Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 an... more Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 and V1 (Mann-Whitney test, p= 0.001). A significant difference in annual water temperature was observed between NB19 and NB20 (Mann-Whitney test, p< 0.001). Fig. 2 shows the differences in water temperature recorded up and downstream of the Mezzocorona plant (NB19 and NB20). During plant operation temperature increased up to 4.5 C during fall and winter, whereas decreased up to 5.9 C during s pring and summer.
Annales De Limnologie-international Journal of Limnology, Jan 1, 2009
... in an Alpine stream (Trentino, Italy) Maria Cristina Bruno1,2*, Bruno Maiolini1, Mauro Caroll... more ... in an Alpine stream (Trentino, Italy) Maria Cristina Bruno1,2*, Bruno Maiolini1, Mauro Carolli1 and Luana Silveri1 ... groundwater, although such interactions in streams are still poorly studied (Strayer, 1994; Boulton, 2000; Schmid-Araya and Shmid, 2000). ...
Bruno, M., Maiolini, B., Carolli, M., &amp;amp;amp;amp;amp;amp; Silveri, L. (2010). Hydropowe... more Bruno, M., Maiolini, B., Carolli, M., &amp;amp;amp;amp;amp;amp; Silveri, L. (2010). Hydropower effects at different temporal scales in an Alpine river. Verhandlungen Internationale Vereinigung für theoretische und angewandte Limnologie, 30(10), 1591-1594. ... There are no files associated with this item.
Carolli, M., Bruno, M., Maiolini, B., &amp;amp;amp;amp; Silveri, L. (2010). Assessment of hyd... more Carolli, M., Bruno, M., Maiolini, B., &amp;amp;amp;amp; Silveri, L. (2010). Assessment of hydropeaking-induced alterations of benthic communities in experimental flumes. Biologia ambientale, 24(1), 215-223. ... There are no files associated with this item. ... Items in OpenPub are ...
In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for ... more In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for the water bodies which receive downstream releases in the form of "hydropeaking", typically consisting in sharp releases of turbinated water in the river reaches below dams. Hydropeaking may significantly affect also the thermal regime of rivers: typically power plants fed by hypolimnetic releases from large dams cause a reduction in summer temperature and an increase in winter temperatures for long distances downstream. Very few studies have addressed the effects of the short-term temperature fluctuations related to hydropeaking (i.e., thermopeaking) on aquatic fauna, although they can be a major cause of riverine habitat degradation posing serious threats to aquatic communities. In the Adige River watershed, warm thermopeaking occurs from September to January and results in additional (up to 4°C) heating to the natural dial fluctuations; cold thermopeaking occurs from March to July and cools down the temperature (up to 6°C), in contrast with the natural trend that would result in heating during the day. The biological effects of thermopeaking are difficult to study in nature, because they are associated with hydropeaking, which is known to cause a high catastrophic drift due to the increased intensity of bed scour. However, controlled simulations of thermopeaking events could be performed in artificial flumes. We used artificial flumes which had proved to perform discharge manipulations which simulate hydropeaking events, and conducted four simulations, two warm thermopeakings in early and late winter, and two cold-thermopeakings, in early and late summer, respectively. The impact of thermopeaking on benthic macroinvertebrates was assessed by collecting those organisms which are displaced from the substrate and drift in the water column. Displacement can be active (i.e., part of the behavioural repertoire of certain insect species), or passive (i.e., catastrophic and generated by any disturbance). Drifting invertebrates were collected at time intervals before the simulation, and at continuous, short-time intervals during the simulation in order to follow the changes in drift over a short time period during the simulation. We assessed the effects of thermopreaking on the benthos community by answering to the following questions: 1) Do thermal alterations induce an increase in drift of benthic invertebrates? 3) Do a reduction or an increase in water temperature have different effects of invertebrate drift? Benthic invertebrates responded more to the cold thermopeaking simulations, with differences among taxa with different life strategies and ecological requirements.
