Increased reactive nitrogen from human activities negatively affects surface water (SW) quality. The hyporheic zone, where SW and groundwater interact, possesses unique biogeochemical conditions that can attenuate contaminants (e.g., denitrification), including mixing-dependent reactions that require components from both water sources. Previous research has explored mixing-dependent denitrification in the hyporheic zone but did not address the effects of varying SW depth as would occur from storms, tides, dam operation, and varying seasons. We simulated steady and unsteady hyporheic flow and transport through a riverbed dune using MODFLOW and SEAM3D, and varied SW depth, degree of sediment heterogeneity, amplitude and frequency of sinusoidal fluctuations, among others to determine these effects. We found that increasing steady state surface water depth from 0.1 to 1.0 m increased non-mixing dependent aerobic respiration by 270% and mixing-dependent denitrification by 78% in homogeneous sediment. Heterogeneous hydraulic conductivity fields yielded similar results, with increases in consumption due to variation in correlation length and variance of less than 5%. Daily SW fluctuation, including variation of amplitude, period, and sinusoidal versus instantaneous changes had significantly less impact than longer-term trends in SW depth. There is potential for the hyporheic zone to attenuate NO3- in upwelling groundwater plumes. Restoration efforts may be able to maximize the potential for mixing-dependent reactions in the hyporheic zone by increasing residence times. / Master of Science / Increased nitrogen in runoff from human activities negatively affects surface water quality. The hyporheic zone is where surface water and groundwater interact, and the mixing between the waters can help to this nitrogen to undergo reaction (denitrification), potentially stopping the contaminant from spreading. Previous research has explored this idea, but has not addressed the impact of varying surface water depth, as would realistically occur due to storms, tides, dam operation, and varying seasons. We simulated both constant and fluctuating surface water conditions on a riverbed dune to see the effects on hyporheic flow and denitrification. Test variables included the surface water depth, the degree of sediment heterogeneity, the amplitude and frequency of surface water fluctuations. We found that increasing the steady-state surface water depth had the most dramatic increase on the amount of reaction undergone. This trend was also seen in heterogeneous sediment. Any daily-scale surface water fluctuations, including runs that varied the amplitude, period, and sinusoidal vs instantaneous changes in surface water depth, had significantly less impact than longer-term trends in surface water depth.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2009. / Härtill 4 uppsatser.

No description available.

Preferential flow paths are areas of substantially higher permeability than surrounding media. Macropores and soil pipes are a type of preferential flow path where conduit-like voids in the subsurface are typically greater than three millimeters in diameter. They are known to occur in agricultural and forest soils, often as a result of biological and physical processes. Macropores also exist in stream banks and have the potential to enhance the exchange of water and solutes between the channel and riparian groundwater, yet the geographic distribution of bank macropores is unknown. Here we determined the abundance, distribution, and geometry of naturally occurring surface-connected macropores in the banks of 20 streams across five physiographic provinces in the Eastern United States. We identified a total of 1,748 macropores, which were present in all 20 streams, with 3.8 cm average width, 3.3 cm average height, 11.5 cm average depth, and 27.9 cm average height above water surface elevation. Macropore abundance, distribution and geometry were statistically different between physiographic provinces, stream orders, and soil textures, with the latter being the most important. Macropores tended to be larger and more abundant in soils with a high cohesiveness and a low hydraulic conductivity compared to soils with a low cohesiveness and high hydraulic conductivity. As a result, streams with greater longitudinal heterogeneity of soil texture also had greater heterogeneity of macropore density. However, macropore size and height above baseflow water surface elevation also increased with stream order and therefore stream size. This work represents the first attempt to characterize macropores across a variety of riverine systems and presents evidence that macropores may play an important role in hyporheic exchange within stream banks. These results may have water quality implications, where macropores may enhance hyporheic exchange yet reduce the filtering capacity of riparian buffer zones. / MS / Preferential flow paths are soil cavities or areas of highly permeable porous media surrounded by media with a significantly lower permeability. Macropores are a type of preferential flow