Sauterleute & Charmasson 2014;Carolli et al. 2015;Greimel et al. 2016). ...
... The temporal resolution of observed discharge data could have been better as we have 60-min resolution in water level/flow data, while there is a 15-min temporal resolution in the water temperature data. The time step of the data clearly affects the precision in the description of Downloaded by [Hogskolen I Finnmark] at 12:24 10 May 2016 the hydro-peaking (Sauterleute & Charmasson 2014;Carolli et al. 2015) as longer time steps tend to smoothen out the effects of rapid changes in parameters describing the hydro-peaking cycle. Along the 8-km river stretch, we have water temperature data from three locations for the calibration period and six locations for the validation period, and discharge data for the upstream boundary. ...
Article
Full-text available
Hydro-peaking is a type of hydropower operation characterized by rapid and frequent changes in flow, possibly also leading to similar changes in water temperature – http://www.nrk.no/tures (‘thermo-peaking’). This study examines water temperature variations caused by the present hydro-peaking regime in Nidelva River (Norway), and the impacts that future changes in the operations of the hydropower system might introduce. The simulated future scenarios indicate that only limited changes are expected to happen compared to the present situation, measured as changes in accumulated degree-days. The model simulations predict a reduction in the range of 50 degree-days for two of the scenarios and an increase in approximately 40 degree-days for the third scenario. These results are further transformed into changes in salmon egg development and time of hatching, which corresponds to a few days delay in hatching in all three scenarios, and also a slight delay in swim-up for two of the three scenarios.
... The characterization of the peaking events was made by COSH-Tool, developed by SINTEF Energy Research, NO-7465 Trondheim, Norway [27]. In contrast with similar analyses, it separates peaking events into rapid increases and rapid decreases. ...
... In contrast with similar analyses, it separates peaking events into rapid increases and rapid decreases. It also analyses daylight conditions during peaking events and calculates the parameters for a specific season of the year defined by the user [27]. The tool characterizes the fluctuations in flow based on three parameters: magnitude, timing and frequency. ...
... The method used in this paper can apply to other river where hydropeaking is an issue. The analysis of hydrological time series using COSH-Tool provides an easy way of describing the peaking regime in the river and it allowed for the investigation of both diurnal and seasonal variations [27]. We combined the results of the hydraulic model with guidelines developed in the EnviPeak project [42], which provided an assessment for hydropeaking impact that could be also used in other rivers [5]. ...
Article
Full-text available
Extreme, short-duration fluctuations caused by hydropeaking occurs when hydropower is regulated to cover demand peaks in the electricity market. Such rapid dewatering processes may have a high impact on the downstream biological conditions, particularly related to stranding of fish and other species. The present work analyzes these fluctuations using a two-dimensional unsteady hydraulic modelling approach for quantification of two important hydro-morphological factors on fish stranding risk: the variation in wetted area and the dewatering ramping rate. This approach was applied on the two-kilometer-long reach of Storåne downstream of the Hol 1 power plant, where topo bathymetric LiDAR (Light Detection and Ranging) data was available providing a high-resolution digital elevation model. Based on this model, hydraulic conditions could be simulated in high detail allowing for an accurate assessment of the hydro morphological factors. Results show the dried area distribution at different flows and dewatering ramping rates. The attenuation of the water level fluctuation due to the damping effect along the river reach controls the dewatering rate. We recommend an alternative scenario operation which can reduce the impact of the peaking operation and estimate the operational mitigation cost. We find that the modelling based on the fine resolution grid provides new opportunities in assessing effects of hydropower regulations on the ecosystem.
... This lack of referencing is likely due to the hindrances in assessing the information, either because records of sub-daily flow fluctuations are inexistent or unavailable. However, the situation has changed in the last few years (Bejarano et al., 2017), with studies proposing flow metrics to quantify the magnitude, frequency and duration of flow fluctuations at sub-daily scales of 15 min (Sauterleute and Charmasson, 2014), 30 min (Zolezzi et al., 2011), and 1 h (Meile et al., 2010;Bevelhimer et al., 2015;Carolli et al., 2015;Chen et al., 2015;Alonso et al., 2017;Bejarano et al., 2017). Flow variability can be described by five components that depict spatio-temporal variations: magnitude, timing, frequency, duration, and rate of change of hydraulic parameters (Poff, 1997;Richter et al., 1996). ...
... Greimel et al., 2016), timing (daylight conditions) (e.g. Sauterleute and Charmasson, 2014), and frequency of peak flows (e.g. Bejarano et al., 2017). ...
... Although it is hard to find available information on finer sub-daily scales, these parameters can either be measured directly in the rivers or computed using hydrodynamic models. Sauterleute and Charmasson (2014) developed a computational tool for the characterization of rapid flow fluctuations, termed the COSH-Tool, which processes time series of discharge and water level, commonly designated as stage, to calculate a wide list of parameters. The authors based their approach on the method by Zolezzi et al. (2011), improving it by independently considering the increase (start of hydropower production) and decrease (shutdown of hydropower production) of flow. ...
Article
Hydropower plant (HPP) operations, in response to variations in market energy demand and electricity production, can generate rapid and frequent fluctuations of discharge in rivers downstream. This phenomenon, termed hydropeaking, may negatively impact fish populations. The present study aims to investigate the effects of hydropeaking on the Iberian barbel (Luciobarbus bocagei) habitat conditions. A two-dimensional (2D) model was used to obtain the habitat suitability downstream of a HPP. The influence of the ecological flow (E-flow) regime on the habitat conditions and flow fluctuations owing to hydropeaking was assessed. COSH-Tool was applied to the sub-daily flow series to quantify and characterize the rapid fluctuations (with and without an Eflow regime) with the purpose of assessing the impacts on fish habitat. The monthly distribution of peaking events showed a marked seasonal pattern associated with the Mediterranean climate, with most of the rapid fluctuations concentrated during thewet season. A peaking event occurred within three days of the lowflow period. Approximately 80% of the 10-year time series returned a zero value of discharge (no power production). The median of the rates of stage (water level change during an increase or decrease of flowdividedby the time of that change) resulted in 30.7 and 28.3 cm/h when the E-flow regime was not considered, and the rate of change was 26.3 and 22.4 cm/h when the E-flow regime was considered respectively for rapid increases and decreases. The flow ratio (peak flow divided by base flow) obtained for the E-flow regime was 334.3. Results showed that the hydrologic parameters associated with hydropeaking are attenuated with the E-flow regime. In certain cases, the E-flow regime should be regarded as an alternative mitigation measure for rivers subjected to hydropeaking.
... Most of them focus on certain components of the flow regime, hence being unable to fully represent it (Meile et al., 2011;Haas et al., 2014;Chen et al., 2015), and only some of them have already been used for the evaluation of sub-daily flow alterations (Zimmerman et al., 2010;Carolli et al., 2015). Sauterleute and Charmasson (2014), Bevelhimer et al. (2015) and Bejarano et al. (2016) developed a more thorough suite of indices quantifying the magnitude, the frequency and rapidity of flow changes during the day. Additionally, Sauterleute and Charmasson's indices provide information on the timing of the flow fluctuations and, together with those proposed by Bejarano et al. (2016), are the only indices which were applied to both discharge and water level. ...
... The computational tool proposed in Sauterleute and Charmasson (2014) was utilized in order to contrast its results with those obtained by means of the graphical method. We used the same flow records and standardized procedures as in our graphical approach. ...
... In all cases, parameters d which limits the minimum duration for a peaking sequence to be considered is 120 min, T for multipeaking sustained flow analysis is 2 h, and fraction p = 0.2 is used in the algorithm's decision tree. The values for parameters T and p are equivalent to those used in Sauterleute and Charmasson (2014). However, the value used for parameter d is 120 min (in practice 1 h, since for hourly-collected data, the algorithm's condition disregards peaking events strictly shorter than two hours), while d is 45 min in the aforementioned article because its case study assesses data which has been registered in 15 minute intervals. ...
... To evaluate the impact of hydropeaking resulting from hydropower production on short-term (e.g., sub-daily) flow regimes, it is necessary to characterize the within-day flow regime along the river reach affected by the hydropower plant and to quantify its deviation from the unaltered state. Metrics available are scarce and do not allow a comprehensive characterization of short-term flow regimes as they do not account for all hydrological attributes of ecological importance (Zimmerman et al., 2010;Meile et al., 2011;Haas et al., 2014;Sauterleute and Charmasson, 2014;Bevelhimer et al., 2015;Carolli et al., 2015;Chen et al., 2015). In addition, most proposed metrics are not conceived to quantify the degree of alteration. ...
... Despite short-term flow analysis being viable with shorter hydrological series than those typically needed to assess seasonal or annual flow patterns (Bevelhimer et al. 2015), the limited availability of hourly and sub-hourly stream flow records and the laborious processing required by such large volume of data have been a handicap for studies at finer resolutions. Moreover, although government agencies from several countries and hydropower companies are recently making their instantaneous flow records available [e.g., the USGS Current Water Data for the Nation (EEUU); the Swedish Meteorological and Hydrological Institute and some Swedish hydropower companies; the Norwegian Water Resources and Energy Directorate; the Rete di Monitoraggio in Tempo Reale dell'Ufficio Dighe (Italy); the Federal Office for the Environment (BAFU; Switzerland), among others], there is still a lack of tools supporting their treatment (but see, for example, Sauterleute and Charmasson 2014;Haas et al. 2014). For our purpose, the Vindel and Ume rivers in northern Sweden were excellent study areas. ...
... The recent increase in hydropower production worldwide has triggered an interest in short-term flow regimes, as these are highly affected by hydropeaking and in recognition of their influence on fluvial ecosystems. However, many studies still have a narrow scope dealing with a small and biased group of metrics (Meile et al., 2011;Zimmerman et al., 2010;Carolli et al., 2015), as long as they are essential for a target species, usually fish (Halleraker et al., 2003), or include larger but still insufficient numbers to account for every ecologically relevant aspect of the sub-daily flow regime (Haas et al., 2014;Sauterleute and Charmasson, 2014;Bevelhimer et al., 2015;Chen et al., 2015). Our proposed metrics have been carefully thought out to enable capturing the full range of within-day hydrological facets which may potentially influence any of the elements (biotic and abiotic) of the fluvial ecosystem, at any time of the life-cycle of different individuals. ...
