�ݺ�ߣshows by User: severinhohensinner

�ݺ�ߣshows by User: severinhohensinner / http://www.slideshare.net/images/logo.gif �ݺ�ߣshows by User: severinhohensinner / Tue, 30 Jul 2013 13:54:34 GMT �ݺ�ߣShare feed for �ݺ�ߣshows by User: severinhohensinner Hohensinner 2011: Importance of multi-dimensional morphodynamics for riverine habitat evolution /slideshow/hohensinner-2011-fluvial-dynamics-habitat-evolution/24774045 hohensinner2011-fluvialdynamicshabitatevolution-130730135434-phpapp02
Human-unimpaired braided/anabranched river systems are characterized by manifold multi-dimensional exchange processes. The intensity of hydrological surface/subsurface connectivity of riverine habitats depends on more than regular or episodic water level fluctuations due to the hydrological regime. Morphodynamic changes are also a basic underlying factor. The case study of the Danube River prior to channelization shows that sudden channel changes (avulsions) extensively altered the riverine habitat conditions with regard to hydrological surface and subsurface connectivity. Between 1812 and 1817 the groundwater table dropped by one meter in some parts of the floodplain, while other parts showed an uplift of the same dimension. Such alterations foster or restrain the potential evolution and the ecological succession of the coenoses at the respective sites. On a larger spatial scale, however, the historical analysis shows that the changes in the depth of the groundwater table were largely balanced. Such a dynamic equilibrium is also evident over the long term (1715-1821) when focusing on the spatial distribution of aquatic habitats. Though the natural river landscape experienced intensive fluvial dynamics, the range of variation in habitat patterns was surprisingly low. This study highlights the key role of morphodynamics for braided/anabranched river landscapes and supports the hypothesis that such river systems naturally feature “shifting habitat mosaics” as long as the given framework conditions (e.g. climate) do not change. The mosaic of habitats representing different types and different ages potentially allowed many riverine species to co-exist in an environment with frequent perturbations. ]]>
Human-unimpaired braided/anabranched river systems are characterized by manifold multi-dimensional exchange processes. The intensity of hydrological surface/subsurface connectivity of riverine habitats depends on more than regular or episodic water level fluctuations due to the hydrological regime. Morphodynamic changes are also a basic underlying factor. The case study of the Danube River prior to channelization shows that sudden channel changes (avulsions) extensively altered the riverine habitat conditions with regard to hydrological surface and subsurface connectivity. Between 1812 and 1817 the groundwater table dropped by one meter in some parts of the floodplain, while other parts showed an uplift of the same dimension. Such alterations foster or restrain the potential evolution and the ecological succession of the coenoses at the respective sites. On a larger spatial scale, however, the historical analysis shows that the changes in the depth of the groundwater table were largely balanced. Such a dynamic equilibrium is also evident over the long term (1715-1821) when focusing on the spatial distribution of aquatic habitats. Though the natural river landscape experienced intensive fluvial dynamics, the range of variation in habitat patterns was surprisingly low. This study highlights the key role of morphodynamics for braided/anabranched river landscapes and supports the hypothesis that such river systems naturally feature “shifting habitat mosaics” as long as the given framework conditions (e.g. climate) do not change. The mosaic of habitats representing different types and different ages potentially allowed many riverine species to co-exist in an environment with frequent perturbations. ]]> Tue, 30 Jul 2013 13:54:34 GMT /slideshow/hohensinner-2011-fluvial-dynamics-habitat-evolution/24774045 severinhohensinner@slideshare.net(severinhohensinner) Hohensinner 2011: Importance of multi-dimensional morphodynamics for riverine habitat evolution severinhohensinner Human-unimpaired braided/anabranched river systems are characterized by manifold multi-dimensional exchange processes. The intensity of hydrological surface/subsurface connectivity of riverine habitats depends on more than regular or episodic water level fluctuations due to the hydrological regime. Morphodynamic changes are also a basic underlying factor. The case study of the Danube River prior to channelization shows that sudden channel changes (avulsions) extensively altered the riverine habitat conditions with regard to hydrological surface and subsurface connectivity. Between 1812 and 1817 the groundwater table dropped by one meter in some parts of the floodplain, while other parts showed an uplift of the same dimension. Such alterations foster or restrain the potential evolution and the ecological succession of the coenoses at the respective sites. On a larger spatial scale, however, the historical analysis shows that the changes in the depth of the groundwater table were largely balanced. Such a dynamic equilibrium is also evident over the long term (1715-1821) when focusing on the spatial distribution of aquatic habitats. Though the natural river landscape experienced intensive fluvial dynamics, the range of variation in habitat patterns was surprisingly low. This study highlights the key role of morphodynamics for braided/anabranched river landscapes and supports the hypothesis that such river systems naturally feature “shifting habitat mosaics” as long as the given framework conditions (e.g. climate) do not change. The mosaic of habitats representing different types and different ages potentially allowed many riverine species to co-exist in an environment with frequent perturbations. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2011-fluvialdynamicshabitatevolution-130730135434-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds" /><br> Human-unimpaired braided/anabranched river systems are characterized by manifold multi-dimensional exchange processes. The intensity of hydrological surface/subsurface connectivity of riverine habitats depends on more than regular or episodic water level fluctuations due to the hydrological regime. Morphodynamic changes are also a basic underlying factor. The case study of the Danube River prior to channelization shows that sudden channel changes (avulsions) extensively altered the riverine habitat conditions with regard to hydrological surface and subsurface connectivity. Between 1812 and 1817 the groundwater table dropped by one meter in some parts of the floodplain, while other parts showed an uplift of the same dimension. Such alterations foster or restrain the potential evolution and the ecological succession of the coenoses at the respective sites. On a larger spatial scale, however, the historical analysis shows that the changes in the depth of the groundwater table were largely balanced. Such a dynamic equilibrium is also evident over the long term (1715-1821) when focusing on the spatial distribution of aquatic habitats. Though the natural river landscape experienced intensive fluvial dynamics, the range of variation in habitat patterns was surprisingly low. This study highlights the key role of morphodynamics for braided/anabranched river landscapes and supports the hypothesis that such river systems naturally feature “shifting habitat mosaics” as long as the given framework conditions (e.g. climate) do not change. The mosaic of habitats representing different types and different ages potentially allowed many riverine species to co-exist in an environment with frequent perturbations.

