Sauter, Martin

[["dc.bibliographiccitation.artnumber","1285"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Water Resources Research"],["dc.bibliographiccitation.volume","39"],["dc.contributor.author","Bauer, S."],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, M."],["dc.date.accessioned","2018-11-07T10:35:30Z"],["dc.date.available","2018-11-07T10:35:30Z"],["dc.date.issued","2003"],["dc.description.abstract","[1] This paper presents a numerical model study simulating the early karstification of a single conduit embedded in a fissured system. A hybrid continuum-discrete pipe flow model (CAVE) is used for the modeling. The effects of coupling of the two flow systems on type and duration of early karstification are studied for different boundary conditions. Assuming fixed head boundaries at both ends of the conduit, coupling of the two flow systems via exchange flow between the conduit and the fissured system leads to an enhanced evolution of the conduit. This effect is valid over a wide range of initial conduit diameters, and karstification is accelerated by a factor of about 100 as compared to the case of no exchange flow. Parameter studies reveal the influence of the exchange coefficient and of the hydraulic conductivity of the fissured system on the development time for the conduit. In a second scenario the upstream fixed head boundary is switched to a fixed flow boundary at a specified flow rate during the evolution, limiting the amount of water draining toward the evolving conduit. Depending on the flow rate specified, conduit evolution may be slowed down or greatly impaired if exchange flow is considered."],["dc.identifier.doi","10.1029/2003WR002218"],["dc.identifier.isi","000186091500003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45110"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Geophysical Union"],["dc.relation.issn","0043-1397"],["dc.title","Modeling of karst aquifer genesis: Influence of exchange flow"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","179"],["dc.bibliographiccitation.issue","1-4"],["dc.bibliographiccitation.journal","Journal of Hydrology"],["dc.bibliographiccitation.lastpage","193"],["dc.bibliographiccitation.volume","286"],["dc.contributor.author","Birk, S."],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, M."],["dc.date.accessioned","2018-11-07T10:51:39Z"],["dc.date.available","2018-11-07T10:51:39Z"],["dc.date.issued","2004"],["dc.description.abstract","Karst aquifers are highly vulnerable to contamination due to the rapid transport of pollutants in conduit systems. Effective strategies for the management and protection of karst aquifers, therefore, require an adequate hydrogeological characterisation of the conduit systems. In particular, the identification and characterisation of conduits transmitting rapid, localised recharge to springs is of great interest for vulnerability assessments. In this work, it is demonstrated that localised recharge and conduit flow in a karst aquifer (Urenbrunnen catchment, southwest Germany) can be characterised by jointly analysing the hydraulic and physico-chemical responses of a spring to recharge events. Conduit volumes are estimated by evaluating time lags between increases in spring discharge and associated changes in the electrical conductivity and temperature of the discharged water. These estimates are confirmed by the results of a combined tracer and recharge test. Variations in electrical conductivity are also shown to assist in the quantification of the fast recharge component associated with short-term recharge pulses. However, spectral analysis of temperature fluctuations reveals that highly mineralised surface waters locally infiltrate into the aquifer during the winter and spring without causing significant electrical conductivity variations in the spring water. Hence, the most consistent conceptual model is obtained by a combined analysis of both physico-chemical parameters. (C) 2003 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.jhydrol.2003.09.007"],["dc.identifier.isi","000188887100012"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/48942"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0022-1694"],["dc.title","Identification of localised recharge and conduit flow by combined analysis of hydraulic and physico-chemical spring responses (Urenbrunnen, SW-Germany)"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","452"],["dc.bibliographiccitation.issue","3-4"],["dc.bibliographiccitation.journal","Journal of Hydrology"],["dc.bibliographiccitation.lastpage","463"],["dc.bibliographiccitation.volume","348"],["dc.contributor.author","Geyer, Tobias"],["dc.contributor.author","Birk, Steffen"],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, Martin"],["dc.date.accessioned","2018-11-07T11:19:07Z"],["dc.date.available","2018-11-07T11:19:07Z"],["dc.date.issued","2008"],["dc.description.abstract","The estimation of the temporal distribution of recharge in karst aquifers is a challenge due to Large heterogeneities in geometric and hydraulic parameters of the vadose and phreatic zone. This article provides a time-continuous approach for the estimation of inflow into the conduit system of a karst aquifer which consists of the sum of direct recharge and flow from the fissured matrix blocks into the conduit system. The approach employs the first time derivative of the spring hydrograph and the recession coefficient of the conduit system for the determination of this function. The first time derivative of the hydrograph describes the rate of change in spring discharge. It reflects the ratio of inflow to and outflow from the conduit system. The recession coefficient depends on the