TY  - JOUR
AB  - Combining multi-model simulations can reduce the uncertainty in model structure and increase the accuracy of agricultural systems modeling results. This improvement is essential for supporting better decision making in irrigation planning and climate change adaptation strategies. Besides the commonly used arithmetic mean and median, many multi-model averaging approaches (MAA), widely examined in groundwater and hydrological modeling, but these additional MAA have not been examined in agricultural system modeling to improve the simulation accuracy. Therefore, the objective of this study is to evaluate the performance of seven MAA: two equal weighted approaches (Simple Model Averaging (SMA) and Median) and five weighted approaches (Inverse Ranking (IR), Bates and Granger Averaging (BGA), and Granger Ramanathan A, B, and C (GRA, GRB, and GRC)) in combining results of multiple agricultural system models. The Granger Ramanathan methods differ in their constraints: GRA employs conventional least squares, GRB requires non-negative weights that total to one, and GRC reduces absolute errors for robustness against outliers. The evaluation was conducted using maize yield and daily ETa simulations for both blind (uncalibrated) and calibrated phases of data from two groups of maize sites (Group A and Group B) across North America. The modeling results from the blind and calibrated phases were combined for all maize models and group maize models. Overall, all MAA performed better than individual crop models for blind and calibration phases. Specifically, the GRB model averaging method provided the closest match to measured values for daily ETa, while GRA was the most accurate for maize yield in most cases across all sites and phases. GRB improved daily ETa estimation over the median by an average of 4 % and 8.5 % in terms of RRMSE, while GRA enhanced maize yield estimation over the median by 7.5 % and 10.9 % for Group A and Group B sites, respectively. Notably, the improvement was greater in the blind phase for both groups of maize sites. An ensemble of group maize models with varied structures performed nearly as well as an ensemble of all maize models in simulating daily ETa and yield for Group A and Group B sites. Based on the results, we recommend GRA for crop yield and GRB for ETa simulations for maize, but both methods require observed yield and ETa data for their application; however, in the absence of observed data, we recommend the SMA method as it performs better than the median. However, the performance of these MAA methods may differ for other crops (e.g., soybean, wheat, canola, potato, alfalfa) or regions, and it should be evaluated in future studies.
AU  - Nand, V.*
AU  - Qi, Z.*
AU  - Ma, L.*
AU  - Helmers, M.J.*
AU  - Madramootoo, C.A.*
AU  - Smith, W.N.*
AU  - Zhang, T.*
AU  - Weber, T.K.D.*
AU  - Pattey, E.*
AU  - Li, Z.*
AU  - Wang, J.*
AU  - Jin, V.L.*
AU  - Jiang, Q.*
AU  - Tenuta, M.*
AU  - Trout, T.J.*
AU  - Cheng, H.*
AU  - Harmel, R.D.*
AU  - Kimball, B.A.*
AU  - Thorp, K.R.*
AU  - Boote, K.J.*
AU  - Stöckle, C.*
AU  - Suyker, A.E.*
AU  - Evett, S.R.*
AU  - Brauer, D.K.*
AU  - Coyle, G.G.*
AU  - Copeland, K.S.*
AU  - Marek, G.W.*
AU  - Colaizzi, P.D.*
AU  - Acutis, M.*
AU  - Alimagham, S.M.*
AU  - Archontoulis, S.*
AU  - Babacar, F.*
AU  - Barcza, Z.*
AU  - Basso, B.*
AU  - Bertuzzi, P.*
AU  - Constantin, J.*
AU  - De Antoni Migliorati, M.*
AU  - Dumont, B.*
AU  - Durand, J.L.*
AU  - Fodor, N.*
AU  - Gaiser, T.*
AU  - Garofalo, P.*
AU  - Gayler, S.*
AU  - Giglio, L.*
AU  - Grant, R.*
AU  - Guan, K.*
AU  - Hoogenboom, G.*
AU  - Kim, S.H.*
AU  - Kisekka, I.*
AU  - Lizaso, J.*
AU  - Masia, S.*
AU  - Meng, H.*
AU  - Mereu, V.*
AU  - Mukhtar, A.*
AU  - Perego, A.*
AU  - Peng, B.*
AU  - Priesack, E.
AU  - Shelia, V.*
AU  - Snyder, R.*
AU  - Soltani, A.*
AU  - Spano, D.*
AU  - Srivastava, A.*
AU  - Thomson, A.*
AU  - Timlin, D.*
AU  - Trabucco, A.*
AU  - Webber, H.*
AU  - Willaume, M.*
AU  - Williams, K.*
AU  - van der Laan, M.*
AU  - Ventrella, D.*
AU  - Viswanathan, M.*
AU  - Xu, X.*
AU  - Zhou, W.*
C1  - 74915
C2  - 57657
CY  - Radarweg 29, 1043 Nx Amsterdam, Netherlands
TI  - Evaluation of multimodel averaging approaches for ensembling evapotranspiration and yield simulations from maize models.
JO  - J. Hydrol.
VL  - 661
PB  - Elsevier
PY  - 2025
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Limestone massifs with a high density of dolines form important karst aquifers in most of the Alps, often with groundwater circulating through deep karst conduits and water coming out of closely spaced springs with flow rates of over some cubic meters per second. Although several hydrogeological studies and tracing experiments were carried out in many of these carbonate mountains in the past, the hydrbgeology of most of these karst aquifers is still poorly known. Geological, hydrodynamic and hydrochemical investigations have been carried out in one of the most representative of these areas (Cansiglio-Monte Cavallo, NE Italy) since spring 2015, in order to enhance the knowledge on this important type of aquifer system. Additionally, a cave-to-spring multitracer test was carried out in late spring 2016 by using three different fluorescent tracers. This hydrogeological study allowed: 1) gathering new detailed information on the geological and tectonic structure of such alpine karst plateau; 2) defining discharge rates of the three main springs (Gorgazzo, Santissima, and Molinetto) by constructing rating curves; 3) understanding the discharging behavior of the system with respect to different recharge conditions; 4) better defining the recharge areas of the three springs. The three nearby springs (the spring front stretches over 5 km), that drain the investigated karst aquifer system, show different behaviors with respect to changing discharge conditions, demonstrating this aquifer to be divided in partially independent drainage systems under low-flow conditions, when their chemistry is clearly differentiated. Under high-flow conditions, waters discharging at all springs show more similar geochemical characteristics. The combination of geochemistry, hydrodynamic monitoring and dye tracing tests has shown that the three springs have different recharge areas. The study points out that even closely spaced karst springs, that apparently drain the same karst mountain, can have different behaviors, and thus distinctive reactions toward polluting events, a characteristic to be taken into account for their management. (C) 2017 Elsevier B.V. All rights reserved.
AU  - Filippini, M.*
AU  - Squarzoni, G.*
AU  - De Waele, J.*
AU  - Fiorucci, A.*
AU  - Vigna, B.*
AU  - Grillo, B.*
AU  - Riva, A.*
AU  - Rossetti, S.*
AU  - Zini, L.*
AU  - Casagrande, G.*
AU  - Stumpp, C.
AU  - Gargini, A.*
C1  - 52526
C2  - 44083
CY  - Amsterdam
SP  - 572-584
TI  - Differentiated spring behavior under changing hydrological conditions in an alpine karst aquifer.
JO  - J. Hydrol.
