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As the global demand for renewable electricity grows, hydropower development of river basins increases across the world. Hydropeaking, i.e., streamflow alteration consisting of daily or subdaily rapid and marked discharge fluctuations, can affect river reaches below hydropower units. Environmental effects of hydropeaking include geomorphological alterations and possible modifications of the freshwater biota. Among affected instream communities, benthic macroinvertebrates are receiving increasing attention and the related scientific research has experienced significant progress in the last decade. In this context, this paper aims to summarize state-of-the-art methods for the assessment of hydropeaking impacts on benthic macroinvertebrate communities. The present review could support the proper design of monitoring plans aimed at assessing the ecological impacts of hydropeaking and the effects of possible mitigation strategies.
Francesca Salmaso; Livia Servanzi; Giuseppe Crosa; Silvia Quadroni; Paolo Espa. Assessing the Impacts of Hydropeaking on River Benthic Macroinvertebrates: A State-of-the-Art Methodological Overview. Environments 2021, 8, 67 .
AMA StyleFrancesca Salmaso, Livia Servanzi, Giuseppe Crosa, Silvia Quadroni, Paolo Espa. Assessing the Impacts of Hydropeaking on River Benthic Macroinvertebrates: A State-of-the-Art Methodological Overview. Environments. 2021; 8 (7):67.
Chicago/Turabian StyleFrancesca Salmaso; Livia Servanzi; Giuseppe Crosa; Silvia Quadroni; Paolo Espa. 2021. "Assessing the Impacts of Hydropeaking on River Benthic Macroinvertebrates: A State-of-the-Art Methodological Overview." Environments 8, no. 7: 67.
An eco-hydraulic survey of the highly regulated Adda River (northern Italy) was carried out to highlight the ecological implications of the current water management, including minimum flows (MFs) set as environmental protection measures. Macroinvertebrates, flows, and other main physico-chemical parameters were monitored from 2010 to 2012 at seven sites located in two river reaches characterized by different water abstraction schemes. In the upper part of the river, water is mainly diverted for hydro-power, and, in water-depleted reaches, discharges equalled MF for more than 100 days y-1, mainly during winter. In the downstream river reach, where irrigation use prevails, discharges were on average three times higher than in the upper part of the river, and flow values similar to MF were detected only for short periods during summer. The two resulting streamflow patterns seem to have shaped different benthic communities, superimposing to the natural downstream variation. The upper reach is characterized by univoltine taxa, while the lower reach by multivoltine taxa adapted to a more disturbed environment. Chironomidae, a well-known tolerant benthic family, dominated at a site affected by point-source pollution, which turned out to be another determinant of macroinvertebrate community. Despite these differences among sites in the benthic community structure, the current water management seems to allow, for all of the investigated river sites, the achievement of the good ecological status as defined by the local law set in accomplishment of the Water Framework Directive.
Francesca Salmaso; Giuseppe Crosa; Paolo Espa; Gaetano Gentili; Silvia Quadroni; Serena Zaccara. Benthic macroinvertebrates response to water management in a lowland river: effects of hydro-power vs irrigation off-stream diversions. Environmental Monitoring and Assessment 2017, 190, 33 .
AMA StyleFrancesca Salmaso, Giuseppe Crosa, Paolo Espa, Gaetano Gentili, Silvia Quadroni, Serena Zaccara. Benthic macroinvertebrates response to water management in a lowland river: effects of hydro-power vs irrigation off-stream diversions. Environmental Monitoring and Assessment. 2017; 190 (1):33.
Chicago/Turabian StyleFrancesca Salmaso; Giuseppe Crosa; Paolo Espa; Gaetano Gentili; Silvia Quadroni; Serena Zaccara. 2017. "Benthic macroinvertebrates response to water management in a lowland river: effects of hydro-power vs irrigation off-stream diversions." Environmental Monitoring and Assessment 190, no. 1: 33.
Water exploitation for hydropower and irrigation alters the natural hydrologic regime of rivers, and consequently instream biocenosis and ecological processes. The identification of management decisions able to protect freshwater ecosystems while maintaining important water uses is a crucial issue for both science and management. This study presents and compares water management schemes into two large Mediterranean river basins. Environmental issues linked to management are discussed taking into account different local features and the regulatory framework.