hydraulic diffusivity, which controls the velocity of the signal transmission through the system. As shown in parameter studies with a simplified serial two-reservoir model, direct recharge into the conduit system clearly dominates the early hydrograph response during recharge events even if the fraction of direct recharge represents just a few percent of total recharge. This behaviour is caused by a large contrast in recession coefficients between conduit system and fissured matrix blocks. The direct recharge component can therefore be separated from the estimated total inflow into the conduit system. Estimation of inflow into the conduit system of the Gallusquelle spring (Swabian Alb, Germany) after a storm event yields similar results as those obtained from parameter studies. The separation of the direct recharge component is in agreement with information from an independent isotope study. The methodology has been further applied to a recharge event initiated by snowmelt. As a result of daily variations of the air temperature, a clearly diurnal cycle of inflow into the conduit system is estimated that is not easily recognizable from the spring hydrograph. The applicability of the proposed methodology requires knowledge about the magnitude of the recession coefficient of the conduit system. The characteristics of the conduit system become also apparent in the rapid transport of tracers. The recession coefficient of the conduit system can, for example, directly be estimated from the reciprocal of the mean tracer travel time. However, for this type of analysis, only tracer experiments, covering the extent of the catchment should be taken into account. For the Gallusquelle catchment the recession coefficient obtained from the tracer experiment corresponds to that obtained from hydrograph recession analysis. The estimated inflow into the conduit system and interpretation of temporal distribution of recharge is therefore based on a plausible and physically based parameter. (c) 2007 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.jhydrol.2007.10.015"],["dc.identifier.isi","000252749000018"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/55196"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0022-1694"],["dc.title","Quantification of temporal distribution of recharge in karst systems from spring hydrographs"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","611"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Groundwater"],["dc.bibliographiccitation.lastpage","621"],["dc.bibliographiccitation.volume","58"],["dc.contributor.author","Giese, Markus"],["dc.contributor.author","Reimann, Thomas"],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Dewandel, Benoit"],["dc.contributor.author","Maréchal, Jean‐Christophe"],["dc.contributor.author","Sauter, Martin"],["dc.date.accessioned","2020-12-10T18:28:49Z"],["dc.date.available","2020-12-10T18:28:49Z"],["dc.date.issued","2019"],["dc.identifier.doi","10.1111/gwat.v58.4"],["dc.identifier.eissn","1745-6584"],["dc.identifier.issn","0017-467X"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/76419"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","An Approximation of Inner Boundary Conditions for Wells Intersecting Highly Conductive Structures"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","184"],["dc.bibliographiccitation.issue","3-4"],["dc.bibliographiccitation.journal","Journal of Hydrology"],["dc.bibliographiccitation.lastpage","198"],["dc.bibliographiccitation.volume","345"],["dc.contributor.author","Brauchler, R."],["dc.contributor.author","Cheng, J.-T."],["dc.contributor.author","Dietrich, P."],["dc.contributor.author","Everett, M."],["dc.contributor.author","Johnson, Brian"],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, M."],["dc.date.accessioned","2018-11-07T10:57:37Z"],["dc.date.available","2018-11-07T10:57:37Z"],["dc.date.issued","2007"],["dc.description.abstract","We present a hydraulic tomographic inversion strategy with an emphasis on the reduction of ambiguity of hydraulic travel time inversion results and the separation of the estimated diffusivity values into hydraulic conductivity and specific storage. Our tomographic inversion strategy is tested by simulated multilevel. interference slug tests in which the positions of the sources (injection ports) and the receivers (observation ports) isolated with packers are varied. Simulations include the delaying effect of wellbore storage on travel times which are quantified and shown to be of increasing importance for shorter travel distances. For the reduction of ambiguity of travel time inversion, we use the full travel time data set, as well as smaller data subsets of specified source-receiver angles. The inversion results of data subsets show different resolution characteristics and improve the reliability of the interpretation. The travel time of a pressure pulse is a function of the diffusivity of the medium between the source and receiver. Thus, it is difficult to directly derive values for hydraulic conductivity and specific storage by inverting travel times. In order to overcome this limitation, we exploit the great computational efficiency of hydraulic travel. time tomography to define the aquifer structure, which is then input into the underlying groundwater flow model MODFLOW-96. Finally, we perform a model calibration (amplitude inversion) using the automatic parameter estimator PEST, enabling us to separate diffusivity into its two components hydraulic conductivity and specific storage. (C) 2007 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.jhydrol.2007.08.011"],["dc.identifier.isi","000250884600005"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/50295"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0022-1694"],["dc.title","An