R. Benischke - Academia.edu (original) (raw)
Papers by R. Benischke
Grundwasser, 2014
ABSTRACT Karst systems fed by an allogenic inflow often show a complex network of interacting con... more ABSTRACT Karst systems fed by an allogenic inflow often show a complex network of interacting conduits that effects groundwater flow and pollutant transport. The combined evaluation of multi-tracer experiments performed at different flow conditions provide information about the hydrodynamic functioning of the karst network. Building on this, a conceptual model to quantify groundwater flow and mass transport has been developed and is presented in this study using the example of the Tanneben Massif, Austria. Within the model, groundwater flow is subdivided into several flow-paths with discrete flow velocity and capacity. As a consequence, model results reveal a dampen but also extended karst response to storm events. Upon exceeding the flow capacity, backwater accumulates at the inflow causing a prolongation of high discharge into the system. Additionally, adjacent karst systems are affected by the activation of interconnecting flow paths at high flow conditions.
Hydrological Processes, 2012
A structure model was used to analyse solute-transport parameter estimates based on tracer breakt... more A structure model was used to analyse solute-transport parameter estimates based on tracer breakthrough curves. In the model system, groundwater flow is envisioned to be organised in a complex conduit network providing a variety of short circuits with relative small carrying capacities along different erosion levels. The discharge through the fully filled conduits is limited owing to void geometries and turbulent flow; thus, a hierarchic overflow system evolves where conduits are (re-)activated or dried up depending on the flow condition. Exemplified on the Lurbach-Tanneben karst aquifer, the applicability of the model approach was tested. Information derived from multi-tracer experiments performed at different volumetric flow rates enabled to develop a structural model of the karst network, under constraint of the geomorphological and hydrological evolution of the site. Depending on the flow rate, groundwater is divided into up to eight flow paths. The spatial hierarchy of flow paths controls the sequence of flow path activation. Conduits of the topmost level are strongly influenced by reversible alteration processes. Sedimentation or blocking causes an overflow of water to the next higher conduit. Flow path specific dissolutional denudation rates were estimated using the temporal development of the partial discharge.
R. BENISCHKE & T. HARUM Institute for Geothermics & Hydrogeology, Joanneum Research, Elisabethstr... more R. BENISCHKE & T. HARUM Institute for Geothermics & Hydrogeology, Joanneum Research, Elisabethstr. 16/2, 8010 Graz, Austria ABSTRACT The attempt to determine exactly discharge rates of turbulent streams in mountainous regions based on current meter measurements can lead to serious problems rising from a badly defined runoff channel geometry and irregular flow patterns. Therefore systematic errors influence the results and make it sometimes impossible to get reliable stage-discharge relations at gauging stations. The development of commercially available computerized systems made it possible to apply the salt tracer dilution method with instantaneous or continuous injection and to monitor the tracer passage in the time-concentration or time-conductivity mode directly at the field site. The result of the measurement is available immediately at the end of the measuring procedure. The experience showed that the salt tracer dilution method is the appropriate method in almost all cases of...
Environmental Geology, 2006
The small and big Prespa Lake and the Ohrid Lake share their water with Albania, FYR of Macedonia... more The small and big Prespa Lake and the Ohrid Lake share their water with Albania, FYR of Macedonia and Greece, and constitute a common hydraulic system (Figs. 1, 2). The elevation of the Prespa Lake is 850 m asl and that of the Ohrid Lake is 695 m asl. The respective surfaces are 274 and 348 km 2. High mountains such as the Mali Thate (2,287 m) in the south and the Galichica (2,262 m) in the north separate them. Geologically these mountains represent a horst constructed mainly of the Upper Triassic-Lower Jurassic massive limestone (AHS 1975). Big graben structures that of Prespa Lake on the east and Ohrid Lake on the west, delimit both sides of the horst. The Pliocene deposits such as clay, sandstone, and conglomerate fill most of the bottom of both lakes. At Ohrid lakeside, in the Albanian-FYROM borderland, are the big karst springs of St. Naum and Tushemisht, which in total
Hydrogeology Journal, 2016
The attempt to determine exactly discharge rates of turbulent streams in mountainous regions base... more The attempt to determine exactly discharge rates of turbulent streams in mountainous regions based on current meter measurements can lead to serious problems rising from a badly defined runoff channel geometry and irregular flow patterns. Therefore systematic errors influence the results and make it sometimes impossible to get reliable stage-discharge relations at gauging stations. The development of commercially available computerized systems made it possible to apply the salt tracer dilution method with instantaneous or continuous injection and to monitor the tracer passage in the time-concentration or time-conductivity mode directly at the field site. The result of the measurement is available immediately at the end of the measuring procedure. The experience showed that the salt tracer dilution method is the appropriate method in almost all cases of turbulent flow conditions and irregular channel geometry. The article describes the theoretical basis of the method, the used measur...