VL  - 556
PB  - Elsevier Science Bv
PY  - 2018
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Stable isotopes oxygen-18 (18O) and deuterium (2H) are commonly used to investigate hydrological processes in catchments. However, only a few isotope studies have been conducted on a large scale and rarely over long time periods. The objective of this study was to identify the spatial and seasonal variability of isotopic composition in river water and how it is affected by geographical and hydrological factors. The stable isotopic composition of river water has been measured in nine large river catchments in Germany for a time period of 12 years or 26 years. We conducted time series and correlation analyses to identify spatial and temporal patterns of the isotopic composition in the rivers. Further, we compared it to isotopic composition in local precipitation and catchments characteristics. In the majority of the rivers, the spatial and temporal patterns of precipitation were directly reflected in river water. The isotopic signals of the river water were time shifted and show attenuated amplitudes. Further deviations from isotopic compositions in local precipitation were observed in catchments with complex flow systems. These deviations were attributed to catchment processes and influences like evaporation, damming and storage. The seasonality of the isotopic composition was mainly determined by the discharge regimes of the rivers. We found correlations between isotopic long-term averages and catchment altitude as well as latitude and longitude, resulting in a northwest-southeast gradient. Furthermore, it was shown that long-term averages of d-excess were inversely related to flow length and catchment size, which indicates that evaporation enrichment has an impact on the isotopic composition even in catchments of humid climates. This study showed that isotopic composition in rivers can serve as a proxy for the local precipitation and can be utilized as an indicator for hydrological processes even in large river basins. In future, such long time series will help to also understand the impact of changes in the hydrological cycle on the larger scales. They can also be used for calibration and validation of flow and transport models at catchment and sub-catchment scale.
AU  - Reckerth, A.
AU  - Stichler, W.
AU  - Schmidt, A.*
AU  - Stumpp, C.
C1  - 51588
C2  - 43250
CY  - Amsterdam
SP  - 718-731
TI  - Long-term data set analysis of stable isotopic composition in German rivers.
JO  - J. Hydrol.
VL  - 552
PB  - Elsevier Science Bv
PY  - 2017
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Variable density flow in porous media has been studied primarily using numerical models because it is a semi-chaotic and transient process. Most of these studies have been 2D, owing to the computational restrictions on 3D simulations, and the ability to observe variable density flow in 2D experimentation. However, it is recognised that variable density flow is a three-dimensional process. A 3D system may cause weaker variable density flow than a 2D system due to stronger dispersion, but may also result in bigger fingers and hence stronger variable density flow because of more space for fingers to coalesce. This study aimed to determine the representativeness of 2D modelling to simulate 3D variable density flow. 3D homogeneous sand column experiments were conducted at three different water flow velocities with three different bromide tracer solutions mixed with methanol resulting in different density ratios. Both 2D axisymmetric and 3D numerical simulations were performed to reproduce experimental data. Experimental results showed that the magnitude of variable density flow increases with decreasing flow rates and decreasing density ratios. The shapes of the observed breakthrough curves differed significantly from those produced by 2D axisymmetric and 3D simulations. Compared to 2D simulations, the onset of instabilities was delayed but the growth was more pronounced in 3D simulations. Despite this difference, both 2D axisymmetric and 3D models successfully simulated mass recovery with high efficiency (between 77% and 99%). This study indicates that 2D simulations are sufficient to understand integrated features of variable density flow in homogeneous sand column experiments.
AU  - Knorr, B.
AU  - Xie, Y.*
AU  - Stumpp, C.
AU  - Maloszewski, P.
AU  - Simmons, C.T.*
C1  - 49862
C2  - 41651
CY  - Amsterdam
SP  - 541-551
TI  - Representativeness of 2D models to simulate 3D unstable variable density flow in porous media.
JO  - J. Hydrol.
VL  - 542
PB  - Elsevier Science Bv
PY  - 2016
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - A multi-layered aquifer system (eastern Po plain, northern Italy) was investigated by means of isotopic data, with the goal of quantifying groundwater recharge from different sources and assessing the intrinsic vulnerability of aquifers to surface sources of contamination. The geology of the area is based on a stratigraphic alternation of several sandy aquifers and silty-clayey aquitards, down to a maximum depth of 200m b.g.s. Water isotopes (δ18O, δ2H), and hydrochemical analyses were performed on groundwater samples collected from a regional network of 70 boreholes distributed on an area of almost 2000km2. In addition to the regional sampling, detailed vertical isotopic profiling was performed in one location by means of groundwater and sediment samples collected through the whole sequence of aquifers and aquitards. Water isotopes indicated mixing from different sources of recharge (i.e., vertical recharge, Po river, deeper aquifers). Mixing calculations were used to quantify the contributions to the aquifers from the different sources. The vertical profiling allowed for integrating and validating the interpretations at a regional scale. The recharge pattern defined for the different aquifers was translated into an index of hydrogeologic interconnections with the surface, which represents a physically based proxy of the intrinsic vulnerability of the aquifers to surficial sources of contamination.The investigated setting can be considered to be representative of many other anthropized and groundwater demanding plain settings around the world. Thus, the proposed method represents a valuable approach for such settings both for recharge quantification (e.g., to be used as input for numerical modeling) and for a physically based assessment of the intrinsic vulnerability.
AU  - Filippini, M.*
AU  - Stumpp, C.
AU  - Nijenhuis, I.*
AU  - Richnow, H.H.*
AU  - Gargini, A.*
C1  - 46715
C2  - 37741
SP  - 1657-1668
TI  - Evaluation of aquifer recharge and vulnerability in an alluvial lowland using environmental tracers.
JO  - J. Hydrol.
VL  - 529
PY  - 2015
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Groundwater is one of the main resources for drinking water. Its quality is still threatened by the widespread contaminant nitrate (NO3−). In order to manage groundwater resources in a sustainable manner, we need to find options of lowering nitrate input. Particularly, a comprehensive knowledge of nitrate sources is required in areas which are important current and future drinking water reservoirs such as pre-alpine aquifers covered with permanent grassland. The objective of the present study was to identify major sources of nitrate in groundwater with low mean nitrate concentrations (8 ± 2 mg/L). To achieve the objective, we used environmental tracer approaches in four pre-alpine groundwater catchments. The stable isotope composition and tritium content of water were used to study the hydrogeology and transit times. Furthermore, nitrate stable isotope methods were applied to trace nitrogen from its sources to groundwater. The results of the nitrate isotope analysis showed that groundwater nitrate was derived from nitrification of a variety of ammonium sources such as atmospheric deposition, mineral and organic fertilizers and soil organic matter. A direct influence of mineral fertilizer, atmospheric deposition and sewage was excluded. Since temporal variation in stable isotopes of nitrate were detected only in surface water and locally at one groundwater monitoring well, aquifers appeared to be well mixed and influenced by a continuous nitrate input mainly from soil derived nitrogen. Hydrogeological analysis supported that the investigated aquifers were less vulnerable to rapid impacts due to long average transit times, ranging from 5 to 21 years. Our study revealed the importance of combining environmental tracer approaches and a comprehensive sampling campaign (local sources of nitrate, soil water, river water, and groundwater) to identify the nitrate sources in groundwater and its vulnerability. In future, the achieved results will help develop targeted strategies for a sustainable groundwater management focusing more on soil nitrogen storage.
AU  - Stoewer, M.*
AU  - Knöller, K.*
AU  - Stumpp, C.
C1  - 44147
C2  - 36742
CY  - Amsterdam
SP  - 753-767
TI  - Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers.
JO  - J. Hydrol.
VL  - 524
PB  - Elsevier Science Bv
PY  - 2015
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Tile drains strongly influence the water cycle in agricultural catchment in terms of water quantity and quality. The connectivity of preferential flow to tile drains can create shortcuts for rapid transport of solutes into surface waters. The leaching of pesticides can be linked to a set of main factors including, rainfall characteristics, soil moisture, chemical properties of the pesticides, soil properties, and preferential flow paths. The connectivity of the macropore system to the tile drain is crucial for pesticide leaching. Concurring influences of the main factors, threshold responses and the role of flow paths are still poorly understood. The objective of this study is to investigate these influences by a replica series of three irrigation experiments on a tile drain field site using natural and artificial tracers together with applied pesticides. We found a clear threshold behavior in the initialization of pesticide transport that was different between the replica experiments. Pre-event soil water contributed significantly to the tile drain flow, and creates a flow path for stored pesticides from the soil matrix to the tile drain. This threshold is controlled by antecedent soil moisture and precipitation characteristics, and the interaction between the soil matrix and preferential flow system. Fast transport of pesticides without retardation and the remobilization could be attributed to this threshold and the interaction between the soil matrix and the preferential flow system. Thus, understanding of the detailed preferential flow processes clearly enhances the understanding of pesticide leaching on event and long term scale, and can further improve risk assessment and modeling approaches.
AU  - Klaus, J.*
AU  - Zehe, E.*
AU  - Elsner, M.