Conference Paper
Full-text available
Many hydropower installations are producing electricity using hydropeaking. Hydropeaking refers to rising or falling discharges caused either by the turning on or off of hydro-turbines to generate electricity according to variations in the market demand. As a result, downstream and upstream river hydrology is altered due to unnatural, rapid and significant fluctuations in discharge, which result also in unnatural changes in hydraulic parameters, in water quality and river morphology. Although river flows vary on multiple temporal scales, it is the assessment of short-term changes in river flow (sub-daily flow variation) that is important for understanding the effects of hydropower generation dams on riparian and aquatic species and communities. However, methods and software available today are only based on mean daily flows which mask the sub-daily fluctuations and are therefore not considered to be precise enough. The aim of this study was to define ecologically meaningful hydrological metrics based on sub-daily flow series and to compare such metrics between free-flowing rivers and rivers with hydropeaking. We used 1-hour interval flow data series measured at gauging stations for the last ten years from the Umea River (regulated by cascades of hydropower plants) and Vindel River (free-flowing) in Northern Sweden. We proposed hydrological metrics that provide information on ecologically significant features of sub-daily flow regimes and related water levels influencing aquatic, wetland and riparian ecosystems based upon a statistical analysis of the sub-daily flows and water levels. Metrics include aspects of magnitude (i.e. magnitude, ramping rate and amplitude (max/min)) and timing (i.e. timing, periodicity, duration and frequency). The metrics were compared and it was quantified how sub-daily flows along regulated rivers differ from natural variability measured at unregulated sites. Then, thresholds of natural sub-daily variation were defined and a degree of hydropeaking alteration were assessed according to deviations from the thresholds. Finally, Indicator of HydroPeaking Alteration (IHPKA) user-friendly software was developed. It is an easy-to-use tool for calculating the characteristics of natural and altered sub-daily flow regimes and will be useful for summarizing long periods of sub-daily hydrological data into a much more manageable series of ecologically relevant hydrological metrics. Devised metrics, identified thresholds and generated software are useful for catchment management plans, defining environmental flow targets, prioritizing river restoration or dam reoperation efforts and contributing information for relicensing hydropower dams.
... To evaluate the impact of hydropeaking resulting from hydropower production on short-term (e.g., sub-daily) flow regimes, it is necessary to characterize the within-day flow regime along the river reach affected by the hydropower plant and to quantify its deviation from the unaltered state. Metrics available are scarce and do not allow a comprehensive characterization of short-term flow regimes as they do not account for all hydrological attributes of ecological importance (Zimmerman et al., 2010;Meile et al., 2011;Haas et al., 2014;Sauterleute and Charmasson, 2014;Bevelhimer et al., 2015;Carolli et al., 2015;Chen et al., 2015). In addition, most proposed metrics are not conceived to quantify the degree of alteration. ...
... Despite short-term flow analysis being viable with shorter hydrological series than those typically needed to assess seasonal or annual flow patterns (Bevelhimer et al. 2015), the limited availability of hourly and sub-hourly stream flow records and the laborious processing required by such large volume of data have been a handicap for studies at finer resolutions. Moreover, although government agencies from several countries and hydropower companies are recently making their instantaneous flow records available [e.g., the USGS Current Water Data for the Nation (EEUU); the Swedish Meteorological and Hydrological Institute and some Swedish hydropower companies; the Norwegian Water Resources and Energy Directorate; the Rete di Monitoraggio in Tempo Reale dell'Ufficio Dighe (Italy); the Federal Office for the Environment (BAFU; Switzerland), among others], there is still a lack of tools supporting their treatment (but see, for example, Sauterleute and Charmasson 2014;Haas et al. 2014). For our purpose, the Vindel and Ume rivers in northern Sweden were excellent study areas. ...
... The recent increase in hydropower production worldwide has triggered an interest in short-term flow regimes, as these are highly affected by hydropeaking and in recognition of their influence on fluvial ecosystems. However, many studies still have a narrow scope dealing with a small and biased group of metrics (Meile et al., 2011;Zimmerman et al., 2010;Carolli et al., 2015), as long as they are essential for a target species, usually fish (Halleraker et al., 2003), or include larger but still insufficient numbers to account for every ecologically relevant aspect of the sub-daily flow regime (Haas et al., 2014;Sauterleute and Charmasson, 2014;Bevelhimer et al., 2015;Chen et al., 2015). Our proposed metrics have been carefully thought out to enable capturing the full range of within-day hydrological facets which may potentially influence any of the elements (biotic and abiotic) of the fluvial ecosystem, at any time of the life-cycle of different individuals. ...
Article
A characterization of short-term changes in river flow is essential for understanding the ecological effects of hydropower plants, which operate by turning the turbines on or off to generate electricity following variations in the market demand (i.e., hydropeaking). The goal of our study was to develop an approach for characterizing the effects of hydropower plant operations on within-day flow regimes across multiple dams and rivers. For this aim we first defined ecologically meaningful metrics that provide a full representation of the flow regime at short time scales from free-flowing rivers and rivers exposed to hydropeaking. We then defined metrics that enable quantification of the deviation of the altered short-term flow regime variables from those of the unaltered state. The approach was successfully tested in two rivers in northern Sweden, one free-flowing and another regulated by cascades of hydropower plants, which were additionally classified based on their impact on short-term flows in sites of similar management. The largest differences between study sites corresponded to metrics describing sub-daily flow magnitudes such as amplitude (i.e., difference between the highest and the lowest hourly flows) and rates (i.e., rise and fall rates of hourly flows). They were closely followed by frequency-related metrics accounting for the numbers of within-day hourly flow patterns (i.e., rises, falls and periods of stability of hourly flows). In comparison, between-site differences for the duration-related metrics were smallest. In general, hydropeaking resulted in higher within-day flow amplitudes and rates and more but shorter periods of a similar hourly flow patterns per day. The impacted flow feature and the characteristics of the impact (i.e., intensity and whether the impact increases or decreases whatever is being described by the metric) varied with season. Our approach is useful for catchment management planning, defining environmental flow targets, prioritizing river restoration or dam reoperation efforts and contributing information for relicensing hydropower dams.
... Hydrological alterations are usually quantified using daily discharge data (Richter et al. 1996), thus ignoring sub-daily variations, and few methods adopt flow data at the higher resolution necessary for the quantification of hydropeaking-induced alterations (Meile et al. 2011;Zimmerman and Letcher 2010;Bevelhimer et al. 2014;Sauterleute and Charmasson 2014). For instance, Meile et al. (2011) proposed a set of three indicators and performed an analysis on different gauging stations along the Upper Rhone river. ...
... Zimmerman and Letcher (2010) developed a predictive method based on four ''flashiness indices'' that can be computed from hourly discharge data, and applied it to 30 gauging stations in the Connecticut River basin (USA) to compare the potential impacts of different types of dam operations. Recently, Sauterleute and Charmasson (2014) proposed an assessment tool based on 18 hydropeaking parameters, grouped by magnitude, time and frequency. Their analysis provides detailed information that can be particularly useful for the assessment of hydrological impacts and potential mitigation measures in relation to hydropeaking. ...
... Bevelhimer et al. (2014) divided a set of streams into three different groups: without alterations, with peaking and run of the river hydropower plants and compared the respective flow regimes using different indicators that quantify magnitude, variation, frequency and rate of change of flow events at sub-daily (hourly) and daily scales. The indicators proposed by Meile et al. (2011) and by Sauterleute and Charmasson (2014) can potentially be used to compare different levels of hydropeaking pressure among different streams but in both cases their application was limited to only one water course. Moreover, their methodology might not be broadly applicable, as the method proposed by Meile et al. (2011) requires long-term data of the same river watershed, which may not always be available. ...
Article
Release of water from storage hydropower plants generates rapid flow and stage fluctuations (hydropeaking) in the receiving water bodies at a variety of sub-daily time-scales. In this paper we present an approach to quantify such variations, which is easy to apply, requires stream flow data at a readily available resolution, and allows for the comparison of hydropeaking flow alteration amongst several gauged stations. Hydropeaking flow alteration is quantified by adopting a rigorous statistical approach and using two indicators related to flow magnitude and rate of change. We utilised a comprehensive stream-flow dataset of 105 gauging stations from Italy, Switzerland and Norway to develop our method. Firstly, we used a GIS approach to objectively assign the stations to one of two groups: gauges with an upstream water release from hydropower plants (peaked group) and without upstream releases (unpeaked group). Secondly, we used the datasets of the unpeaked group to calculate one threshold for each of the two indicators. Thresholds defined three different classes: absent or low pressure, medium, and high pressure, and all stations were classified according to these pressure levels. Thirdly, we showed that the thresholds can change, depending on the country dataset, the year chosen for the analysis, the number of gauging stations, and the temporal resolution of the dataset, but the outcome of the classification remains the same. Hence, the classification method we propose can be considered very robust since it is almost insensitive to the hydropeaking thresholds variability. Therefore, the method is broadly applicable to procedures for the evaluation of flow regime alterations and classification of river hydromorphological quality, and may help to guide river restoration actions.
... This approach is equivalent to measuring the bedload passing through a given location per time unit in river sediment studies. Many ecohydrological studies have built upon this Eulerian perspective to characterize and describe hydropeaking waves and sub-daily run-off regimes (e.g., Bevelhimer, McManamay, & O'Connor, 2015;Courret, Baran, & Larinier, 2021;Greimel et al., 2016;Li & Pasternack, 2021;Sauterleute & Charmasson, 2014). Hydrological data drawn from Eulerian assessments are commonly used to predict alterations to biological effects, both at the local scale (Auer, Zeiringer, Führer, Tonolla, & Schmutz, 2017;Saltveit, Halleraker, Arnekleiv, & Harby, 2001) and linked to the population scale (Hayes et al., 2021;Schmutz et al., 2015). ...
... So far, most hydrological hydropeaking studies aim to characterize artificial flow fluctuations and establish transferable tools to do so (e.g., Bevelhimer et al., 2015;Courret et al., 2021;Greimel et al., 2016;Li & Pasternack, 2021;Sauterleute & Charmasson, 2014). ...