The impact of a single hydropeaking event was studied in the Alpine stream Noce Bianco. Four stat... more The impact of a single hydropeaking event was studied in the Alpine stream Noce Bianco. Four stations were selected, one upstream and three, respectively, at 0.25, 6, and 8 km downstream from a hydropower plant. We collected drifting invertebrates during a planned water release that increased the discharge 7-fold. At the onset of the hydropeaking wave the number of invertebrates lost from the riverbed per minute to the drift increased 9-fold at the first downstream station and the same effects propagated 8 km downstream. The drift was composed mainly of aquatic insect larvae (Chironomidae, Plecoptera, Ephemeroptera Baetidae, and Psychodidae, with Chironomidae as the most abundant taxon at all stations) and partly by larval and adult riparian insects, and by Oligochaeta, which were particularly abundant at the station 6 km downstream. We monitored drift for 30 min from the start of the water release: peaks in drifting invertebrates occurred within 5–10 min of the beginning of the hydropeaking wave, and most of the invertebrates were washed out within the first 15 min of the water release. The different timeframes were possibly due to habitat preferences (most of the taxa that increased in the drift at the arrival of the wave were associated with algae and organic debris, which were washed off quickly by the increase in discharge) and/or behavioral adaptations (other taxa initially resisted the shear stress and began to drift with a delay of 5–10 min). The temporal pattern and drift composition corresponded well with those reported in literature, and indicate that repeated high-flow events of similar magnitude cause considerable losses from benthic populations to drift.
Pesticide loads in streams are potentially one of the most relevant stressors for macroinvertebra... more Pesticide loads in streams are potentially one of the most relevant stressors for macroinvertebrate communities. Nevertheless, real effects provoked at the community level are still largely unknown. Model ecosystems are frequently used as tools for the risk assessment of pesticides, especially for their regulation, however, they can be also applied to site-specific risk assessment in order to gain better understanding of the responses of aquatic ecosystems to chemical stress. In the present work, an experimental system was composed of 5 artificial streams that reproduced a mountain lotic environment under controlled conditions. This study was aimed to better understand, whether (and how) the biological community was influenced by pesticides pulse exposures. 5 mixture load events were simulated over the productive season (March–July 2010): biological community was regularly sampled and nominal concentrations of water were tested. The results were interpreted comparing the output of different metrics and statistical methodologies. The sensitivity of different metrics was analyzed considering single exposure events (maximum Toxic Units) as well as overall temporal trends. Results showed how some common taxonomic metrics (e.g. taxa richness, Shannon’s index, total abundance of organisms, and the Extended Biotic Index) were not suitable to identify the effects of pesticides at community level. On the contrary EPT%, SPEARpesticide and the Principal Response Curve methodology proved to be sensitive to this kind of stress, providing comparable results. Temporal trends of these metrics proved to be related to the concentration of chemicals. Remarkably, the first Principal Response Curve illustrates the trend followed by the most vulnerable species, while the second is more related to the trend of opportunistic species. A high potential risk for the invertebrate community was highlighted by a statistically significant decline of 40 points (comparison with the control) in both SPEARpesticide and EPT%.
ABSTRACT Hydropeaking induced by storage hydropower plants can modify the natural flow regime at ... more ABSTRACT Hydropeaking induced by storage hydropower plants can modify the natural flow regime at different time scales, with severe impacts on the biodiversity of the downstream river ecosystems. In this research, a case study on the Noce River (NE Italy) is presented, where habitat simulation models and habitat time series were used to compare restoration scenarios and develop flow management criteria. Habitat time series analyses are based on the assumption that habitat events occurring rarely in nature create stress to aquatic fauna and shape the community. The identification of habitat stressor thresholds (HST) provided a means of quantitatively comparing different flow magnitude scenarios as well as duration and frequency of events. Results indicate that (i) the proposed flow management plan should nullify the rare habitat stress events to support the recovery of existing fish populations and (ii) HST can be used to identify flow release strategies in rivers affected by hydropeaking.