AU  - Palm, J.*
AU  - Schneider, D.*
AU  - Schröder, B.*
AU  - Steinbeiss, S.
AU  - van Schaik, L.*
AU  - West, S.*
C1  - 31222
C2  - 34212
SP  - 528-539
TI  - Controls of event-based pesticide leaching in natural soils: A systematic study based on replicated field scale irrigation experiments.
JO  - J. Hydrol.
VL  - 512
PY  - 2014
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - The Diass horst aquifer system located 50 km east of Dakar (Senegal) is exploited in two main aquifers covered by a sandy superficial aquifer: the confined/unconfined Palaeocene karstic limestone and the confined Maastrichtian sandstone aquifer underneath. This system has experienced intensive groundwater abstraction during the last 50 years to supply increasing water demand, agricultural and industrial needs. The high abstraction rate from 1989 to 2009 (about 109,000 m3/d) has caused a continuous groundwater level decline (up to 30 m), a modification of the groundwater flow and salinization in parts of the aquifers. The objective of the study is to improve our understanding of the system functioning with regards to high pumping, identify the geochemical reactions that take place in the system, infer origin and timing of recharge by using mainly stable (δ18O, δ2H, 13C) and radioactive (3H and 14C) isotopes. Water types defined in the Piper diagram vary in order of abundance from Ca–HCO3 (65%), Ca/Na–Cl (20%), Na–HCO3 (3%) and Na–Cl (12%). Values of δ18O and δ2H for the superficial aquifer range between −5.8 and −4.2‰ and between −42 and −31‰, respectively. For the Palaeocene aquifer they range from −5.8 to −5.0‰ and from −38 to −31‰, respectively; values in the Maastrichtian aquifer are between −5.9 and −4.3‰ for δ18O and −38 to −26‰ for δ2H. Plotted against the conventional δ18O vs δ2H diagram, data from the upper aquifer exhibit a dispersed distribution with respect to isotopic fractionation while those of the Palaeocene and Maastrichtian aquifers are aligned parallel and slightly below/or on the Global Meteoric Water Line (GMWL) evidencing ancient waters which had evaporated during infiltration. The low tritium (generally <0.7 TU) and 14C (0.7–57.2 pmc) contents indicate predominance of older water being recharged during the Pleistocene and Holocene periods. However, few boreholes which exhibit high tritium (1.2–4.3 TU) and 14C (65.7–70.8 pmc) values indicate some mixture with recent water likely through faulting and vertical drainage from the upper to deeper aquifers as well as lateral flow along flow paths to the piezometric depressions created by pumping.
AU  - Madioune, D.H.*
AU  - Faye, S.*
AU  - Orban, P.*
AU  - Brouyère, S.*
AU  - Dassargues, A.*
AU  - Mudry, J.*
AU  - Stumpp, C.
AU  - Maloszewski, P.
C1  - 30732
C2  - 33802
SP  - 443-459
TI  - Application of isotopic tracers as a tool for understanding hydrodynamic behavior of the highly exploited Diass aquifer system (Senegal).
JO  - J. Hydrol.
VL  - 511
PY  - 2014
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Assessing temporal variations in soil water flow is important, especially at the hillslope scale, to identify mechanisms of runoff and flood generation and pathways for nutrients and pollutants in soils. While surface processes are well considered and parameterized, the assessment of subsurface processes at the hillslope scale is still challenging since measurement of hydrological pathways is connected to high efforts in time, money and personnel work. The latter might not even be possible in alpine environments with harsh winter processes. Soil water stable isotope profiles may offer a time-integrating fingerprint of subsurface water pathways. In this study, we investigated the suitability of soil water stable isotope (δ18O) depth profiles to identify water flow paths along two transects of steep subalpine hillslopes in the Swiss Alps. We applied a one-dimensional advection–dispersion model using δ18O values of precipitation (ranging from −24.7 to −2.9‰) as input data to simulate the δ18O profiles of soil water. The variability of δ18O values with depth within each soil profile and a comparison of the simulated and measured δ18O profiles were used to infer information about subsurface hydrological pathways. The temporal pattern of δ18O in precipitation was found in several profiles, ranging from −14.5 to −4.0‰. This suggests that vertical percolation plays an important role even at slope angles of up to 46°. Lateral subsurface flow and/or mixing of soil water at lower slope angles might occur in deeper soil layers and at sites near a small stream. The difference between several observed and simulated δ18O profiles revealed spatially highly variable infiltration patterns during the snowmelt periods: The δ18O value of snow (−17.7 ± 1.9‰) was absent in several measured δ18O profiles but present in the respective simulated δ18O profiles. This indicated overland flow and/or preferential flow through the soil profile during the melt period. The applied methods proved to be a fast and promising tool to obtain time-integrated information on soil water flow paths at the hillslope scale in steep subalpine slopes.
AU  - Müller, M.H.*
AU  - Alaoui, A.*
AU  - Kuells, C.*
AU  - Leistert, H.*
AU  - Meusburger, K.*
AU  - Stumpp, C.
AU  - Weiler, M.*
AU  - Alewell, C.*
C1  - 31894
C2  - 34841
CY  - Amsterdam
SP  - 340-352
TI  - Tracking water pathways in steep hillslopes by δ18O depth profiles of soil water.
JO  - J. Hydrol.
VL  - 519
PB  - Elsevier Science Bv
PY  - 2014
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Stable water isotopes in precipitation (18O and 2H) have been frequently used as environmental tracers to understand processes and timescales in hydrology and climate research. Capturing changes of isotopic composition over time and investigating long-term processes requires long-term data set analysis. In Germany, we have one of the world’s densest national networks for long-term isotopic analysis of precipitation covering up to 36 years of time series at 28 locations. These data were used to identify the average as well as the temporal evolution of isotopic composition in German precipitation and how it is related to meteorological and geographical parameters. We found that individual Local Meteoric Water Lines (LMWL) and the long-term averages of δ18O and δ2H depend on latitude and elevation. More variable isotopic compositions and more enriched averages were found at the coast compared to more stable compositions and depleted averages in the South, South-East and at higher elevations. This continentality effect was strongly influenced by seasonal isotope-temperature dependencies. Removing the seasonality and looking at the changes over time compared to long-term averages indicate similar patterns for temperatures and 18O at some locations. We concluded that temperature and isotopes are in equilibrium in inland air masses only. The trend in temperature evolution was consistent on the national level, and temperature increases were observed in almost all stations. In contrast, temporal patterns of 18O revealed different patterns and increases were only observed in 20 out of 28 locations. Therefore, changes in isotopic composition in precipitation are not only influenced by large scale processes (i.e. temperature) but also by local factors which need to be further investigated.
AU  - Stumpp, C.
AU  - Klaus, J.*
AU  - Stichler, W.
C1  - 31588
C2  - 34572
CY  - Amsterdam
SP  - 351-361
TI  - Analysis of long-term stable isotopic composition in German precipitation.
JO  - J. Hydrol.
VL  - 517
PB  - Elsevier Science Bv
PY  - 2014
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - The heterogeneity and dynamic of water flow and solute transport processes were investigated in the upper 6 m of a surficial, glacial till in southern Saskatchewan, Canada. Continuous core samples from three vertical sites located over a maximum spatial distance of 65 m were collected and analyzed for particle size distribution, porosity, and water content. High-resolution (0.2 m) profiles of δ18O and δ2H in pore waters were also measured for the three sites on a seasonal basis. Depth profiles of all measured parameters indicate highly heterogeneous structures in the upper 6 m. In two coreholes, depleted water isotopes measured at different depths below ground (0.7 and 3 m) were in the range of winter precipitation values, suggesting preferential flow of meltwater in spring accompanied by a rising water table. A one-dimensional equilibrium flow and transport model failed to simulate the isotope-depth distributions with depleted winter values, and could not reproduce the measured values even when accounting for vertical, preferential flow. A conceptual model was created, based on the consistency of all measured data and assuming preferential lateral flow as the controlling flow and transport mechanism after snowmelt. In the model, water from surface runoff (after snowmelt) drains into an ephemeral depression that crosses the study site. As this water infiltrates, it forms a water table mound that slowly propagates away from the depression. As the water table propagates outwards, dynamic vertical flow processes result in net upward and downward fluxes.