Article
Full-text available
Hydropeaking is known for its adverse impacts on river ecosystems. However, the implementation of mitigation measures is still largely pending due to conflicting priorities of ecology and economics, which require scenario building to assess trade-offs. Therefore, widely applicable and standardized tools are needed to analyze hydropeaking hydrology in affected rivers to expedite mitigation efforts. Here, we present a novel empirical approach – PeakTrace – that can (i) detect and follow source-specific hydropeaking waves in the downstream direction by using multiple hydrographs and (ii) describe how flow metrics of hydropeaking waves change along a river’s course. In detail, PeakTrace first identifies associated flow events and then models translation and retention processes between neighboring hydrographs. Finally, the models can be combined to establish a non-linear hydropower plant-specific model. We demonstrate the PeakTrace method’s usability at 16 Austrian case studies. The results underline the high performance of PeakTrace, describing the longitudinal development of flow metrics with high model accuracy up to 25 km or more. Ecologically-relevant metrics, such as rate of change or amplitude, decrease with distance from the hydropower outlet regarding down-ramping events; the same pattern can be observed for up-ramping events too, except for the rate of change for which an intensity increase may be observed, probably due to slope and the roughness difference between base flow and peak flow. Overall, this paper underlines the usability of PeakTrace as a basis to assess hydropower plant-specific hydro-ecological impacts and evaluate hydropeaking mitigation measures, especially by incorporating critical flow thresholds of river biota and life stages.
... The flow ratio was 8.6, defined as the peak discharge (60 l.s -1 ) divided by the base-flow discharge (7 l.s -1 ) [77]. A flow ratio of this value is considered high for fish species according to the literature [41,77]. ...
... The flow ratio was 8.6, defined as the peak discharge (60 l.s -1 ) divided by the base-flow discharge (7 l.s -1 ) [77]. A flow ratio of this value is considered high for fish species according to the literature [41,77]. Two flow events were simulated; hydropeaking (HP) and base-flow events (BF) (Fig 1C). ...
Article
Full-text available
Hydropeaking is the rapid change in the water flow downstream of a hydropower plant, driven by changes in daily electricity demand. These fluctuations may produce negative effects in freshwater fish. To minimize these impacts, previous studies have proposed habitat enhancement structures as potential mitigation measures for salmonids. However, the recommendation of these mitigation measures for cyprinids remains scarce and their effects unknown. In this study, the effects of potential habitat mitigation structures under simulated hydropeaking and base-flow conditions are examined for Iberian barbel (Luciobarbus bocagei) in an indoor flume. Solid triangular pyramids and v-shaped structures were evaluated as potential flow-refuging areas and compared with a configuration without structures. A novel, interdisciplinary approach is applied to investigate individual and group responses to rapidly changing flows, by assessing physiological (glucose and lactate), movement behaviour (structure use, sprints and drifts) and the pressure distribution using a fish-inspired artificial lateral line flow sensor. The major findings of this study are four-fold: 1) Under hydropeaking conditions, the v-shaped structures triggered a lactate response and stimulated individual structure use, whereas solid structures did not elicit physiological adjustments and favoured individual and group structure use. Overall, both solid structures and their absence stimulated sprints and drifts. 2) The hydrodynamic conditions created in hydropeaking did not always reflect increased physiological responses or swimming activity. 3) Each event-structure combination resulted in unique hydrodynamic conditions which were reflected in the different fish responses. 4) The most relevant flow variable measured was the pressure asymmetry, which is caused by the vortex size and shedding frequency of the structures. Considering the non-uniform nature of hydropeaking events, and the observation that the fish responded differently to specific flow event-structure combinations, a diverse set of instream structures should be considered for habitat-based hydropeaking mitigation measures for Iberian barbel.
... The experimental design consisted of different hydropeaking events that combined flow magnitude and duration. The peak event flow ratio (magnitude) is defined as the maximum flow divided by the minimum flow (Sauterleute & Charmasson, 2014). Given three tested discharges, that is, two peak flows (20 and 60 L s −1 ) and a base flow (7 L s −1 ), the flow ratios were 2.9 and 8.6, which are considered moderate to high (Harby & Noack, 2013;Sauterleute & Charmasson, 2014) the flume reservoir to its maximum capacity, and at the same time, the discharge was manually controlled until attaining the tested peak flow. ...
... The peak event flow ratio (magnitude) is defined as the maximum flow divided by the minimum flow (Sauterleute & Charmasson, 2014). Given three tested discharges, that is, two peak flows (20 and 60 L s −1 ) and a base flow (7 L s −1 ), the flow ratios were 2.9 and 8.6, which are considered moderate to high (Harby & Noack, 2013;Sauterleute & Charmasson, 2014) the flume reservoir to its maximum capacity, and at the same time, the discharge was manually controlled until attaining the tested peak flow. Afterwards, the upstream gate was suddenly opened to a maximum of 10°while releasing the tested peak flow. ...
Article
The rapid flow fluctuations experienced downstream of hydropeaking facilities can alter the river hydromorphology. Given the dependence of riverine fish on physical habitat, those alterations have the potential to change the physiology and behaviour of fish. We assessed whether artificial velocity refuges mitigated the physiological and behavioural consequences of hydropeaking for the Iberian barbel (Luciobarbus bocagei). Hydropeaking trials were conducted in an indoor flume equipped with deflectors that created low flow velocity areas to serve as refuges. The FLOW‐3D® was used to obtain detailed characterizations of the different velocity fields, which facilitated the interpretation of fish responses. Changes in flow magnitude and duration triggered stress responses, demonstrated by the increased blood glucose levels in the single up‐ramping event for 60 l.s‐1 and in the step up‐ramping event. Fish tended to seek out velocity refuges to avoid higher flow velocities and harsh hydraulic conditions at peak‐flows, and during the longer events. The movement behaviour frequency increased when fish were subjected to the highest peak‐flow (60 l.s‐1), particularly the individual sprints, and the drifts. For the base‐flow (7 l.s‐1) and the lowest peak‐flow (20 l.s‐1) conditions, fish swam freely in the flume, whereas in the harshest hydraulic conditions they showed more difficulty in finding velocity refuges. This research presents a novel approach by combining physiology and behavioural observations with hydraulic modelling to assess the extent to which artificial flow refuges mitigate the consequences of hydropeaking. Our work serves as a model approach for future mitigation studies for fish in hydropeaking rivers.
... Power production by hydro-electric plants in response to short-term variations in market energy demand and electricity generation is Science of the Total Environment 573 (2016) 574-584 referred to as hydropeaking. If the power plant has its outlet on a river, hydropeaking may cause frequent and rapid fluctuations of discharge and water level in the stream (stream hydropeaking; Sauterleute and Charmasson, 2014). The discharge and water level fluctuations may have negative impacts on the riverine ecosystem (Bruno et al., 2013;Cereghino and Lavandier, 1998;Cushman, 1985;Liebig et al., 1999;Meile et al., 2011;Moog, 1993;Scruton et al., 2008;Vehanen et al., 2003). ...
... While sub-hourly intervals are important with respect to stranding of fish during dewatering, population dynamics extend over long periods, making it necessary to use a weekly time-step interval in the IBM in order to decrease computation time to a reasonable level. Therefore, we could not link dewatering or stranding events explicitly with the population model input record, i.e. the discharge time series; this would have required a sub-hourly time-step interval (Sauterleute and Charmasson, 2014). Instead, we defined a general hydropeaking regime with a defined number of dewatering events within a given period, a corresponding proportion of dewatered area and a related stranding probability and mortality dependent on the most important influencing factors. ...
Article
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Studies of hydropeaking-induced stranding mortality on fish populations have been confined to analysis of empirical data and/or short-term hydraulic-habitat modelling of individual events, and are thus limited as to how they may be used to infer long-term effects in fish populations. In this study, the effects of stranding mortality on an Atlantic salmon population were simulated using an individual-based Atlantic salmon population model with the objective of determining the sensitivity of population dynamics to stranding. It was found that density-dependent mortality (an alternative source of mortality in juvenile Atlantic salmon) partially compensated for stranding mortality, acting as a negative feedback mechanism that dampened change in population abundance. Stranding caused a perturbation in population dynamics, and effects of individual stranding events persisted in time across the life-stages of the population. Effects on population abundance depended on the time of year when stranding was applied, both because of intra-annual changes in stranding mortality probability and because of intra-annual changes in the ability of density-dependent mortality to compensate for stranding mortality. We concluded that empirical measurements of stranding mortality have limited potential for inference of overall effects on the population, and a more dynamic modelling approach, incorporating system feedback, allows for a better modelling of the impact of stranding. Sensitivity analysis showed that population abundance was highly sensitive to density-dependent mortality, and we suggest that this area should be prioritised for further research when investigating the effects of hydropeaking on rivers.
... Taking a sine/cosine process as an example, if its period changes from 2π to 4π then it is obvious that the process becomes flatter but retains its original SD. The contour type takes the abscissa of process into consideration and mainly describes the shape of process, such as its slope [5,25,28,29], rotation angle3031323334, number of reversals [5,25,29,35], and length [26]. In our earlier study on quantifying fluctuation [30], the rotation angle was used to calculate the fluctuation of the combined output of a pumped storage station and a thermal station. ...
... Taking a sine/cosine process as an example, if its period changes from 2π to 4π then it is obvious that the process becomes flatter but retains its original SD. The contour type takes the abscissa of process into consideration and mainly describes the shape of process, such as its slope [5,25,28,29], rotation angle3031323334, number of reversals [5,25,29,35], and length [26]. In our earlier study on quantifying fluctuation [30], the rotation angle was used to calculate the fluctuation of the combined output of a pumped storage station and a thermal station. ...
Article
Full-text available
Hydro-wind system output fluctuations are the primary factors used to assess the effects of hydropower on power companies compensating for wind power intermittency. Considering that most fluctuation indices can only characterize one aspect of fluctuations, namely, the quantitative or contour variations, we present a new index that uses the standard deviation (SD) and rotation angle to detect the quantitative variations and contour changes, respectively. Herein, the new index is compared with commonly used indices, specifically, the first-order difference, SD, and Richards-Baker flashiness indices. The results of tests performed using various processes and disposals show that: (1) when dealing with the process by moving average, repeating or overlay disposal, the new index performs comparably to the other indices, while when dealing with the process by zooming disposal, it more fully describes the fluctuation characteristics by taking both quantitative and contour variations into consideration; (2) when the new index is used to characterize the hydro-wind output fluctuations with different resources and capacities, the outcomes coincide with the mechanisms of hydro-wind systems. This study presents a new way to characterize the fluctuation of hydro-wind output.
... Sauterleute and Charmasson 2014 [21] Any subdaily interval ...
... Finally, no tools to date enable the assessment of the alteration of short-term regimes (Table 1). Specifically, COSH-Tool founds the characterization of subdaily regimes on peaking events (to some extend similar to the so-called pulses by other authors) previously identified by the user based on subjectively defined thresholds (e.g., [4,21,28,30]; Table 1). As our results show, the use of peaking events as characterization units prevents the characterization of natural (or slightly affected) series usually lacking such events. ...
