Tanja Liesch

Uranium in groundwater — Fertilizers versus geogenic sources

Due to its radiological and toxicological properties even at low concentration levels, uranium is increasingly recognized as relevant contaminant in drinking water from aquifers. Uranium originates from different sources, including natural or geogenic, mining and industrial activities, and fertilizers in agriculture. The goal of this study was to obtain insights into the origin of uranium in groundwater while differentiating between geogenic sources and fertilizers. A literature review concerning the sources and geochemical processes affecting the occurrence and distribution of uranium in the lithosphere, pedosphere and hydrosphere provided the background for the evaluation of data on uranium in groundwater at regional scale. The state of Baden-Württemberg, Germany, was selected for this study, because of its hydrogeological and land-use diversity, and for reasons of data availability. Uranium and other parameters from N=1935 groundwater monitoring sites were analyzed statistically and geospatially. Results show that (i) 1.6% of all water samples exceed the German legal limit for drinking water (10 μg/L); (ii) The range and spatial distribution of uranium and occasional peak values seem to be related to geogenic sources; (iii) There is a clear relation between agricultural land-use and low-level uranium concentrations, indicating that fertilizers generate a measurable but low background of uranium in groundwater.

Erratum: Impact of managed aquifer recharge on the chemical and isotopic composition of a karst aquifer, Wala reservoir, Jordan

Storm-water harvesting and storage via managed aquifer recharge (MAR) is a promising approach to combat water scarcity in semi-arid regions, but poses a challenge for karst aquifers and regions with highly variable water availability. The infiltration of low-mineralized surface water and its impact on highly mineralized groundwater of a karst aquifer was investigated at Wala reservoir in Jordan over a period of approximately 10 years. The results show significant groundwater-level rise in a wellfield, in response to the yearly average infiltration of about 6.7 million m3. This corresponds to about 60 % of the yearly average abstraction of about 11.7 million m3, confirmed by mixing calculations with tritium. A decreasing trend in infiltration due to sedimentation is observed. Mean groundwater residence times of several thousand years, derived from carbon-14 dating, indicate a large storage capacity of the aquifer. The heterogeneous distribution of the residence times is caused by strong groundwater withdrawals and artificial recharge along with karst-specific aquifer characteristics. Temporal groundwater salinity fluctuations in the wellfield are observed after the first MAR infiltration. Enhanced groundwater flow along the wadi course was demonstrated, which is an important aspect with regards to future MAR projects in similar wadis of the region.

Isotopic constraints on water source mixing, network leakage and contamination in an urban groundwater system

Water supply in developing countries is prone to large water losses due to leaky distribution networks and defective sewers, which may affect groundwater quality and quantity in urban areas and result in complex subsurface mixing dynamics. In this study, a multi-stable isotope approach was used to investigate spatiotemporal fluctuations of surface and sub-surface water source partitioning and mixing, and to assess nitrogen (N) contamination in the urban water cycle of As-Salt, Jordan. Water import from the King Abdullah Canal (KAC), mains waters from the network, and wastewater are characterized by distinct isotopic signatures, which allowed us to quantify city effluents into the groundwater. Temporal variations in isotopic signatures of polluted groundwater are explained by seasonally fluctuating inflow, and dilution by water that originates from Lake Tiberias and enters the urban water cycle via the KAC. Isotopic analysis (N and O) and comparison between groundwater nitrate and nitrate from mains water, water imports and wastewater confirmed that septic waste from leaky sewers is the main contributor of nitrate contamination. The nitrate of strongly contaminated groundwater was characterized by highest δ15NNO3 values (13.3±1.8‰), whereas lowest δ15NNO3 values were measured in unpolluted groundwater (6.9‰). Analogously, nitrate concentration and isotopic ratios were used for source partitioning and qualitatively confirmed δDH2O and δ18OH2O-based estimates. Dual water isotope endmember mixing calculations suggest that city effluents from leaky networks and sewers contribute 30-64% to the heavily polluted groundwater. Ternary mixing calculations including also chloride revealed that 5-18% of the polluted groundwater is wastewater. Up to two thirds of the groundwater originates from mains, indicating excessive water loss from the network, and calling for improved water supply management.