AU  - Stumpp, C.
AU  - Hendry, M.J.*
C1  - 7409
C2  - 29705
SP  - 203-214
TI  - Spatial and temporal dynamics of water flow and solute transport in a heterogeneous glacial till: The application of high-resolution profiles of δ18O and δ2H in pore waters.
JO  - J. Hydrol.
VL  - 438-439
PB  - Elsevier
PY  - 2012
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Hydrochemical indices are commonly used to ascertain aquifer characteristics, salinity problems, anthropogenic inputs and resource management, among others. This study was conducted to test the applicability of a binary decision tree model to aquifer evaluation using hydrochemical indices as input. The main advantage of the tree-based model compared to other commonly used statistical procedures such as cluster and factor analyses is the ability to classify groundwater samples with assigned probability and the reduction of a large data set into a few significant variables without creating new factors. We tested the model using data sets collected from headwater springs of the Jordan River, Israel. The model evaluation consisted of several levels of complexity, from simple separation between the calcium-magnesium-bicarbonate water type of karstic aquifers to the more challenging separation of calcium-sodium-bicarbonate water type flowing through perched and regional basaltic aquifers. In all cases, the model assigned measures for goodness of fit in the form of misclassification errors and singled out the most significant variable in the analysis. The model proceeded through a sequence of partitions providing insight into different possible pathways and changing lithology. The model results were extremely useful in constraining the interpretation of geological heterogeneity and constructing a conceptual flow model for a given aquifer. The tree model clearly identified the hydrochemical indices that were excluded from the analysis, thus providing information that can lead to a decrease in the number of routinely analyzed variables and a significant reduction in laboratory cost.
AU  - Litaor, M.I.*
AU  - Brielmann, H.
AU  - Reichmann, O.*
AU  - Shenker, M.*
C1  - 2594
C2  - 27451
SP  - 273-282
TI  - Hydrochemical analysis of groundwater using a tree-based model.
JO  - J. Hydrol.
VL  - 387
IS  - 3-4
PB  - Elsevier
PY  - 2010
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - We present a method to quantify preferential flow in the unsaturated zone of cropped soils. This method was developed for bare soils (Stumpp et al., 2007) and is now applied to a lysimeter containing an undisturbed soil monolith planted with different crops. The lysimeter experiment was operated under natural atmospheric conditions over more than 5 years. The mean precipitation was equal to 953 mm/a while the mean outflow was 538 mm/a. Preferential flow was quantified with a two component flow approach using hydrological data and stable isotope contents (δ18O) as tracer, which were measured in precipitation and discharge. The results of the tracer transport modelling with a numerical transient and with a lumped dispersion model from a previous study (Stumpp et al., 2009b) were used here to evaluate the differences between the total and matrix flow. The application of the two component mixing approach yielded a mean preferential flow rate of 0.85 mm/week and 0.42 mm/week using a transient numerical and lumped parameter approach, respectively. However, except of some few events, preferential flow was found in the same weeks independently on the model approach. The amounts showed a seasonal variation that was explainable by the vegetation cover. Directly after harvest and before sowing the highest rates of preferential flow were observed that decreased during the plant growth periods. In mean 1–3% or 4–6% of the precipitation amount, which corresponds to 2–5% or 7–10% of the discharge, was flowing preferentially through the soil depending on the vegetation by applying transient and lumped approaches, respectively. Finally, the results from the lumped parameter modelling were used to construct vegetation specific vulnerability diagrams. These diagrams give information about flow heterogeneities and show the transit time distribution functions and water balance for the different vegetations.
AU  - Stumpp, C.
AU  - Maloszewski, P.
C1  - 5586
C2  - 27679
SP  - 407-415
TI  - Quantification of preferential flow and flow heterogeneities in an unsaturated soil planted with different crops using the environmental isotope δ¹⁸O.
JO  - J. Hydrol.
VL  - 394
IS  - 3-4
PB  - Elsevier
PY  - 2010
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - A fundamental prerequisite of any remedial activity is a sound knowledge of both the biotic and abiotic processes involved in transport and degradation of contaminants. Investigations of these aspects in situ often seem infeasible due to the complexity of interacting processes. A simplified portrayal of nature can be facilitated in laboratory-based two-dimensional (2D) sediment flow-through microcosms. This paper describes the versatility of such simple aquifer model systems with respect to biodegradation of aromatic hydrocarbons, i.e. toluene and ethylbenzene, under various environmental conditions. Initially constructed to study non-reactive and bioreactive transport of organic contaminants in homogeneous porous media under steady state hydraulic conditions, experimental setups developed towards more realistic heterogeneous sediment packing and transient hydraulic conditions. High-resolution spatial and temporal sampling allowed to obtain new insights on the distribution of bioactivities in contaminant plumes and associated controlling and limiting factors. Major biodegradation activities in saturated porous sediments are located at the fringes of contaminant plumes and are driven by dispersive mixing. These hot-spots of contaminant biotransformation are characterized by steep physical-chemical gradients in the millimeter to centimeter range. Sediment heterogeneity, i.e. high-conductivity zones, was shown to significantly enhance transverse mixing and subsequently biodegradation. On the contrary, transient hydraulic conditions may generate intermediate disturbances to biodegrader populations and thus may interfere with optimized contaminant conversion. However, a bacterial strain aerobically degrading toluene, i.e. Pseudomonas putida F1, was shown to adapt to vertically moving contaminant plumes, in the way that it regained full biodegradation potential two-times faster in areas with a midterm (days to weeks) contamination history than in areas not contaminated before. The 2D flow-through microcosms facilitated to combine a number of physicochemical and microbiological methods, such as high-resolution non-invasive oxygen measurements, conservative tracer tests, compound-specific isotope analysis (CSIA), fluorescence in situ hybridization (FISH), and numerical transport modelling, to name a few. Moreover, due to the defined and well-controlled operating conditions, these bench-scale flow-through systems allow to investigate theoretical concepts and to develop and test predictive models. They represent a valuable tool in helping to bridge the current knowledge gap concerning transport and degradation of contaminants in groundwater from the small-scale (i.e. oversimplified batch systems, disregarding transport processes) to the highly complex field conditions. The promising potential of applications is by far not exhausted. Further possibilities include testing ecological theories such as the resource-ratio theory, island biogeography, area-species richness relationships and relations between community structure, microbial abundance and process rates as well as the importance and effects of bacterial chemotaxis.
AU  - Bauer, R.D.
AU  - Rolle, M.*
AU  - Kürzinger, P.
AU  - Grathwohl, P.*
AU  - Meckenstock, R.U.
AU  - Griebler, C.
C1  - 2249
C2  - 26196
SP  - 284-295
TI  - Two-dimensional flow-through microcosms - Versatile test systems to study biodegradation processes in porous aquifers.
JO  - J. Hydrol.
VL  - 369
IS  - 3-4
PB  - Elsevier Science
PY  - 2009
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - H-3, delta O-18 and delta H-2 measurements on groundwater and chemical and isotope analyses on groundwater sulfate were used to determine the origin and mean transit times of groundwater and the sources affecting groundwater sulfate in a high-alpine karstic catchment area in southern Germany. Modelling results using a lumped parameter approach yielded mean transit times of water between 4 and 12 years for different karst springs. However, results obtained from delta O-18 and delta H-2 measurements on groundwater showed that a calculated mean transit time of 12 years for groundwater flow in one karst system can only be explained by mixing of young and old tritium-free ice and snowmelt water. Groundwater sulfate characterized by delta S-34 values of around 20 parts per thousand and delta O-18 values of ca. 12% in concert with sulfate concentrations of approximately 11 mg/L are probably affected by evaporites. In contrast, delta S-34 values of around 6 parts per thousand, and delta O-18 values up to 9.4 parts per thousand, in concert with sulfate concentrations between 1 and 7 mg/L mainly derive from atmospheric deposition. However, a delta S-34 value of -7.3 parts per thousand identified for one of the karst springs demonstrates that the oxidation of sulfide-containing minerals must be considered as an additional source, affecting sulfate concentrations in groundwater. The estimated transit time distribution of groundwater shows relatively high mean transit times between 2 and 5 years with a low contribution of very short transit times of less than 1 year. The high contribution of long mean transit times of groundwater in the alpine karst system, which represents an important drinking water resource, is an important function for drinking water supplies.
