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Okke Batelaan - One of the best experts on this subject based on the ideXlab platform.
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Delineation of spatial-temporal patterns of groundWater/surface-Water Interaction along a river reach (Aa River, Belgium) with transient thermal modeling
Hydrogeology Journal, 2017Co-Authors: Christian Anibas, Abebe Debele Tolche, Gert Ghysels, Jiri Nossent, Uwe Schneidewind, Marijke Huysmans, Okke BatelaanAbstract:Among the advances made in analytical and numerical analysis methods to quantify groundWater/surface-Water Interaction, one methodology that stands out is the use of heat as an environmental tracer. A large data set of river and riverbed temperature profiles from the Aa River in Belgium has been used to examine the spatial-temporal variations of groundWater/surface-Water Interaction. Exchange fluxes were calculated with the numerical heat-transport code STRIVE. The code was applied in transient mode to overcome previous limitations of steady-state analysis, and allowed for the calculation of model quality. In autumn and winter the mean exchange fluxes reached −90 mm d−1, while in spring and early summer fluxes were −42 mm d−1. Predominantly gaining conditions occurred along the river reach; however, in a few areas the direction of flow changed in time. The river banks showed elevated fluxes up to a factor of 3 compared to the center of the river. Higher fluxes were detected in the upstream section of the reach. Due to the influence of exchange fluxes along the river banks, larger temporal variations were found in the downstream section. The exchange fluxes at the river banks seemed more driven by variable local exchange flows, while the center of the river was dominated by deep and steady regional groundWater flows. These spatial and temporal differences in groundWater/surface-Water exchange show the importance of long-term investigations on the driving forces of hyporheic processes across different scales.
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From streambed temperature measurements to spatial-temporal flux quantification : using the LPML method to study GroundWater-Surface Water Interaction
Hydrological Processes, 2015Co-Authors: Christian Anibas, Uwe Schneidewind, Gerd Vandersteen, Ingeborg Joris, Piet Seuntjens, Okke BatelaanAbstract:Knowledge on groundWater–surface Water Interaction and especially on exchange fluxes between streams and aquifers is an important prerequisite for the study of transport and fate of contaminants and nutrients in the hyporheic zone. One possibility to quantify groundWater–surface Water exchange fluxes is by using heat as an environmlental tracer. Modern field equipment including multilevel temperature sticks and the novel open-source analysis tool LPML make this technique ever more attractive. The recently developed LPML method solves the one-dimensional fluid flow and heat transport equation by combining a local polynomial method with a maximum likelihood estimator. In this study, we apply the LPML method on field data to quantify the spatial and temporal variability of vertical fluxes and their uncertainties from temperature–time series measured in a Belgian lowland stream. Over several months, temperature data were collected with multilevel temperature sticks at the streambed top and at six depths for a small stream section. Long-term estimates show a range from gaining fluxes of −291 mm day−1 to loosing fluxes of 12 mm day−1; average seasonal fluxes ranged from −138 mm day−1 in winter to −16 mm day−1 in summer. With our analyses, we could determine a high spatial and temporal variability of vertical exchange fluxes for the investigated stream section. Such spatial and temporal variability should be taken into account in biogeochemical cycling of carbon, nutrients and metals and in fate analysis of contaminant plumes. In general, the stream section was gaining during most of the observation period. Two short-term high stream stage events, seemingly caused by blockage of the stream outlet, led to a change in flow direction from gaining to losing conditions. We also found more discharge occurring at the outer stream bank than at the inner one indicating a local flow-through system. With the conducted analyses, we were able to advance our understanding of the regional groundWater flow system. Copyright © 2015 John Wiley & Sons, Ltd.
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Combining flux estimation techniques to improve characterization of groundWater–surface-Water Interaction in the Zenne River, Belgium
Hydrogeology Journal, 2014Co-Authors: Juliette Dujardin, Christian Anibas, Serge Brouyère, Jan Bronders, Pierre Jamin, Kelly Hamonts, Winnie Dejonghe, Okke BatelaanAbstract:The management of urban rivers which drain contaminated groundWater is suffering from high uncertainties regarding reliable quantification of groundWater fluxes. Independent techniques are combined for estimating these fluxes towards the Zenne River, Belgium. Measured hydraulic gradients, temperature gradients in conjunction with a 1D-heat and fluid transport model, direct flux measurement with the finite volume point dilution method (FVPDM), and a numerical groundWater flow model are applied, to estimate vertical and horizontal groundWater fluxes and groundWater–surface-Water Interaction. Hydraulic gradient analysis, the temperature-based method, and the groundWater flow model yielded average vertical fluxes of –61, –45 and –40 mm/d, respectively. The negative sign indicates upward flow to the river. Changes in exchange fluxes are sensitive to precipitation but the river remained gaining during the examined period. The FVPDM, compared to the groundWater flow model, results in two very high estimates of the horizontal Darcy fluxes (2,600 and 500 mm/d), depending on the depth of application. The obtained results allow an evaluation of the temporal and spatial variability of estimated fluxes, thereby helping to curtail possible consequences of pollution of the Zenne River as final receptor, and contribute to the setup of a suitable remediation plan for the contaminated study site.
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GroundWater-Surface Water Interaction in Lake Nasser, Southern Egypt
Hydrological Processes, 2012Co-Authors: Mohamed Elsawwaf, Okke Batelaan, Jan Feyen, M BakrAbstract:A cross-sectional model, based on the two dimensional groundWater flow equation of Edelman, was applied at seven transects distributed over four geological cross sections to estimate groundWater heads and recharge from/or groundWater discharge to Lake Nasser. The lake with a length of 500 km and an average width of 12 km was created over the period 1964–1970, the time for constructing the Aswan High Dam (AHD). The model, constrained by regional-scale groundWater flow and groundWater head data in the vicinity of the lake, was successfully calibrated to timeseries of piezometeric heads collected at the cross sections in the period 1965–2004. Inverse modeling yielded high values for the horizontal hydraulic conductivity in the range of 6.0 to 31.1 m day−1 and storage coefficient between 0.01 and 0.40. The results showed the existence of a strong vertical anisotropy of the aquifer. The calibrated horizontal permeability is systematically higher than the vertical permeability (≈1000:1). The calibrated model was used to explore the recharge from/or groundWater discharge to Lake Nasser at the seven transects for a 40-year period, i.e. from 1965 to 2004. The analysis for the last 20-year period, 1985–2004, revealed that recharge from Lake Nasser reduced by 37% compared to the estimates for the first 20-year period, 1965–1984. In the period 1965–2004, seepage of Lake Nasser to the surrounding was estimated at 1.15 × 109 m3 year−1. This led to a significant rise of the groundWater table. Variance-based sensitivity and uncertainty analysis on the Edelman results were conducted applying quasi-Monte Carlo sequences (Latin Hypercube sampling). The maximum standard deviation of the total uncertainty on the groundWater table was 0.88 m at Toshka (west of the lake). The distance from the lake, followed by the storage coefficient and hydraulic conductivity, were identified as the most sensitive parameters. Copyright © 2012 John Wiley & Sons, Ltd.