In this paper an approach of distributed hydrological modelling of water balance components in a ... more In this paper an approach of distributed hydrological modelling of water balance components in a karstic mountainous region is presented. In karstic regions hydrological catchment boundaries are usually not known a priori. The idea is to combine water balance modelling results based on the orographic catchment boundaries with disparate sources of information in an iterative way to identify hydrographic catchment boundaries and subsurface water ways. The additional data and information are derived by region-wide point measurements of discharge, field surveys, isotope data, tracer tests, electric conductivity data, soil and (hydro-)geological surveys and mapping, snow depth data, etc.. These data sources are complementary to the usually used rainfall and runoff data and assist in model building, parameter calibration and interpreting the results. Also, to get information about the meteorological input in a high-alpine region comprehensive regionalisation and correction methods are ass...
Grundwasser, 2010
Zusammenfassung Die Komplexität von Karstaquiferen drückt sich darin aus, dass die orographische... more Zusammenfassung Die Komplexität von Karstaquiferen drückt sich darin aus, dass die orographischen Einzugsgebiete mit hydrographischen selten übereinstimmen. Hauptzielrichtung der vorliegenden Studie ist die Erarbeitung von methodischen Grundlagen zur Erkundung von Karstaquiferen in Gebirgsräumen und damit verbunden die Abgrenzung hydrographisch wirksamer Einzugsgebiete unter Einsatz physikalisch basierter hydrologischer Modelle am Beispiel des Kaisergebirges. Für die Simulation der Teilkomponenten des Wasserhaushalts wurde das flächendetaillierte
Proceedings of the 12th …, 1997
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Geomorphology, 2011
The transition zone of the Eastern Alps to the Pannonian Basin provides one of the best sources o... more The transition zone of the Eastern Alps to the Pannonian Basin provides one of the best sources of information on landscape evolution of the Eastern Alpine mountain range. The region was nonglaciated during the entire Pleistocene. Thus, direct influence of glacial carving as a landscape forming process can be excluded and relics of landforms are preserved that date back to at least the Late Neogene. In this study, we provide a correlation between various planation surfaces across the orogen-basin transition. In particular, we use stream terraces, planation surfaces and cave levels that cover a vertical spread of some 700 m. Our correlation is used to show that both sides of the transition zone uplifted together starting at least about 5 Ma ago. For our correlation we use recently published terrestrial cosmogenic nuclide (TCN) burial ages from cave sediments, new optically stimulated luminescence (OSL) ages of a stream terrace and U-Th ages from speleothems. Minimum age constraints of cave levels from burial ages of cave sediments covering the last ~ 4 Ma are used to place age constraints on surface features by parallelizing cave levels with planation surfaces. The OSL results for the top section of the type locality of the Helfbrunn terrace suggest an Early Würm development (80.5 ± 3.7 to 68.7 ± 4.0 ka). The terrace origin as a penultimate gravel deposit (in classical Alpine terminology Riss) is therefore questioned. U-series speleothem ages from caves nearby indicate formation during Marine Isotope Stages (MIS) 5c and 5a which are both interstadial warm periods. As OSL ages from the terrace also show a time of deposition during MIS 5a ending at the MIS 5/4 transition, this supports the idea of temperate climatic conditions at the time of deposition. In general, tectonic activity is interpreted to be the main driving force for the formation and evolution of these landforms, whilst climate change is © 2011 Elsevier B.V.
