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  • 1
    Language: English
    In: Journal of Hydrology, Dec 19, 2012, Vol.475, p.1(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2012.06.050 Byline: Lisa Angermann (a)(b)(c), Jorg Lewandowski (a), Jan H. Fleckenstein (b)(c), Gunnar Nutzmann (a)(d) Keywords: Flow patterns; Flow direction; Flow velocity; Hyporheic zone; Heat pulse technique Abstract: a* We developed a method to determine flow direction and velocity in the hyporheic zone. a* The method is based on a heat pulse technique with analytical data analysis algorithm. a* Error-proneness and accuracy of the method were assessed in the lab and in situ. a* The first field application gives insight in hyporheic flow patterns of a lowland river. Author Affiliation: (a) Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Department Ecohydrology, Muggelseedamm 310, D-12587 Berlin, Germany (b) Helmholtz Center for Environmental Research - UFZ, Department of Hydrogeology, Permoserstr. 15, D-04318 Leipzig, Germany (c) University of Bayreuth, Department of Hydrology, Universitatsstr. 30, D-95440 Bayreuth, Germany (d) Humboldt-University of Berlin, Geographical Institute, Rudower Chaussee 16, D-12489 Berlin, Germany Article History: Received 27 October 2011; Revised 21 June 2012; Accepted 26 June 2012 Article Note: (miscellaneous) This manuscript was handled by Philippe Baveye, Editor-in-Chief, with the assistance of Nunzio Romano, Associate Editor
    Keywords: Hydrogeology -- Analysis ; Sensors -- Analysis ; Flow (Dynamics) -- Analysis
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Journal of Hydrology, Feb 13, 2014, Vol.509, p.601(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2013.12.005 Byline: Svenja Bartsch, Sven Frei, Marianne Ruidisch, Christopher L. Shope, Stefan Peiffer, Bomchul Kim, Jan H. Fleckenstein Abstract: acents Temporal variability of river-aquifer exchange fluxes is controlled by the monsoon. acents Monsoonal extreme precipitation events are dominant drivers for flow reversals. acents Frequent flow reversals affect the local water quality. Article History: Received 26 August 2013; Revised 3 December 2013; Accepted 5 December 2013 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of Philippe Negrel, Associate Editor
    Keywords: Aquifers ; Rain ; Climate
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Journal of Hydrology, October 2015, Vol.529, pp.969-979
    Description: Coupling surface and subsurface water flow in fully integrated hydrological codes is becoming common in hydrological research; however, the coupling of surface–subsurface solute transport has received much less attention. Previous studies on fully integrated solute transport focus on small scales, simple geometric domains, and have not utilised many different field data sources. The objective of this study is to demonstrate the inclusion of both flow and solute transport in a 3D, fully integrated catchment model, utilising high resolution observations of dissolved organic carbon (DOC) export from a wetland complex during a rainfall event. A sensitivity analysis is performed to span a range of transport conditions for the surface–subsurface boundary (e.g. advective exchange only, advection plus diffusion, advection plus full mechanical dispersion) and subsurface dispersivities. The catchment model captures some aspects of observed catchment behaviour (e.g. solute discharge at the catchment outlet, increasing discharge from wetlands with increased stream discharge, and counter-clockwise concentration–discharge relationships), although other known behaviours are not well represented in the model (e.g. slope of concentration–discharge plots). Including surface–subsurface solute transport aids in evaluating internal model processes, however there are challenges related to the influence of dispersion across the surface–subsurface interface, and non-uniqueness of the solute transport solution. This highlights that obtaining solute field data is especially important for constraining integrated models of solute transport.
    Keywords: Solute Transport ; Surface–Subsurface Coupling ; Integrated Modelling ; Catchment Modelling ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 4
    Language: English
    In: Journal of hydrology, 2012, Vol.475, pp.1-11
    Description: The hyporheic zone is strongly influenced by the adjacent surface water and groundwater systems. It is subject to hydraulic head and pressure fluctuations at different space and time scales, causing dynamic and heterogeneous flow patterns. These patterns are crucial for many biogeochemical processes in the shallow sediment and need to be considered in investigations of this hydraulically dynamic and biogeochemical active interface. For this purpose a device employing heat as an artificial tracer and a data analysis routine were developed. The method aims at measuring hyporheic flow direction and velocity in three dimensions at a scale of a few centimeters. A short heat pulse is injected into the sediment by a point source and its propagation is detected by up to 24temperature sensors arranged cylindrically around the heater. The resulting breakthrough curves are analyzed using an analytical solution of the heat transport equation. The device was tested in two laboratory flow-through tanks with defined flow velocities and directions. Using different flow situations and sensor arrays the sensitivity of the method was evaluated. After operational reliability was demonstrated in the laboratory, its applicability in the field was tested in the hyporheic zone of a low gradient stream with sandy streambed in NE-Germany. Median and maximum flow velocity in the hyporheic zone at the site were determined as 0.9×10⁻⁴ and 2.1×10⁻⁴ms⁻¹ respectively. Horizontal flow components were found to be spatially very heterogeneous, while vertical flow component appear to be predominantly driven by the streambed morphology. ; p. 1-11.