inversion strategy for hydraulic tomography: Coupling travel time and amplitude inversion"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","296"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","ENVIRONMENTAL GEOLOGY"],["dc.bibliographiccitation.lastpage","306"],["dc.bibliographiccitation.volume","48"],["dc.contributor.author","Birk, S."],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, M."],["dc.contributor.author","Teutsch, G."],["dc.date.accessioned","2018-11-07T09:02:33Z"],["dc.date.available","2018-11-07T09:02:33Z"],["dc.date.issued","2005"],["dc.description.abstract","The development of gypsum maze caves under artesian conditions has been simulated. The numerical model simulations show that the evolution of maze caves in this type of setting requires structural preferences such as laterally extended fissure networks in a horizon of the gypsum layer. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The most important stage for the development of horizontal caves under artesian conditions is found to be the initial karstification period. During this period the structure of the mature conduit system is established. The solutional enlargement of conduits is spatially extended, total dissolution rates are higher than the later ones."],["dc.identifier.doi","10.1007/s00254-005-1276-4"],["dc.identifier.isi","000230813000003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/24712"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0943-0105"],["dc.title","Simulation of the development of gypsum maze caves"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","W11503"],["dc.bibliographiccitation.journal","Water Resources Research"],["dc.bibliographiccitation.volume","47"],["dc.contributor.author","Reimann, Thomas"],["dc.contributor.author","Geyer, Tobias"],["dc.contributor.author","Shoemaker, W. Barclay"],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, Martin"],["dc.date.accessioned","2018-11-07T08:49:58Z"],["dc.date.available","2018-11-07T08:49:58Z"],["dc.date.issued","2011"],["dc.description.abstract","Well-developed karst aquifers consist of highly conductive conduits and a relatively low permeability fractured and/or porous rock matrix and therefore behave as a dual-hydraulic system. Groundwater flow within highly permeable strata is rapid and transient and depends on local flow conditions, i.e., pressurized or nonpressurized flow. The characterization of karst aquifers is a necessary and challenging task because information about hydraulic and spatial conduit properties is poorly defined or unknown. To investigate karst aquifers, hydraulic stresses such as large recharge events can be simulated with hybrid (coupled discrete continuum) models. Since existing hybrid models are simplifications of the system dynamics, a new karst model (ModBraC) is presented that accounts for unsteady and nonuniform discrete flow in variably saturated conduits employing the Saint-Venant equations. Model performance tests indicate that ModBraC is able to simulate (1) unsteady and nonuniform flow in variably filled conduits, (2) draining and refilling of conduits with stable transition between free-surface and pressurized flow and correct storage representation, (3) water exchange between matrix and variably filled conduits, and (4) discharge routing through branched and intermeshed conduit networks. Subsequently, ModBraC is applied to an idealized catchment to investigate the significance of free-surface flow representation. A parameter study is conducted with two different initial conditions: (1) pressurized flow and (2) free-surface flow. If free-surface flow prevails, the systems is characterized by (1) a time lag for signal transmission, (2) a typical spring discharge pattern representing the transition from pressurized to free-surface flow, and (3) a reduced conduit-matrix interaction during free-surface flow."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [LI 727/11-1, SA 501/24-1]"],["dc.identifier.doi","10.1029/2011WR010446"],["dc.identifier.isi","000296622300002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21580"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Geophysical Union"],["dc.relation.issn","0043-1397"],["dc.title","Effects of dynamically variable saturation and matrix-conduit coupling of flow in karst aquifers"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","36"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","GROUND WATER"],["dc.bibliographiccitation.lastpage","45"],["dc.bibliographiccitation.volume","45"],["dc.contributor.author","Geyer, Tobias"],["dc.contributor.author","Birk, Steffen"],["dc.contributor.author","Licha, Tobias"],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, Martin"],["dc.date.accessioned","2018-11-07T11:06:37Z"],["dc.date.available","2018-11-07T11:06:37Z"],["dc.date.issued","2007"],["dc.description.abstract","A method to estimate reactive transport parameters as well as geometric conduit parameters from a multitracer test in a karst aquifer is provided. For this purpose, a calibration strategy was developed applying the two-region nonequilibrium model CXTFIT. The ambiguity of the model calibration was reduced by first calibrating the model with respect to conservative tracer breakthrough and later transferring conservative transport parameters to the reactive model calibration. The reactive transport parameters were only allowed to be within a defined sensible range to get reasonable calibration values. This calibration strategy was applied to breakthrough curves obtained from a large-scale multitracer test, which was performed