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A hierarchical approach on GroundWater-Surface Water Interaction in wetlands along the upper Biebrza River, Poland
Hydrology and Earth System Sciences, 2012Co-Authors: Christian Anibas, Kerst Buis, Patrick Meire, Boud Verbeiren, Jarosław Chormański, L. De Doncker, Tomasz Okruszko, Okke BatelaanAbstract:As recognized in the European Water Framework Directive, groundWater-dependent wetlands and their diverse ecosystems have important functions which need to be protected. The vegetation in such habitats is often dependent on quality, quantity and patterns of river discharge and GroundWater-Surface Water Interaction on a local or reach scale. Since GroundWater-Surface Water exchange studies on natural rivers and wetlands with organic soils are scarce, more functional analysis is needed. To this end we combined different field methods including piezometer nests, temperature as tracer and seepage meter measurements. Some of these measurements were used as inputs and/or as validation for the numerical 1-D heat transport model STRIVE. In transient mode the model was used to calculate spatially distributed vertical exchange fluxes from temperature profiles measured at the upper Biebrza River in Poland over a period of nine months. Time series of estimated fluxes and hydraulic head gradients in the hyporheic zone were used to estimate the temporal variability of GroundWater-Surface Water exchange. This paper presents a hierarchical approach for quantifying and interpreting GroundWater-Surface Water Interaction in space and time. The results for the upper Biebrza show predominantly upward Water fluxes, sections of recharge, however, exist along the reach. The fluxes depend more on hydraulic gradients than on riverbed conductivity. This indicates that the fluvio-plain scale is required for interpreting the exchange fluxes, which are estimated on a local scale. The paper shows that a conceptual framework is necessary for understanding the GroundWater-Surface Water Interaction processes, where the exchange fluxes are influenced by local factors like the composition of the riverbed and the position of the measurement on a local scale, and by regional factors like the hydrogeology and topography on a fluvio-plain scale. The hierarchical methodology increases the confidence in the estimated exchange fluxes and improves the process understanding. The accuracy of the measurements and related uncertainties, however, remain challenges for wetland environments. Gaining quantitative information on GroundWater-Surface Water Interaction can improve modeling confidence and as a consequence helps to develop effective procedures for management and conservation of valuable groundWater dependent wetlands.
Christian Anibas - One of the best experts on this subject based on the ideXlab platform.
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Delineation of spatial-temporal patterns of groundWater/surface-Water Interaction along a river reach (Aa River, Belgium) with transient thermal modeling
Hydrogeology Journal, 2017Co-Authors: Christian Anibas, Abebe Debele Tolche, Gert Ghysels, Jiri Nossent, Uwe Schneidewind, Marijke Huysmans, Okke BatelaanAbstract:Among the advances made in analytical and numerical analysis methods to quantify groundWater/surface-Water Interaction, one methodology that stands out is the use of heat as an environmental tracer. A large data set of river and riverbed temperature profiles from the Aa River in Belgium has been used to examine the spatial-temporal variations of groundWater/surface-Water Interaction. Exchange fluxes were calculated with the numerical heat-transport code STRIVE. The code was applied in transient mode to overcome previous limitations of steady-state analysis, and allowed for the calculation of model quality. In autumn and winter the mean exchange fluxes reached −90 mm d−1, while in spring and early summer fluxes were −42 mm d−1. Predominantly gaining conditions occurred along the river reach; however, in a few areas the direction of flow changed in time. The river banks showed elevated fluxes up to a factor of 3 compared to the center of the river. Higher fluxes were detected in the upstream section of the reach. Due to the influence of exchange fluxes along the river banks, larger temporal variations were found in the downstream section. The exchange fluxes at the river banks seemed more driven by variable local exchange flows, while the center of the river was dominated by deep and steady regional groundWater flows. These spatial and temporal differences in groundWater/surface-Water exchange show the importance of long-term investigations on the driving forces of hyporheic processes across different scales.
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From streambed temperature measurements to spatial-temporal flux quantification : using the LPML method to study GroundWater-Surface Water Interaction
Hydrological Processes, 2015Co-Authors: Christian Anibas, Uwe Schneidewind, Gerd Vandersteen, Ingeborg Joris, Piet Seuntjens, Okke BatelaanAbstract:Knowledge on groundWater–surface Water Interaction and especially on exchange fluxes between streams and aquifers is an important prerequisite for the study of transport and fate of contaminants and nutrients in the hyporheic zone. One possibility to quantify groundWater–surface Water exchange fluxes is by using heat as an environmlental tracer. Modern field equipment including multilevel temperature sticks and the novel open-source analysis tool LPML make this technique ever more attractive. The recently developed LPML method solves the one-dimensional fluid flow and heat transport equation by combining a local polynomial method with a maximum likelihood estimator. In this study, we apply the LPML method on field data to quantify the spatial and temporal variability of vertical fluxes and their uncertainties from temperature–time series measured in a Belgian lowland stream. Over several months, temperature data were collected with multilevel temperature sticks at the streambed top and at six depths for a small stream section. Long-term estimates show a range from gaining fluxes of −291 mm day−1 to loosing fluxes of 12 mm day−1; average seasonal fluxes ranged from −138 mm day−1 in winter to −16 mm day−1 in summer. With our analyses, we could determine a high spatial and temporal variability of vertical exchange fluxes for the investigated stream section. Such spatial and temporal variability should be taken into account in biogeochemical cycling of carbon, nutrients and metals and in fate analysis of contaminant plumes. In general, the stream section was gaining during most of the observation period. Two short-term high stream stage events, seemingly caused by blockage of the stream outlet, led to a change in flow direction from gaining to losing conditions. We also found more discharge occurring at the outer stream bank than at the inner one indicating a local flow-through system. With the conducted analyses, we were able to advance our understanding of the regional groundWater flow system. Copyright © 2015 John Wiley & Sons, Ltd.