Grundwasser, 2014
ABSTRACT Karst systems fed by an allogenic inflow often show a complex network of interacting con... more ABSTRACT Karst systems fed by an allogenic inflow often show a complex network of interacting conduits that effects groundwater flow and pollutant transport. The combined evaluation of multi-tracer experiments performed at different flow conditions provide information about the hydrodynamic functioning of the karst network. Building on this, a conceptual model to quantify groundwater flow and mass transport has been developed and is presented in this study using the example of the Tanneben Massif, Austria. Within the model, groundwater flow is subdivided into several flow-paths with discrete flow velocity and capacity. As a consequence, model results reveal a dampen but also extended karst response to storm events. Upon exceeding the flow capacity, backwater accumulates at the inflow causing a prolongation of high discharge into the system. Additionally, adjacent karst systems are affected by the activation of interconnecting flow paths at high flow conditions.
Hydrological Processes, 2012
A structure model was used to analyse solute-transport parameter estimates based on tracer breakt... more A structure model was used to analyse solute-transport parameter estimates based on tracer breakthrough curves. In the model system, groundwater flow is envisioned to be organised in a complex conduit network providing a variety of short circuits with relative small carrying capacities along different erosion levels. The discharge through the fully filled conduits is limited owing to void geometries and turbulent flow; thus, a hierarchic overflow system evolves where conduits are (re-)activated or dried up depending on the flow condition. Exemplified on the Lurbach-Tanneben karst aquifer, the applicability of the model approach was tested. Information derived from multi-tracer experiments performed at different volumetric flow rates enabled to develop a structural model of the karst network, under constraint of the geomorphological and hydrological evolution of the site. Depending on the flow rate, groundwater is divided into up to eight flow paths. The spatial hierarchy of flow paths controls the sequence of flow path activation. Conduits of the topmost level are strongly influenced by reversible alteration processes. Sedimentation or blocking causes an overflow of water to the next higher conduit. Flow path specific dissolutional denudation rates were estimated using the temporal development of the partial discharge.
R. BENISCHKE & T. HARUM Institute for Geothermics & Hydrogeology, Joanneum Research, Elisabethstr... more R. BENISCHKE & T. HARUM Institute for Geothermics & Hydrogeology, Joanneum Research, Elisabethstr. 16/2, 8010 Graz, Austria ABSTRACT The attempt to determine exactly discharge rates of turbulent streams in mountainous regions based on current meter measurements can lead to serious problems rising from a badly defined runoff channel geometry and irregular flow patterns. Therefore systematic errors influence the results and make it sometimes impossible to get reliable stage-discharge relations at gauging stations. The development of commercially available computerized systems made it possible to apply the salt tracer dilution method with instantaneous or continuous injection and to monitor the tracer passage in the time-concentration or time-conductivity mode directly at the field site. The result of the measurement is available immediately at the end of the measuring procedure. The experience showed that the salt tracer dilution method is the appropriate method in almost all cases of...
Environmental Geology, 2006
The small and big Prespa Lake and the Ohrid Lake share their water with Albania, FYR of Macedonia... more The small and big Prespa Lake and the Ohrid Lake share their water with Albania, FYR of Macedonia and Greece, and constitute a common hydraulic system (Figs. 1, 2). The elevation of the Prespa Lake is 850 m asl and that of the Ohrid Lake is 695 m asl. The respective surfaces are 274 and 348 km 2. High mountains such as the Mali Thate (2,287 m) in the south and the Galichica (2,262 m) in the north separate them. Geologically these mountains represent a horst constructed mainly of the Upper Triassic-Lower Jurassic massive limestone (AHS 1975). Big graben structures that of Prespa Lake on the east and Ohrid Lake on the west, delimit both sides of the horst. The Pliocene deposits such as clay, sandstone, and conglomerate fill most of the bottom of both lakes. At Ohrid lakeside, in the Albanian-FYROM borderland, are the big karst springs of St. Naum and Tushemisht, which in total
Hydrogeology Journal, 2016
The attempt to determine exactly discharge rates of turbulent streams in mountainous regions base... more The attempt to determine exactly discharge rates of turbulent streams in mountainous regions based on current meter measurements can lead to serious problems rising from a badly defined runoff channel geometry and irregular flow patterns. Therefore systematic errors influence the results and make it sometimes impossible to get reliable stage-discharge relations at gauging stations. The development of commercially available computerized systems made it possible to apply the salt tracer dilution method with instantaneous or continuous injection and to monitor the tracer passage in the time-concentration or time-conductivity mode directly at the field site. The result of the measurement is available immediately at the end of the measuring procedure. The experience showed that the salt tracer dilution method is the appropriate method in almost all cases of turbulent flow conditions and irregular channel geometry. The article describes the theoretical basis of the method, the used measur...
