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Research paper thumbnail of Ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken

Österreichische Wasser- und Abfallwirtschaft, Oct 20, 2016

Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organ... more Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organismen kommt es durch Laufkraftwerke zu einer bedeutenden Störung des longitudinalen Feststofftransports. In dieser Arbeit werden sowohl die generellen Aspekte und Auswirkungen einer Veränderung der Feststoffdynamik durch den Kraftwerksbetrieb erläutert, es wird aber auch detailliert auf die Problematik einer Beeinflussung des Feststofftransports bei Kleinwasserkraftwerken eingegangen. Ziel des vorliegenden Fachbeitrags ist es, die ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken aufzuzeigen. Es werden sowohl die notwendigen Grundlagenerhebungen (Messungen und Modellierungen) für wasserbauliche Maßnahmenplanungen beschrieben, als auch konkret die Möglichkeiten zur naturnahen/ technischen Optimierung angesprochen. Vor allem auf die eigendynamische Entwicklung von Kieslaichplätzen im Nahbereich dieser technischen Anlagen zur Wasserkraftnutzung wird im Detail eingegangen. Die Möglichkeiten zur Laichplatzentwicklung, welche im Zuge umfangreicher Feldarbeiten validiert wurden, zeigen, dass sich im und durch den Einflussbereich von Kleinwasserkraftwerken mitunter Kieslaichplätze entwickeln können. Die Bedeutung von strukturellen Aufwertungen von Kleinwasserkraftanlagen

Research paper thumbnail of Physical laboratory analyses of intergravel flow through brown trout redds (Salmo trutta fario) in response to coarse sand infiltration

Earth Surface Processes and Landforms, Aug 25, 2016

In the spawning environment of salmonids, the quality of the intergravel flow is an essential abi... more In the spawning environment of salmonids, the quality of the intergravel flow is an essential abiotic requirement for the survival success of incubated embryos. As one of the most frequently investigated anthropogenic environmental impacts, the enhanced mobilization of fine sediments (<1 mm) and their entry into riverine ecosystems is considered as a major cause for the degradation of a variety of biological processes and habitats, including the spawning habitats of salmonids. In catchments draining crystalline bedrock, however, like the Bohemian Massif in the northern part of Austria, the excessive loading of river channels with coarse sand and fine gravel sediments (D = 1-10 mm) and less cohesive than fines is common as a consequence of altered catchment land use. Here, far less understanding exists of the mechanism and the possible implications of coarse sand infiltration on the functioning of the intergravel flow in salmonid redds. To investigate the intergravel flow hydraulics in response to coarse sand infiltration (D 50 = 2 mm) in brown trout spawning redds (Salmo trutta fario) under controlled conditions, a laboratory flume experiment with three infiltration scenarios was conducted: (1) no infiltration; (2) segmental infiltration; and (3) full section infiltration. A more than two times drop in the average intergravel flow velocity was documented from scenario 1 (5.85 cms À1) to scenario 2 (2.53 cms À1) and another clear reduction was seen from scenario 2 (2.53 cms À1) to scenario 3 (1.61 cms À1). Moreover, in scenario 3, a clear reduction of the intergravel flow distance traveled was observed. Based on the findings we conclude that future considerations regarding the sustainable catchment management of salmonid fisheries should include programs to reduce not only the excessive entry of fines, but, in the relevant catchments, also the entry of excessive coarse sand into the riverine ecosystem.

Research paper thumbnail of Abiotic Characterization of Brown Trout (Salmo trutta f. fario ) and Rainbow Trout (Oncorhynchus mykiss ) Spawning Redds Affected by Small Hydropower Plants - Case Studies from Austria

River Research and Applications, May 3, 2016

Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting i... more Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting in potential declines of the spawning habitats of salmonids. To assess the restrictions and possible quality of hydropower-influenced river sections for salmonid, spawning redd densities of brown trout and rainbow trout were monitored in two rivers in 2014 and 2015. The results showed spawning close to small hydropower facilities for both investigated specieswith similarities in redd characteristics like pit and tail length. Differences occurred concerning the distance of redd construction to the next shore. Brown trout spawn close to the banks in comparison to rainbow trout which use the entire active channel width. In addition to the preference of brown trout for certain cover types, it turned out that the presence of high quality spawning gravel in the river is the dictating abiotic variable (probably bottleneck) in the control of salmonid populations even for river reaches impacted by small hydropower plants. Moreover, the assessments of spawning redd densities enabled a discussion of different opportunities for spawning habitat enhancement of salmonids in river sections regulated by small hydropower facilities. Here, in conclusion, it was found that the fill-up of the backwater sites by transported sediments or the structural modification (e.g. boulder placement) in the tail of the backwater could improve the spawning situation in a sustainable way.