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Combining flux estimation techniques to improve characterization of groundWater–surface-Water Interaction in the Zenne River, Belgium
Hydrogeology Journal, 2014Co-Authors: Juliette Dujardin, Christian Anibas, Serge Brouyère, Jan Bronders, Pierre Jamin, Kelly Hamonts, Winnie Dejonghe, Okke BatelaanAbstract:The management of urban rivers which drain contaminated groundWater is suffering from high uncertainties regarding reliable quantification of groundWater fluxes. Independent techniques are combined for estimating these fluxes towards the Zenne River, Belgium. Measured hydraulic gradients, temperature gradients in conjunction with a 1D-heat and fluid transport model, direct flux measurement with the finite volume point dilution method (FVPDM), and a numerical groundWater flow model are applied, to estimate vertical and horizontal groundWater fluxes and groundWater–surface-Water Interaction. Hydraulic gradient analysis, the temperature-based method, and the groundWater flow model yielded average vertical fluxes of –61, –45 and –40 mm/d, respectively. The negative sign indicates upward flow to the river. Changes in exchange fluxes are sensitive to precipitation but the river remained gaining during the examined period. The FVPDM, compared to the groundWater flow model, results in two very high estimates of the horizontal Darcy fluxes (2,600 and 500 mm/d), depending on the depth of application. The obtained results allow an evaluation of the temporal and spatial variability of estimated fluxes, thereby helping to curtail possible consequences of pollution of the Zenne River as final receptor, and contribute to the setup of a suitable remediation plan for the contaminated study site.
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A hierarchical approach on GroundWater-Surface Water Interaction in wetlands along the upper Biebrza River, Poland
Hydrology and Earth System Sciences, 2012Co-Authors: Christian Anibas, Kerst Buis, Patrick Meire, Boud Verbeiren, Jarosław Chormański, L. De Doncker, Tomasz Okruszko, Okke BatelaanAbstract:As recognized in the European Water Framework Directive, groundWater-dependent wetlands and their diverse ecosystems have important functions which need to be protected. The vegetation in such habitats is often dependent on quality, quantity and patterns of river discharge and GroundWater-Surface Water Interaction on a local or reach scale. Since GroundWater-Surface Water exchange studies on natural rivers and wetlands with organic soils are scarce, more functional analysis is needed. To this end we combined different field methods including piezometer nests, temperature as tracer and seepage meter measurements. Some of these measurements were used as inputs and/or as validation for the numerical 1-D heat transport model STRIVE. In transient mode the model was used to calculate spatially distributed vertical exchange fluxes from temperature profiles measured at the upper Biebrza River in Poland over a period of nine months. Time series of estimated fluxes and hydraulic head gradients in the hyporheic zone were used to estimate the temporal variability of GroundWater-Surface Water exchange. This paper presents a hierarchical approach for quantifying and interpreting GroundWater-Surface Water Interaction in space and time. The results for the upper Biebrza show predominantly upward Water fluxes, sections of recharge, however, exist along the reach. The fluxes depend more on hydraulic gradients than on riverbed conductivity. This indicates that the fluvio-plain scale is required for interpreting the exchange fluxes, which are estimated on a local scale. The paper shows that a conceptual framework is necessary for understanding the GroundWater-Surface Water Interaction processes, where the exchange fluxes are influenced by local factors like the composition of the riverbed and the position of the measurement on a local scale, and by regional factors like the hydrogeology and topography on a fluvio-plain scale. The hierarchical methodology increases the confidence in the estimated exchange fluxes and improves the process understanding. The accuracy of the measurements and related uncertainties, however, remain challenges for wetland environments. Gaining quantitative information on GroundWater-Surface Water Interaction can improve modeling confidence and as a consequence helps to develop effective procedures for management and conservation of valuable groundWater dependent wetlands.
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A hierarchical approach on GroundWater-Surface Water Interaction in wetlands along the upper Biebrza River, Poland
Hydrology and Earth System Sciences Discussions, 2011Co-Authors: Christian Anibas, Kerst Buis, Patrick Meire, Boud Verbeiren, Jarosław Chormański, L. De Doncker, Tomasz Okruszko, Okke BatelaanAbstract:Abstract. GroundWater-Surface Water exchange studies on natural rivers and wetlands dominated by organic soils are scarce. We present a hierarchical approach to quantitatively investigate and interpret GroundWater-Surface Water Interaction in space and time by applying a combination of different field methods including piezometer nests, temperature and seepage measurements. The numerical 1-D heat transport model of STRIVE is used in transient mode to calculate vertical fluxes from thermal profiles measured along the upper Biebrza River, Poland over a period of nine months. The calculated fluxes show no clear spatial pattern of exchange fluxes unless an interpolation of the point estimates on a reach scale is performed. Significance of differences in net exchange rates versus morphological features are investigated with statistical tests. Time series of temperature and hydraulic head of the hyporheic zone are used to estimate the temporal variability of the GroundWater-Surface Water exchange. Seepage meter measurements and slug tests were used for cross validation of modelled fluxes. Results show a strong heterogeneity of the thermal and physical soil properties along the reach, leading to a classification of these parameters for modelling purposes. The GroundWater-Surface Water exchange shows predominantly upward Water fluxes, however alternating sections of recharge exist. The exchange fluxes are significantly different dependent on the position of the river in the valley floor and the river morphology where fluxes are more dependent on hydraulic gradients than on river bed conductivity. Sections of higher fluxes are linked to the vicinity of the morainic plateau surrounding the rivers alluvium and to meanders, indicating that a perspective on the fluvio-plain scale is required for interpreting the estimated exchange fluxes. Since the vertical component of the exchange fluxes cannot explain the magnitude of the change in river discharge, a lateral flow component across the alluvial plain has to be responsible. The hierarchical methodology increases the confidence in the estimated exchange fluxes and improves the process understanding, however the accuracy of the measurements and related uncertainties remain challenges for wetland environments.
Jonathan Levy - One of the best experts on this subject based on the ideXlab platform.