AU  - Einsiedl, F.
AU  - Maloszewski, P.
AU  - Stichler, W.
C1  - 1598
C2  - 25968
SP  - 113-121
TI  - Multiple isotope approach to the determination of the natural attenuation potential of a high-alpine karst system.
JO  - J. Hydrol.
VL  - 365
IS  - 1-2
PB  - Elsevier
PY  - 2009
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - The mean transit time of groundwater is commonly expected to increase gradually with increasing depth below water table. The present study provides evidence that the theoretical distribution of transit times may be significantly altered depending on the thickness of the unsaturated zone. An unconfined porous groundwater system formed by Tertiary sediments (Test Field Scheyern close to Munich in southern Germany) is overlain by an unsaturated zone with variable thickness between 4 and 60 m. Between 1992 and 2007 the groundwater system has been repeatedly sampled for tritium contents at different depths using two high-resolved wells. Modelled tritium concentrations by using a lumped parameter approach yielded depth profiles of mean transit times of tracer. In one well the profile was characterized by two local transit time maxima, each of approximately 100 years. A moving particle approach (MPA) developed in this study was used on the streamlines between the recharge zones linked to different sampling depths in the well. This suggested that the observed transit time in the profile was mainly governed by variable travel distances of the tracer through the unsaturated zone at the points of recharge. This finding was confirmed at a second multi-level well of the test site. The lumped parameter modelling of chlorofluorocarbon data yielded lower transit times as compared to those obtained from tritium data. This effect was explained by the different behaviour of tritium and chlorofluorocarbons in the unsaturated zone. The study clearly shows that the impact of a variable thickness of the unsaturated zone may overweigh the effect of local heterogeneities. Such transit time distributions of water in porous aquifers as observed in the present study can only be achieved with the help of environmental tracer data.
AU  - Schwientek, M.
AU  - Maloszewski, P.
AU  - Einsiedl, F.
C1  - 1466
C2  - 26315
SP  - 516-526
TI  - Effect of the unsaturated zone thickness on the distribution of water mean transit times in a porous aquifer.
JO  - J. Hydrol.
VL  - 373
IS  - 3-4
PB  - Elsevier
PY  - 2009
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - In this paper, five model approaches with different physical and mathematical concepts varying in their model complexity and requirements were applied to identify the transport processes in the unsaturated zone. The applicability of these model approaches were compared and evaluated investigating two tracer breakthrough curves (bromide, deuterium) in a cropped, free-draining lysimeter experiment under natural atmospheric boundary conditions. The data set consisted of time series of water balance, depth resolved water contents, pressure heads and resident concentrations measured during 800 days. The tracer transport parameters were determined using a simple stochastic (stream tube model), three lumped parameter (constant water content model, multi-flow dispersion model, variable flow dispersion model) and a transient model approach. All of them were able to fit the tracer breakthrough curves. The identified transport parameters of each model approach were compared. Despite the differing physical and mathematical concepts the resulting parameters (mean water contents, mean water flux, dispersivities) of the five model approaches were all in the same range. The results indicate that the flow processes are also describable assuming steady state conditions. Homogeneous matrix flow is dominant and a small pore volume with enhanced flow velocities near saturation was identified with variable saturation flow and transport approach. The multi-flow dispersion model also identified preferential flow and additionally suggested a third less mobile flow component. Due to high fitting accuracy and parameter similarity all model approaches indicated reliable results.
AU  - Stumpp, C.
AU  - Nützmann, G.*
AU  - Maciejewski, S.*
AU  - Maloszewski, P.
C1  - 111
C2  - 26578
SP  - 566-577
TI  - A comparative modeling study of a dual tracer experiment in a large lysimeter under atmospheric conditions.
JO  - J. Hydrol.
VL  - 375
IS  - 3-4
PB  - Elsevier
PY  - 2009
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - An attempt was made to improve the application of a lumped parameter model in the unsaturated soils planted with different crops. A first step of such an improvement was shown in Stumpp et al. [Stumpp, C., Maloszewski, P., Stichler, W., Fank, J., 2009. Application of the environmental isotope delta O-18 to study the water flow in unsaturated soils planted with different crops: 1. Case study - Lysimeter station "Wagna", Austria. journal of Hydrology] where the tracer concentrations in the recharging water were weighted according to the precipitation rate and by separating the observation period to different vegetation sub periods. However, during strongly variable flow conditions this improvement was still not sufficient enough to yield adequate modelling results. Therefore, in the present paper we investigated the flow processes in a high sophisticated lysimeter setup. The lysimeter had a length of 2 in and a surface area of 1 m(2) and was weighable which yielded water content as a function of time. This data enabled a further development of the lumped parameter approach to variable flow conditions. A new method was found to estimate the tracer concentration in the recharging water (input function) that takes the actual evapotranspiration rates into account which was indirectly determined from weighing the lysimeters' mass. Thus, it was possible to use a lumped dispersion model with such a new estimated input function to investigate the 8180 transport in soils planted with crop rotation with relatively high accuracy. The results obtained with the lumped dispersion model were compared with more exact numerical transient flow modelling, which however requires more detailed soil hydraulic data. The results of both modelling approaches yielded similar system parameters. The lumped parameter approach resulted in water contents of 0.14-0.30 cm(3) cm(-3) during the different vegetation periods and a mean value of 0.22 cm(3) cm(-3) for the whole observation period. The transient flow modelling yielded a mean water content of 0.21 cm(3) cm(-3). The dispersion parameter found in both models was in the same range. This study shows that a lumped dispersion model is applicable in the unsaturated zone even under strongly variable flow conditions having additional information about the water balance.
AU  - Stumpp, C.
AU  - Stichler, W.
AU  - Maloszewski, P.
C1  - 777
C2  - 26212
SP  - 68-78
TI  - Application of the environmental isotope δ¹⁸ to study water flow in unsaturated soils planted with different crops: Case study of a weighable lysimeter from the research field in Neuherberg, Germany.
JO  - J. Hydrol.
VL  - 368
IS  - 1-4
PB  - Elsevier
PY  - 2009
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Modelling variable soil water fluxes and transport processes under natural conditions in the unsaturated zone is often restricted and difficult to perform. Highly sophisticated numerical models are required and numerous parameters are needed. However, these parameters are difficult to estimate especially for heterogeneous systems. Therefore, the aim of this study was to investigate whether a simple lumped parameter approach is applicable in the unsaturated zone of cropped soils. The environmental isotope contents of delta O-18 and delta H-2 were used as tracers to study the flow processes in two lysimeters containing the same soil and planted with different crops (maize monoculture and crop rotation). The results from lumped parameter modelling were compared with those obtained with a numerical model approach. It was shown that the lumped parameter approach is, to some extent, applicable in the unsaturated zone. The simulations of the isotope contents in the discharge gave a general trend of mean transit times when the estimation of the tracer concentration in the inflow (input function) was weighted according to the amount of precipitation as well as when the observation period was separated into single vegetation periods. The resulting flow and transport parameters were similar to those from numerical modelling. The lumped model yielded adequate results particularly during the winter periods with grass cover. Although filled with the same soil material, different hydraulic flow systems were established in both lysimeters due to the differences in crop growth. In general, smaller fluxes were observed during crop rotation compared to maize monoculture whereas the smallest fluxes were found for canola.
AU  - Stumpp, C.
AU  - Maloszewski, P.
AU  - Stichler, W.
AU  - Fank, J.*
C1  - 1238
C2  - 26217
SP  - 198-208
TI  - Environmental isotope (Y¹⁸O) and hydrological data to assess water flow in unsaturated soils planted with different crops: Case study lysimeter station "Wagna" (Austria).
JO  - J. Hydrol.