    Keywords: Groundwater ; Labeling Techniques ; Space And Time ; Sediments ; Surface Water ; Streams ; Algorithms ; Field Experimentation ; Heat ; Heaters ; Tanks
    ISSN: 0022-1694
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 5
    Language: English
    In: Journal of Hydrology, 19 December 2012, Vol.475, pp.1-11
    Description: ► We developed a method to determine flow direction and velocity in the hyporheic zone. ► The method is based on a heat pulse technique with analytical data analysis algorithm. ► Error-proneness and accuracy of the method were assessed in the lab and . ► The first field application gives insight in hyporheic flow patterns of a lowland river. The hyporheic zone is strongly influenced by the adjacent surface water and groundwater systems. It is subject to hydraulic head and pressure fluctuations at different space and time scales, causing dynamic and heterogeneous flow patterns. These patterns are crucial for many biogeochemical processes in the shallow sediment and need to be considered in investigations of this hydraulically dynamic and biogeochemical active interface. For this purpose a device employing heat as an artificial tracer and a data analysis routine were developed. The method aims at measuring hyporheic flow direction and velocity in three dimensions at a scale of a few centimeters. A short heat pulse is injected into the sediment by a point source and its propagation is detected by up to 24 temperature sensors arranged cylindrically around the heater. The resulting breakthrough curves are analyzed using an analytical solution of the heat transport equation. The device was tested in two laboratory flow-through tanks with defined flow velocities and directions. Using different flow situations and sensor arrays the sensitivity of the method was evaluated. After operational reliability was demonstrated in the laboratory, its applicability in the field was tested in the hyporheic zone of a low gradient stream with sandy streambed in NE-Germany. Median and maximum flow velocity in the hyporheic zone at the site were determined as 0.9 × 10 and 2.1 × 10 m s respectively. Horizontal flow components were found to be spatially very heterogeneous, while vertical flow component appear to be predominantly driven by the streambed morphology.
    Keywords: Flow Patterns ; Flow Direction ; Flow Velocity ; Hyporheic Zone ; Heat Pulse Technique ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 6
    In: Fundamental and Applied Limnology / Archiv für Hydrobiologie, June 2014, Vol.184(3), pp.173-181
    Description: Heat is increasingly used as a natural tracer to quantify water fluxes at the groundwater-surface water-interface. We present a systematic approach to monitor and evaluate stream and streambed temperatures to derive daily-updated temperature-based water exchange fluxes between the stream and the streambed. Specifically designed multi-level temperature sensors coupled with a data logger and GSM modem are used to monitor temperature in the stream and streambed and transfer this data daily to a database. A suite of MATLAB scripts with structured query language (SQL) commands is applied to extract the data for processing using an inverse numerical model to estimate water flow based on the measured temperatures. Compared to common analytical approaches, which typically require sinusoidal diurnal temperature pattern, our numerical model can utilize temperature records without daily variations. Temperature-based calculations to quantify vertical water fluxes at the stream-groundwater interface can provide a supplement to, or even a replacement of, calculations based on vertical hydraulic gradients and Darcy' law.
    Keywords: Groundwater - Surface Water - Interface
    ISSN: 1863-9135
    E-ISSN: 23637110
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  • 7
    Language: English
    In: Water Research, 01 March 2018, Vol.130, pp.185-199
    Description: Nitrate contamination in ground- and surface water is a persistent problem in countries with intense agriculture. The transition zone between rivers and their riparian aquifers, where river water and groundwater interact, may play an important role in mediating nitrate exports, as it can facilitate intensive denitrification, which permanently removes nitrate from the aquatic system. However, the in-situ factors controlling riparian denitrification are not fully understood, as they are often strongly linked and their effects superimpose each other. In this study, we present the evaluation of hydrochemical and isotopic data from a 2-year sampling period of river water and groundwater in the riparian zone along a 3rd order river in Central Germany. Based on bi- and multivariate statistics (Spearman's rank correlation and partial least squares regression) we can show, that highest rates for oxygen consumption and denitrification in the riparian aquifer occur where the fraction of infiltrated river water and at the same time groundwater temperature, are high. River discharge and depth to groundwater are additional explanatory variables for those reaction rates, but of minor importance. Our data and analyses suggest that at locations in the riparian aquifer, which show significant river water infiltration, heterotrophic microbial reactions in the riparian zone may be fueled by bioavailable organic carbon derived from the river water. We conclude that interactions between rivers and riparian groundwater are likely to be a key control of nitrate removal and should be considered as a measure to mitigate high nitrate exports from agricultural catchments.