Research paper thumbnail of Abiotic Characterization of Brown Trout (Salmo trutta f. fario ) and Rainbow Trout (Oncorhynchus mykiss ) Spawning Redds Affected by Small Hydropower Plants - Case Studies from Austria

River Research and Applications, 2016

Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting i... more Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting in potential declines of the spawning habitats of salmonids. To assess the restrictions and possible quality of hydropower-influenced river sections for salmonid, spawning redd densities of brown trout and rainbow trout were monitored in two rivers in 2014 and 2015. The results showed spawning close to small hydropower facilities for both investigated specieswith similarities in redd characteristics like pit and tail length. Differences occurred concerning the distance of redd construction to the next shore. Brown trout spawn close to the banks in comparison to rainbow trout which use the entire active channel width. In addition to the preference of brown trout for certain cover types, it turned out that the presence of high quality spawning gravel in the river is the dictating abiotic variable (probably bottleneck) in the control of salmonid populations even for river reaches impacted by small hydropower plants. Moreover, the assessments of spawning redd densities enabled a discussion of different opportunities for spawning habitat enhancement of salmonids in river sections regulated by small hydropower facilities. Here, in conclusion, it was found that the fill-up of the backwater sites by transported sediments or the structural modification (e.g. boulder placement) in the tail of the backwater could improve the spawning situation in a sustainable way.

Research paper thumbnail of Ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken

Österreichische Wasser- und Abfallwirtschaft, 2016

Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organ... more Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organismen kommt es durch Laufkraftwerke zu einer bedeutenden Störung des longitudinalen Feststofftransports. In dieser Arbeit werden sowohl die generellen Aspekte und Auswirkungen einer Veränderung der Feststoffdynamik durch den Kraftwerksbetrieb erläutert, es wird aber auch detailliert auf die Problematik einer Beeinflussung des Feststofftransports bei Kleinwasserkraftwerken eingegangen. Ziel des vorliegenden Fachbeitrags ist es, die ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken aufzuzeigen. Es werden sowohl die notwendigen Grundlagenerhebungen (Messungen und Modellierungen) für wasserbauliche Maßnahmenplanungen beschrieben, als auch konkret die Möglichkeiten zur naturnahen/ technischen Optimierung angesprochen. Vor allem auf die eigendynamische Entwicklung von Kieslaichplätzen im Nahbereich dieser technischen Anlagen zur Wasserkraftnutzung wird im Detail eingegangen. Die Möglichkeiten zur Laichplatzentwicklung, welche im Zuge umfangreicher Feldarbeiten validiert wurden, zeigen, dass sich im und durch den Einflussbereich von Kleinwasserkraftwerken mitunter Kieslaichplätze entwickeln können. Die Bedeutung von strukturellen Aufwertungen von Kleinwasserkraftanlagen

Research paper thumbnail of Physical laboratory analyses of intergravel flow through brown trout redds (Salmo trutta fario) in response to coarse sand infiltration

Earth Surface Processes and Landforms, 2016

In the spawning environment of salmonids, the quality of the intergravel flow is an essential abi... more In the spawning environment of salmonids, the quality of the intergravel flow is an essential abiotic requirement for the survival success of incubated embryos. As one of the most frequently investigated anthropogenic environmental impacts, the enhanced mobilization of fine sediments (<1 mm) and their entry into riverine ecosystems is considered as a major cause for the degradation of a variety of biological processes and habitats, including the spawning habitats of salmonids. In catchments draining crystalline bedrock, however, like the Bohemian Massif in the northern part of Austria, the excessive loading of river channels with coarse sand and fine gravel sediments (D = 1-10 mm) and less cohesive than fines is common as a consequence of altered catchment land use. Here, far less understanding exists of the mechanism and the possible implications of coarse sand infiltration on the functioning of the intergravel flow in salmonid redds. To investigate the intergravel flow hydraulics in response to coarse sand infiltration (D 50 = 2 mm) in brown trout spawning redds (Salmo trutta fario) under controlled conditions, a laboratory flume experiment with three infiltration scenarios was conducted: (1) no infiltration; (2) segmental infiltration; and (3) full section infiltration. A more than two times drop in the average intergravel flow velocity was documented from scenario 1 (5.85 cms À1) to scenario 2 (2.53 cms À1) and another clear reduction was seen from scenario 2 (2.53 cms À1) to scenario 3 (1.61 cms À1). Moreover, in scenario 3, a clear reduction of the intergravel flow distance traveled was observed. Based on the findings we conclude that future considerations regarding the sustainable catchment management of salmonid fisheries should include programs to reduce not only the excessive entry of fines, but, in the relevant catchments, also the entry of excessive coarse sand into the riverine ecosystem.