Comparison of GRACE data and groundwater levels for the assessment of groundwater depletion in Jordan

Gravity Recovery and Climate Experiment (GRACE) derived groundwater storage (GWS) data are compared with in-situ groundwater levels from five groundwater basins in Jordan, using newly gridded GRACE GRCTellus land data. It is shown that (1) the time series for GRACE-derived GWS data and in-situ groundwater-level measurements can be correlated, with R2 from 0.55 to 0.74, (2) the correlation can be widely ascribed to the seasonal and trend component, since the detrended and deseasonalized time series show no significant correlation for most cases, implying that anomalous signals that deviate from the trend or seasonal behaviour are overlaid by noise, (3) estimates for water losses in Jordan based on the trend of GRACE data from 2003 to 2013 could be up to four times higher than previously assumed using estimated recharge and abstraction rates, and (4) a significant time-lagged cross correlation of the monthly changes in GRACE-derived groundwater storage and precipitation data was found, suggesting that the conventional method for deriving GWS from GRACE data probably does not account for the typical conditions in the study basins. Furthermore, a new method for deriving plausible specific yields from GRACE data and groundwater levels is demonstrated.RésuméLes données des réserves d’eau souterraine issues du système GRACE (Gravity Recovery and Climate Experiment) sont comparées avec les données piézométriques mesurées in-situ dans cinq bassins hydrogéologiques en Jordanie, en utilisant une nouvelle grille de données GRSTellusland du système GRACE. Il a été montré que (1) les séries temporelles des données de la réserve en eau souterraine issues du système GRACE et les mesures piézométriques in-situ peuvent être corrélées, avec un coefficient R2 compris entre 0.55 et 0.74, (2) la corrélation peut être largement attribuée à la composante tendancielle et saisonnière, puisque les séries temporelles défaites de la tendance et désaisonnalisées ne montrent pas de corrélation significative dans la plupart des cas, ce qui indique que les signaux d’anomalies qui s’écartent de la tendance ou du comportement saisonnier sont couverts par le bruit de fond, (3) les estimations pour les pertes d’eau en Jordanie basées sur la tendance des données de GRACE de 2003 à 2013 pourraient être plus de quatre fois supérieures aux estimations antérieures de recharge et de taux de prélèvement, et (4) une importante corrélation croisée décalée dans le temps des variations mensuelles du stock d’eau souterraine dérivé des données de GRACE et des données de précipitations a été mise en évidence, suggérant que la méthode conventionnelle pour évaluer les réserves en eau souterraine à partir des données de GRACE ne tient probablement pas compte des conditions spécifiques des bassins étudiés. De plus, une nouvelle méthode pour dériver des productivités spécifiques plausibles à partir des données de GRACE et des niveaux piézométriques est démontrée.ResumenSe comparan los datos derivados del almacenamiento de agua subterránea (GWS) del Gravity Recovery and Climate Experiment (GRACE) con los niveles de agua subterránea medidos in situ en cinco