path where conduit-like voids in the subsurface are typically greater than three millimeters in diameter. Their formation is often the result of biological processes, such as animal burrows and plant roots, erosive action in subsurface flow, or cracks in the soil, and can enable rapid movement of water. Macropores are known to exist in stream banks and have the potential to enhance the exchange of water and solutes between the stream channel and riparian groundwater, yet the geographic distribution of bank macropores is unknown. This research examines the distribution, abundance, and geometry of naturally occurring macropores in the banks of 20 streams across five physiographic provinces in the eastern United States. Macropores were present in all 20 streams despite variations in physiographic province, stream order, and soil texture. However, soil texture appeared to have the greatest influence on the distribution, abundance, and geometry of macropores. For example, soils primarily containing silt and clay had more macropores than soils consisting of sand or gravel. We suspect this is due to differences in soil cohesiveness and/or hydraulic conductivity. This work represents the first attempt to characterize macropores across a variety of riverine systems and presents evidence that macropores may play an important role in surface water and groundwater exchange within stream banks. These results may have water quality implications, for example, how macropores affect the pollutant filtering capacity of riparian buffer zones.

<p>Topography is one of the primary drivers of physical processes in the rivers and floodplains. Advances in remote-sensing and survey techniques have provided high-resolution representation of the floodplains but information regarding the 3D representation of river channels (commonly known as river bathymetry) is sparsely available. Field surveys along an entire river network in a watershed remains infeasible and algorithms for estimating simple but effective characterization of river channel geometry are hindered by an incomplete understanding of the role of river bathymetry in surface and subsurface processes. </p> <p> The first objective of this dissertation develops an automated framework – System for Producing RIver Network Geometry (SPRING) for improving the geospatial descriptors of a river network. The tool takes as input the DEM and erroneous river centerline to produce spatially consistent river centerlines, banks, and an improved representation of river channel geometry. SPRING can process entire river networks and is not limited single reach applications. The proposed framework is flexible in terms of data requirements, resolution of output datasets and user preferences. It has a user-friendly graphic user interface (GUI) and is appropriate for large-scale applications since it requires minimal user input.</p> <p> A better understanding of the role of bathymetric characteristics in surface-subsurface hydrology and hydrodynamics can facilitate an efficient incorporation of river bathymetry in large river networks. The second objective explores the level of bathymetric detail required for accurately simulating surface and subsurface processes by developing four bathymetric representations using SPRING with reducing level of detail. These bathymetric configurations are simulated using a physically based tightly coupled hydrologic and hydrodynamic model to estimate surface and subsurface fluxes in the floodplains. Comparison of fluxes for the four bathymetric configurations show that the impact of river bathymetry extends beyond surface routing to surface water – groundwater interactions. Channel conveyance capacity and thalweg elevation are the most important characteristics controlling these interactions followed by channel side slope and channel asymmetry. </p> <p> The final objective aims to develop benchmarks for bathymetric characteristics for accurately simulating flooding related physical processes. The sensitivity of surface and subsurface fluxes to error in channel conveyance capacity is investigated across reaches with varying geomorphological characteristics. SPRING is used to create six bathymetric configurations with varying range of error in channel conveyance capacity (ranging from 25% to 300%). They are simulated using a tightly coupled physically distributed model for a flood event and the estimates of water surface elevation, infiltration and lateral seepage are compared. Results show that incorporating channel conveyance capacity with an error of within 25% significantly improves the estimates of surface and subsurface fluxes as compared to those not having any bathymetric correction. For certain reaches, such as those with high drainage area (>1000km²) or low sinuosity (< 1.25), errors of up to 100% in channel conveyance capacity can still improve H&H modeling.</p>