Francesca Salmaso; Paolo Espa; Ramon J. Batalla; Giuseppe Crosa; Gaetano Gentili; Livia M. L. Servanzi; Silvia Quadroni. Water Management and Related Environmental Issues in Large Mediterranean Basins: Case Studies from the Ebro and the Po Catchments. Plant-Microbes-Engineered Nano-particles (PM-ENPs) Nexus in Agro-Ecosystems 2017, 759 -761.
AMA StyleFrancesca Salmaso, Paolo Espa, Ramon J. Batalla, Giuseppe Crosa, Gaetano Gentili, Livia M. L. Servanzi, Silvia Quadroni. Water Management and Related Environmental Issues in Large Mediterranean Basins: Case Studies from the Ebro and the Po Catchments. Plant-Microbes-Engineered Nano-particles (PM-ENPs) Nexus in Agro-Ecosystems. 2017; ():759-761.
Chicago/Turabian StyleFrancesca Salmaso; Paolo Espa; Ramon J. Batalla; Giuseppe Crosa; Gaetano Gentili; Livia M. L. Servanzi; Silvia Quadroni. 2017. "Water Management and Related Environmental Issues in Large Mediterranean Basins: Case Studies from the Ebro and the Po Catchments." Plant-Microbes-Engineered Nano-particles (PM-ENPs) Nexus in Agro-Ecosystems , no. : 759-761.
Sediment transport and riverbed sedimentation were investigated in an alpine stream below a small hydropower reservoir desilted by a controlled sediment flushing (CSF) operation. The term “controlled” refers to the operational tasks implemented to mitigate the downstream environmental impact of the operation. The experimental dataset acquired before, during, and after the CSF was also used to carry out and calibrate a one-dimensional sediment transport model of the monitored event. The investigated reservoir is located in the central Italian Alps, and its original storage was 160,000 m3, about 30% filled by a mixture of sand and silt/clay before the CSF. Downstream sediment concentration was controlled by releasing clear water from upstream reservoirs and regulating the work of earth-moving equipment in the emptied reservoir. A 3.6-km-long reach with average slope of 0.015 was monitored: concentration and grain size of suspended sediment were measured during the CSF and the riverbed alteration was evaluated by volumetric sampling and measurements of the deposits’ thickness. Sedimentation and River Hydraulics—One Dimensional (SRH-1D) was used to simulate sediment transport during the monitored CSF. Model parameters were calibrated by comparing the computed and the observed amount of sediment deposited along the study reach. Sediment flushing was carried out in October 2010 for 3 days. Ca. 16,000 m3 of sediment were evacuated, representing approximately 30% silt/clay and 70% sand. 2.4 Mm3 of clear water was released to reduce sediment concentration and increase transport capacity downstream. About 3000 m3 of sand was deposited in the study reach after the CSF, with maximum height up to 0.2 m. Although the riverbed before the CSF was simply set as mono-granular, after calibrating the parameters, good agreement was achieved between the depositional pattern computed by SRH-1D and the one observed, both in terms of deposit thickness and grain size of deposited sediment. The sensitivity analysis revealed a major role of the parameters controlling bed mixing processes in affecting the simulated deposition after the CSF. Sediment below 0.1 mm in diameter was not detected in river deposits after the flushing: the effects on river biota associated with substrate clogging by very fine sediment were therefore minimized. After proper calibration, 1-D sediment transport modeling can effectively support the planning of CSF operations: to minimize the downstream environmental effects, concurrently achieving acceptable flushing efficiency, the analyzed scenarios as well as the model outputs need to be carefully evaluated from a multidisciplinary perspective.
Maria Laura Brignoli; Paolo Espa; Ramon J. Batalla. Sediment transport below a small alpine reservoir desilted by controlled flushing: field assessment and one-dimensional numerical simulation. Journal of Soils and Sediments 2017, 17, 2187 -2201.
AMA StyleMaria Laura Brignoli, Paolo Espa, Ramon J. Batalla. Sediment transport below a small alpine reservoir desilted by controlled flushing: field assessment and one-dimensional numerical simulation. Journal of Soils and Sediments. 2017; 17 (8):2187-2201.
Chicago/Turabian StyleMaria Laura Brignoli; Paolo Espa; Ramon J. Batalla. 2017. "Sediment transport below a small alpine reservoir desilted by controlled flushing: field assessment and one-dimensional numerical simulation." Journal of Soils and Sediments 17, no. 8: 2187-2201.