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Review: GroundWater management and groundWater/surface-Water Interaction in the context of South African Water policy
Hydrogeology Journal, 2012Co-Authors: Jonathan Levy, Yongxin XuAbstract:RésuméL’Interaction eau souterraine/eau de surface est un centre d’intérêt croissant en Afrique étant donné son importance pour les systèmes écologiques et leur pérennité. Dans le National Water Act sud-africain de 1998 (NWA), des autorisations d’utilisation de l’eau, incluant l’eau souterraine, sont accordées seulement après évaluation de la Réserve, de la quantité d’eau requise pour satisfaire les besoins humains essentiels et préserver une certaine intégrité écologique. Une évaluation précise des contributions de l’eau souterraine aux écosystèmes pour la mise en œuvre du NWA s’avère être un défi; beaucoup d’aquifères d’Afrique du Sud sont dans des encaissants rocheux fracturés hétérogènes et anisotropes. Cet article passe en revue les concepts et approches actuels des Interactions eau souterraine/eau de surface dans le contexte des politiques d’Afrique du Sud. Certaines expériences piège sélectionnées sont mises en évidence. L’approche la plus commune en Afrique du Sud est l’estimation des flux annuels moyens à l’échelle des bassins versants du quatrième ordre (∼500 km^2) avec des techniques de séparation du débit de base, puis de soustraction des taux de décharge et de recharge. Cette approche pourrait être un bon début, mais elle ignore la variabilité spatiale et temporelle, éludant potentiellement les impacts locaux associés à la localisation des puits de production. Comme le NWA d’Afrique du Sud a déjà fait des émules dans de nombreux pays dont la Zambie, le Zimbabwe et le Kenya, les succès et les échecs de l’expérience sud-africaine concernant l’Interaction eau souterraine/eau de surface seront analysés pour guider les orientations de la politique future.ResumoA interacção água subterrânea/água superficial recebe cada vez maior atenção em África, devido à sua importância para os sistemas ecológicos e para a sustentabilidade. Na África do Sul, no Acto Nacional da Água (NWA) de 1998, as licenças de uso da água, incluindo a água subterrânea, são garantidas apenas depois de definidas as Reservas, a quantidade de água necessária para suprimir as necessidades humanas básicas e a preservação de alguma integridade ecológica. A quantificação acurada das contribuições da água subterrânea para os ecossistemas para uma aplicação com sucesso da implementação do NWA provou-se ser desafiadora; muitos dos aquíferos situam-se em meios heterogéneos e anisotrópicos, em rochas fracturadas. Este documento revê a conceptualização corrente e os processos de investigação que têm sido aplicados às interacções águas subterrâneas/águas superficiais no contexto das políticas Sul-Africanas. Algumas experiências seleccionadas são enfatizadas. A aproximação mais comum na Áfria do Sul é a estimação dos fluxos anuais médios à escala da bacia de quarta ordem (∼500 km^2), utilizando técnicas de separação do fluxo de base e subtraindo então a descarga subterrânea da taxa de recarga. Esta aproximação pode ser um bom começo, mas ignora a variabilidade espacial e temporal, negligenciando potencialmente os impactes locais associados à exploração de campos de captações. Como o NWA Sul-Africano já foi emulado por muitos outros países, incluindo a Zâmbia, o Zimbabué e o Quénia, os sucessos e insucessos da experiência Sul-Africana ao lidar com as interacções águas subterrâneas/águas superficiais serão analisadas, para guiar as direcções políticas futuras.AbstractGroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km^2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions.ResumenLa interacción agua subterránea/agua superficial está recibiendo una creciente atención en África debido a su importancia en los sistema ecológicos y su sustentabilidad. En Sudáfrica, según la Ley Nacional de Agua (NWA) de 1998, las licencias de uso del agua, incluidas las aguas subterráneas, sólo se conceden después de definir la Reserva, que es la cantidad de agua necesaria para abastecer las necesidades humanas básicas y para preservar la integridad ecológica. La cuantificación precisa de la contribución del agua subterránea a los ecosistemas para la implementación exitosa de la NWA resulta difícil, ya que muchos de los acuíferos de Sudáfrica presentan la configuración heterogénea y anisotrópica en rocas fracturadas. En este documento se realiza un revisión de los conceptos y enfoques actuales de la investigación de la interacción aguas subterráneas/aguas superficiales en el contexto de las políticas de Sudáfrica. Se destacan algunas experiencias seleccionadas con las dificultades encontradas. El enfoque más común en Sudáfrica es la estimación de los flujos anuales promedio en cuencas de drenaje de cuarto orden (∼500 km^2) utilizando las técnicas de separación del flujo de base y luego restando la tasa de descarga del agua subterránea a la tasa de recarga. Este enfoque podría ser un buen comienzo, pero no tiene en cuenta la variabilidad espacial y temporal, faltando los impactos locales asociados a la ubicación de los pozos de producción. Como la NWA de Sudáfrica ha sido emulada en muchos países, incluyendo Zambia, Zimbabwe, Kenia, los éxitos y fracasos de la experiencia de Sudáfrica sobre la interacción aguas subterráneas/aguas superficiales deberán ser analizados para guiar las futuras orientaciones políticas.
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review groundWater management and groundWater surface Water Interaction in the context of south african Water policy
Hydrogeology Journal, 2012Co-Authors: Jonathan Levy, Yongxin XuAbstract:GroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions.