    Keywords: Riparian Zone ; Nitrate Contamination ; Nitrate Stable Isotopes ; River-Groundwater Interaction ; Denitrification ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 8
    Language: English
    In: Journal of Hydrology, 13 February 2014, Vol.509, pp.601-614
    Description: An important prerequisite to better understand the transport of nutrients and contaminants across the river-aquifer interface and possible implications for biogeochemical transformations is to accurately characterize and asses the exchange fluxes. In this study we investigate how monsoonal precipitation events and the resulting variability in river discharge affect the dynamics of river-aquifer exchange and the corresponding flux rates. We evaluate potential impacts of the investigated exchange fluxes on local water quality. Hydraulic gradients along a piezometer transect were monitored at a river reach in a small catchment in South Korea, where the hydrologic dynamics are driven by the East-Asian Monsoon. We used heat as a tracer to constrain river-aquifer exchange fluxes in a two-dimensional flow and heat transport model implemented in the numerical code HydroGeoSphere, which was calibrated to the measured temperature and total head data. To elucidate potential effects of river-aquifer exchange dynamics on biogeochemical transformations at the river-aquifer interface, river water and groundwater samples were collected and analyzed for dissolved organic carbon (DOC), nitrate (NO ) and dissolved oxygen saturation (DO ). Our results illustrate highly variable hydrologic conditions during the monsoon season characterized by temporal and spatial variability in river-aquifer exchange fluxes with frequent flow reversals (changes between gaining and losing conditions). Intense monsoonal precipitation events and the associated rapid changes in river stage are the dominant driver for the observed riverbed flow reversals. The chemical data suggest that the flow reversals, when river water high in DOC is pushed into the nitrate-rich groundwater below the stream and subsequently returns to the stream may facilitate and enhance the natural attenuation of nitrate in the shallow groundwater.
    Keywords: River-Aquifer Exchange Fluxes ; Heat As a Natural Tracer ; Monsoonal-Type Climate ; Hydraulic Gradient Reversals ; Hydrogeosphere ; Natural Attenuation of Nitrate ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 9
    In: Hydrological Processes, 30 October 2013, Vol.27(22), pp.3240-3253
    Description: Exchange of groundwater and lake water with typically quite different chemical composition is an important driver for biogeochemical processes at the groundwater‐lake interface, which can affect the water quality of lakes. This is of particular relevance in mine lakes where anoxic and slightly acidic groundwater mixes with oxic and acidic lake water (pH 330 nmol g d) compared to alternating sites (〈220 nmol g d). Although differences in sulfate reduction rates could not be explained solely by different flux rates, they were clearly related to the prevailing groundwater‐lake exchange patterns and the associated pH conditions. Our findings strongly suggest that groundwater‐lake exchange has significant effects on the biogeochemical processes that are coupled to sulfate reduction such as acidity retention and precipitation of iron sulfides. Copyright © 2012 John Wiley & Sons, Ltd.
    Keywords: Groundwater‐Lake Exchange ; Acid Mine Lake ; Seepage Flux ; Ph‐Profiles ; Chloride Profiles ; Acid Neutralization Processes
    ISSN: 0885-6087
    E-ISSN: 1099-1085
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  • 10
    In: Journal of Geophysical Research: Biogeosciences, September 2012, Vol.117(G3), pp.n/a-n/a
    Description: Although land‐water carbon (C) transport represents a critical link in the global C cycle, rare attempts have been made to compare hydrologic controls over storm pulses of dissolved organic C (DOC) and particulate organic C (POC) in mountainous watersheds. An immersible UV/Vis spectrophotometer was used to comparatively investigate the rapid storm responses of stream water DOC and POC in a small mountainous forested watershed in South Korea. High‐frequency measurements at 5‐min intervals during 42 hydrologic events, including monsoon storms and winter snowmelts, showed consistent patterns: POC concentrations were lower than DOC concentrations during base flow and small storm events but exceeded them during the peak flow periods of intense storm events. Although both the DOC and POC concentrations had hysteretic relationships with discharge, the POC concentrations showed larger increases and variations after crossing a threshold discharge on the rising limb of the storm hydrograph. Stronger responses to intense storms resulted in a disproportionately large export of POC at high flow, whereas a large portion of the total DOC flux was exported under prevailing low‐flow conditions. The results demonstrate the potential of in situ optical measurements for investigating fine‐resolution dynamics of the DOC and POC export during storm events. Stronger storm responses of the POC export compared to the limited response range of the DOC export suggest that erosion‐induced POC export will become more important as a major pathway for the hydrologic soil C loss from mountainous watersheds in response to an increasing occurrence of extreme storm events. In situ optical monitoring captured differential storm responses of DOC and POC POC export was more variable on rising discharge than limited DOC responses Strong storm responses lead to disproportionately large POC export at high flow
    Keywords: Dissolved Organic Carbon ; Extreme Events ; In Situ Sensors ; Mountainous Watersheds ; Particulate Organic Carbon ; Soil Carbon Loss
    ISSN: 0148-0227
    E-ISSN: 2156-2202
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