In this paper an approach of distributed hydrological modelling of water balance components in a ... more In this paper an approach of distributed hydrological modelling of water balance components in a karstic mountainous region is presented. In karstic regions hydrological catchment boundaries are usually not known a priori. The idea is to combine water balance modelling results based on the orographic catchment boundaries with disparate sources of information in an iterative way to identify hydrographic catchment boundaries and subsurface water ways. The additional data and information are derived by region-wide point measurements of discharge, field surveys, isotope data, tracer tests, electric conductivity data, soil and (hydro-)geological surveys and mapping, snow depth data, etc.. These data sources are complementary to the usually used rainfall and runoff data and assist in model building, parameter calibration and interpreting the results. Also, to get information about the meteorological input in a high-alpine region comprehensive regionalisation and correction methods are ass...
Grundwasser, 2010
Zusammenfassung Die Komplexität von Karstaquiferen drückt sich darin aus, dass die orographische... more Zusammenfassung Die Komplexität von Karstaquiferen drückt sich darin aus, dass die orographischen Einzugsgebiete mit hydrographischen selten übereinstimmen. Hauptzielrichtung der vorliegenden Studie ist die Erarbeitung von methodischen Grundlagen zur Erkundung von Karstaquiferen in Gebirgsräumen und damit verbunden die Abgrenzung hydrographisch wirksamer Einzugsgebiete unter Einsatz physikalisch basierter hydrologischer Modelle am Beispiel des Kaisergebirges. Für die Simulation der Teilkomponenten des Wasserhaushalts wurde das flächendetaillierte
Proceedings of the 12th …, 1997
Home. ...
Geomorphology, 2011
The transition zone of the Eastern Alps to the Pannonian Basin provides one of the best sources o... more The transition zone of the Eastern Alps to the Pannonian Basin provides one of the best sources of information on landscape evolution of the Eastern Alpine mountain range. The region was nonglaciated during the entire Pleistocene. Thus, direct influence of glacial carving as a landscape forming process can be excluded and relics of landforms are preserved that date back to at least the Late Neogene. In this study, we provide a correlation between various planation surfaces across the orogen-basin transition. In particular, we use stream terraces, planation surfaces and cave levels that cover a vertical spread of some 700 m. Our correlation is used to show that both sides of the transition zone uplifted together starting at least about 5 Ma ago. For our correlation we use recently published terrestrial cosmogenic nuclide (TCN) burial ages from cave sediments, new optically stimulated luminescence (OSL) ages of a stream terrace and U-Th ages from speleothems. Minimum age constraints of cave levels from burial ages of cave sediments covering the last ~ 4 Ma are used to place age constraints on surface features by parallelizing cave levels with planation surfaces. The OSL results for the top section of the type locality of the Helfbrunn terrace suggest an Early Würm development (80.5 ± 3.7 to 68.7 ± 4.0 ka). The terrace origin as a penultimate gravel deposit (in classical Alpine terminology Riss) is therefore questioned. U-series speleothem ages from caves nearby indicate formation during Marine Isotope Stages (MIS) 5c and 5a which are both interstadial warm periods. As OSL ages from the terrace also show a time of deposition during MIS 5a ending at the MIS 5/4 transition, this supports the idea of temperate climatic conditions at the time of deposition. In general, tectonic activity is interpreted to be the main driving force for the formation and evolution of these landforms, whilst climate change is © 2011 Elsevier B.V.