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Review: GroundWater management and groundWater/surface-Water Interaction in the context of South African Water policy
Hydrogeology Journal, 2012Co-Authors: Jonathan Levy, Yongxin XuAbstract:GroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km^2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions. La interacción agua subterránea/agua superficial está recibiendo una creciente atención en África debido a su importancia en los sistema ecológicos y su sustentabilidad. En Sudáfrica, según la Ley Nacional de Agua (NWA) de 1998, las licencias de uso del agua, incluidas las aguas subterráneas, sólo se conceden después de definir la Reserva, que es la cantidad de agua necesaria para abastecer las necesidades humanas básicas y para preservar la integridad ecológica. La cuantificación precisa de la contribución del agua subterránea a los ecosistemas para la implementación exitosa de la NWA resulta difícil, ya que muchos de los acuíferos de Sudáfrica presentan la configuración heterogénea y anisotrópica en rocas fracturadas. En este documento se realiza un revisión de los conceptos y enfoques actuales de la investigación de la interacción aguas subterráneas/aguas superficiales en el contexto de las políticas de Sudáfrica. Se destacan algunas experiencias seleccionadas con las dificultades encontradas. El enfoque más común en Sudáfrica es la estimación de los flujos anuales promedio en cuencas de drenaje de cuarto orden (∼500 km^2) utilizando las técnicas de separación del flujo de base y luego restando la tasa de descarga del agua subterránea a la tasa de recarga. Este enfoque podría ser un buen comienzo, pero no tiene en cuenta la variabilidad espacial y temporal, faltando los impactos locales asociados a la ubicación de los pozos de producción. Como la NWA de Sudáfrica ha sido emulada en muchos países, incluyendo Zambia, Zimbabwe, Kenia, los éxitos y fracasos de la experiencia de Sudáfrica sobre la interacción aguas subterráneas/aguas superficiales deberán ser analizados para guiar las futuras orientaciones políticas. L’Interaction eau souterraine/eau de surface est un centre d’intérêt croissant en Afrique étant donné son importance pour les systèmes écologiques et leur pérennité. Dans le National Water Act sud-africain de 1998 (NWA), des autorisations d’utilisation de l’eau, incluant l’eau souterraine, sont accordées seulement après évaluation de la Réserve, de la quantité d’eau requise pour satisfaire les besoins humains essentiels et préserver une certaine intégrité écologique. Une évaluation précise des contributions de l’eau souterraine aux écosystèmes pour la mise en œuvre du NWA s’avère être un défi; beaucoup d’aquifères d’Afrique du Sud sont dans des encaissants rocheux fracturés hétérogènes et anisotropes. Cet article passe en revue les concepts et approches actuels des Interactions eau souterraine/eau de surface dans le contexte des politiques d’Afrique du Sud. Certaines expériences piège sélectionnées sont mises en évidence. L’approche la plus commune en Afrique du Sud est l’estimation des flux annuels moyens à l’échelle des bassins versants du quatrième ordre (∼500 km^2) avec des techniques de séparation du débit de base, puis de soustraction des taux de décharge et de recharge. Cette approche pourrait être un bon début, mais elle ignore la variabilité spatiale et temporelle, éludant potentiellement les impacts locaux associés à la localisation des puits de production. Comme le NWA d’Afrique du Sud a déjà fait des émules dans de nombreux pays dont la Zambie, le Zimbabwe et le Kenya, les succès et les échecs de l’expérience sud-africaine concernant l’Interaction eau souterraine/eau de surface seront analysés pour guider les orientations de la politique future. A interacção água subterrânea/água superficial recebe cada vez maior atenção em África, devido à sua importância para os sistemas ecológicos e para a sustentabilidade. Na África do Sul, no Acto Nacional da Água (NWA) de 1998, as licenças de uso da água, incluindo a água subterrânea, são garantidas apenas depois de definidas as Reservas, a quantidade de água necessária para suprimir as necessidades humanas básicas e a preservação de alguma integridade ecológica. A quantificação acurada das contribuições da água subterrânea para os ecossistemas para uma aplicação com sucesso da implementação do NWA provou-se ser desafiadora; muitos dos aquíferos situam-se em meios heterogéneos e anisotrópicos, em rochas fracturadas. Este documento revê a conceptualização corrente e os processos de investigação que têm sido aplicados às interacções águas subterrâneas/águas superficiais no contexto das políticas Sul-Africanas. Algumas experiências seleccionadas são enfatizadas. A aproximação mais comum na Áfria do Sul é a estimação dos fluxos anuais médios à escala da bacia de quarta ordem (∼500 km^2), utilizando técnicas de separação do fluxo de base e subtraindo então a descarga subterrânea da taxa de recarga. Esta aproximação pode ser um bom começo, mas ignora a variabilidade espacial e temporal, negligenciando potencialmente os impactes locais associados à exploração de campos de captações. Como o NWA Sul-Africano já foi emulado por muitos outros países, incluindo a Zâmbia, o Zimbabué e o Quénia, os sucessos e insucessos da experiência Sul-Africana ao lidar com as interacções águas subterrâneas/águas superficiais serão analisadas, para guiar as direcções políticas futuras.
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Review: GroundWater management and groundWater/surface-Water Interaction in the context of South African Water policy
Hydrogeology Journal, 2011Co-Authors: Jonathan LevyAbstract:GroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions.
Yongxin Xu - One of the best experts on this subject based on the ideXlab platform.
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Review: GroundWater management and groundWater/surface-Water Interaction in the context of South African Water policy
Hydrogeology Journal, 2012Co-Authors: Jonathan Levy, Yongxin XuAbstract:RésuméL’Interaction eau souterraine/eau de surface est un centre d’intérêt croissant en Afrique étant donné son importance pour les systèmes écologiques et leur pérennité. Dans le National Water Act sud-africain de 1998 (NWA), des autorisations d’utilisation de l’eau, incluant l’eau souterraine, sont accordées seulement après évaluation de la Réserve, de la quantité d’eau requise pour satisfaire les besoins humains essentiels et préserver une certaine intégrité écologique. Une évaluation précise des contributions de l’eau souterraine aux écosystèmes pour la mise en œuvre du NWA s’avère être un défi; beaucoup d’aquifères d’Afrique du Sud sont dans des encaissants rocheux fracturés hétérogènes et anisotropes. Cet article passe en revue les concepts et approches actuels des Interactions eau souterraine/eau de surface dans le contexte des politiques d’Afrique du Sud. Certaines expériences piège sélectionnées sont mises en évidence. L’approche la plus commune en Afrique du Sud est l’estimation des flux annuels moyens à l’échelle des bassins versants du quatrième ordre (∼500 km^2) avec des techniques de séparation du débit de base, puis de soustraction des taux de décharge et de recharge. Cette approche pourrait être un bon début, mais elle ignore la variabilité spatiale et temporelle, éludant potentiellement les impacts locaux associés à la localisation des puits de production. Comme le NWA d’Afrique du Sud a déjà fait des émules dans de nombreux pays dont la Zambie, le Zimbabwe et le Kenya, les succès et les échecs de l’expérience sud-africaine concernant l’Interaction eau souterraine/eau de surface seront analysés pour guider les orientations de la politique future.ResumoA interacção água subterrânea/água superficial recebe cada vez maior atenção em África, devido à sua importância para os sistemas ecológicos e para a