Sediment flushing may be effective to preserve reservoir storage, but concerns arise about sustainability for downstream freshwater ecosystems. We report on the controlled flushing of approximately 110,000 tons of silt from a 120 Mm(3) reservoir on the Adda River, the main tributary of Lake Como, Italy. Technical constraints prevented flushing during high flows, and the operation had to be spread out over three consecutive years (2010-2012) and, for each year, over a rather long time span (40-50 days). To mitigate the downstream impact, the suspended sediment concentration (SSC) of the evacuated water was controlled by regulating the dislodging works inside the reservoir, increasing the streamflow in the regulated tributaries, and operating an instream settling basin. SSC and water flow as well as benthic macroinvertebrates and trout were monitored as far as 28 km below the reservoir. At the most upstream gauging station, SSC peaked up to 100 g/l and ranged from 3.5 to 8 g/l on average per each operation. Stream quality metrics based on macroinvertebrate data evidenced the impairment due to flushing; however, the benthic community showed high resilience, recovering to pre-flushing conditions in 6-9 months. Trout data were biased by stocking and sport fishing and were more difficult to be interpreted. The trout population wouldn't seem remarkably altered, even if a non-negligible impact could be deduced through pre/post-event sample comparison.
Paolo Espa; Maria Laura Brignoli; Giuseppe Crosa; Gaetano Gentili; Silvia Quadroni. Controlled sediment flushing at the Cancano Reservoir (Italian Alps): Management of the operation and downstream environmental impact. Journal of Environmental Management 2016, 182, 1 -12.
AMA StylePaolo Espa, Maria Laura Brignoli, Giuseppe Crosa, Gaetano Gentili, Silvia Quadroni. Controlled sediment flushing at the Cancano Reservoir (Italian Alps): Management of the operation and downstream environmental impact. Journal of Environmental Management. 2016; 182 ():1-12.
Chicago/Turabian StylePaolo Espa; Maria Laura Brignoli; Giuseppe Crosa; Gaetano Gentili; Silvia Quadroni. 2016. "Controlled sediment flushing at the Cancano Reservoir (Italian Alps): Management of the operation and downstream environmental impact." Journal of Environmental Management 182, no. : 1-12.
Sediment flushing may be effective to tackle the loss of reservoir storage as a result of siltation. When operationally possible, the impact of this practice on the downstream aquatic environment can be mitigated by limiting the sediment concentration of the discharged waters (controlled sediment flushing). However, this topic is poorly documented, and concerns arise when limits are discussed. We present the results of a 3‐year field investigation concerning the controlled sediment flushing of a small reservoir on the Adda River, the main tributary of Lake Como—Italy. Two limits for suspended solid concentration (SSC) were adopted: 1.5 g L−1, as average value throughout the whole working day, and 3.0 g L−1, as alert threshold to adjust the ongoing activity. These constraints were essentially fulfilled in the course of the documented operations. The first year sediment flushing was more significant than the following year: 25 000 tons of fines below 2 mm in diameter were flushed in six non‐consecutive days in summer 2010, while, one year earlier, 75 000 tons were flushed in 16 non‐consecutive days. In the third year of investigation (2011), no sediment evacuation took place. The benthic macroinvertebrate and the fish communities were surveyed a short distance below the reservoir, that is, in the potentially more affected river reach. Clear pieces of evidence of environmental quality degradation were not detected; the adopted strategies can therefore be considered to be appropriate when planning sediment flushing management in comparable contexts. Copyright © 2014 John Wiley & Sons, Ltd.
Paolo Espa; Giuseppe Crosa; G. Gentili; Silvia Quadroni; Geoffrey E Petts. Downstream Ecological Impacts of Controlled Sediment Flushing in an Alpine Valley River: A Case Study. River Research and Applications 2014, 31, 931 -942.
AMA StylePaolo Espa, Giuseppe Crosa, G. Gentili, Silvia Quadroni, Geoffrey E Petts. Downstream Ecological Impacts of Controlled Sediment Flushing in an Alpine Valley River: A Case Study. River Research and Applications. 2014; 31 (8):931-942.
Chicago/Turabian StylePaolo Espa; Giuseppe Crosa; G. Gentili; Silvia Quadroni; Geoffrey E Petts. 2014. "Downstream Ecological Impacts of Controlled Sediment Flushing in an Alpine Valley River: A Case Study." River Research and Applications 31, no. 8: 931-942.