Article
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The computational tool InSTHAn (indicators of short-term hydrological alteration) was developed to summarize data on sub-daily stream flows or water levels into manageable, comprehensive and ecologically meaningful metrics, and to qualify and quantify their deviation from unaltered states. The pronunciation of the acronym refers to the recording interval of input data (i.e., instant). We compared InSTHAn with the tool COSH-Tool in a characterization of the subdaily flow variability of the Colorado River downstream from the Glen Canyon dam, and in an evaluation of the effects of the dam on this variability. Both tools captured the hydropeaking caused by a dam operation, but only InSTHAn quantified the alteration of key flow attributes, highlighting significant increases in the range of within-day flow variations and in their rates of change. This information is vital to evaluate the potential ecological consequences of the hydrological alteration, and whether they may be irreversible, making InSTHAn a key tool for river flow management.
... The tested hydropeaking events mimicked the operation of a Portuguese hydropower plant (Pragana et al., 2017). Given the three discharges in test, i.e. two peak discharges (40 l.s −1 and 60 l.s −1 ) and a base-flow discharge (7 l.s −1 ), the flow ratios, defined as the maximum flow divided by the minimum flow (Q Peak /Q Base ) (Sauterleute and Charmasson, 2014), were 5.7 and 8.6 respectively, which are considered high (Harby and Noack, 2013;Sauterleute and Charmasson, 2014). A hydropeaking event was defined as a sequence of discharges, differing in peak-type event and peak frequency, where the time of exposure to each discharge was at least 20 min (Fig. 3). ...
... The tested hydropeaking events mimicked the operation of a Portuguese hydropower plant (Pragana et al., 2017). Given the three discharges in test, i.e. two peak discharges (40 l.s −1 and 60 l.s −1 ) and a base-flow discharge (7 l.s −1 ), the flow ratios, defined as the maximum flow divided by the minimum flow (Q Peak /Q Base ) (Sauterleute and Charmasson, 2014), were 5.7 and 8.6 respectively, which are considered high (Harby and Noack, 2013;Sauterleute and Charmasson, 2014). A hydropeaking event was defined as a sequence of discharges, differing in peak-type event and peak frequency, where the time of exposure to each discharge was at least 20 min (Fig. 3). ...
Article
Fish responses to hydropeaking may range from sub-organismal adjustments to key life-event changes. It is currently difficult to quantify these responses and to assess the potential of artificial refuges accordingly. To address this problem, two experimental trials were conducted in an indoor flume. In the first, two hydropeaking events were tested in the presence of deflectors as flow refuges. In the second, the presence and absence of deflectors was tested for the same hydropeaking event. A multidisciplinary approach combined physiological and movement behaviour responses of Iberian barbel (Luciobarbus bocagei) with hydrodynamic models. These were used as a complementary tool to explain the fish responses. In the first experiment, no evident physiological adjustments occurred. However, individual refuge use and swimming activity were higher in the single-step event where velocities above 0.6 m.s⁻¹ were observed. In the second experiment, the levels of glucose were the highest in the repeated single-step event with deflectors, whereas in their absence no visible changes were observed. The sequence of discharges affected the frequency of individual sprints and group drifts, particularly evident with deflectors. Additionally, the deflector use increased in the first peak in opposition to the second. Overall, the fish responses were indicative that the low velocity areas (<0.1 m.s⁻¹) existing behind the deflectors were favourable under hydropeaking conditions. However, the flow complexity resulting from the presence of deflectors impaired their ability to successfully find them. The integrated approach used in this study provided novel insight considering the responses of cyprinids to hydropeaking in the presence and absence of deflectors as a mitigation measure. This study emphasized the importance of characterizing the hydrodynamic conditions due to hydropeaking, particularly after including the artificial refuges.
... Thus, more detailed information on flow variation over a shorter interval (hourly or subhourly) may be needed to identify impacts to biota. Some metrics that utilize sub-daily data have previously been proposed [10][11][12][13][14][15]. These studies show that the operations of reservoirs, even the small ones, have the potential to cause modifications to the sub-daily hydrological regime. ...
... Thus, more detailed information on flow variation over a shorter interval (hourly or sub-hourly) may be needed to identify impacts to biota. Some metrics that utilize sub-daily data have previously been proposed [10][11][12][13][14][15]. These studies show that the operations of reservoirs, even the small ones, have the potential to cause modifications to the sub-daily hydrological regime. ...
Article
Full-text available
This work aims to evaluate the hydrologic changes caused by a small hydropower plant on the watercourse in which it is installed. Since hydrologic research with data of temporal frequencies less than a day is less common than daily measurements, there are few indicators and methodologies capable of treating such records. For this reason, 17 indicators are proposed which describe the magnitude, duration, frequency and rate of changes in hydrologic conditions occurring in a watercourse at a sub-daily frequency. These 17 indicators were used to assess changes in the flow regimes at sub-daily scales across the Itiquira hydroelectric facility in Mato Grosso, Brazil. During the dry season the river was more susceptible to hydroelectric operations than during the wet season. Eighty-eight percent of the proposed indicators were significantly altered during the dry season compared to 71% during the rainy season. In addition to the number of indicators that changed between the seasons, the magnitude of the change was different. During the dry season, 53% of the magnitudes of the proposed indicators were classified as having a high magnitude of change, while in the rainy season only 6% of the indicators were characterized as having a high magnitude of change.
... Hydropeaking is highly fluctuating flow (often within a day) caused by the release of water from reservoir hydroelectric power stations when the operations are matched with marked demand (Sauterleute and Charmasson, 2014). These unnatural downstream flow fluctuations can potentially have large impacts on ecosystems and fish communities if the fluctuations strongly exceed the flow variation that the biota is adapted to (Young et al., 2011). ...
... By addressing this phenomenon directly, important biotic and physical effects of hydropeaking can be explored and understood in the future. Similar to hydropeaking (Sauterleute and Charmasson, 2014), saturopeaking can be defined as the artificial, rapid, periodic and frequent (often within a day) fluctuation of gas saturation caused by hydropower operations according to the electricity market demand. ...
Article
During the monitoring of total dissolved gas (TDG) saturation in the Vetlefjordelva River in western Norway in 2014-2015, characteristic waves of supersaturated water were discovered. These waves were significantly correlated with hydropower operation, which was run by hydropeaking (R(2)=0.82, p<0.001). The TDG saturation varied between 99% and 108%, with a median of 105%. The term "saturopeaking" is introduced for these waves, defined as the artificial, rapid, periodic and frequent fluctuation of gas saturation caused by hydropeaking. Hydropeaking is recognized as hydropower operation that rapidly fluctuates according to the electricity market demand. Though the observed TDG saturation levels were moderate and not likely to cause acute effects on biota, we expect that the observed saturopeaking may have significant ecological impacts in general, especially in cases with TDG saturation levels >110^% which is considered as potentially lethal for fish in rivers.
... Power production by hydro-electric plants in response to short-term variations in market energy demand and electricity generation is Science of the Total Environment 573 (2016) 574-584 referred to as hydropeaking. If the power plant has its outlet on a river, hydropeaking may cause frequent and rapid fluctuations of discharge and water level in the stream (stream hydropeaking; Sauterleute and Charmasson, 2014). The discharge and water level fluctuations may have negative impacts on the riverine ecosystem (Bruno et al., 2013;Cereghino and Lavandier, 1998;Cushman, 1985;Liebig et al., 1999;Meile et al., 2011;Moog, 1993;Scruton et al., 2008;Vehanen et al., 2003). ...
... While sub-hourly intervals are important with respect to stranding of fish during dewatering, population dynamics extend over long periods, making it necessary to use a weekly time-step interval in the IBM in order to decrease computation time to a reasonable level. Therefore, we could not link dewatering or stranding events explicitly with the population model input record, i.e. the discharge time series; this would have required a sub-hourly time-step interval (Sauterleute and Charmasson, 2014). Instead, we defined a general hydropeaking regime with a defined number of dewatering events within a given period, a corresponding proportion of dewatered area and a related stranding probability and mortality dependent on the most important influencing factors. ...
Article
Rapid dewatering in rivers as a consequence of hydropower operations may cause stranding of juvenile fish and have a negative impact on fish populations. We implemented stranding into an Atlantic salmon population model in order to evaluate long-term effects on the population in the Dale River, Western Norway. Furthermore, we assessed the sensitivity of the stranding model to dewatered area in comparison to biological parameters, and compared different methods for calculating wetted area, the main abiotic input parameter to the population model. Five scenarios were simulated dependent on fish life-stage, season and light level. Our simulation results showed largest negative effect on the population abundance for hydropeaking during winter daylight. Salmon smolt production had highest sensitivity to the stranding mortality of older juvenile fish, suggesting that stranding of fish at these life-stages is likely to have greater population impacts than that of earlier life-stages. Downstream retention effects on the ramping velocity were found to be negligible in the stranding model, but are suggested to be important in the context of mitigation measure design.
... It is not a well-established, quantitative definition in the literature on how large or how rapid the changes must be in order to be categorized as hydropeaking operations. Carolli et al. (2015) and Bevelhimer, McManamay, and O'Connor (2015) have proposed procedures to characterize hydropeaking regimes based on the hydrological description of flow patterns, while Sauterleute and Charmasson (2014) and Greimel et al. (2016) developed calculation methods for such characterization. ...
... were calculated by use of the COSH-Tool (Sauterleute & Charmasson, 2014 For the purpose of the assessment of the four case study rivers, data were to a large extent taken from previous work, and the specific data references are given in each of the result tables. ...
Article
Full-text available
This article proposes and demonstrates a new classification system of fish population level effects of hydropeaking operations in rivers. The classification of impacts is developed along two axes; first, the hydromorphological effect axis assesses the ecohydraulic alterations in rivers introduced by rapid and frequent variations in flow and water level, second the vulnerability axis assesses the site-specific vulnerability of the fish population. Finally, the population level impact is classified into four classes from small to very large by combining the two axes. The system was tested in four rivers in Norway exposed to hydropeaking, and they displayed a range of outcomes from small to very large impacts on the salmon populations. The river with a relatively high base flow and ramping restrictions scored better than rivers with the lower base flow or limited ramping restrictions, indicating that hydropeaking effects can be mitigated while maintaining high hydropower flexibility. Most effect factors could easily be calculated from timeseries of discharge and water level, whereas the use of hydraulic models to estimate potential stranding areas may require more work. The vulnerability factors are mainly qualitative and depend more heavily on expert judgments and are thus more uncertain. The system was deemed suitable for the purpose of supporting management decisions for rivers exposed to hydropeaking operations. It evaluates the severity of the additional pressures due to hydropeaking operations and proved useful to identify mitigating measures. While the system was developed for Atlantic salmon river systems, it could be adapted to other species or systems.