cuencas de aguas subterráneas en Jordania, utilizando los datos de GRACE GRCTellus reticulados recientemente. Se muestra que (1) la serie temporal de datos de GWS derivados de GRACE y las mediciones in situ del nivel del agua subterránea se pueden correlacionar con R2 a partir 0.55 a 0.74; (2) la correlación puede ser ampliamente atribuida a la componente estacional y a la tendencia , ya que la serie de tiempo desestacionalizada y sin tendencia no muestra ninguna correlación significativa en la mayoría de los casos, lo que implica que las señales anómalas que se apartan de la tendencia o comportamiento estacional, se superponen con el ruido, (3) las pérdidas de agua estimadas en Jordania sobre la base de la tendencia de los datos de GRACE 2003–2013 podría ser hasta cuatro veces mayor de lo que se supone usando las tasas de recarga y de extracción estimados, y (4) la correlación cruzada encontró que un tiempo significativo de retardo entre la variaciones mensuales de almacenamiento de agua subterránea derivada de GRACE y datos de precipitación, lo que sugiere que el método convencional para derivar GWS de los datos de GRACE, probablemente, no tiene en cuenta las condiciones típicas en las cuencas de estudio. Por otra parte, se muestra un nuevo método para derivar los posibles rendimientos específicos a partir de los datos de GRACE y de los niveles del agua subterránea.摘要利用新划分网格的GRACE GRCTellus土地数据,对GRACE导出的地下水储存数据和约旦5个地下水盆地现场的地下水位进行了对比。结果显示,(1)GRACE导出的地下水储存数据和现场地下水位测量结果的时间序列可以相互关联,R2的范围为0.55 到 0.74,(2)关联性广泛归因于季节性和趋势因素,因为大多数情况下去趋势化的和消除季节的时间序列没有显示出多大的关联性,意味着偏离趋势和季节性行为的异常信号被噪音覆盖,(3)根据2003年到2013年GRACE数据趋势得到的约旦水损耗估算结果可能是先前采用估算的补给和抽取率假设的结果的4倍,(4)发现GRACE导出的地下水储存量和降水数据月度变化有重要的时间延迟相互关联性,表明从GRACE数据导出地下水储存量的常规方法可能解释不了研究区的典型情况。此外,本文还论述了从GRACE数据和地下水位导出似乎可信的单位出水量的一种新方法。ResumoDados de armazenamento de água subterrânea (AAS) derivados do satélite GRACE (Gravity Recovery and Climate Experiment) foram comparados com níveis de água subterrânea in-loco de cinco bacias subterrâneas na Jordânia. Utilizaram-se os novos dados em grade do GRACE (GRCTellus). Mostra-se que (1) as séries temporais para os dados de AAS derivados do GRACE e as medições in-loco de níveis de água subterrânea podem ser correlacionadas, com 0.55 ≤ R2 ≤ 0.74, (2) a correlação pode ser largamente atribuída às componentes de tendência e sazonalidade, uma vez que as séries temporais após remoção de tendência e sazonalidade não apresentam correlação significativa na maioria dos casos, indicando que sinais anômalos que desviam da tendência ou do comportamento sazonal são sobrepostos por ruído, (3) estimativas para perda de água na Jordânia baseadas em tendências de dados GRACE de 2003 a 2013 podem ser até quatro vezes maiores que as previamente assumidas utilizando a recarga estimada e taxas de abstração, e (4) uma significante correlação cruzada defasada no tempo entre mudanças mensais no armazenamento de água subterrânea derivada do GRACE e dados de precipitação foi encontrada, sugerindo que o método convencional para derivar AAS a partir de dados GRACE provavelmente não considera condições típicas da área de estudo. Além disso, um novo método para derivar rendimentos específicos plausíveis a partir de dados GRACE e níveis das águas subterrâneas é demonstrado.