Sediment flushing may be effective in mitigating loss of reservoir storage due to siltation, but flushing must be controlled to limit the impact on the downstream environment. A reliable prediction of the environmental effects of sediment flushing is hindered by the limited scientific information currently available. Consequently, there may be some controversy as regards to management decisions, planning the work, and monitoring strategies. This paper summarizes the main results of a monitoring campaign on the stream below a small alpine hydropower reservoir subjected to annual flushing between 2006 and 2009. The removed sediment was essentially silt, and the suspended solid concentration (SSC) of the discharged water was controlled to alleviate downstream impact. Control was achieved through hydraulic regulation and mechanical digging, alternating daytime sediment evacuation, and nocturnal clear water release. The four operations lasted about two weeks each and had an average SSC of about 4 g L(-1). Maximum values of SSC were generally kept below 10 g L(-1). Downstream impact was quantified through sampling of fish fauna (brown trout) and macroinvertebrate in the final reach of the effluent stream. The benthic community was severely impaired by the flushing operations, but recovered to pre-flushing values in a few months. As expected, the impact on brown trout was heavier on juveniles. While data biasing due to fish removal and re-stocking cannot be ruled out, the fish community seems to have reached a state of equilibrium characterized by a lower density than was measured before the flushing operations.
Paolo Espa; Elena Castelli; Giuseppe Crosa; Gaetano Gentili. Environmental Effects of Storage Preservation Practices: Controlled Flushing of Fine Sediment from a Small Hydropower Reservoir. Environmental Management 2013, 52, 261 -276.
AMA StylePaolo Espa, Elena Castelli, Giuseppe Crosa, Gaetano Gentili. Environmental Effects of Storage Preservation Practices: Controlled Flushing of Fine Sediment from a Small Hydropower Reservoir. Environmental Management. 2013; 52 (1):261-276.
Chicago/Turabian StylePaolo Espa; Elena Castelli; Giuseppe Crosa; Gaetano Gentili. 2013. "Environmental Effects of Storage Preservation Practices: Controlled Flushing of Fine Sediment from a Small Hydropower Reservoir." Environmental Management 52, no. 1: 261-276.
The downstream ecological consequences of two controlled “free flow” flushing operations designed to remove sediments accumulated in an alpine reservoir are described. The main objectives of the study were (a) to verify to what extent the suspended solid concentration (SSC) in the receiving water course can be controlled by flushing operations, (b) to determine the biological consequences of flushing operations, and (c) to produce technical guidelines for the future planning and monitoring of these activities. We found that the flushing of large volumes of accumulated sediment had clear effects on the stream ecosystem due to the unpredictability of short duration SSC peaks (70–80 g L−1) and the high average SSC (4–5 g L−1) within flushing periods. The main impacts were decreased fish densities (up to 73%) and biomass (up to 66%). A greater mortality recorded for juveniles will likely result in long-term impairment of the age-structures of future fish populations. The zoobenthic assemblages, despite exhibiting a drastic reduction in abundance following the first floods, showed substantial recovery within 3 months of the beginning of flushing operations. Regular sediment removal by yearly flushing is recommended in order to avoid SSC peaks and to facilitate the control of scouring effects caused by the water used to wash out sediments. We also recommend maximum allowable SSCs of 10 g L−1 (daily average) and 5 g L−1 (overall average) for flushing operations carried out in similar environmental contexts.
Giuseppe Crosa; Elena Castelli; Gaetano Gentili; Paolo Espa. Effects of suspended sediments from reservoir flushing on fish and macroinvertebrates in an alpine stream. Schweizerische Zeitschrift für Hydrologie 2009, 72, 85 -95.
AMA StyleGiuseppe Crosa, Elena Castelli, Gaetano Gentili, Paolo Espa. Effects of suspended sediments from reservoir flushing on fish and macroinvertebrates in an alpine stream. Schweizerische Zeitschrift für Hydrologie. 2009; 72 (1):85-95.
Chicago/Turabian StyleGiuseppe Crosa; Elena Castelli; Gaetano Gentili; Paolo Espa. 2009. "Effects of suspended sediments from reservoir flushing on fish and macroinvertebrates in an alpine stream." Schweizerische Zeitschrift für Hydrologie 72, no. 1: 85-95.