sustentabilidade. Na África do Sul, no Acto Nacional da Água (NWA) de 1998, as licenças de uso da água, incluindo a água subterrânea, são garantidas apenas depois de definidas as Reservas, a quantidade de água necessária para suprimir as necessidades humanas básicas e a preservação de alguma integridade ecológica. A quantificação acurada das contribuições da água subterrânea para os ecossistemas para uma aplicação com sucesso da implementação do NWA provou-se ser desafiadora; muitos dos aquíferos situam-se em meios heterogéneos e anisotrópicos, em rochas fracturadas. Este documento revê a conceptualização corrente e os processos de investigação que têm sido aplicados às interacções águas subterrâneas/águas superficiais no contexto das políticas Sul-Africanas. Algumas experiências seleccionadas são enfatizadas. A aproximação mais comum na Áfria do Sul é a estimação dos fluxos anuais médios à escala da bacia de quarta ordem (∼500 km^2), utilizando técnicas de separação do fluxo de base e subtraindo então a descarga subterrânea da taxa de recarga. Esta aproximação pode ser um bom começo, mas ignora a variabilidade espacial e temporal, negligenciando potencialmente os impactes locais associados à exploração de campos de captações. Como o NWA Sul-Africano já foi emulado por muitos outros países, incluindo a Zâmbia, o Zimbabué e o Quénia, os sucessos e insucessos da experiência Sul-Africana ao lidar com as interacções águas subterrâneas/águas superficiais serão analisadas, para guiar as direcções políticas futuras.AbstractGroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km^2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions.ResumenLa interacción agua subterránea/agua superficial está recibiendo una creciente atención en África debido a su importancia en los sistema ecológicos y su sustentabilidad. En Sudáfrica, según la Ley Nacional de Agua (NWA) de 1998, las licencias de uso del agua, incluidas las aguas subterráneas, sólo se conceden después de definir la Reserva, que es la cantidad de agua necesaria para abastecer las necesidades humanas básicas y para preservar la integridad ecológica. La cuantificación precisa de la contribución del agua subterránea a los ecosistemas para la implementación exitosa de la NWA resulta difícil, ya que muchos de los acuíferos de Sudáfrica presentan la configuración heterogénea y anisotrópica en rocas fracturadas. En este documento se realiza un revisión de los conceptos y enfoques actuales de la investigación de la interacción aguas subterráneas/aguas superficiales en el contexto de las políticas de Sudáfrica. Se destacan algunas experiencias seleccionadas con las dificultades encontradas. El enfoque más común en Sudáfrica es la estimación de los flujos anuales promedio en cuencas de drenaje de cuarto orden (∼500 km^2) utilizando las técnicas de separación del flujo de base y luego restando la tasa de descarga del agua subterránea a la tasa de recarga. Este enfoque podría ser un buen comienzo, pero no tiene en cuenta la variabilidad espacial y temporal, faltando los impactos locales asociados a la ubicación de los pozos de producción. Como la NWA de Sudáfrica ha sido emulada en muchos países, incluyendo Zambia, Zimbabwe, Kenia, los éxitos y fracasos de la experiencia de Sudáfrica sobre la interacción aguas subterráneas/aguas superficiales deberán ser analizados para guiar las futuras orientaciones políticas.
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review groundWater management and groundWater surface Water Interaction in the context of south african Water policy
Hydrogeology Journal, 2012Co-Authors: Jonathan Levy, Yongxin XuAbstract:GroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions.
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Review: GroundWater management and groundWater/surface-Water Interaction in the context of South African Water policy
Hydrogeology Journal, 2012Co-Authors: Jonathan Levy, Yongxin XuAbstract:GroundWater/surface-Water Interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. In South Africa’s 1998 National Water Act (NWA), Water-use licenses, including groundWater, are granted only after defining the Reserve, the amount of Water needed to supply basic human needs and preserve some ecological integrity. Accurate quantification of groundWater contributions to ecosystems for successful implementation of the NWA proves challenging; many of South Africa’s aquifers are in heterogeneous and anisotropic fractured-rock settings. This paper reviews the current conceptualizations and investigative approaches regarding groundWater/surface-Water Interactions in the context of South African policies. Some selected pitfall experiences are emphasized. The most common approach in South Africa is estimation of average annual fluxes at the scale of fourth-order catchments (∼500 km^2) with baseflow separation techniques and then subtracting the groundWater discharge rate from the recharge rate. This approach might be a good start, but it ignores spatial and temporal variability, potentially missing local impacts associated with production-well placement. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundWater/surface-Water Interaction will be analyzed to guide future policy directions. La interacción agua subterránea/agua superficial está recibiendo una creciente atención en África debido a su importancia en los sistema ecológicos y su sustentabilidad. En Sudáfrica, según la Ley Nacional de Agua (NWA) de 1998, las licencias de uso del agua, incluidas las aguas subterráneas, sólo se conceden después de definir la Reserva, que es la cantidad de agua necesaria para abastecer las necesidades humanas básicas y para preservar la integridad ecológica. La cuantificación precisa de la contribución del agua subterránea a los ecosistemas para la implementación exitosa de la NWA resulta difícil, ya que muchos de los acuíferos de Sudáfrica presentan la configuración heterogénea y anisotrópica en rocas fracturadas. En este documento se realiza un revisión de los conceptos y enfoques actuales de la investigación de la interacción aguas subterráneas/aguas superficiales en el contexto de las políticas de Sudáfrica. Se destacan algunas experiencias seleccionadas con las dificultades encontradas. El enfoque más común en Sudáfrica es la estimación de los flujos anuales promedio en cuencas de drenaje de cuarto orden (∼500 km^2) utilizando las técnicas de separación del flujo de base y luego restando la tasa de descarga del agua subterránea a la tasa de recarga. Este enfoque podría ser un buen comienzo, pero no tiene en cuenta la variabilidad espacial y temporal, faltando los impactos locales asociados a la ubicación de los pozos de producción. Como la NWA de Sudáfrica ha sido emulada en muchos países, incluyendo Zambia, Zimbabwe, Kenia, los éxitos y fracasos de la experiencia de Sudáfrica sobre la interacción aguas subterráneas/aguas superficiales deberán ser analizados para guiar las futuras orientaciones políticas. L’Interaction eau souterraine/eau de surface est un centre d’intérêt croissant en Afrique étant donné son importance pour les systèmes écologiques et leur pérennité. Dans le National Water Act sud-africain de 1998 (NWA), des autorisations d’utilisation de l’eau, incluant l’eau souterraine, sont accordées seulement après évaluation de la Réserve, de la quantité d’eau requise pour satisfaire les besoins humains essentiels et préserver une certaine intégrité écologique. Une évaluation précise des contributions de l’eau souterraine aux écosystèmes pour la mise en œuvre du NWA s’avère être un défi; beaucoup d’aquifères d’Afrique du Sud sont dans des encaissants rocheux fracturés hétérogènes et anisotropes. Cet article passe en revue les concepts et approches actuels des Interactions eau souterraine/eau de surface dans le contexte des politiques d’Afrique du Sud. Certaines expériences piège sélectionnées sont mises en évidence. L’approche