The Swedish municipalities of Gävle and Älvkarleby need new sources of drinking water as the population grows. Gästrike vatten AB has employed the consultant firm Midvatten AB to assess the possibility of a new groundwater extraction site on the Uppsala esker between Älvkarleby and Skutskär in northern Uppland county. It has been observed that the natural recharge to the aquifer in the Uppsala esker might be too low to compensate for a future groundwater extraction and that there is a risk of induced infiltration from the river Dalälven if the water table is lowered. River water might bring organic contaminants into the aquifer and negatively affect the groundwater quality.A solution proposed by Midvatten is to infiltrate the esker with river water free from organic contaminants at infiltration sites. This artificial infiltration is estimated to create new groundwater to compensate for the extraction and stop river water from reaching the extraction wells. There is however, a need to estimate the magnitude of infiltrating river water when the infiltration sites are active.The aim of this study was to estimate the flow of water between the river and a section of the Uppsala esker for a test period during 2017, specifically, the infiltration from the river. In addition to this, changes in flow depending on proposed pumping and infiltration scenarios were modelled.A MODFLOW model was developed in the graphical user interface Groundwater Modeling System (GMS) and its performance was validated against observed aquifer head. The model could accurately represent the head close to the river but was less accurate with increasing distance from the river. Average infiltration from the river varied from 3 to 25 l s-1. The calculated infiltration depended on which extraction well or artificial infiltration site was active and the rate of flow.It was concluded that the distribution of hydraulic conductivity in the aquifer was not sufficiently detailed. A solution could have been to use stratigraphic data from borehole logs instead of a general quaternary deposits map as basis for the distribution of hydraulic conductivity. Artificial infiltration close to the river prevented large volumes of induced infiltration. The accuracy of the model could have been improved if the results were compared to other methods such as particle-tracking, tracer tests and with measurements of the streambed such as seepage meters. / Gävle och Älvkarlebys kommuner är i behov av nya grundvattentäkter för att kunna försörja invånarna med dricksvatten i framtiden. Ett område som är av intresse för de två kommunerna är ett grundvattenmagasin i Uppsalaåsen intill Dalälven mellan Älvkarleby och Skutskär. Vid ett dricksvattenuttag kan vattenbalansen i magasinet ändras. I magasinet uppskattas grundvattenbildningen vara för låg för att pumpa upp nog mycket vatten och bibehålla en stabil dricksvattenförsörjning. När uttaget av grundvatten är högre än grundvattenbildningen sänks grundvattenytan och vatten flödar från andra delar av magasinet eller älven för att kompensera. Älvvattnet bedöms ha en stark hydraulisk koppling med grundvattnet, vilket innebär att det finns en risk att älvvattnet infiltrerar i magasinet och sänker kvalitén på framtida dricksvatten.Konsultföretaget Midvatten AB har i uppdrag att bedöma möjligheten till ett framtida dricksvattenuttag. Midvatten har som lösning anlagt stationer med sprinklerinfiltration för att i framtiden kunna infiltrera avhumifierat älvvatten som på sikt omvandlas till grundvatten. Denna konstgjorda infiltration är också tänkt att hindra älvvatten från att ta sig in i magasinet genom att förse magasinet med den mängd vatten som går förlorad av dricksvattenuttag. Hur mycket älvvatten som tar sig in till grundvattenmagasinet och når brunnarna vid ett framtida uttag och konstgjord infiltration, är dock oklart.Syftet med denna studie var att uppskatta flödet mellan åsens grundvattenmagasin och Dalälven och specifikt infiltrationen av älvvatten. Detta gjordes genom att utveckla en digital MODFLOW-flödesmodell i programmet GMS. Modellen kunde, med hjälp av uppmätta vattennivåer i grundvattenmagasinet och älven, räkna ut hur mycket vatten som flödade in från älven (infiltrerade). Den uträknade infiltrationen låg i genomsnitt på 3-25 l s-1. Infiltrationsmängden berodde på vilken brunn som vattnet pumpades ur, hur mycket som pumpades ut och hur mycket artificiell infiltration som tillfördes i de tre infiltrationsområdena under en period av 2017. Modellen användes även till att uppskatta flödet från älven för 28 tilltänkta scenarier under 2017 med konstant pumpning och konstgjord infiltration i de olika brunnarna och infiltrationsstationerna.Resultaten visade att modellen kunde uppskatta grundvattenmagasinets vattennivåer nära älven men inte på längre avstånd ifrån älven. Detta berodde på att magasinets hydrauliska parametrar inte var korrekt fördelade. Fördelningen kunde ha förbättrats om de baserats på jordarter från borrprotokoll istället för en jordartskarta. Modellen visade att mycket lite älvvatten flödar in i akviferen om vatten artificiellt infiltreras nära älven. För att resultaten av den här studien ska bli tillförlitliga krävs det att resultaten jämförs med andra metoder som använder sig av förslagsvis partikelspårningsmodeller, spårämnesstudier eller flödesmätningar av flodbädden.