in a karst aquifer of the Swabian Alb, Germany. The multitracer test was conducted by the simultaneous injection of uranine, sulforhodamine G, and tinopal CBS-X. The model succeeds to represent the tracer breakthrough curves (TBCs) of uranine and sulforhodamine G and verifies that tracer-rock interactions preferably occur in the immobile fluid region, although the fraction of this region amounts to only 3.5% of the total water. However, the model failed to account for the long tailing observed in the TBC of tinopal CBS-X. Sensitivity analyses reveal that model results for the conservative tracer transport are most sensitive to average velocity and volume fraction of the mobile fluid region, while dispersion and mass transfer coefficients are least influential. Consequently, reactive tracer calibration allows the determination of sorption sites in the mobile and immobile fluid region at small retardation coefficients."],["dc.identifier.doi","10.1111/j.1745-6584.2006.00261.x"],["dc.identifier.isi","000243474000011"],["dc.identifier.pmid","17257337"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/52358"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Blackwell Publishing"],["dc.relation.issn","0017-467X"],["dc.title","Multitracer test approach to characterize reactive transport in karst aquifers"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","W09416"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Water Resources Research"],["dc.bibliographiccitation.volume","41"],["dc.contributor.author","Bauer, S."],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, M."],["dc.date.accessioned","2018-11-07T10:55:44Z"],["dc.date.available","2018-11-07T10:55:44Z"],["dc.date.issued","2005"],["dc.description.abstract","The epikarst, a zone of increased weathering near the land surface, determines the distribution of recharge to a karst aquifer in both space and time. It links climatic and near-surface geological conditions with the karstification of a limestone aquifer, defining both the hydraulic and the chemical boundary conditions for the development of the karst system. Realistic modeling of the epikarst is therefore a prerequisite for the simulation of karst aquifer genesis. A conceptual model of the joint karst-epikarst evolution is presented in this paper. An epikarst module is developed and implemented in a numerical continuum-discrete conduit flow model for karst genesis, which accounts for the joint evolution of the epikarst and the main karstic conduit network under unconfined conditions. The influence of epikarst genesis on the evolution of the underlying karst aquifer is investigated in four scenarios. It is found that only the interaction of epikarst and initial heterogeneity in the underlying carbonate rock leads to the development of a dendritic cave system. If no heterogeneity in the initial conduit network or in the recharge distribution is included, maze-type caves develop."],["dc.identifier.doi","10.1029/2004WR003321"],["dc.identifier.isi","000232185100001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/49855"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Geophysical Union"],["dc.relation.issn","0043-1397"],["dc.title","Modeling the influence of epikarst evolution on karst aquifer genesis: A time-variant recharge boundary condition for joint karst-epikarst development"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","832"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","GROUND WATER"],["dc.bibliographiccitation.lastpage","836"],["dc.bibliographiccitation.volume","44"],["dc.contributor.author","Birk, Steffen"],["dc.contributor.author","Liedl, Rudolf"],["dc.contributor.author","Sauter, Martin"],["dc.date.accessioned","2018-11-07T09:01:12Z"],["dc.date.available","2018-11-07T09:01:12Z"],["dc.date.issued","2006"],["dc.description.abstract","Ground water in karst terrains is highly vulnerable to contamination due to the rapid transport of contaminants through the highly conductive conduit system. For contamination risk assessment purposes, information about hydraulic and geometric characteristics of the conduits and their hydraulic interaction with the fissured porous rock is an important prerequisite. The relationship between aquifer characteristics and short-term responses to recharge events of both spring discharge and physicochemical parameters of the discharged water was examined using a process-based flow and transport model. In the respective software, a pipe-network model, representing fast conduit flow, is coupled to MODFLOW, which simulates flow in the fissured porous rock. This hybrid flow model was extended to include modules simulating heat and reactive solute transport in conduits. The application of this modeling tool demonstrates that variations of physicochemical parameters, such as solute concentration and water temperature, depend to a large extent on the intensity and duration of recharge events and provide information about the structure and geometry of the conduit system as well as about the interaction between conduits and fissured porous rock. Moreover, the responses of solute concentration and temperature of spring discharge appear to reflect different processes, thus complementing each other in the aquifer characterization."],["dc.identifier.doi","10.1111/j.1745-6584.2006.00175.x"],["dc.identifier.isi","000241622600011"],["dc.identifier.pmid","17087755"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/24357"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Blackwell Publishing"],["dc.relation.issn","0017-467X"],["dc.title","Karst spring responses examined by process-based modeling"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]