... Norwegian Ministry of Petroleum and Energy, 2012). However, while different approaches and methodologies are available for the quantification of sub-daily flow regime alteration (Zimmerman et al., 2010;Meile et al., 2011;Bevelhimer et al., 2014;Sauterleute and Charmasson, 2014;Carolli et al., 2015), little attention has been devoted to the subdaily thermal alterations in rivers so far. ...
Article
The thermal regime of rivers is threatened by anthropogenic stresses at a large variety of time scales. We focus on sub-daily thermal alterations induced by the release of hypolimnetic water for hydropower production (thermopeaking). We analyse the thermal signal focusing on the following characteristics that are potentially affected by hypolimnetic releases: i) subdaily thermal rate of change and ii) oscillation frequencies contained in the thermal signal. Through a proper scaling we derive two dimensionless at-a-station indicators to compare alterations among stations with different locations and physiographic characteristics of the basins. Then we analyse the data from two different thermal datasets (Italy/Switzerland) for a total of 48 stations with 10 minutes time resolution of temperature data. The stations are grouped according to the absence of upstream hydropeaking releases (29 stations, reference group) and the existence of upstream hydropeaking, hence potentially impacted by thermopeaking (19 stations, altered group). Using a simple statistical approach, based on a non-parametric definition of outliers, we identify the range of variability of the two indicators for the reference, unaltered group. This range measures the "natural" subdaily thermal variability of the proposed indicators. Finally, we investigate the seasonality effects on the two proposed indicators and it results that sub-daily alterations mostly occur during summer. The two indicators represent a novel tool for the assessment of river thermal regime alterations and can be easily included in existing methodologies to asses river quality.
... The physical template of rivers has dramatically changed due to dams and river regulation affecting the downstream hydrology (Graf, 1999(Graf, , 2006, sediment dynamics (Kondolf, 1997;McCully, 1996) and river morphology (Brandt, 2000;Petts, 1984), with consequent changes in habitat quality and distribution (Ward and Stanford, 1995;Schmidt and Wilcock, 2008). As a specific form of an altered flow regime downstream of dams, artificial flow fluctuations due to energy production on demand are classified as hydropeaking (Sauterleute and Charmasson, 2014). In alpine rivers, hydropeaking is identified as one of the most significant impacts on rivers downstream of dams (Moog, 1993;Saltveit et al., 2001). ...
... It will also contribute information for relicensing hydropower dams. In response to this need, several authors have developed sub-daily flow metrics during recent years (Zimmerman et al., 2010;Meile, Boillat & Schleiss, 2011;Sauterleute & Charmasson, 2014;Bevelhimer, McManamay & O'Connor, 2015;Carolli et al., 2015;Chen et al., 2015;. However, researchers still have to devise a comprehensive but non-redundant set of metrics, as most of the available metrics only quantify specific facets Zolezzi et al., 2011). ...
Article
Full-text available
Hydropeaking refers to frequent, rapid and short-term fluctuations in water flow and water levels downstream and upstream of hydropower stations. Such fluctuations are becoming increasingly common worldwide and are known to have far-reaching effects on riverine vegetation. Novel hydrology caused by hydropeaking has no natural correspondence in freshwater systems, and hence few species have adaptations to all its aspects. Here, we review the literature on hydropeaking effects on riverine plants and define the state of the information on this human alteration of riverine ecosystems. We focus on riparian plants, but also draw on information from aquatic plant species, which exhibit a wide variety of adaptations to inundation and associated processes. Riparian plants face both physiological and physical constraints because of the shifts between submergence and drainage, and erosion of substrates. At the population level, hydropeaking may favour dispersal within, but not between, reservoirs, but may hamper germination, establishment, growth and reproduction. At the community level, strong filtering towards easily dispersed, flexible, flood-tolerant and amphibious plants is expected, although few species share these traits. Hence, most riparian plant species are expected to disappear or be pushed towards the upper boundaries of the regulated river margin. Future research should examine more closely global variation in hydropeaking effects, including other taxonomic groups of species and the diversity of hydropeaking regimes. There is also a need for studies focusing on identifying the boundaries within which hydropeaking could operate without impairing plant life.
... Eco-hydrographs were determined based on the relationship between discharge and fish habitat conditions, which was assessed by the improved habitat model. The variation range in water level is an extremely important factor during the fish spawning period (Zhou et al., 1980;Zeng, 1990;Hofreiter and Stewart, 2009;Appels et al., 2011;Forman et al., 2014;Jager, 2014;Sauterleute and Charmasson, 2014) and should be considered in eco-hydrograph estimations. In this paper, the variation range of the water level was taken into account in the design of ecological hydropeaking. ...
... Eco-hydrographs were determined based on the relationship between discharge and fish habitat conditions, which was assessed by the improved habitat model. The variation range in water level is an extremely important factor during the fish spawning period (Zhou et al., 1980;Zeng, 1990;Hofreiter and Stewart, 2009;Appels et al., 2011;Forman et al., 2014;Jager, 2014;Sauterleute and Charmasson, 2014) and should be considered in eco-hydrograph estimations. In this paper, the variation range of the water level was taken into account in the design of ecological hydropeaking. ...
Article
Global conflict over water has become increasingly problematic. To meet water demands for economic growth in China, a large number of hydro-projects have been developed and operated, which have significantly altered the natural hydrological regime of many rivers and imposed profound impact on aquatic ecosystems. Conservation of appropriate ecological flow is essential to balance river ecosystem health and economic development. We proposed an innovative method for river eco-hydrograph determination based on the protection of fish spawning habitat. An integrated hydro-environmental-habitat model was developed and applied in de-watered channels in the middle of Yalong River, China, where water was diverted for hydropower generation. Schizothorax chongi (S. chongi), the dominant and commercial indigenous fish, was selected as the target species. Different from previous research, the impacts of fragmentation and water level variation on fish habitat were analyzed in the spawning period. Eco-hydrographs for different preservation levels of S. chongi spawning habitat were estimated using the developed model and the suitable one was recommended. Compared with traditional hydrologic and hydraulic methods, the improved habitat method not only determined the ecological water demand of the species more meaningfully, but also increased water use efficiency. This article is protected by copyright. All rights reserved.
... To our knowledge, study on prediction of 'unimpaired' or natural hourly streamflow series in regulated rivers for ecological purposes is not widely reported in literature. Sauterleute and Charmasson (2014) developed a computational tool, which enables the quantification of short-term (rapid) fluctuations of flow and stage occurring in rivers resulting from hydropeaking, by means of processing the time series. However, the authors noted that the tool was not developed to enable comparisons between rivers with and without hydropeaking, or those with natural flow regimes. ...
Article
Prediction of natural streamflow in regulated rivers for derivation of ecologically relevant streamflow metrics (ERSFMs) and prediction in ungauged basins (PUB) are important in management of water resources. However, specific studies on comparison of methods for predicting hourly flow regime relevant to ecological study in regulated (hydropeaking) rivers are rare in literature. Therefore, using catchments in mid Norway, we performed comparative evaluation of prediction of hourly streamflow series and flow duration curves (FDCs) in ungauged basins. We developed a regional regression model based on relationships among streamflow percentiles and drainage areas and performed a regional calibration of a streamflow recession based precipitation–runoff (P–R) model.
... In the European Alps, 79% of river reaches are subjected to hydropower operations (Truffer et al., 2003). Among the hydrological alterations induced by hydropower production a relevant and frequent phenomenon is hydropeaking, defined as "rapid variations in power production by hydro-electric plants as a consequence of varying electricity generation and fluctuations in demand in the electricity market" (Sauterleute and Charmasson, 2014). Hydropeaking induces artificial sudden water depth and streamflow variations in rivers and lakes, with a direct effect on sub-daily and seasonal flow regimes and with known ecological consequences (Scruton et al., 2005;Looy et al., 2007;Bruno et al., 2009;Bruno et al., 2010;Tuhtan et al., 2012;Jones, 2013;Carolli et al., 2015). ...
Article
Abstract Cultural and recreational river ecosystem services and their relations with the flow regime are still poorly investigated. We develop a modelling-based approach to assess recreational flow requirements and the spatially distributed river suitability for white-water rafting, a typical service offered by mountain streams, with potential conflicts of interest with hydropower regulation. The approach is based on the principles of habitat suitability modelling using water depth as the main attribute, with preference curves defined through interviews with local rafting guides. The methodology allows to compute streamflow thresholds for conditions of suitability and optimality of a river reach in relation to rafting. Rafting suitability response to past, present and future flow management scenarios can be predicted on the basis of a hydrological model, which is incorporated in the methodology and is able to account for anthropic effects. Rafting suitability is expressed through a novel metric, the “Rafting hydro-suitability index” (RHSI) which quantifies the cumulative duration of suitable and optimal conditions for rafting. The approach is applied on the Noce River (NE Italy), an Alpine River regulated by hydropower production and affected by hydropeaking, which influences suitability at a sub-daily scale. A dedicated algorithm is developed within the hydrological model to resemble hydropeaking conditions with daily flow data. In the Noce River, peak flows associated with hydropeaking support rafting activities in late summer, highlighting the dual nature of hydropeaking in regulated rivers. Rafting suitability is slightly reduced under present, hydropower-regulated flow conditions compared to an idealized flow regime characterised by no water abstractions. Localized water abstractions for small, run-of-the-river hydropower plants are predicted to negatively affect rafting suitability. The proposed methodology can be extended to support decision making for flow management in hydropower regulated streams, as it has the potential to quantify the response of different ecosystem services to flow regulation.
... Physical processes Hydraulic, hydrological and topographical modelling including simulations, particle tracking techniques, assessment of river topography and morphology through geomatics, thermal imagery, remote sensing, experimentation in hydraulic laboratories Brasington, Vericat, & Rychkov, 2012;Carolli et al., 2015;Sauterleute & Charmasson, 2014 Biology Habitat and population modelling; underwater cameras and telemetry for behavioral observations; experimentation in hydraulic laboratories and open-air flumes; impacts classification systems Bakken et al., 2021;Boavida et al., 2021;Bruno et al., 2016;Capra et al., 2017;Costa et al, 2019b;Hedger et al., 2018;Holzapfel et al., 2017;Person, Bieri, Peter, & Schleiss, 2014;Schneider et al., 2017;Schülting et al., 2018 Optimising hydropower plant operation ...