Proceedings of the 4th ECRR (European Center for River Restoration) International Conference for River Restoration. Venice, Jun 1, 2008
Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 an... more Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 and V1 (Mann-Whitney test, p= 0.001). A significant difference in annual water temperature was observed between NB19 and NB20 (Mann-Whitney test, p< 0.001). Fig. 2 shows the differences in water temperature recorded up and downstream of the Mezzocorona plant (NB19 and NB20). During plant operation temperature increased up to 4.5 C during fall and winter, whereas decreased up to 5.9 C during s pring and summer.
Release of water from storage hydropower plants generates rapid flow and stage fluctuations (hydr... more 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.
Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 an... more Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 and V1 (Mann-Whitney test, p= 0.001). A significant difference in annual water temperature was observed between NB19 and NB20 (Mann-Whitney test, p< 0.001). Fig. 2 shows the differences in water temperature recorded up and downstream of the Mezzocorona plant (NB19 and NB20). During plant operation temperature increased up to 4.5 C during fall and winter, whereas decreased up to 5.9 C during s pring and summer.
Annales De Limnologie-international Journal of Limnology, Jan 1, 2009
... in an Alpine stream (Trentino, Italy) Maria Cristina Bruno1,2*, Bruno Maiolini1, Mauro Caroll... more ... in an Alpine stream (Trentino, Italy) Maria Cristina Bruno1,2*, Bruno Maiolini1, Mauro Carolli1 and Luana Silveri1 ... groundwater, although such interactions in streams are still poorly studied (Strayer, 1994; Boulton, 2000; Schmid-Araya and Shmid, 2000). ...
Bruno, M., Maiolini, B., Carolli, M., &amp;amp;amp;amp;amp;amp; Silveri, L. (2010). Hydropowe... more Bruno, M., Maiolini, B., Carolli, M., &amp;amp;amp;amp;amp;amp; Silveri, L. (2010). Hydropower effects at different temporal scales in an Alpine river. Verhandlungen Internationale Vereinigung für theoretische und angewandte Limnologie, 30(10), 1591-1594. ... There are no files associated with this item.
Carolli, M., Bruno, M., Maiolini, B., &amp;amp;amp;amp; Silveri, L. (2010). Assessment of hyd... more Carolli, M., Bruno, M., Maiolini, B., &amp;amp;amp;amp; Silveri, L. (2010). Assessment of hydropeaking-induced alterations of benthic communities in experimental flumes. Biologia ambientale, 24(1), 215-223. ... There are no files associated with this item. ... Items in OpenPub are ...
In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for ... more In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for the water bodies which receive downstream releases in the form of "hydropeaking", typically consisting in sharp releases of turbinated water in the river reaches below dams. Hydropeaking may significantly affect also the thermal regime of rivers: typically power plants fed by hypolimnetic releases from large dams cause a reduction in summer temperature and an increase in winter temperatures for long distances downstream. Very few studies have addressed the effects of the short-term temperature fluctuations related to hydropeaking (i.e., thermopeaking) on aquatic fauna, although they can be a major cause of riverine habitat degradation posing serious threats to aquatic communities. In the Adige River watershed, warm thermopeaking occurs from September to January and results in additional (up to 4°C) heating to the natural dial fluctuations; cold thermopeaking occurs from March to July and cools down the temperature (up to 6°C), in contrast with the natural trend that would result in heating during the day. The biological effects of thermopeaking are difficult to study in nature, because they are associated with hydropeaking, which is known to cause a high catastrophic drift due to the increased intensity of bed scour. However, controlled simulations of thermopeaking events could be performed in artificial flumes. We used artificial flumes which had proved to perform discharge manipulations which simulate hydropeaking events, and conducted four simulations, two warm thermopeakings in early and late winter, and two cold-thermopeakings, in early and late summer, respectively. The impact of thermopeaking on benthic macroinvertebrates was assessed by collecting those organisms which are displaced from the substrate and drift in the water column. Displacement can be active (i.e., part of the behavioural repertoire of certain insect species), or passive (i.e., catastrophic and generated by any disturbance). Drifting invertebrates were collected at time intervals before the simulation, and at continuous, short-time intervals during the simulation in order to follow the changes in drift over a short time period during the simulation. We assessed the effects of thermopreaking on the benthos community by answering to the following questions: 1) Do thermal alterations induce an increase in drift of benthic invertebrates? 3) Do a reduction or an increase in water temperature have different effects of invertebrate drift? Benthic invertebrates responded more to the cold thermopeaking simulations, with differences among taxa with different life strategies and ecological requirements.