Hohensinner 2011: Importance of multi-dimensional morphodynamics for riverine habitat evolution from Institute of Hydrobiology and Aquatic Ecosystem Management, BOKU Vienna

]]> 459 2 https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2011-fluvialdynamicshabitatevolution-130730135434-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds presentation �±�ß http://activitystrea.ms/schema/1.0/post

http://activitystrea.ms/schema/1.0/posted

0 Hohensinner 2008: Danube River in the Machland floodplain 1715-1991 https://de.slideshare.net/slideshow/hohensinner-2008-danube-river-in-the-machland-floodplain-17151991/24773664 hohensinner2008-danuberiverinmachland1715-1991-130730134341-phpapp02
This work contributes to research on river type-specific reference conditions (“visionary Leitbild”) and is focused on the natural characteristics of alluvial Danube river landscapes. The analyses are based on river morphological reconstructions of the Danube River in the eastern Machland (Upper/Lower Austria, river-km 2094.4-2084.0) since 1715. These reconstructions yield detailed information on the former habitat composition and fluvial processes. This enables conclusions to be drawn about the original fish fauna of the river-floodplain system and the riparian vegetation. Prior to channelization, the river landscape comprised a complex network of river channels, numerous gravel bars and large islands (anabranched river type). The channel system was dominated (>90 %) by the main channel and lotic side arms (eupotamon) that primarily promoted the rheophilic Danube fish fauna. The results support the central hypothesis of the dissertation that – despite the high degree of hydromorphological turnover – a dynamic equilibrium of aggradation and erosion processes largely existed. This state of the riverine ecosystem can be described as a “shifting-mosaic steady-state”, characterized by a gradient of differently developed habitats. The balance of habitat succession and regeneration is reflected by a morphologically very young river landscape with a comparably brief habitat life-time cycle. River channelization and hydropower plant construction since the 19th century increasingly stabilized the river landscape. As a consequence, the former dynamic habitat types have been heavily reduced. The natural cycle of aggradation and erosion became disrupted and the current river landscape is characterized by missing habitat regeneration and prevailing senescence. Altogether, this state no longer constitutes a “shifting-mosaic steady-state system” but rather a “static-state system”. ]]>
This work contributes to research on river type-specific reference conditions (“visionary Leitbild”) and is focused on the natural characteristics of alluvial Danube river landscapes. The analyses are based on river morphological reconstructions of the Danube River in the eastern Machland (Upper/Lower Austria, river-km 2094.4-2084.0) since 1715. These reconstructions yield detailed information on the former habitat composition and fluvial processes. This enables conclusions to be drawn about the original fish fauna of the river-floodplain system and the riparian vegetation. Prior to channelization, the river landscape comprised a complex network of river channels, numerous gravel bars and large islands (anabranched river type). The channel system was dominated (>90 %) by the main channel and lotic side arms (eupotamon) that primarily promoted the rheophilic Danube fish fauna. The results support the central hypothesis of the dissertation that – despite the high degree of hydromorphological turnover – a dynamic equilibrium of aggradation and erosion processes largely existed. This state of the riverine ecosystem can be described as a “shifting-mosaic steady-state”, characterized by a gradient of differently developed habitats. The balance of habitat succession and regeneration is reflected by a morphologically very young river landscape with a comparably brief habitat life-time cycle. River channelization and hydropower plant construction since the 19th century increasingly stabilized the river landscape. As a consequence, the former dynamic habitat types have been heavily reduced. The natural cycle of aggradation and erosion became disrupted and the current river landscape is characterized by missing habitat regeneration and prevailing