VL  - 369
IS  - 1-2
PB  - Elsevier Science Bv
PY  - 2009
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Stable isotope measurements of oxygen and hydrogen (delta18O and deltaD) in stream waters and precipitation were used to investigate hydrological pathways and residence times in the River Sava catchment in Slovenia. delta18O and deltaD values of precipitation exhibited strong seasonal variations. Precipitation is of mixed Atlantic–Mediterranean origin which is also reflected in the isotopic composition of River Sava surface waters. The isotopic content of the river water is dependent on temperature, elevation of the recharge area and amount of precipitation. Spatially, rivers water is 16O-enriched in the high mountain areas due to higher amount of precipitation, lower temperature and higher elevation of the recharge area, while in the lower part of the River Sava catchments the delta18O values are higher. It is also observed that the River Sava responds quickly to precipitation which is reflected in its delta18O and deltaD values and the low residence time estimated in the river. Using an exponential flow model it was calculated that mean stream water residence times varied between 0.4 and 2.1 years. The shortest residence time determined at Savica is connected mainly to the higher amount of precipitation in the upper Sava watershed and the mountains carbonate karst terrain characterized by a higher runoff. The mean residence time in the main stream water of the River Sava was estimated to be 1.32 years and is in a good agreement with the residence time determined using 3H measurements. These data extend our knowledge in understanding the hydrological cycle of the River Sava, the interactions between precipitation, surface water and groundwater and, at the same time, demonstrate the utility of isotope tracers in determining catchments characteristics.
AU  - Ogrinc, N.*
AU  - Kanduc, T.*
AU  - Stichler, W.
AU  - Vreca, P.*
C1  - 2375
C2  - 25546
SP  - 303-312
TI  - Spatial and seasonal variations in delta18O and deltaD values in the River Sava in Slovenia.
JO  - J. Hydrol.
VL  - 359
IS  - 3-4
PB  - Elsevier
PY  - 2008
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Lake–ground water interactions in the vicinity of a dredge lake (Lake Leis; SW Germany) were studied by means of the stable isotopes (18O, 2H) mainly to determine the capture zone of a pumping well for the drinking water supply to the nearby town of Baden-Baden. The water supply is situated in a Quaternary gravel aquifer of the Rhine Valley. Numerical simulation performed using a two-dimensional water flow model was not able to characterise the capture zone uniquely. Several best fit options were possible by applying the values of hydraulic conductivities obtained from the pumping tests. As a result it was not possible to define whether Lake Leis is situated either completely inside or fully outside of the capture zone. To overcome this problem and to define the shape of the catchment area of the water supply precisely, a two-dimensional water flow and tracer transport model was established using both hydraulic heads and isotope data. The isotope data were applied to determine the proportion of lake water in down-gradient pumping and observation wells. Additionally, the isotope compositions of lake water and those in observation wells, measured as a function of time, were used to determine the mean water velocity (v = 0.6 m/d) along some selected 200 m long flow-paths. Based on known porosity and hydraulic gradient values, a hydraulic conductivity of about k = 6 × 10-4 m/s was determined for the central area down-gradient of the lake. This hydraulic conductivity and the proportion of lake water in the groundwater were used to calibrate a numerical two-dimensional regional scale transport model. The study demonstrates that it is possible to calibrate a water flow model in the vicinity of a dredge lake uniquely, only when stable isotope signals measured in a time series in both the lake and groundwater are taken into consideration. The calibrated model finally enables the capture zone of the production well to be precisely defined.
AU  - Stichler, W.
AU  - Maloszewski, P.
AU  - Bertleff, B.*
AU  - Watzel, R.*
C1  - 1692
C2  - 25711
SP  - 220-233
TI  - Use of environmental isotopes to define the capture zone of a drinking water supply situated near a dredge lake.
JO  - J. Hydrol.
VL  - 362
IS  - 3-4
PB  - Elsevier
PY  - 2008
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - A challenge of soil water transport modelling is the assessment of various uncertainties resulting from input data, from parameterisation of soil hydraulic characteristics and from estimation of sink terms like plant water uptake and soil evaporation. The objective of this study is to evaluate different modelling approaches for the estimation of soil hydraulic characteristics and evapotranspiration. A dataset from a lysimeter study in South-Germany with rotative crop vegetations over 5 years was used to perform the analysis. The pedotransfer functions that were used to estimate parameters for the representation of soil water retention and hydraulic conductivity have shown to be appropriate for water flow simulations. Although the simulated annual percolation amount is not very sensitive to the used soil hydraulic characteristics for the chosen boundary conditions, the diurnal percolation dynamics are highly sensitive to the soil hydraulic characteristics. The results show a strong dependence of simulated percolation on the used potential evpotranspiration (ETp) model. The Penman, Penman–Monteith and Haude approach overestimate the measured cumulative actual evapotranspiration in the present study. The measured outflow from the lysimeters can be correctly simulated, if a modified Haude approach is used. However, in the simulation of daily evapotranspiration fluxes the physically based Penman–Monteith approach has higher correlation with measurements than the empirical approach of Haude. For the tested lysimeter data we show that depending on ETp model choice the simulated percolation amounts vary between 52% and 126% of the measured amounts. Compared to this, the influence of the parameterisation of the soil hydraulic characteristics is small with a variation of up to 5% of the measured outflow.
AU  - Loos, C.
AU  - Gayler, S.
AU  - Priesack, E.
C1  - 1790
C2  - 24341
SP  - 259-270
TI  - Assessment of water balance simulations for large-scale weighing lysimeters.
JO  - J. Hydrol.
VL  - 335
IS  - 3-4
PB  - Elsevier
PY  - 2007
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Stable isotope approaches are often used for estimating water balances of lakes. Such studies require regional background information about hydrogen and oxygen isotope variability of lakes and their potential inflows. Here, a stable isotope database (?2H and ?18O) is presented for estimating evaporation to inflow ratios (E/I) of lakes in semi-arid southern Patagonia. Water samples of 23 lakes and ponds located in the Patagonian steppe at about 52°S were sampled during three subsequent austral summers. Two deep crater lakes, Laguna Azul and Laguna Potrok Aike, were studied in more detail during a two-years monitoring. Furthermore, precipitation, groundwater and atmospheric water vapor were sampled for isotope analyses. Presented data imply that the isotopic composition of rainfall in southeastern Patagonia is predominantly determined by precipitation amount and moisture source area. For the investigated area, the first meteoric water and evaporation lines in ?2H vs. ?18O space are presented. The database was further used to estimate the water balances of the two crater lakes, Laguna Azul and Laguna Potrok Aike, which are in the focus of recent paleoclimatic investigations. According to that approach about 50% and 60%, respectively, of the water entering Laguna Azul and Laguna Potrok Aike via surface and subsurface inflow evaporates. These results testify a considerable flow of lake waters into the groundwater.
AU  - Mayr, C.*
AU  - Lucke, A.*
AU  - Stichler, W.
AU  - Trimborn, P.
AU  - Ercolano, B.*
AU  - Oliva, G.*
AU  - Ohlendorf, C.*
AU  - Soto, J.*
AU  - Fey, M.*
AU  - Haberzettl, T.*
AU  - Janssen, S.*
AU  - Schabitz, F.*
AU  - Schleser, G.H.*
AU  - Wille, M.*
AU  - Zolitschka, B.*
C1  - 2307
C2  - 24985
SP  - 53-63
TI  - Precipitation origin and evaporation of lakes in semi-arid Patagonia (Argentina) inferred from stable isotopes (delta18O, deltaH-2).
JO  - J. Hydrol.
VL  - 334
IS  - 1-2
PB  - Elsevier
PY  - 2007
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Maloszewski, P.
AU  - Wachniew, P.*
AU  - Czuprynski, P.*
C1  - 2849
C2  - 24067
SP  - 630-642
TI  - Study of hydraulic parameters in heterogeneous gravel beds: Constructed wetland in Nowa Slupia (Poland).
JO  - J. Hydrol.
VL  - 331
PY  - 2006
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Boronina, A.*
AU  - Balderer, W.*
AU  - Renard, P.*
AU  - Stichler, W.
C1  - 5357
C2  - 22851
SP  - 214-226
TI  - Study of stable isotopes in the Kouris catchment (Cyprus) for the description of the regional groundwater flow.