The impact of a single hydropeaking event was studied in the Alpine stream Noce Bianco. Four stat... more The impact of a single hydropeaking event was studied in the Alpine stream Noce Bianco. Four stations were selected, one upstream and three, respectively, at 0.25, 6, and 8 km downstream from a hydropower plant. We collected drifting invertebrates during a planned water release that increased the discharge 7-fold. At the onset of the hydropeaking wave the number of invertebrates lost from the riverbed per minute to the drift increased 9-fold at the first downstream station and the same effects propagated 8 km downstream. The drift was composed mainly of aquatic insect larvae (Chironomidae, Plecoptera, Ephemeroptera Baetidae, and Psychodidae, with Chironomidae as the most abundant taxon at all stations) and partly by larval and adult riparian insects, and by Oligochaeta, which were particularly abundant at the station 6 km downstream. We monitored drift for 30 min from the start of the water release: peaks in drifting invertebrates occurred within 5–10 min of the beginning of the hydropeaking wave, and most of the invertebrates were washed out within the first 15 min of the water release. The different timeframes were possibly due to habitat preferences (most of the taxa that increased in the drift at the arrival of the wave were associated with algae and organic debris, which were washed off quickly by the increase in discharge) and/or behavioral adaptations (other taxa initially resisted the shear stress and began to drift with a delay of 5–10 min). The temporal pattern and drift composition corresponded well with those reported in literature, and indicate that repeated high-flow events of similar magnitude cause considerable losses from benthic populations to drift.
Pesticide loads in streams are potentially one of the most relevant stressors for macroinvertebra... more Pesticide loads in streams are potentially one of the most relevant stressors for macroinvertebrate communities. Nevertheless, real effects provoked at the community level are still largely unknown. Model ecosystems are frequently used as tools for the risk assessment of pesticides, especially for their regulation, however, they can be also applied to site-specific risk assessment in order to gain better understanding of the responses of aquatic ecosystems to chemical stress. In the present work, an experimental system was composed of 5 artificial streams that reproduced a mountain lotic environment under controlled conditions. This study was aimed to better understand, whether (and how) the biological community was influenced by pesticides pulse exposures. 5 mixture load events were simulated over the productive season (March–July 2010): biological community was regularly sampled and nominal concentrations of water were tested. The results were interpreted comparing the output of different metrics and statistical methodologies. The sensitivity of different metrics was analyzed considering single exposure events (maximum Toxic Units) as well as overall temporal trends. Results showed how some common taxonomic metrics (e.g. taxa richness, Shannon’s index, total abundance of organisms, and the Extended Biotic Index) were not suitable to identify the effects of pesticides at community level. On the contrary EPT%, SPEARpesticide and the Principal Response Curve methodology proved to be sensitive to this kind of stress, providing comparable results. Temporal trends of these metrics proved to be related to the concentration of chemicals. Remarkably, the first Principal Response Curve illustrates the trend followed by the most vulnerable species, while the second is more related to the trend of opportunistic species. A high potential risk for the invertebrate community was highlighted by a statistically significant decline of 40 points (comparison with the control) in both SPEARpesticide and EPT%.