This thesis shows how the Process Analysis Method (PAM) can be applied to assess technologies used to mitigate arsenic from drinking water in rural India, using a set of sustainability indicators. Stakeholder perspectives, gathered from a fieldwork survey of 933 households in West Bengal in 2012, played a significant role in this assessment. This research found that the ‘Most Important’ issues as specified by the technology users are cost, trust, distance from their home to the clean water source (an indicator of convenience), and understanding the health effects of arsenic. It was also found that none of the ten technologies evaluated are economically viable, as many do not charge user-fees, which creates reliance upon donations to meet recurring costs. Utilisation of a technology is strongly related to sociocultural capital, but in many cases, features that contribute to sociocultural value, like regular testing of the treated water, are not included in the financial budget. It is suggested that increased awareness might change attitudes to arsenic-rich waste and its disposal protocols. This waste is often currently discarded in an uncontrolled manner in the local environment, giving rise to the possibility of point-source recontamination. All technologies proved to have difficulties in dealing with waste, except the Tipot and Dug wells which produce no waste. Of the methods considered, the BESU technology scored highest, but still only with 47-62% of the maximum scores achievable within each domain. This explains the widespread failure of mitigation projects across the region. The indicators and metrics show where improvements can be made. A model scheme based on these findings is outlined which could be applied with the objective of increasing utilisation and improving sustainability. It can be concluded that a product stewardship approach should be taken in regard to design, implementation and operation of the technologies, including the creation of a regulated toxic waste collection and disposal industry.

Groundwater flow modelling provides an important quantitative instrument for addressing issues related to the quantity and quality of groundwater and the connected water resources. Consequently, groundwater flow models have been developed and used ubiquitously in science to deepen the understanding of subsurface processes and their drivers as well as management and planning tools. The present work investigates how numerical models can be linked to field investigations and public databases to quantitatively approach questions in the area of groundwater research. The primary goal is to develop new, efficient ways to overcome limitations of the individual hydrological concepts for solving specific hydrological problems and to increase the understanding of practical applicability of different methods. For this purpose, tailor-made approaches were developed for different study areas covering diverse spatial scales: the hydrology of a small mining lake, the riparian aquifer at the scale of a single meander as well as the aquifer systems of a large-scale river basin in China. The first part of the work deals with the physical and mathematical modelling of water constituents balance in a meromictic mining lake in Lusatia. The capability of using a rather simple mass-balance model based on a sufficient dataset of field data to evaluate lake stratification and lake-groundwater interaction were shown. In the second part, a transient numerical groundwater flow model was developed for the riparian aquifer of a stream meander and was calibrated by three different salt tracer tests. The model was used to proof the reliability of subsurface travel times derived from time series analysis and to give insights in the riparian zone dynamics during changing hydraulic gradients. The third part of the work describes the methodology to conduct risk assessment of groundwater contamination on the large catchment scale of the Songhua River in China. A comprehensive literature study was conducted to get an overview about measurement data on water quality data in China. A three-dimensional numerical flow and mass transport model was applied to access the flow and matter transport dynamics in the aquifer system of a sub-basin considering changing groundwater exploitation scenarios. Consequently, numerical groundwater modelling was combined with processed remote sensing and web mapping service data to overcome field data limitations and to derive