JO  - J. Hydrol.
VL  - 308
PY  - 2005
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Einsiedl, F.
C1  - 4899
C2  - 22882
SP  - 312-321
TI  - Flow system dynamics and water storage of a fissured-porous karst aquifer characterized by artificial and environmental tracers.
JO  - J. Hydrol.
VL  - 312
PY  - 2005
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Mallén, G.
AU  - Maloszewski, P.
AU  - Flynn, R.*
AU  - Rossi, B.*
AU  - Engel, M.
AU  - Seiler, K.-P.
C1  - 836
C2  - 22657
SP  - 21-36
TI  - Determination of bacterial and viral transport parameters in a gravel aquifer assuming linear kinetic sorption and desorption.
JO  - J. Hydrol.
VL  - 306
PY  - 2005
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Maloszewski, P.
AU  - Stichler, W.
AU  - Zuber, A.*
AU  - Rank, D.*
C1  - 22047
C2  - 20661
SP  - 48-59
TI  - Identifying the flow systems in a karstic-fissured-porous aquifer, the Schneealpe, Austria, by  modelling of environmental 18O and 3H isotopes.
JO  - J. Hydrol.
VL  - 256
PY  - 2002
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Zimmermann, L.
AU  - Zimmermann, F.*
C1  - 22046
C2  - 20660
SP  - 166-175
TI  - Fog deposition to Norway Spruce stands at high-elevation sites in the Eastern Erzgebirge ( Germany).
JO  - J. Hydrol.
VL  - 256
PY  - 2002
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Maloszewski, P.
AU  - Moser, H.
AU  - Stichler, W.
AU  - Trimborn, P.
C1  - 22205
C2  - 20913
SP  - 149-166
TI  - Isotope hydrology investigations in large refuse lysimeters.
JO  - J. Hydrol.
VL  - 167
PY  - 1995
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Isotope and hydrochemical data of the thermal water system in Cieplice Ṡlaskie Zdrój (Spa) indicate the existence of two subsystems that greatly differ in volume and which meet at the fault zones of a granitic horst, where they discharge at an altitude of about 340m. One of the subsystems is very small (about 4 × 103 m3) as indicated by the tritium age of the order of 10 years and a low outflow rate. Its recharge area found from the δ18O and δD values, is about 200m above the springs, most probably on the slopes of the foothills of the Karkonosze Mountains south-southwest of the spa. The large subsystem contains water which is free of tritium and whose 14C content is from 1 to 8 pmc with δ13C = -8.0 to -9.2‰. The isotopic composition of this water reflects either the climatic effect (low-altitude recharge during a cooler pre-Holocene climate) or the altitude effect (recharge in the early Holocene period at about 1000m at the heights of the Karkonosze assuming that the 14C concentration is strongly reduced by exchange with calcite in veins). For the former hypothesis, the recharge area of this water is probably either at the foot of the southeastern slopes of the Kaczawa Mountains or/and at the foot of the Rudawy Janowickie Mountains, to the east of Cieplice. The noble gas temperatures are more consistent with the pre-Holocene recharge. Similarly, the 4He excess and 40Ar 36Ar ratio support the hypothesis of a pre-Holecene age. The constant 3He 4He ratio of 26 × 10-8 for highly different helium contents indicates crustal origin of helium. For the pre-Holocene age of water its volume is calculated at >- 109m3 (stagnant water in micropores and mobile water in fractures) and the hydraulic conductivity of the host granite massif is estimated at about 7 × 10-8 ms-1. Two outflows from this subsystem have different and variable fractions of a modern water component (bomb age), most probably originating from the bank infiltration of a nearby stream.
AU  - Ciȩzkowski, W.*
AU  - Gröning, M.*
AU  - Leśniak, P.M.*
AU  - Weise, S.M.
AU  - Zuber, A.*
C1  - 40539
C2  - 38021
SP  - 89-117
TI  - Origin and age of thermal waters in Cieplice Spa, Sudeten, Poland, inferred from isotope, chemical and noble gas data.
JO  - J. Hydrol.
VL  - 140
IS  - 1-4
PY  - 1992
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Measurements of tritium and 18O concentrations in precipitation and runoff were used to provide further insight into the groundwater storage properties of the Wimbachtal Valley, a catchment area of 33.4 km2, extending between 636 and 2713 m a.s.l. in the Berchtesgaden Alps. The catchment includes three aquifer types: a dominant porous aquifer; a fractured dolomite; a karstic limestone aquifer. Employing a simple hydrological model, information about mean transit times of environmental tracers is derived for the groundwater runoff component and several karst springs from the application of the exponential and dispersion flow models to the isotopic input and output data. The mean transit times calculated from a dispersion model with transit times of 4.1 years for 18O and 4.2 years for tritium, which agree well, allow calculation of total (mobile + stagnant) groundwater storage volume, which is equivalent to 6.6 m of water depth. Direct runoff appears negligible as in many other cases.
AU  - Maloszewski, P.
AU  - Rauert, W.
AU  - Trimborn, P.
AU  - Herrmann, A.*
AU  - Rau, R.*
C1  - 40544
C2  - 38784
SP  - 343-360
TI  - Isotope hydrological study of mean transit times in an alpine basin (Wimbachtal, Germany).
JO  - J. Hydrol.
VL  - 140
IS  - 1-4
PY  - 1992
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  -  The migration of arsenic and cadmium species in ground water was investigated with the aid of tracer experiments at a test site in a fluvioglacial aquifer. Experimental breakthrough curves, obtained under natural flow conditions, characterize the migration of arsenic and cadmium species in the ground water in relation to a conservative tracer. Transport velocities of arsenic species corresponded to those of the groundwater flow and resulted in a rapid breakthrough in the observation wells. The recovery of the arsenic species, calculated with respect to the conservative tracer, averaged about 50%. Intensity of sorption increased with decreasing concentrations of arsenic species. The migration of cadmium species, however, was controlled by chemical precipitation of otavite and a slow redissolution of this compound. The breakthrough of cadmium in the observation wells, thus, was much slower with respect to the water movement. A recovery of about 40% was observed after more than 1 year of observation. Increased concentrations of chloride or/and sulphate resulted in remobilization of cadmium. Breakthrough curves are described by a commonly used dispersion model. It appears that a retardation factor is not sufficient to describe the asymmetrical breakthrough curves; it must be supplemented by recovery rates and a specific dispersivity, defined by the time variance of concentration at a given point. Longer flow distances or lower initial concentrations caused reduced recoveries, higher specific dispersivities and retardations both for arsenic and for cadmium species.
AU  - Zahn, M.T.
AU  - Seiler, K.-P.
C1  - 19451
C2  - 12545
SP  - 201-214
TI  - Field Studies on the Migration of Arsenic and Cadmium in a Carbonate Gravel Aquifer Near Munich (F.R.G.).
JO  - J. Hydrol.
VL  - 133
IS  - 3-4
PB  - Elsevier
PY  - 1992
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Das, B.K.*
AU  - Kakar, Y.P.*
AU  - Moser, H.
AU  - Stichler, W.
C1  - 40853
C2  - 36393
SP  - 387-389
TI  - Deuterium and oxygen-18 studies in groundwater of the Delhi area, India - Reply.
JO  - J. Hydrol.
VL  - 113
IS  - 1-4
PY  - 1990
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - The organic carbon cycle of slowly permeable, clayey glacial till deposits in the Western Interior Great Plains, southern Alberta, was investigated by examining the relationship between solid organic matter (SOM) in the till sediments and dissolved organic carbon (DOC) in the till porewaters. Geochemically, the tills can be divided into two distinct zones: an upper oxidized (low SOM) till zone, and a lower unoxidized (high SOM) till zone. Till porewaters in both zones are characterized by high DOC contents. Radiocarbon dating and comparison of SOM and DOC fractions suggest DOC in the deep unoxidized zone originated during deglaciation, and is probably representative of groundwater ages in this till zone. In the oxidized zone, DOC originates from variable mixtures of soluble organic matter emplaced during deglaciation, and Cretaceous age coal fragments in this till zone. SOM in the upper till zone was mainly oxidized to CO2 gas during lowered water table conditions of the Altithermal climatic period. The subsurface production of fossil CO2 gas has serious implications for using the conventional dissolved inorganic carbon (DIC) 14C groundwater dating method in these clayey till porewaters.