Article
An increase in the demand for renewable energy is driving hydropower development and its integration with variable renewable energy sources. When hydropower is produced flexibly from hydropower plants, it causes rapid and frequent artificial flow fluctuations in rivers, a phenomenon known as hydropeaking. Hydropeaking and associated hydrological alterations cause multiple impacts on riverine habitats with cascading effects on ecosystem functioning and structure. Given the significance of its ecological and socio‐economic implications, mitigation of hydropeaking requires an inter‐ and transdisciplinary approach. An interdisciplinary network called HyPeak has been conceived to enrich international research initiatives and support hydropower planning and policy. HyPeak has been founded based on exchange and networking activities linking scientists from several countries where hydropeaking has been widespread for decades and numerous studies dedicated to the topic have been carried out. HyPeak aims to integrate members from other countries and continents in which hydropower production plays a relevant role, and grow to be a reference group that provides expert advice on the topic to policy‐makers, as well as researchers, stakeholders, and practitioners in the field of hydropeaking.
... Nevertheless, storage operation results in frequent discharge pulses commonly referred to as "hydropeaking" (Bratrich et al., 2004;Bretschko & Moog, 1990;Sauterleute & Charmasson, 2014). Peaking hydroelectric operation leads to modifications of downstream hydrological characteristics, such as the wetted width, water depth, flow velocity, and bottom shear stress (Schmutz et al., 2015) and may additionally alter the thermal regime and the sediment budget (Hauer, 2016;Zolezzi, Siviglia, Toffolon, & Maiolini, 2011). ...
Article
Full-text available
Intermittent storage hydropower production is the only renewable source offering both, a sufficient storage potential and a high temporal flexibility in production to ensure grid stability. However, hydropeaking (generation of peak discharges by hydro‐electric operation) causes fluctuations in the wetted width, water depth, flow velocity and bottom shear stress downstream of a hydro‐electric facility. River biota are known to be affected by these changes, which leads for example to increased drift. Correspondingly, abundance and biomass of macroinvertebrates are frequently found to be reduced in impacted river stretches. While there is sufficient evidence for increasing drift proportions due to hydropeaking, only few studies have highlighted the role of the rapidity of flow increase before and flow decrease after a peak event (ramping velocity). Here, we present the outcome of experimental hydropeaking in artificial flumes, mimicking two different ramping velocity treatments (T1: 0.5 cm/min, T2: 1 cm/min water table change) in early and late spring (June’14, March ‘15). Macroinvertebrate drift was significantly higher in treatments as compared to control flumes. Drift proportions peaked during the up‐ramping phase and were slightly lower during the peak discharge phase. Drift proportions of T2 treatments were significantly higher than those of T1 in June, but not in March. Our findings suggest that hydropeaking requires thoughtful ramping management, to allow macroinvertebrates to seek for refugia on the stream bottom during the peak event. However, the evidence of daytime‐dependent and seasonal drift patterns also plea for adaptive management, to account for the temporal variability of macroinvertebrate drift.
... This means that hydropower is likely to be increasingly important in the future, balancing variation in wind and solar power production to ensure that electricity demands are met and the frequency in the electricity grid remains stable (Riml et al., 2018). Hydropower can increase or decrease production within minutes by adjusting flow at hydropower stations (Sauterleute and Charmasson, 2014), a practice called hydropeaking (Moog, 1993). ...
Article
Hydropeaking, defined as rapid and frequent changes in flow to optimize hydropower production, is an increasingly common procedure negatively affecting lotic habitats in riverine ecosystems. An important aspect of hydropeaking is zero-flow events, occurring when hydropower stations are stopped due to low energy demand or low electricity prices. We quantified the ecological benefits and consequences for hydropower production of restricting zero-flow events. The 19 major hydropower stations in the Ume River system in northern Sweden stand still with no discharge 9% to 55% of the time a hydrologically normal year, transforming lotic habitat to stagnant water. The duration of zero-flow events is exacerbated in dry years, with no discharge for 28% of the time in a typical station, to be compared with 7% in a wet year. Zero-flow events affect the behavior of fish, altering the fish community, and potentially result in low oxygen levels and low food supply to filter-feeding macroinvertebrates. We modelled the consequences of restricting zero-flow events by introducing minimum flows equaling mean annual low flow or higher for the entire Ume River catchment. The measure would result in an additional 240 ha of shallow lotic habitat with gravel to boulder streambeds having flow velocity exceeding 0.1 m/s, i.e. suitable for lotic species such as grayling Thymallus thymallus. In addition, the measure would enable creating another 107 ha of similar habitat after structural rehabilitation of river reaches. All measures would result in a mean loss of hydropower production of 0.5% per year for the entire river system, 98% of which would occur between May and October when the demand for electricity is lower. Hydropower production would also be partly moved from daytime to nighttime. As zero-flow events are common in several other river systems, restrictions on their frequency and duration could be implemented in many areas.
... To evaluate the level of balancing services vs potential riverine impacts from the HPP with several years of turbine data, Kenawi (2020) initially processed the sub-daily flow series by use of the COSH-tool software (Sauterleute and Charmasson, 2014). Due to difficulties in separating minor from major flow ramping events from COSH, a R-script was made following the guidelines offered by Greimel et al. (2016) to detect the ecologically most relevant flow ramping descriptors. ...
Article
Full-text available
Hydropower production is a key electricity generation technology in many parts of the world which can play a significant role in the transition towards a green and clean energy system. Hydropower can mobilize flexible energy on demand (hydropeaking) to balance out intermittent electricity from wind and photovoltaics. Adoption of hydropower as a peaking power source could lead to increased frequency of flow ramping in rivers downstream hydropower tailraces, which is one of the main stressors for riverine biota in alpine rivers. Both planned and accidental shutdowns of hydropower turbines need ecological mitigation. Our survey revealed that >3000 km of rivers downstream ca 800 hydropower plants in Norway may be ecologically impacted by non-natural flow fluctuations, and few have appropriate mitigation thresholds. A considerable eco-friendly peaking service may come from the Norwegian hydropower portfolio of over 19 GW installed capacity, with outlets into fjords, reservoirs or other large water bodies which normally dampen the ecological impacts of flow ramping. Intensive flow ramping occurs with irregular intervals from most types of hydropower. Although the highest frequency of stops were revealed in hydropower turbines not impacting river flow from storage hydropower, a significant number of turbine flow stops lasting over half a day in most types and categories of diversion hydropower. We suggest that further emerging ecosystem-based mitigations need to be adapted in hydropower licenses. This includes operational thresholds for both up and down ramping, constructional measures like by-pass valves, retention basins and increased base-flow or flow cap to ensure sustainability for hydropower operations. Our data reveal some of the most intensive hydropeaking operations from hydropower impacting longer rivers. Hence, our data underpins the potential for restoring downstream modified flow by ecosystem based measures related to both up and down ramping events in many regulated rivers.
... Peaking operation of hydroelectric facilities can strongly alter river hydrology, resulting in displacement of water volumes on various time scales (daily, weekly or even seasonally depending on the storage capacity of the facilities) and also rapid and frequent changes in river flow downstream of power plants Bejarano et al. 2017;Carolli et al. 2015;Sauterleute et al. 2014;Zimmerman et al. 2010). These variations in flow have direct impacts on hydrodynamic conditions and consequently on aquatic habitat and fauna. ...
... Eflows) or residual base flow (when HP turbine flow is stopped or 211 at low production) in the river downstream the HP tailrace. 212To evaluate the level of balancing services vs potential riverine impacts from the HP with several 213 years of turbine data,(Kenawi, 2020) initially processed the sub-daily flow series by use of the COSH-214 software(Sauterleute & Charmasson, 2014). Due to difficulties to separate minor from major flow 215 ramping events from COSH, a script was made following the guideline of(Greimel et al., 2016) to 216 detect the ecological most relevant flow ramping descriptors. ...
Article
HIGHLIGHTS - Intensity of hydropeaking is still severe in many Norwegian rivers - An eco-peaking potential of over 19 GW can be utilised without river flow ramping - Ecological effects of hydropeaking are partly overlooked in management plans - A national hydropower mitigation strategy is needed to ensure sustainability - Flow ramping mitigation also relevant in small scale hydro, without large reservoirs
... This means that hydropower is likely to be increasingly important in the future, balancing variation in wind and solar power production to ensure that electricity demands are met and the frequency in the electricity grid remains stable (Riml et al., 2018). Hydropower can increase or decrease production within minutes by adjusting flow at hydropower stations (Sauterleute and Charmasson, 2014), a practice called hydropeaking (Moog, 1993). ...
Article
Full-text available
To enable prioritization among measures for ecological restoration, knowing the expected benefits and consequences of implementation is imperative, but rarely explicitly quantified. We developed a novel method to prioritize among environmental-flow measures to rehabilitate ecosystems in the Ume River catchment in northern Sweden, a river system heavily regulated for hydropower production. Our strategy was to identify measures with minimal impact on hydropower production while providing substantial environmental benefits. Based on field surveys of remaining natural values and potential for ecological rehabilitation, we quantified the projected gain in habitat area of implementing environmental flows for target organism groups, e.g. lotic fish species and riparian vegetation, along the whole river length. We quantified the consequences for hydropower production by identifying a set of hydropower operational rules reflecting the constraints added by environmental flows. We then used production optimization software to calculate changes in hydropower production and revenues. Implementing restrictions on zero-flow events by mandating minimum discharge at all run-of-river hydropower stations, and allocating 1-12% of mean annual discharge to bypassed reaches in the entire catchment, would result in a 2.1% loss of annual electricity production. Adding flow to fishways would increase the loss to 3.1% per year. With implementation of more natural water-level fluctuations in run-of-river impoundments, the loss increases to 3.8%. These actions would increase the habitat for lotic species like the grayling Thymallus thymallus more than threefold, and increase the area of riparian vegetation by about 66%. Our method forms a basis for ongoing implementation of nation-wide environmental rehabilitation schemes.
... Hydropeaking operation results in short-term changes in river flows occurring downstream of hydroelectric facilities, due to the turning on and off of turbines, a consequence of varying electricity generation and fluctuation in demand in the electricity market (Moog, 1993;Sauterleute and Charmasson, 2014). This leads to displacement of water volumes on various time scales (daily, weekly or even seasonally depending on the storage capacity of the facilities) and is likely to affect several components of stream hydrology. ...