groundwater vulnerability, groundwater hazard and groundwater risk maps for the entire Songhua River Basin. Summarizing, this doctoral thesis could develop new methods of combining field measurements, data assimilation and aggregation from various sources and groundwater modelling strategies and successfully apply these methods to find solutions on problems of multiple scales and across water systems. / Die Grundwassermodellierung stellt eine wichtige wissenschaftliche Methode zur quantitativen Analyse von Fragestellungen zum Schutz der Menge und Güte der Grundwasserressourcen sowie der angeschlossenen Wasserkörper dar. Dementsprechend werden Grundwassermodelle sowohl für Planungs- und Bewertungszwecke im Wasserressourcenmanagement als auch zur wissenschaftlichen Erforschung der Prozesse im Untergrund entwickelt und angewendet. Die vorliegende Arbeit untersucht in diesem Rahmen, wie numerische Modelle, Feldmessungen und Daten generiert aus Fernerkundungsdaten und Webplattformen systematisch verknüpft werden können, um Fragestellungen im Bereich der Grundwasserforschung quantitativ zu beantworten. Das Ziel der Arbeit ist es neue effiziente Abläufe zu entwickeln, die die Limitierung der einzelnen Methoden überwinden und diese auf deren Anwendbarkeit für die Lösung spezifischer hydrologischer Probleme zu analysieren. Zu diesem Zweck wurden in dieser Doktorarbeit fallspezifische Lösungen für verschiedene Untersuchungsgebiete entwickelt, die sowohl in der räumlichen Skale als auch in den zu untersuchenden hydrologischen Fragestellungen eine große Diversität aufweisen. Im ersten Teil der Arbeit wurde die Massenbilanz von Wasserinhaltsstoffen in einem meromiktischen Tagebaurestsee im Lausitzer Revier durch physikalische und mathematische Modellierungsmethoden untersucht. Dabei konnte gezeigt werden, dass auf Basis einer gewonnenen mehrjährigen Zeitreihe von Messdaten ein einfaches Massenbilanzmodell in der Lage ist, sowohl Seeschichtungs- als auch Grundwasseraustauschdynamiken quantitativ zu beschreiben. Der zweite Teil der Arbeit umfasst die Entwicklung eines transienten numerischen Grundwassermodells für den quartären Uferaquifer im Bereich eines Flussmäanders der Selke welches anhand von Daten aus mehreren Salztracertests kalibriert wurde. Das Modell wurde dafür verwendet die transienten Verweilzeiten in der gesättigten Zone des Mäanderbogens unter dem Einfluss dynamischer hydraulischer Bedingungen zu untersuchen. Die Ergebnisse wurden im Anschluss mit Verweilzeiten verglichen, die aus der Analyse der zeitlichen Verschiebung von gemessenen elektrischen Leitfähigkeitszeitreihen zwischen Fluss und Grundwassermessstellen gewonnen wurden. Durch dieses kombinierte Verfahren konnten sowohl die Beschränkungen der zeitreihenbasierten Verweilzeitberechnung aufgezeigt als auch ein tieferes Systemverständnis für die Interaktionsdynamiken zwischen Grund- und Flusswasser auf der Mäanderskala gewonnen werden. Der dritte Teil der Arbeit beschreibt die Vorgehensweise für die Bewertung des Grundwasserkontaminationsrisikos im Einzugsgebiet des Songhua Flusses in China. Eine umfassende Literaturstudie wurde durchgeführt, um einen Überblick über die Verfügbarkeit von Messdaten zur Belastung der Wasserressourcen Chinas mit organischen Schadstoffen zu erhalten. Danach wurde für ein Teileinzugsgebiet ein dreidimensionales numerisches Grundwassermodell auf Basis der vorhandenen hydrogeologischen Daten aufgebaut. Dieses wurde dazu verwendet die Änderungen im Stofftransports und den Schadstoffkonzentrationen innerhalb des Aquifersystems unter steigenden Entnahmeraten zu analysieren. Basierend auf diesen Studien wurden auf der Skale des Gesamteinzugsgebiets, um die beschränkte Verfügbarkeit von Felddaten auszugleichen, die Ergebnisse der numerischen Grundwassermodellierung mit Fernerkundungsdaten und Webdatenbanken in einem Indexsystem kombiniert mit dem für die oberflächennahen Aquifere Vulnerabilität, Gefährdungspotential und Verschmutzungsrisiko in einer räumlichen Auflösung von 1 km² bestimmt wurden. Zusammenfassend konnten durch die vorliegende Doktorarbeit neue passgenaue Methoden zur effektiven Kombination von in-situ Messungen, der Datenerhebung und Datenintegration aus vielfältigen Datenquellen sowie numerischen Grundwassermodellierungsstrategien entwickelt und zur Lösung der untersuchten hydrologischer Fragestellen auf den verschiedenen Skalen und über die Grenzen der einzelnen hydrologischen Teilsysteme hinaus erfolgreich angewandt werden.