AU  - Wassenaar, L.I.*
AU  - Hendry, M.J.*
AU  - Aravena, R.A.*
AU  - Fritz, P.J.
C1  - 42131
C2  - 40266
SP  - 251-270
TI  - Organic carbon isotope geochemistry of clayey deposits and their associated porewaters, southern Alberta.
JO  - J. Hydrol.
VL  - 120
IS  - 1-4
PY  - 1990
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - The migration of arsenic and cadmium species in ground water was investigated with the aid of tracer experiments at a test site in a fluvinglacial aquifer. Experimental breakthrought curves, obtained under natural flow conditions, characterize the migration of arsenic and cadmium species in the ground water in relation to a conservative tracer. Transport velocities of arsenic species corresponded to those of the groundwater flow and resulted in a rapid breakthrough in the observation weells. The recovery of the arsenic species, calculated with respect to the conservative tracer, averaged about 50%. Intensity of sorption increased with decreasing concentrations of arsenic species. The migration of cadmium species, however, was controlled by chemical precipitation of otavite and a slow redissolution of this compound. The breakthrough of cadmium in the observation wells, thus, was much slower with respect to the water movement. A recovery of about 40% was observed after more than 1 year of observation. Increased concentrations of chloride or/and sulphate resulted in remobilization of cadmium. Breakthrough curves are described by a commonly used dispersion model. It appears that a retardation factor is not sufficient to describe the asymmetrical breakthrough curves; it must be supplemented by recovery rates and a specific dispersitivity, defined by the time variance of concentration at a given point. Longer flow distances or lower initial concentrations caused reduced recoveries, higher specific dispersivities and retardations both for arsenic and for cadmium species.
AU  - Zahn, M.T.
AU  - Seiler, K.-P.
C1  - 18581
C2  - 11710
SP  - 201-214
TI  - Field Studies on Migration of Arsenic and Cadmium in a Carbonatic Gravel-Sand Aquifer.
JO  - J. Hydrol.
VL  - 133
IS  - 3-4
PY  - 1990
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - In the Upper Jurassic carbonates of the southern Franconian Alb (F.R.G.), groundwater flow is much more pronounced in fissures than in solution channels. With increasing thickness of the aquifer, and with the predominance of dolomitic reef facies, tracer dilution becomes stronger. The evaluation of dispersion in the study area was based on the one-dimensional approximation of tracer transport in the fissured aquifer and considers diffusive tracer exchange between mobile and quasi-stagnant water. The dispersion parameter (1/Pe) was found in each tracer experiment by applying the fitting procedure with the Single Fissure Dispersion Model (SFDM). In solution channels, dispersion seems not to depend significantly upon flow distance. In fissures, however, dispersivities increase comparatively strongly with flow distance. Calculated dispersivities range from 4m in solution channels to some ten meters in fissures. All dispersivities are related to recovery rate, which can be judged as a measure of the draining influence of flow in solution channels on fissure flow.
AU  - Seiler, K.P.
AU  - Maloszewski, P.
AU  - Behrens, H.
C1  - 42547
C2  - 36428
SP  - 235-247
TI  - Hydrodynamic dispersion in karstified limestones and dolomites in the Upper Jurassic of the Franconian Alb, F.R.G.
JO  - J. Hydrol.
VL  - 108
PY  - 1989
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Groundwater in the Delhi area occurs under different hydrogeological conditions: west of the Delhi Ridge, closed basin of Chattarpur, between the Ridge and the Yamuna River and east of the Yamuna River with depth to the water table ranging from 1.53 to 19.12m below ground level. A comparison of isotopic data of groundwater with that of rainfall (during the period 1961-1978) indicates that groundwater in all the subbasins and at different depths is of meteoric origin having undergone direct evaporation and is genetically similar. Deviation of the points from the meteoric line on a D- 18O diagram is attributed to evaporation from falling rain drops and retardation in infiltration rate of rainwater, the latter due to the predominance of clayey soils at several places. The present study has shown that the major sources of high salinity are high rate of evaporation, recycling of irrigation water, and re-solution of precipitated minerals by monsoon recharge along with nonflushing of deeper waters. This is contrary to the findings of earlier workers who proposed that the high salinity of groundwater is related to marine origin and/or fallout of airborne salts from the Arabian Sea.
AU  - Das, B.K.*
AU  - Kakar, Y.P.*
AU  - Moser, H.
AU  - Stichler, W.
C1  - 33863
C2  - 38256
SP  - 133-146
TI  - Deuterium and oxygen-18 studies in groundwater of the Delhi area, India.
JO  - J. Hydrol.
VL  - 98
IS  - 1-2
PY  - 1988
SN  - 0022-1694
ER  - 

TY  - JOUR
AU  - Seiler, K.-P.
AU  - Maloszewski, P.
AU  - Behrens, H.
C1  - 17206
C2  - 10247
TI  - Hydrodynamic Dispersion in karstified Limestones and Dolomites in the upper Jura of Franconian Alb/FRG.
JO  - J. Hydrol.
PY  - 1988
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - The area under investigation concerns a 0.3 km2 island in the Danube River near Passau (F.R.G.). Measurements of 18O-content were used to determine the portion of bank infiltrated river water making up the groundwater of the island. Values of 77 and 96% have been found for different measuring points. Applying mathematical flow models to the environmental tracer data, mean transit times of 48-120 days for the bank infiltrated water and dispersion parameter (D/vx) of about 0.12 have been calculated. These estimates permitted prediction of the migration of possible pollution from the river to the observation and production wells.
AU  - Stichler, W.
AU  - Maloszewski, P.*
AU  - Moser, H.
C1  - 33003
C2  - 35570
SP  - 355-365
TI  - Modelling of river water infiltration using oxygen-18 data.
JO  - J. Hydrol.
VL  - 83
IS  - 3-4
PY  - 1986
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Measurements of tritium and deuterium concentrations in precipitation and runoff were in addition to conventional investigation methods used to provide some further insight into the storage properties of Lainbach valley, a catchment area of 18.7 km2 and 670 to 1801 m above sea level in the Bavarian Alps. The basin was modeled using different simple hydrological models. Information about mean transit times of subsurface water and storage volumes of basin reservoirs is derived from the application of specific flow models to the isotopic output data. Based on fitted mean transit times of 0.8 yr. for the upper subsurface reservoir and 7.5 yr. for the lower subsurface reservoir, storage volume equivalents were obtained of 0.6 and 1.9 m of water depth, respectively.
AU  - Maloszewski, P.
AU  - Rauert, W.
AU  - Stichler, W.
AU  - Herrmann, A.*
C1  - 41341
C2  - 38642
SP  - 319-330
TI  - Application of flow models in an alpine catchment area using tritium and deuterium data.
JO  - J. Hydrol.
VL  - 66
IS  - 1-4
PY  - 1983
SN  - 0022-1694
ER  - 

TY  - JOUR
AB  - Laboratory test results on longitudinal dispersion of soluble material in loose rocks with artificially composed or natural grain-size distributions are compared with one another and with results of field tests. In this way it can be demonstrated that it is quite possible to translate laboratory results to field conditions, if sedimentological properties of the loose materials are comparable, if bedding (geological interfaces) runs parallel to the flow direction and is hydraulically ineffective, and if distances between injection and detection are about less than 50 m. Transverse dispersion is difficult to determine. At first approximation the width of tracer cloud from a line injection was determined and the aperture angle of the resultant cloud calculated. The laboratory and field experiments showed an aperture angle of about 5° on distances between 10 and 2500 m.
AU  - Klotz, D.
AU  - Seiler, K.P.
AU  - Moser, H.
AU  - Neumaier, F.
C1  - 40938
C2  - 38540
SP  - 169-184
TI  - Dispersivity and velocity relationship from laboratory and field experiments.
JO  - J. Hydrol.
VL  - 45
IS  - 3-4
PY  - 1980
SN  - 0022-1694
ER  -