Article
Hydropeaking by hydroelectric facilities generates sudden changes in river flows and can affect the composition, abundance and structure of fish and invertebrate populations over long distances. To assess the level of hydrological alteration, as a factor of risk of biological impacts, a synthetic indicator was developed. Based on the analysis of 97 hydrometric stations and 1575 years of unaltered flow data, rates of change in flow were calculated. Formulas representing the fastest natural variations, depending on the mean stream flow, the type of variation (increase or decrease) and the range of variation were established. Based on the analysis of 80 hydrometric stations and 491 years of flow data affected by hydropeaking, a method was developed to identify hydropeaks, essentially defined as variations with a rate of change greater than the maximum natural value computed using the formulas. A synthetic indicator differentiating five levels of hydrological alteration was developed using linear discriminant analysis based on five parameters characterizing hydropeaking regimes. Examples show that this indicator is sensitive to changes in the management of hydroelectric facilities and provides information on the spatial and temporal evolutions in hydropeaking regimes, including the progressive attenuation during downstream propagation.
... While this approach successfully fused the benefits of both these methods, their work is limited to the daily flow of an individual river. After that, an algorithm named COSH was developed to analyze the temporal variation of hydropeaking flow (Sauterleute et al. 2014). Unfortunately, even though COSH made an important advance in mining hydropeaking features automatically, it still requires iterative adjustments to thresholds to detect hydropeaking events for each river. ...
Article
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Hydropeaking, a hydroelectricity generation strategy involving rapid changes to flow releases from dams in response to fluctuations in hourly-adjusted electricity markets has been widely applied due to its economic efficiency. However, these operational practices produce sub-daily flow fluctuations that pose substantial hazards to riverine ecosystems and human activities. To ascertain the downstream impacts of hydropeaking, features of hydropeaking have been analyzed with respect to ecologically relevant hydrologic variables. However, since studies aiming to characterize hydropeaking regime often require manual feature extraction, they are commonly limited to small temporal and spatial scales. Additionally, riverine ecologists have commonly treated hydropeaking as a broadly similar flow-alteration pattern regardless of the complexities of the electricity market and differences in the natural settings where it is applied. Therefore, this study sought to determine whether significantly different hydropeaking patterns exist on a regional scale, as revealed by temporal variations in hydropeaking over a long temporal scale (> five years). To fulfill this goal, a new algorithm, the Hydropeaking Event Detection Algorithm (HEDA), was developed in R to automate the characterization of hydropeaking flow regimes. Clustering analyses were conducted to explore the similarities and differences of hydropeaking regimes among 33 sites in numerous hydrologic regions of California. Four distinct classes of hydropeaking flow regimes were identified and distinguished by the duration and frequency of hydropeaking. Meanwhile, rate of change, amplitude and timing of hdyropeaking played less important roles in the classification.
... Many metrics were used to describe the hydropeaking or hydrograph ramping due to operations of water turbines [68,77,78]. The main metrics that were clearly observed in the lower reaches of the river (and that were considered in this study) were the range of water levels (the difference between the base-flow and peak-flow or their ratios), the rate at which the water levels rise and fall, and the distance after which the ramping almost disappears. ...
Article
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Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices.
... The two mentioned hydro peaking indicators, for example, do not permit conclusions regarding frequency and timing (daylight conditions) of sub-daily FFs. A recently developed 'computational tool for the characterization of rapid flow fluctuations' enables analysis of frequency and timing of FFs based on a wide list of calculated parameters separately for increase and decrease events (Sauterleute and Charmasson, 2014). Furthermore, this tool can be applied to time series with any data resolution. ...
Article
Hydro peaking causes an important environmental impact on running water ecosystems. Many affected rivers have a poor ecological status. In rivers affected by hydro peaking, the flow conditions are highly complex and difficult to grasp. To develop a general framework for detecting and characterizing sub-daily flow fluctuations, we analysed more than 500 Austrian hydrographs, covering the whole range from unimpacted to heavily impacted rivers. Different fluctuation types could be identified according to the potential source: e.g. sub-daily flow fluctuations caused by hydro peaking, rainfall or snow and glacier melt. Additionally, the term 'hydro fibrillation' was established, to indicate frequently occurring artificial fluctuations with comparably low intensities. An automatic procedure was used to detect frequency and intensity of each flow fluctuation. Using variables based on duration curves of flow fluctuation rates (ramping rates), amplitudes, flow ratios, durations and daily numbers of fluctuations, a predictive model (linear discriminant analysis) was fitted to classify hydrographs into predominant fluctuation regimes. This is the basis for a detailed investigation of present sub-daily flow regimes and to analyse the differences between the regimes. Based on the results, we finally propose a general framework that enables a standardized assessment of flow fluctuations regarding event intensities and/or event timing. The proposed framework offers a standardized selection of particular flow fluctuations referring to increase and decrease events separately. The selection of specific flow fluctuations can be defined with respect to several research questions (e.g. ecologically relevant fluctuations), which offers a wide range of applications.
... Two flow events, hydropeaking events (HP) of 60 l/s and baseflow events (BF) of 10 l/s, were simulated to test the behavioral response of L. bocagei and P. polylepis. The HP/BF flow ratio, defined as the maximum flow divided by the minimum flow (QPeak/QBase), was considered representative of low and high flow discharge conditions based on previous experiments at Instituto Superior Tecnico (Costa et al., 2018a(Costa et al., , 2018bCosta et al., 2019aCosta et al., , 2019bCosta et al., , 2019cMoreira et al., 2020) and publications by Harby (2013) and Sauterleute and Charmasson (2014). ...
Article
A novel study that focuses on the capacity of vegetation to provide shelter for fish species under hydropeaking regimes is presented. Two artificial patches mimicking the structure and density of Carex sp. mats were installed in an experimental flume to test whether submerged plants can offer flow refuge to two cyprinid species, Luciobarbus bocagei and Pseudochondrostoma polylepis, under baseflow and hydropeaking scenarios. Local flow fields were characterized using a Lateral Line Probe (LLP) and an Acoustic Doppler Velocimeter (ADV) and 33 h of video analysis were viewed to report, on a per-second basis, fish use of 1) patches with plants, 2) patches upstream and 3) downstream from vegetation and 4) patches without vegetation. Data on flow fields and fish patch use were integrated and analyzed to assess whether plants favored fish sheltering behavior. Vegetation created hydraulically stable areas suitable for fish to shelter, triggering changes in fish patch usage. Although both species sheltered under hydropeaking, L. bocagei presented a stronger preference than P. polylepis for vegetated patches and areas downstream from plants, taking advantage of sheltered regions more frequently. P. polylepis weaker search for shelter could be related to species-specific factors and territorial behavior interferences rather than to fish performance relative to flume hydraulic conditions. Despite a weaker response, some P. polylepis individuals used patches downstream from plants more during the second half of the hydropeaking trials. A trade-off between reducing swimming effort and territoriality might explain this response. Results indicate that vegetation can help to counterbalance the impact of hydropeaking on fish while providing river functioning benefits. Evaluating fish sheltering to a wide set of river plants and patch designs on a species-by-species basis would help targeting vegetation-based actions for restoring hydropeaking rivers.
... According to refs. [11,14,36,37], there is a far higher risk of fish stranding during daylight in winter conditions due to the activity patterns of the fish [35]. Therefore, restricting dewatering to the night may reduce the risk of stranding. ...
Article
Full-text available
The Norwegian electrical energy supply system is based on hydropower. The now deregulated energy market has led to increased use of hydropeaking production, leading to greater fluctuations in discharge and water levels below hydropower stations. The power station HOL 1, with an outlet to the Storåne River, is a large hydropeaking facility. With over 300 rapid flow increases and decreases per year since 2012, it is a river subjected to frequent hydropeaking. To quantify the stranding risk downstream of the power plant, the effect of a series of different turbine shutdown scenarios was simulated in an earlier study. The residual flow of 6 m3·s−1 and a full production of 66 m3·s−1 were considered as the baselines for the calculation of dewatered areas. A three-year study of juvenile fish density both upstream as a reference and downstream of the power plant was undertaken. There were very low densities or even an absence of brown trout (Salmo trutta) older than young-of-the-year (YoY) below the outlet of the power station, despite high densities of YoY in previous years. This is probably due to the large and rapid changes in flow below the power station. Hydropeaking has less impact on the earliest life stages of brown trout during spring and summer, as well as on spawning and egg development during winter. This is attributed spawning in late autumn occurring at a low flow seldom reached during hydropeaking. The high survival of YoY during the first summer and early autumn is likely due to a lower frequency of hydropeaking and higher residual flows, leaving a larger wetted area.
... Correcting ramping rates (attenuation between the discharge station and the fish reach) The hydraulic ramping-rates attenuate with distance from the water release (Nestler et al. 1989;Hauer et al. 2013;Sauterleute and Charmasson 2014). The attenuation is site-specific and complicated to characterize, depending for example on flow velocity, bed morphology and roughness. ...
Article
Full-text available
Hydropeaking corresponds to rapid artificial discharge variations, designed to address sub-daily peaks in electricity demand. It generates rapid changes in physical habitat (e.g., flow velocity and water depth) with potential impacts on stream assemblages. For assessing the generality of hydropeaking effects on fish assemblages, we present an original combination of spatial (among 45 reaches, including six groups of nearby reaches) and temporal (over 3-17 years) analyses of these effects. Our analyses involved descriptions of natural and artificial hydraulic variations in reaches, obtained after translating hourly discharge data into hydraulics. We found that the influence of hydropeaking was secondary compared to well-known spatial variations in fish assemblage structure along longitudinal gradients, and negative influences of floods on annual densities. However, the spatial and temporal analyses consistently suggested that hydropeaking may disfavour fish species typical of medium-sized streams relative to species of headwater streams (Salmo trutta, Phoxinus phoxinus, Cottus gobio). The magnitude of hydropeaking effects observed here, as well as an apparent weaker effect of ramping rates than the frequency of hydropeaks, may be due to lower ramping rates in our data set than in other studies.
... Electricity generation by large hydropower plants (HPP) usually response to short-term daily variations in energy demand. In most cases large HPP has its outlet into a river what causes frequent and rapid fluctuations of water level and discharge in the river stretch downstream HPP, what is called hydropeaking (Sauterleute, Charmasson, 2014). Such operating regime possibly has impact on river biotic and abiotic environment (L' Abée-Lund, Otero, 2018;Juárez et al., 2019;Hayes et al., 2019). ...