Groundwater flow modelling provides an important quantitative instrument for addressing issues related to the quantity and quality of groundwater and the connected water resources. Consequently, groundwater flow models have been developed and used ubiquitously in science to deepen the understanding of subsurface processes and their drivers as well as management and planning tools. The present work investigates how numerical models can be linked to field investigations and public databases to quantitatively approach questions in the area of groundwater research. The primary goal is to develop new, efficient ways to overcome limitations of the individual hydrological concepts for solving specific hydrological problems and to increase the understanding of practical applicability of different methods. For this purpose, tailor-made approaches were developed for different study areas covering diverse spatial scales: the hydrology of a small mining lake, the riparian aquifer at the scale of a single meander as well as the aquifer systems of a large-scale river basin in China. The first part of the work deals with the physical and mathematical modelling of water constituents balance in a meromictic mining lake in Lusatia. The capability of using a rather simple mass-balance model based on a sufficient dataset of field data to evaluate lake stratification and lake-groundwater interaction were shown. In the second part, a transient numerical groundwater flow model was developed for the riparian aquifer of a stream meander and was calibrated by three different salt tracer tests. The model was used to proof the reliability of subsurface travel times derived from time series analysis and to give insights in the riparian zone dynamics during changing hydraulic gradients. The third part of the work describes the methodology to conduct risk assessment of groundwater contamination on the large catchment scale of the Songhua River in China. A comprehensive literature study was conducted to get an overview about measurement data on water quality data in China. A three-dimensional numerical flow and mass transport model was applied to access the flow and matter transport dynamics in the aquifer system of a sub-basin considering changing groundwater exploitation scenarios. Consequently, numerical groundwater modelling was combined with processed remote sensing and web mapping service data to overcome field data limitations and to derive groundwater vulnerability, groundwater hazard and groundwater risk maps for the entire Songhua River Basin. Summarizing, this doctoral thesis could develop new methods of combining field measurements, data assimilation and aggregation from various sources and groundwater modelling strategies and successfully apply these methods to find solutions on problems of multiple scales and across water systems. / Die Grundwassermodellierung stellt eine wichtige wissenschaftliche Methode zur quantitativen Analyse von Fragestellungen zum Schutz der Menge und Güte der Grundwasserressourcen sowie der angeschlossenen Wasserkörper dar. Dementsprechend werden Grundwassermodelle sowohl für Planungs- und Bewertungszwecke im Wasserressourcenmanagement als auch zur wissenschaftlichen Erforschung der Prozesse im Untergrund entwickelt und angewendet. Die vorliegende Arbeit untersucht in diesem Rahmen, wie numerische Modelle, Feldmessungen und Daten generiert aus Fernerkundungsdaten und Webplattformen systematisch verknüpft werden