la plus commune en Afrique du Sud est l’estimation des flux annuels moyens à l’échelle des bassins versants du quatrième ordre (∼500 km^2) avec des techniques de séparation du débit de base, puis de soustraction des taux de décharge et de recharge. Cette approche pourrait être un bon début, mais elle ignore la variabilité spatiale et temporelle, éludant potentiellement les impacts locaux associés à la localisation des puits de production. Comme le NWA d’Afrique du Sud a déjà fait des émules dans de nombreux pays dont la Zambie, le Zimbabwe et le Kenya, les succès et les échecs de l’expérience sud-africaine concernant l’Interaction eau souterraine/eau de surface seront analysés pour guider les orientations de la politique future. A interacção água subterrânea/água superficial recebe cada vez maior atenção em África, devido à sua importância para os sistemas ecológicos e para a sustentabilidade. Na África do Sul, no Acto Nacional da Água (NWA) de 1998, as licenças de uso da água, incluindo a água subterrânea, são garantidas apenas depois de definidas as Reservas, a quantidade de água necessária para suprimir as necessidades humanas básicas e a preservação de alguma integridade ecológica. A quantificação acurada das contribuições da água subterrânea para os ecossistemas para uma aplicação com sucesso da implementação do NWA provou-se ser desafiadora; muitos dos aquíferos situam-se em meios heterogéneos e anisotrópicos, em rochas fracturadas. Este documento revê a conceptualização corrente e os processos de investigação que têm sido aplicados às interacções águas subterrâneas/águas superficiais no contexto das políticas Sul-Africanas. Algumas experiências seleccionadas são enfatizadas. A aproximação mais comum na Áfria do Sul é a estimação dos fluxos anuais médios à escala da bacia de quarta ordem (∼500 km^2), utilizando técnicas de separação do fluxo de base e subtraindo então a descarga subterrânea da taxa de recarga. Esta aproximação pode ser um bom começo, mas ignora a variabilidade espacial e temporal, negligenciando potencialmente os impactes locais associados à exploração de campos de captações. Como o NWA Sul-Africano já foi emulado por muitos outros países, incluindo a Zâmbia, o Zimbabué e o Quénia, os sucessos e insucessos da experiência Sul-Africana ao lidar com as interacções águas subterrâneas/águas superficiais serão analisadas, para guiar as direcções políticas futuras.
Patrick Meire - One of the best experts on this subject based on the ideXlab platform.
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A hierarchical approach on GroundWater-Surface Water Interaction in wetlands along the upper Biebrza River, Poland
Hydrology and Earth System Sciences, 2012Co-Authors: Christian Anibas, Kerst Buis, Patrick Meire, Boud Verbeiren, Jarosław Chormański, L. De Doncker, Tomasz Okruszko, Okke BatelaanAbstract:As recognized in the European Water Framework Directive, groundWater-dependent wetlands and their diverse ecosystems have important functions which need to be protected. The vegetation in such habitats is often dependent on quality, quantity and patterns of river discharge and GroundWater-Surface Water Interaction on a local or reach scale. Since GroundWater-Surface Water exchange studies on natural rivers and wetlands with organic soils are scarce, more functional analysis is needed. To this end we combined different field methods including piezometer nests, temperature as tracer and seepage meter measurements. Some of these measurements were used as inputs and/or as validation for the numerical 1-D heat transport model STRIVE. In transient mode the model was used to calculate spatially distributed vertical exchange fluxes from temperature profiles measured at the upper Biebrza River in Poland over a period of nine months. Time series of estimated fluxes and hydraulic head gradients in the hyporheic zone were used to estimate the temporal variability of GroundWater-Surface Water exchange. This paper presents a hierarchical approach for quantifying and interpreting GroundWater-Surface Water Interaction in space and time. The results for the upper Biebrza show predominantly upward Water fluxes, sections of recharge, however, exist along the reach. The fluxes depend more on hydraulic gradients than on riverbed conductivity. This indicates that the fluvio-plain scale is required for interpreting the exchange fluxes, which are estimated on a local scale. The paper shows that a conceptual framework is necessary for understanding the GroundWater-Surface Water Interaction processes, where the exchange fluxes are influenced by local factors like the composition of the riverbed and the position of the measurement on a local scale, and by regional factors like the hydrogeology and topography on a fluvio-plain scale. The hierarchical methodology increases the confidence in the estimated exchange fluxes and improves the process understanding. The accuracy of the measurements and related uncertainties, however, remain challenges for wetland environments. Gaining quantitative information on GroundWater-Surface Water Interaction can improve modeling confidence and as a consequence helps to develop effective procedures for management and conservation of valuable groundWater dependent wetlands.
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A hierarchical approach on GroundWater-Surface Water Interaction in wetlands along the upper Biebrza River, Poland
Hydrology and Earth System Sciences Discussions, 2011Co-Authors: Christian Anibas, Kerst Buis, Patrick Meire, Boud Verbeiren, Jarosław Chormański, L. De Doncker, Tomasz Okruszko, Okke BatelaanAbstract:Abstract. GroundWater-Surface Water exchange studies on natural rivers and wetlands dominated by organic soils are scarce. We present a hierarchical approach to quantitatively investigate and interpret GroundWater-Surface Water Interaction in space and time by applying a combination of different field methods including piezometer nests, temperature and seepage measurements. The numerical 1-D heat transport model of STRIVE is used in transient mode to calculate vertical fluxes from thermal profiles measured along the upper Biebrza River, Poland over a period of nine months. The calculated fluxes show no clear spatial pattern of exchange fluxes unless an interpolation of the point estimates on a reach scale is performed. Significance of differences in net exchange rates versus morphological features are investigated with statistical tests. Time series of temperature and hydraulic head of the hyporheic zone are used to estimate the temporal variability of the GroundWater-Surface Water exchange. Seepage meter measurements and slug tests were used for cross validation of modelled fluxes. Results show a strong heterogeneity of the thermal and physical soil properties along the reach, leading to a classification of these parameters for modelling purposes. The GroundWater-Surface Water exchange shows predominantly upward Water fluxes, however alternating sections of recharge exist. The exchange fluxes are significantly different dependent on the position of the river in the valley floor and the river morphology where fluxes are more dependent on hydraulic gradients than on river bed conductivity. Sections of higher fluxes are linked to the vicinity of the morainic plateau surrounding the rivers alluvium and to meanders, indicating that a perspective on the fluvio-plain scale is required for interpreting the estimated exchange fluxes. Since the vertical component of the exchange fluxes cannot explain the magnitude of the change in river discharge, a lateral flow component across the alluvial plain has to be responsible. The hierarchical methodology increases the confidence in the estimated exchange fluxes and improves the process understanding, however the accuracy of the measurements and related uncertainties remain challenges for wetland environments.