senescence. Altogether, this state no longer constitutes a “shifting-mosaic steady-state system” but rather a “static-state system”. ]]> Tue, 30 Jul 2013 13:43:41 GMT https://de.slideshare.net/slideshow/hohensinner-2008-danube-river-in-the-machland-floodplain-17151991/24773664 severinhohensinner@slideshare.net(severinhohensinner) Hohensinner 2008: Danube River in the Machland floodplain 1715-1991 severinhohensinner This work contributes to research on river type-specific reference conditions (“visionary Leitbild”) and is focused on the natural characteristics of alluvial Danube river landscapes. The analyses are based on river morphological reconstructions of the Danube River in the eastern Machland (Upper/Lower Austria, river-km 2094.4-2084.0) since 1715. These reconstructions yield detailed information on the former habitat composition and fluvial processes. This enables conclusions to be drawn about the original fish fauna of the river-floodplain system and the riparian vegetation. Prior to channelization, the river landscape comprised a complex network of river channels, numerous gravel bars and large islands (anabranched river type). The channel system was dominated (>90 %) by the main channel and lotic side arms (eupotamon) that primarily promoted the rheophilic Danube fish fauna. The results support the central hypothesis of the dissertation that – despite the high degree of hydromorphological turnover – a dynamic equilibrium of aggradation and erosion processes largely existed. This state of the riverine ecosystem can be described as a “shifting-mosaic steady-state”, characterized by a gradient of differently developed habitats. The balance of habitat succession and regeneration is reflected by a morphologically very young river landscape with a comparably brief habitat life-time cycle. River channelization and hydropower plant construction since the 19th century increasingly stabilized the river landscape. As a consequence, the former dynamic habitat types have been heavily reduced. The natural cycle of aggradation and erosion became disrupted and the current river landscape is characterized by missing habitat regeneration and prevailing senescence. Altogether, this state no longer constitutes a “shifting-mosaic steady-state system” but rather a “static-state system”. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2008-danuberiverinmachland1715-1991-130730134341-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds" /><br> This work contributes to research on river type-specific reference conditions (“visionary Leitbild”) and is focused on the natural characteristics of alluvial Danube river landscapes. The analyses are based on river morphological reconstructions of the Danube River in the eastern Machland (Upper/Lower Austria, river-km 2094.4-2084.0) since 1715. These reconstructions yield detailed information on the former habitat composition and fluvial processes. This enables conclusions to be drawn about the original fish fauna of the river-floodplain system and the riparian vegetation. Prior to channelization, the river landscape comprised a complex network of river channels, numerous gravel bars and large islands (anabranched river type). The channel system was dominated (>90 %) by the main channel and lotic side arms (eupotamon) that primarily promoted the rheophilic Danube fish fauna. The results support the central hypothesis of the dissertation that – despite the high degree of hydromorphological turnover – a dynamic equilibrium of aggradation and erosion processes largely existed. This state of the riverine ecosystem can be described as a “shifting-mosaic steady-state”, characterized by a gradient of differently developed habitats. The balance of habitat succession and regeneration is reflected by a morphologically very young river landscape with a comparably brief habitat life-time cycle. River channelization and hydropower plant construction since the 19th century increasingly stabilized the river landscape. As a consequence, the former dynamic habitat types have been heavily reduced. The natural cycle of aggradation and erosion became disrupted and the current river landscape is characterized by missing habitat regeneration and prevailing senescence. Altogether, this state no longer constitutes a “shifting-mosaic steady-state system” but rather a “static-state system”.