ABSTRACT Hydropeaking induced by storage hydropower plants can modify the natural flow regime at ... more ABSTRACT Hydropeaking induced by storage hydropower plants can modify the natural flow regime at different time scales, with severe impacts on the biodiversity of the downstream river ecosystems. In this research, a case study on the Noce River (NE Italy) is presented, where habitat simulation models and habitat time series were used to compare restoration scenarios and develop flow management criteria. Habitat time series analyses are based on the assumption that habitat events occurring rarely in nature create stress to aquatic fauna and shape the community. The identification of habitat stressor thresholds (HST) provided a means of quantitatively comparing different flow magnitude scenarios as well as duration and frequency of events. Results indicate that (i) the proposed flow management plan should nullify the rare habitat stress events to support the recovery of existing fish populations and (ii) HST can be used to identify flow release strategies in rivers affected by hydropeaking.
Proceedings of the 4th ECRR (European Center for River Restoration) International Conference for River Restoration. Venice, Jun 1, 2008
Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 an... more Degree–days were not significantly different between NB19 and NB20, while they were it for NB8 and V1 (Mann-Whitney test, p= 0.001). A significant difference in annual water temperature was observed between NB19 and NB20 (Mann-Whitney test, p< 0.001). Fig. 2 shows the differences in water temperature recorded up and downstream of the Mezzocorona plant (NB19 and NB20). During plant operation temperature increased up to 4.5 C during fall and winter, whereas decreased up to 5.9 C during s pring and summer.
Release of water from storage hydropower plants generates rapid flow and stage fluctuations (hydr... more 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.
\textcopyright} 2016Most flow regime characterizations focus on long time scale flow patterns, wh... more \textcopyright} 2016Most flow regime characterizations focus on long time scale flow patterns, which are not precise enough to capture key components of short-term flow fluctuations. Recent proposed methods describing sub-daily flow fluctuations are focused on limited components of the flow regime being unable to fully represent it, or on the identification of peaking events based on subjectively defined thresholds, being unsuitable for evaluations of short-term flow regime alterations through comparisons between regulated and free-flowing rivers. This study aims to launch an innovative approach based on the visual display of quantitative information to address the challenge of the short-term hydrologic characterization and evaluation of alteration resulting from hydropeaking. We propose a graphical method to represent a discrete set of ecologically relevant indices that characterize and evaluate the alteration of sub-daily flow regimes. The frequency of occurrence of classified values of a descriptive hydrological variable is represented in a map-like graph where longitude, latitude and altitude represent the Julian day, the value of the variable and the frequency of occurrence, respectively. Subsequently, we tested the method on several rivers, both free-flowing and subjected to hydropower production. The advantages of our approach compared to other analytical methods are: (i) it displays a great amount of information without oversimplification; (ii) it takes into account changes in the intensity, timing and frequency of the sub-daily flows, without needing a priori defined thresholds to identify hydropeaking events; and (iii) it supports the Water Framework Directive goal. Specifically, results from applications of our graphical method agree with Sauterleute and Charmasson (2014) analytical method.
\textcopyright} Springer International Publishing Switzerland 2015.Habitat simulation models are ... more \textcopyright} Springer International Publishing Switzerland 2015.Habitat simulation models are effective tools which can be used to estimate spatial and temporal habitat availability for aquatic organisms, and to design and evaluate habitat restoration actions. Based on the meso-scale resolution, the present work proposes two indices to evaluate the spatial and temporal alteration of instream habitats. Firstly, the Index of Habitat Quantity (IHq) describes the relative amount of habitat loss due to flow diversion, and, secondly, the Index of Habitat Stress Days (IHSD) measures the increase of continuous duration of events when habitat bottlenecks create stress to the fauna. Two case studies from the mountainous areas of Northern Italy are presented as applicatory examples. The achieved results indicate that (i) the meso-scale can be considered an appropriate scale resolution to link fish habitat requirements to fluvial morphological characteristics, and (ii) the proposed indices are flexible tools since they can capture both spatial and temporal alterations of habitat structure and can be applied to different kind of pressures (e.g., hydropower generation, hydropeaking).
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Papers by Mauro Carolli