Research paper thumbnail of Ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken

Österreichische Wasser- und Abfallwirtschaft, Oct 20, 2016

Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organ... more Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organismen kommt es durch Laufkraftwerke zu einer bedeutenden Störung des longitudinalen Feststofftransports. In dieser Arbeit werden sowohl die generellen Aspekte und Auswirkungen einer Veränderung der Feststoffdynamik durch den Kraftwerksbetrieb erläutert, es wird aber auch detailliert auf die Problematik einer Beeinflussung des Feststofftransports bei Kleinwasserkraftwerken eingegangen. Ziel des vorliegenden Fachbeitrags ist es, die ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken aufzuzeigen. Es werden sowohl die notwendigen Grundlagenerhebungen (Messungen und Modellierungen) für wasserbauliche Maßnahmenplanungen beschrieben, als auch konkret die Möglichkeiten zur naturnahen/ technischen Optimierung angesprochen. Vor allem auf die eigendynamische Entwicklung von Kieslaichplätzen im Nahbereich dieser technischen Anlagen zur Wasserkraftnutzung wird im Detail eingegangen. Die Möglichkeiten zur Laichplatzentwicklung, welche im Zuge umfangreicher Feldarbeiten validiert wurden, zeigen, dass sich im und durch den Einflussbereich von Kleinwasserkraftwerken mitunter Kieslaichplätze entwickeln können. Die Bedeutung von strukturellen Aufwertungen von Kleinwasserkraftanlagen

Research paper thumbnail of Physical laboratory analyses of intergravel flow through brown trout redds (Salmo trutta fario) in response to coarse sand infiltration

Earth Surface Processes and Landforms, Aug 25, 2016

In the spawning environment of salmonids, the quality of the intergravel flow is an essential abi... more In the spawning environment of salmonids, the quality of the intergravel flow is an essential abiotic requirement for the survival success of incubated embryos. As one of the most frequently investigated anthropogenic environmental impacts, the enhanced mobilization of fine sediments (<1 mm) and their entry into riverine ecosystems is considered as a major cause for the degradation of a variety of biological processes and habitats, including the spawning habitats of salmonids. In catchments draining crystalline bedrock, however, like the Bohemian Massif in the northern part of Austria, the excessive loading of river channels with coarse sand and fine gravel sediments (D = 1-10 mm) and less cohesive than fines is common as a consequence of altered catchment land use. Here, far less understanding exists of the mechanism and the possible implications of coarse sand infiltration on the functioning of the intergravel flow in salmonid redds. To investigate the intergravel flow hydraulics in response to coarse sand infiltration (D 50 = 2 mm) in brown trout spawning redds (Salmo trutta fario) under controlled conditions, a laboratory flume experiment with three infiltration scenarios was conducted: (1) no infiltration; (2) segmental infiltration; and (3) full section infiltration. A more than two times drop in the average intergravel flow velocity was documented from scenario 1 (5.85 cms À1) to scenario 2 (2.53 cms À1) and another clear reduction was seen from scenario 2 (2.53 cms À1) to scenario 3 (1.61 cms À1). Moreover, in scenario 3, a clear reduction of the intergravel flow distance traveled was observed. Based on the findings we conclude that future considerations regarding the sustainable catchment management of salmonid fisheries should include programs to reduce not only the excessive entry of fines, but, in the relevant catchments, also the entry of excessive coarse sand into the riverine ecosystem.

Research paper thumbnail of Abiotic Characterization of Brown Trout (Salmo trutta f. fario ) and Rainbow Trout (Oncorhynchus mykiss ) Spawning Redds Affected by Small Hydropower Plants - Case Studies from Austria

River Research and Applications, May 3, 2016

Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting i... more Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting in potential declines of the spawning habitats of salmonids. To assess the restrictions and possible quality of hydropower-influenced river sections for salmonid, spawning redd densities of brown trout and rainbow trout were monitored in two rivers in 2014 and 2015. The results showed spawning close to small hydropower facilities for both investigated specieswith similarities in redd characteristics like pit and tail length. Differences occurred concerning the distance of redd construction to the next shore. Brown trout spawn close to the banks in comparison to rainbow trout which use the entire active channel width. In addition to the preference of brown trout for certain cover types, it turned out that the presence of high quality spawning gravel in the river is the dictating abiotic variable (probably bottleneck) in the control of salmonid populations even for river reaches impacted by small hydropower plants. Moreover, the assessments of spawning redd densities enabled a discussion of different opportunities for spawning habitat enhancement of salmonids in river sections regulated by small hydropower facilities. Here, in conclusion, it was found that the fill-up of the backwater sites by transported sediments or the structural modification (e.g. boulder placement) in the tail of the backwater could improve the spawning situation in a sustainable way.