from Institute of Hydrobiology and Aquatic Ecosystem Management, BOKU Vienna

]]> 744 6 https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2008-danuberiverinmachland1715-1991-130730134341-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds presentation �±�ß http://activitystrea.ms/schema/1.0/post

http://activitystrea.ms/schema/1.0/posted

0 Hohensinner 2013: GIS-reconstruction of river landscapes /slideshow/hohensinner-2013-gisreconstruction-river-landscapes/24773020 hohensinner2013-gis-reconstructionriverlandscapes-130730132451-phpapp02
Over centuries, hundreds of thousands of historical sources that contain information on the Viennese Danube river landscape have been stored in various archives. This unique wealth of historical material provides an excellent basis for the in-depth GIS reconstruction of Vienna’s topography over the past 500 years. However, the numerous – partly contradictory – sources must be critically assessed, making an authoritative reconstruction even more complicated. This paper describes the different types of historical sources used for the GIS-based reconstruction, the underlying methodological approach and its limitations regarding reliability and information value. The reconstruction was based on three cornerstones: (1) the available historical sources; (2) knowledge about morphological processes typical for the Austrian Danube prior to regulation; and (3) the interpretation of past hydraulic measures with respect to their effectiveness and their impact on the river’s behaviour. The current state of the Viennese river landscape served as a starting point for the GIS work; from there, ten historical states were reconstructed step-by-step going backwards in time to the least well-known situation in the early 16th century. After one reconstruction had been completed, its relevance for the temporally younger situations was evaluated. Such a regressive-iterative approach allows for permanent critical revision of the reconstructed time segments already processed. The resulting maps of the Danube floodplain from 1529 to 2010 provide a solid basis for interpreting the environmental conditions for Vienna’s urban development. They also help to localise certain riverine and urban landmarks (such as river arms or bridges) relevant for the history of Vienna. We conclude that the diversity of approaches and findings of the historical and natural sciences (river morphology, hydrology) provide key synergies. ]]>
Over centuries, hundreds of thousands of historical sources that contain information on the Viennese Danube river landscape have been stored in various archives. This unique wealth of historical material provides an excellent basis for the in-depth GIS reconstruction of Vienna’s topography over the past 500 years. However, the numerous – partly contradictory – sources must be critically assessed, making an authoritative reconstruction even more complicated. This paper describes the different types of historical sources used for the GIS-based reconstruction, the underlying methodological approach and its limitations regarding reliability and information value. The reconstruction was based on three cornerstones: (1) the available historical sources; (2) knowledge about morphological processes typical for the Austrian Danube prior to regulation; and (3) the interpretation of past hydraulic measures with respect to their effectiveness and their impact on the river’s behaviour. The current state of the Viennese river landscape served as a starting point for the GIS work; from there, ten historical states were reconstructed step-by-step going backwards in time to the least well-known situation in the early 16th century. After one reconstruction had been completed, its relevance for the temporally younger situations was evaluated. Such a regressive-iterative approach allows for permanent critical revision of the reconstructed time segments already processed. The resulting maps of the Danube floodplain from 1529 to 2010 provide a solid basis for interpreting the environmental conditions for Vienna’s urban development. They also help to localise certain riverine and urban landmarks (such as river arms or bridges) relevant for the history of Vienna. We conclude that the diversity of approaches and findings of the historical and natural sciences (river morphology, hydrology) provide key synergies. ]]> Tue, 30 Jul 2013 13:24:51 GMT /slideshow/hohensinner-2013-gisreconstruction-river-landscapes/24773020 severinhohensinner@slideshare.net(severinhohensinner) Hohensinner 2013: GIS-reconstruction of river landscapes severinhohensinner Over centuries, hundreds of thousands of historical sources that contain information on the Viennese Danube river landscape have been stored in various archives. This unique wealth of historical material provides an excellent basis for the in-depth GIS reconstruction of Vienna’s topography over the past 500 years. However, the numerous – partly contradictory – sources must be critically assessed, making an authoritative reconstruction even more complicated. This paper describes the different types of historical sources used for the GIS-based reconstruction, the underlying methodological approach and its limitations regarding reliability and information value. The reconstruction was based on three cornerstones: (1) the available historical sources; (2) knowledge about morphological processes typical for the Austrian Danube prior to regulation; and (3) the interpretation of past hydraulic measures with respect to their effectiveness and their impact on the river’s behaviour. The current state of the Viennese river landscape served as a starting point for the GIS work; from there, ten historical states were reconstructed step-by-step going backwards in time to the least well-known situation in the early 16th century. After one reconstruction had been completed, its relevance for the temporally younger situations was evaluated. Such a regressive-iterative approach allows for permanent critical revision of the reconstructed time segments already processed. The resulting maps of the Danube floodplain from 1529 to 2010 provide a solid basis for interpreting the environmental conditions for Vienna’s urban development. They also help to localise certain riverine and urban landmarks (such as river arms or bridges) relevant for the history of Vienna. We conclude that the diversity of approaches and findings of the historical and natural sciences (river morphology, hydrology) provide key synergies. <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2013-gis-reconstructionriverlandscapes-130730132451-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds" /><br> Over centuries, hundreds of thousands of historical sources that contain information on the Viennese Danube river landscape have been stored in various archives. This unique wealth of historical material provides an excellent basis for the in-depth GIS reconstruction of Vienna’s topography over the past 500 years. However, the numerous – partly contradictory – sources must be critically assessed, making an authoritative reconstruction even more complicated. This paper describes the different types of historical sources used for the GIS-based reconstruction, the underlying methodological approach and its limitations regarding reliability and information value. The reconstruction was based on three cornerstones: (1) the available historical sources; (2) knowledge about morphological processes typical for the Austrian Danube prior to regulation; and (3) the interpretation of past hydraulic measures with respect to their effectiveness and their impact on the river’s behaviour. The current state of the Viennese river landscape served as a starting point for the GIS work; from there, ten historical states were reconstructed step-by-step going backwards in time to the least well-known situation in the early 16th century. After one reconstruction had been completed, its relevance for the temporally younger situations was evaluated. Such a regressive-iterative approach allows for permanent critical revision of the reconstructed time segments already processed. The resulting maps of the Danube floodplain from 1529 to 2010 provide a solid basis for interpreting the environmental conditions for Vienna’s urban development. They also help to localise certain riverine and urban landmarks (such as river arms or bridges) relevant for the history of Vienna. We conclude that the diversity of approaches and findings of the historical and natural sciences (river morphology, hydrology) provide key synergies.