können, um Fragestellungen im Bereich der Grundwasserforschung quantitativ zu beantworten. Das Ziel der Arbeit ist es neue effiziente Abläufe zu entwickeln, die die Limitierung der einzelnen Methoden überwinden und diese auf deren Anwendbarkeit für die Lösung spezifischer hydrologischer Probleme zu analysieren. Zu diesem Zweck wurden in dieser Doktorarbeit fallspezifische Lösungen für verschiedene Untersuchungsgebiete entwickelt, die sowohl in der räumlichen Skale als auch in den zu untersuchenden hydrologischen Fragestellungen eine große Diversität aufweisen. Im ersten Teil der Arbeit wurde die Massenbilanz von Wasserinhaltsstoffen in einem meromiktischen Tagebaurestsee im Lausitzer Revier durch physikalische und mathematische Modellierungsmethoden untersucht. Dabei konnte gezeigt werden, dass auf Basis einer gewonnenen mehrjährigen Zeitreihe von Messdaten ein einfaches Massenbilanzmodell in der Lage ist, sowohl Seeschichtungs- als auch Grundwasseraustauschdynamiken quantitativ zu beschreiben. Der zweite Teil der Arbeit umfasst die Entwicklung eines transienten numerischen Grundwassermodells für den quartären Uferaquifer im Bereich eines Flussmäanders der Selke welches anhand von Daten aus mehreren Salztracertests kalibriert wurde. Das Modell wurde dafür verwendet die transienten Verweilzeiten in der gesättigten Zone des Mäanderbogens unter dem Einfluss dynamischer hydraulischer Bedingungen zu untersuchen. Die Ergebnisse wurden im Anschluss mit Verweilzeiten verglichen, die aus der Analyse der zeitlichen Verschiebung von gemessenen elektrischen Leitfähigkeitszeitreihen zwischen Fluss und Grundwassermessstellen gewonnen wurden. Durch dieses kombinierte Verfahren konnten sowohl die Beschränkungen der zeitreihenbasierten Verweilzeitberechnung aufgezeigt als auch ein tieferes Systemverständnis für die Interaktionsdynamiken zwischen Grund- und Flusswasser auf der Mäanderskala gewonnen werden. Der dritte Teil der Arbeit beschreibt die Vorgehensweise für die Bewertung des Grundwasserkontaminationsrisikos im Einzugsgebiet des Songhua Flusses in China. Eine umfassende Literaturstudie wurde durchgeführt, um einen Überblick über die Verfügbarkeit von Messdaten zur Belastung der Wasserressourcen Chinas mit organischen Schadstoffen zu erhalten. Danach wurde für ein Teileinzugsgebiet ein dreidimensionales numerisches Grundwassermodell auf Basis der vorhandenen hydrogeologischen Daten aufgebaut. Dieses wurde dazu verwendet die Änderungen im Stofftransports und den Schadstoffkonzentrationen innerhalb des Aquifersystems unter steigenden Entnahmeraten zu analysieren. Basierend auf diesen Studien wurden auf der Skale des Gesamteinzugsgebiets, um die beschränkte Verfügbarkeit von Felddaten auszugleichen, die Ergebnisse der numerischen Grundwassermodellierung mit Fernerkundungsdaten und Webdatenbanken in einem Indexsystem kombiniert mit dem für die oberflächennahen Aquifere Vulnerabilität, Gefährdungspotential und Verschmutzungsrisiko in einer räumlichen Auflösung von 1 km² bestimmt wurden. Zusammenfassend konnten durch die vorliegende Doktorarbeit neue passgenaue Methoden zur effektiven Kombination von in-situ Messungen, der Datenerhebung und Datenintegration aus vielfältigen Datenquellen sowie numerischen Grundwassermodellierungsstrategien entwickelt und zur Lösung der untersuchten hydrologischer Fragestellen auf den verschiedenen Skalen und über die Grenzen der einzelnen hydrologischen Teilsysteme hinaus erfolgreich angewandt werden.