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a simple thermal mapping method for seasonal spatial patterns of groundWater surface Water Interaction
Journal of Hydrology, 2011Co-Authors: Christian Anibas, Kerst Buis, Ronny Verhoeven, Patrick Meire, Okke BatelaanAbstract:Summary A simple thermal mapping method for simulating seasonal and spatial patterns of groundWater–surface Water Interaction is developed and tested for a segment of the Aa River, Belgium. Spatially distributed temperature profiles in the hyporheic zone of the river are measured in winter and summer seasons of three consecutive years. Inverse modeling of the one-dimensional heat transport equation is applied to estimate vertical advective fluxes using the numerical STRIVE model and an analytical model. Results of the study show that seasonal flux estimates for summer and winter can be derived with a minimum data input and simulation effort. The estimated fluxes are analyzed via non-parametric statistical tests, while spatial interpolation techniques are used to generate maps of distributed flux exchange. The estimated seepage is compared with volumetric flux obtained from piezometer measurements and output of a groundWater model. The thermal method shows higher discharge rates in winter and that the relative contribution of exfiltration to the river discharge is higher in summer. A higher flux and a more heterogeneous flow pattern are observed in the upper reach of the river compared to the lower reach. This spatial difference shows the importance of the local geomorphology and to a lesser extent the hydrogeologic setting on hyporheic flux exchange in the river. A significantly higher flux is noted on the banks than in the center of the river, which is driven by the relatively high hydraulic conductivity of the river banks. It is concluded that bank flow in groundWater–surface Water Interaction deserves more attention. The main channel of the Aa River alone accounts for about 15% of the total river discharge at its outlet. As the developed thermal method is cost-effective, simple and fast, it is recommended for use in identifying zones of interest in initial stages of field investigations of groundWater–surface Water Interaction.
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A simple thermal mapping method for seasonal spatial patterns of groundWater–surface Water Interaction
Journal of Hydrology, 2011Co-Authors: Christian Anibas, Kerst Buis, Ronny Verhoeven, Patrick Meire, Okke BatelaanAbstract:A simple thermal mapping method for simulating seasonal and spatial patterns of groundWater–surface Water Interaction is developed and tested for a segment of the Aa River, Belgium. Spatially distributed temperature profiles in the hyporheic zone of the river are measured in winter and summer seasons of three consecutive years. Inverse modeling of the one-dimensional heat transport equation is applied to estimate vertical advective fluxes using the numerical STRIVE model and an analytical model. Results of the study show that seasonal flux estimates for summer and winter can be derived with a minimum data input and simulation effort. The estimated fluxes are analyzed via non-parametric statistical tests, while spatial interpolation techniques are used to generate maps of distributed flux exchange. The estimated seepage is compared with volumetric flux obtained from piezometer measurements and output of a groundWater model. The thermal method shows higher discharge rates in winter and that the relative contribution of exfiltration to the river discharge is higher in summer. A higher flux and a more heterogeneous flow pattern are observed in the upper reach of the river compared to the lower reach. This spatial difference shows the importance of the local geomorphology and to a lesser extent the hydrogeologic setting on hyporheic flux exchange in the river. A significantly higher flux is noted on the banks than in the center of the river, which is driven by the relatively high hydraulic conductivity of the river banks. It is concluded that bank flow in groundWater–surface Water Interaction deserves more attention. The main channel of the Aa River alone accounts for about 15% of the total river discharge at its outlet. As the developed thermal method is cost-effective, simple and fast, it is recommended for use in identifying zones of interest in initial stages of field investigations of groundWater–surface Water Interaction.status: publishe
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A simple thermal mapping method for seasonal spatial patterns of groundWater–surface Water Interaction
Journal of Hydrology, 2010Co-Authors: Christian Anibas, Kerst Buis, Ronny Verhoeven, Patrick Meire, Okke BatelaanAbstract:Summary A simple thermal mapping method for simulating seasonal and spatial patterns of groundWater–surface Water Interaction is developed and tested for a segment of the Aa River, Belgium. Spatially distributed temperature profiles in the hyporheic zone of the river are measured in winter and summer seasons of three consecutive years. Inverse modeling of the one-dimensional heat transport equation is applied to estimate vertical advective fluxes using the numerical STRIVE model and an analytical model. Results of the study show that seasonal flux estimates for summer and winter can be derived with a minimum data input and simulation effort. The estimated fluxes are analyzed via non-parametric statistical tests, while spatial interpolation techniques are used to generate maps of distributed flux exchange. The estimated seepage is compared with volumetric flux obtained from piezometer measurements and output of a groundWater model. The thermal method shows higher discharge rates in winter and that the relative contribution of exfiltration to the river discharge is higher in summer. A higher flux and a more heterogeneous flow pattern are observed in the upper reach of the river compared to the lower reach. This spatial difference shows the importance of the local geomorphology and to a lesser extent the hydrogeologic setting on hyporheic flux exchange in the river. A significantly higher flux is noted on the banks than in the center of the river, which is driven by the relatively high hydraulic conductivity of the river banks. It is concluded that bank flow in groundWater–surface Water Interaction deserves more attention. The main channel of the Aa River alone accounts for about 15% of the total river discharge at its outlet. As the developed thermal method is cost-effective, simple and fast, it is recommended for use in identifying zones of interest in initial stages of field investigations of groundWater–surface Water Interaction.