Hohensinner 2013: GIS-reconstruction of river landscapes from Institute of Hydrobiology and Aquatic Ecosystem Management, BOKU Vienna

]]> 554 6 https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2013-gis-reconstructionriverlandscapes-130730132451-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds presentation �±�ß http://activitystrea.ms/schema/1.0/post

http://activitystrea.ms/schema/1.0/posted

0 https://cdn.slidesharecdn.com/profile-photo-severinhohensinner-48x48.jpg?cb=1523175869 https://forschung.boku.ac.at/fis/suchen.person_uebersicht?sprache_in=en&ansicht_in=&menue_id_in=101&id_in=6313 https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2011-fluvialdynamicshabitatevolution-130730135434-phpapp02-thumbnail.jpg?width=320&height=320&fit=bounds slideshow/hohensinner-2011-fluvial-dynamics-habitat-evolution/24774045 Hohensinner 2011: Impo... https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2008-danuberiverinmachland1715-1991-130730134341-phpapp02-thumbnail.jpg?width=320&height=320&fit=bounds slideshow/hohensinner-2008-danube-river-in-the-machland-floodplain-17151991/24773664 Hohensinner 2008: Danu... https://cdn.slidesharecdn.com/ss_thumbnails/hohensinner2013-gis-reconstructionriverlandscapes-130730132451-phpapp02-thumbnail.jpg?width=320&height=320&fit=bounds slideshow/hohensinner-2013-gisreconstruction-river-landscapes/24773020 Hohensinner 2013: GIS-...