Article
Full-text available
Hydropower is oldest available source for renewable energy generation in Lithuania and the world. However, because of unequal demand of electricity during the day large hydropower plants are adapted to work in hydropeaking regime, which causes rapid water level and discharge fluctuations and has impact on the environment. To assess the extent of this impact in this study 2D numerical hydrodynamic modelling was carried out to reveal the dewatered or flooded stream channel areas at the Nemunas River downstream Kaunas Hydropower Plant. Such estimation of dewatered or flooded areas, considering different operating modes of hydropower plant, was carried out for the first time in Lithuania. It was revealed that largest areas are flooded when Kaunas hydropower plant starts its operation with two and four turbines and accordingly are dewatered when the plant stops such operations. During this study the impact of water level and discharge fluctuations on river ecosystems was not analysed, however the obtained results will be the initial data for more detailed assessment of fish habitats quality under impact of hydropeaking.
... To our knowledge, study on prediction of 'unimpaired' or natural hourly streamflow series in regulated rivers for ecological purposes is not widely reported in literature. Sauterleute and Charmasson (2014) developed a computational tool, which enables the quantification of short-term (rapid) fluctuations of flow and stage occurring in rivers resulting from hydropeaking, by means of processing the time series. However, the authors noted that the tool was not developed to enable comparisons between rivers with and without hydropeaking, or those with natural flow regimes. ...
Article
Prediction of natural streamflow in regulated rivers for derivation of ecologically relevant streamflow metrics (ERSFMs) and prediction in ungauged basins (PUB) are important in management of water resources. However, specific studies on comparison of methods for predicting hourly flow regime relevant to ecological study in regulated (hydropeaking) rivers are rare in literature. Therefore, using catchments in mid Norway, we performed comparative evaluation of prediction of hourly streamflow series and flow duration curves (FDCs) in ungauged basins. We developed a regional regression model based on relationships among streamflow percentiles and drainage areas and performed a regional calibration of a streamflow recession based precipitation-runoff (P-R) model. A leave one out cross-validation procedure was used to evaluate the regional models. The results indicate that the regional regression model with transferring of streamflow information based on the nearest neighbour performed better than both transferring optimal parameters from local calibration and regional parameter sets corresponding to maximum regional weighted average Nash-Sutcliffe efficiency of the P-R model (NSE MRWA). We also evaluated the models based on prediction of some environmental indices: the daily range, daily standard deviation, flashiness, maximum ramping rate, number of rise and falls and daily flow changes. However, both modelling strategies predicted hourly streamflow indices well and appeared stable over most indices while the largest differences occurred in the rise and fall counts. The models were further applied for prediction of the natural streamflow time series at Sokna hydropeaking plant. The observed hydrograph exhibits continuous sudden fluctuations while the predicted natural flow hydrograph exhibits smooth pattern. The within a year FDCs for observed flow exhibits sharp transitions from high to low flows. There is clear differences between the environmental indices obtained for the observed and the modelled data series, with the general observation that the NSE MRWA computing a smaller variability than the regression model.
... The standard deviation is usually used to capture the Qv. The contour type, i.e., contour variation (Cv), includes the rotation angle (see definition in the "Method" section), the slope (Sauterleute and Charmasson 2014), the number of reversals (Bevelhimer et al. 2015), and the length (Gustafson et al. 2004). The rotation angle is more efficient for measuring the Cv. ...
Article
The process of river runoff confluence is highly complex and combines both tendency and chaos. Research on the temporal and spatial tendencies of river runoff variability can yield significant information to understand river systems. This paper aims to identify rainfall-runoff variability tendencies using a novel variability metric: the Mei-Wang Fluctuation (MWF) index, which estimates the variability as a compound measurement of quantitative variation (Qv) and contour variation (Cv) and has been successfully applied to quantify the variability of power output. Six rainfall rivers located in North Carolina and Texas with few reservoirs are chosen as the study case. The results show several novel tendencies of the runoff variability, including the following: (1) when the temporal resolution length decreases from 1 day to 1 month, the runoff variability indices, Cv and MWF, conspicuously decrease, while Qv declines slightly; (2) from a spatial perspective, when the drainage area rises, these indices increase, and notably, Qv increases in a linear pattern (sharply in a narrow river basin, slowly in a broad river basin); and (3) these spatial tendencies are further demonstrated by replacing the outflow of a reservoir with its inflow. Additionally, the linear tendency exhibited between Qv and drainage area calls for further exploration that could contribute to hydrological analysis.
... In the 71 past, the effects of hydropeaking, i.e., sudden fluctuations in river stage at the sub-daily scale 72 caused by the release or storage of water in artificial reservoirs, lead to river discharge 73 fluctuations with a relatively constant frequency throughout the year. Nowadays, since the 74 liberalization of the electricity market, hydropeaking depends on variations in the energy demand 75 ( Sauterleute and Charmasson, 2014;Wagner et al., 2015) and it is more challenging to be 76 predicted at the daily and hourly time scales due to the uncertainty affecting electricity price 77 forecast ( Gaudard et al., 2016;Maran et al., 2014). In this work, we will show that such changes 78 occurring at the sub-daily scale can cause a detectable change point also when analyzing daily 79 time series. ...
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Conference Paper
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A operação de um aproveitamento hidroelétrico em resposta às variações do equilíbrio produção/consumo de eletricidade pode gerar alterações rápidas e frequentes no caudal e na cota da superfície livre do curso de água a jusante. O fenómeno, designado por hydropeaking, tem consequências no ecossistema aquático, com especial incidência na fauna piscícola. Para implementar medidas de mitigação apropriadas, é fundamental caracterizar-se não só a magnitude, frequência e duração das referidas alterações do regime hidrológico, como também a sua respetiva influência no habitat. O presente estudo tem como principal objetivo a análise da operação de uma central hidroelétrica e o seu impacto no habitat piscícola de um rio mediterrâneo. O estudo, que analisa o habitat do barbo ibérico (Luciobarbus bocagei) a jusante da barragem de Pracana, divide-se em duas partes: determinação da disponibilidade de habitat em função do caudal; e caracterização estatística das variações rápidas de caudal e cota da superfície livre. A modelação hidrodinâmica bidimensional do escoamento e do habitat foram realizadas com recurso ao modelo River2D. Aplicaram-se curvas de preferência de habitat para juvenis e adultos. A utilização do software COSH-Tool para a quantificação das referidas variações rápidas permitiu aferir a influência da introdução de um regime de caudais ecológicos nas mesmas. Adicionalmente avaliaram-se as limitações da aplicação da COSH-Tool a rios mediterrâneos. Os resultados fornecem informação sobre as condições de habitat, consoante o estágio de vida, e defendem a importância da utilização de modelos hidráulicos e de habitat em paralelo com a análise de séries hidrológicas.
Article
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To directly reflect the effect of coordinate control of wind power and hydropower, by the fluctuation of output, a method based on quantitive dimension and contoured dimension (QC) was proposed. Compared with current common method, RBF (Richards-Baker Flashiness Index), the validity and superiority of the proposed method was testified with random and actual measured processes and several disposals such as moving average, superposed average and zoom, etc. With application QC in case study of coordinate control of wind power and hydropower, the results accorded well with the objective rules. Results show the feasibility of apply QC to quantify the fluctuation of output of combined wind and hydropower. © 2016, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.
Book
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This book summarises state-of-the art about environmental impacts from hydro-peaking operations in rivers, introducing rapid and frequent changes in discharge and water level. The book is considered relevant also for other types of abrupt changes in the operation of hydropower plants such as fallouts, or other controlled or non-controlled operations causing rapid changes in discharge downstream the outlet of the power plant. The book describes and evaluates mitigating measures to reduce the impacts from hydro-peaking operations, and should be considered an operative tool in order to move in the direction of more environmental friendly operation of hydropower plants.
Article
Anthropogene Wasserspiegelschwankungen besitzen wesentliche negative Auswirkungen auf die aquatische Fauna und Flora. Diese als Sunk/Schwall bezeichneten Wasserspiegeländerungen wurden bisher hauptsächlich in Bezug auf die Großwasserkraft untersucht und mögliche Verbesserungsmaßnahmen wurden für diese speziellen Wasserkrafttypen erarbeitet. Auch im Bereich der Kleinwasserkraft besteht durch betriebstechnische Probleme bzw. auch Stör- und Unfälle die Möglichkeit, dass kurzfristige Abfluss- und Wasserspiegelschwankungen entstehen, die sich aufgrund von automatisierten Steuerungen in einem Fließgewässer über eine Kraftwerkskette hinweg weiter fortsetzen. In diesem Fachbeitrag werden, neben einer Darstellung der allgemeinen Problematik, vor allem neue Methoden zur Steuerung von Kleinwasserkraftanlagen vorgestellt, die im Vergleich zur Großwasserkraft mitunter die einzige Möglichkeit für eine gezielte Verbesserung bieten.
Article
Reservoirs play an important role in modifying the natural hydrological regime. Reservoir-induced changes in flow fluctuations at monthly and hourly scales were analyzed through a case study of a tributary of the Yangtze River (China), the Qingyi River, where the Chencun reservoir is located at the upper reaches. Monthly and hourly flow data were collected from two flow gauging stations monitoring the inflow and outflow regimes, respectively. The flow fluctuations were characterized by coefficient of variation (CV) and concentration degree (Cd). Continuous Morlet wavelet transform was applied to detect diurnal period. The influence of the reservoir was revealed comparing the postdam with the predam conditions by and comparing the affected with the natural conditions. The results indicate two opposite change patterns. Reservoir impoundment may mitigate flow fluctuations at both of the monthly and the hourly scales. At a monthly scale, reservoirs usually impound water in the flood season for the dry season. At an hourly scale, reservoirs may restrain a flood pulse and strictly control the outflow. Thus, the reservoirs reduce variation and concentration of the runoff distribution within a year and within a day. In contrast, the reservoirs may aggravate the hourly flow fluctuation by releasing hydropeaking waves for hydropower generation and superimpose a diurnal period to the downstream flow regime. But the artificial diurnal fluctuation is of some uncertainty in terms of appearance time and duration. This work may deepen the understanding of the reservoirs influence mechanism on the downstream flow regime.
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Many French rivers are concerned by hydropeaking management. Sudden flow variations cause disturbances of the aquatic environment, fish habitat being particularly affected. The abundance of the most sensitive life stages of brown trout (age groups 0+ and 1+) in the River Oriege (Pyrenees, France) were studied 330 m upstream, and 700 and 3,000 m downstream of a hydroelectric power plant with hypolimnetic releases from a nearby high-altitude reservoir. The natural flow of the river was preserved when the plant was inoperative. Hydropeaking strongly reduced densities of young trout and disturbed their choice of mesohabitat 700 m below the plant, but such effects were attenuated 3,000 m downstream, mainly due to reduction of the slope. These results provide elements to assess the capacity of a regulated stream to support the early life stages of trout, and therefore the whole population.
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