Research paper thumbnail of Abiotic Characterization of Brown Trout (Salmo trutta f. fario ) and Rainbow Trout (Oncorhynchus mykiss ) Spawning Redds Affected by Small Hydropower Plants - Case Studies from Austria

River Research and Applications, 2016

Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting i... more Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting in potential declines of the spawning habitats of salmonids. To assess the restrictions and possible quality of hydropower-influenced river sections for salmonid, spawning redd densities of brown trout and rainbow trout were monitored in two rivers in 2014 and 2015. The results showed spawning close to small hydropower facilities for both investigated specieswith similarities in redd characteristics like pit and tail length. Differences occurred concerning the distance of redd construction to the next shore. Brown trout spawn close to the banks in comparison to rainbow trout which use the entire active channel width. In addition to the preference of brown trout for certain cover types, it turned out that the presence of high quality spawning gravel in the river is the dictating abiotic variable (probably bottleneck) in the control of salmonid populations even for river reaches impacted by small hydropower plants. Moreover, the assessments of spawning redd densities enabled a discussion of different opportunities for spawning habitat enhancement of salmonids in river sections regulated by small hydropower facilities. Here, in conclusion, it was found that the fill-up of the backwater sites by transported sediments or the structural modification (e.g. boulder placement) in the tail of the backwater could improve the spawning situation in a sustainable way.

Research paper thumbnail of Ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken

Österreichische Wasser- und Abfallwirtschaft, 2016

Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organ... more Zusammenfassung Neben einer Unterbrechung des Längskontinuums für die Migration aquatischer Organismen kommt es durch Laufkraftwerke zu einer bedeutenden Störung des longitudinalen Feststofftransports. In dieser Arbeit werden sowohl die generellen Aspekte und Auswirkungen einer Veränderung der Feststoffdynamik durch den Kraftwerksbetrieb erläutert, es wird aber auch detailliert auf die Problematik einer Beeinflussung des Feststofftransports bei Kleinwasserkraftwerken eingegangen. Ziel des vorliegenden Fachbeitrags ist es, die ökologische Bedeutung von Feststoffen und gewässermorphologischen Strukturen im Nahbereich von Kleinwasserkraftwerken aufzuzeigen. Es werden sowohl die notwendigen Grundlagenerhebungen (Messungen und Modellierungen) für wasserbauliche Maßnahmenplanungen beschrieben, als auch konkret die Möglichkeiten zur naturnahen/ technischen Optimierung angesprochen. Vor allem auf die eigendynamische Entwicklung von Kieslaichplätzen im Nahbereich dieser technischen Anlagen zur Wasserkraftnutzung wird im Detail eingegangen. Die Möglichkeiten zur Laichplatzentwicklung, welche im Zuge umfangreicher Feldarbeiten validiert wurden, zeigen, dass sich im und durch den Einflussbereich von Kleinwasserkraftwerken mitunter Kieslaichplätze entwickeln können. Die Bedeutung von strukturellen Aufwertungen von Kleinwasserkraftanlagen

Research paper thumbnail of Physical laboratory analyses of intergravel flow through brown trout redds (Salmo trutta fario) in response to coarse sand infiltration

Earth Surface Processes and Landforms, 2016

In the spawning environment of salmonids, the quality of the intergravel flow is an essential abi... more In the spawning environment of salmonids, the quality of the intergravel flow is an essential abiotic requirement for the survival success of incubated embryos. As one of the most frequently investigated anthropogenic environmental impacts, the enhanced mobilization of fine sediments (<1 mm) and their entry into riverine ecosystems is considered as a major cause for the degradation of a variety of biological processes and habitats, including the spawning habitats of salmonids. In catchments draining crystalline bedrock, however, like the Bohemian Massif in the northern part of Austria, the excessive loading of river channels with coarse sand and fine gravel sediments (D = 1-10 mm) and less cohesive than fines is common as a consequence of altered catchment land use. Here, far less understanding exists of the mechanism and the possible implications of coarse sand infiltration on the functioning of the intergravel flow in salmonid redds. To investigate the intergravel flow hydraulics in response to coarse sand infiltration (D 50 = 2 mm) in brown trout spawning redds (Salmo trutta fario) under controlled conditions, a laboratory flume experiment with three infiltration scenarios was conducted: (1) no infiltration; (2) segmental infiltration; and (3) full section infiltration. A more than two times drop in the average intergravel flow velocity was documented from scenario 1 (5.85 cms À1) to scenario 2 (2.53 cms À1) and another clear reduction was seen from scenario 2 (2.53 cms À1) to scenario 3 (1.61 cms À1). Moreover, in scenario 3, a clear reduction of the intergravel flow distance traveled was observed. Based on the findings we conclude that future considerations regarding the sustainable catchment management of salmonid fisheries should include programs to reduce not only the excessive entry of fines, but, in the relevant catchments, also the entry of excessive coarse sand into the riverine ecosystem.