Modelling groundwater over-extraction in the southern Jordan Valley with scarce data

To deal with the challenge of groundwater over-extraction in arid and semi-arid environments, it is necessary to establish management strategies based on the knowledge of hydrogeological conditions, which can be difficult in places where hydrogeological data are dispersed, scarce or present potential misinformation. Groundwater levels in the southern Jordan Valley (Jordan) have decreased drastically in the last three decades, caused by over-extraction of groundwater for irrigation purposes. This study presents a local, two-dimensional and transient numerical groundwater model, using MODFLOW, to characterise the groundwater system and the water balance in the southern Jordan Valley. Furthermore, scenarios are simulated regarding hydrological conditions and management options, like extension of arable land and closure of illegal wells, influencing the projection of groundwater extraction. A limited dataset, literature values, field surveys, and the ‘crop water-requirement method’ are combined to determine boundary conditions, aquifer parameters, and sources and sinks. The model results show good agreement between predicted and observed values; groundwater-level contours agree with the conceptual model and expected flow direction, and, in terms of water balance, flow volumes are in accordance with literature values. Average annual water consumption for irrigation is estimated to be 29 million m3 and simulation results show that a reduction of groundwater pumping by 40% could recover groundwater heads, reducing the water taken from storage. This study presents an example of how to develop a local numerical groundwater model to support management strategies under the condition of data scarcity.RésuméPour relever le défi de la surexploitation des eaux souterraines dans les milieu arides et semi-arides, il est nécessaire d’établir des stratégies de gestion basées sur la connaissance des conditions hydrogéologiques. Cela peut être difficiles dans les endroits où les données hydrogéologiques sont dispersées, rares ou présentent une désinformation potentielle. Les niveaux des eaux souterraines dans le Sud de la Vallée du Jourdain (Jordanie) ont diminué de façon drastique au cours des trois dernières décennies, en raison de la surexploitation des eaux souterraines à des fins d’irrigation. Cette étude présente un modèle numérique bidimensionnel et transitoire des eaux souterraines à l’échelle locale, utilisant MODFLOW, afin de caractériser le système aquifère et le bilan hydrique dans la vallée méridionale du Jourdain. En outre, des scénarios sont simulés en ce qui concerne les conditions hydrologiques et les options de gestion, comme l’extension des terres arables et l’arrêt d’exploitation de puits illégaux, influençant la projection de l’exploitation des eaux souterraines. Un ensemble de données limité, des valeurs de la littérature, des enquêtes de terrain, et la ‘méthode d’évaluation de la demande d’eau des cultures’ sont combinés pour déterminer les conditions aux limites, les paramètres de l’aquifère, et les termes sources et puits. Les résultats du modèle montrent une bonne cohérence entre les valeurs prédites et observées; les contours piézométriques sont concordants avec le modèle conceptuel et les directions d’écoulement attendues, et, du point de vue du bilan hydraulique, les volumes écoulés sont conformes aux valeurs de la littérature. La consommation annuelle moyenne en eau pour l’irrigation est estimée à 29 millions m3 et les résultats des simulations montrent qu’une réduction des pompages d’eau souterraine de 40% pourrait permettre de récupérer les niveaux piézométriques, limitant ainsi les prélèvements d’eau stockée. Cette étude présente un exemple de la façon de développer un modèle numérique des eaux souterraines à l’échelle locale pour soutenir les stratégies de gestion en condition de rareté de données.ResumenPara enfrentar el desafío de la sobreextracción de agua subterránea en ambientes áridos y semiáridos, es necesario establecer estrategias de gestión basadas en el conocimiento de condiciones hidrogeológicas. Esto puede ser difícil en lugares donde los datos hidrogeológicos son dispersos, escasos o presentan posibles informaciones erróneas. Los niveles de agua subterránea en el valle del Jordán meridional (Jordania) han disminuido drásticamente en las últimas tres décadas, causado por la sobreexplotación de aguas subterráneas con fines de riego. Este estudio presenta un modelo numérico de aguas subterráneas local, bidimensional y de régimen transiente, utilizando MODFLOW, para caracterizar el sistema de aguas subterráneas y el balance hídrico en el valle del Jordán meridional. Además, se simulan escenarios sobre condiciones hidrológicas y opciones de gestión, como la extensión de tierras de cultivo y el cierre de pozos ilegales, que influyen en la proyección de la extracción de aguas subterráneas. Un conjunto de datos limitado, valores obtenidos de la literatura, evaluaciones en terreno y el “método de necesidades de riego de los cultivos” se combinan para determinar las condiciones de borde, los parámetros del acuífero y las recargas y extracciones. Los resultados del modelo muestran una buena relación entre los valores pronosticados y observados; los mapas de contornos concuerdan con el modelo conceptual y la dirección esperada del flujo y, en términos de balance hídrico, los volúmenes de flujo están en conformidad con los valores de la literatura. El consumo promedio anual de agua para riego es estimado en 29 millones de m3 y los resultados de la simulación muestran que una reducción del 40% de la captación de agua subterránea podría recuperar los niveles de agua subterránea, reduciendo el agua proveniente del almacenamiento. Este estudio presenta un ejemplo de cómo desarrollar un modelo numérico local de aguas subterráneas para apoyar estrategias de gestión bajo la condición de escasez de datos.摘要为了应对干旱、半干旱环境下地下水超采的挑战,有必要建立基于掌握水文地质条件的管理策略。这可能在水文地质数据零散、匮乏和有潜在错误信息的地方非常困难。(约旦)约旦河谷南部地下水位过去三十年来大幅下降,由地下水超采用于灌溉引起。本研究展示了一个局部的、二维和瞬时数值地下水模型,利用MODFLOW来描述约旦河谷南部的地下水系统和水平衡。此外,针对水文条件和管理选择,如影响地下水开采规划的可耕地扩展、非法井的关闭,对各种方案进行了模拟。有限的数据集、文献价值、野外调查及 “作物需水方法”联合在一起确定边界条件、含水层参数以及汇和源。模型结果显示,预测的值和观测的值非常吻合;地下水位等高图与概念模型和预计的水流方向一致,在水平衡方面,流量与文献值一致。平均每年灌溉水消耗量估计为2900万立方,模拟结果显示,地下水抽取减少40%就能恢复地下水水头,减少储存的使用量。本研究展示了怎样建立一个局部的地下水模型以支持数据匮乏条件下管理策略的例子。ResumoPara lidar com o desafio do excesso de extração de águas subterrâneas em ambientes áridos e semiáridos, é necessário estabelecer estratégias de gerenciamento baseadas no conhecimento das condições hidrogeológicas. Isso pode ser difícil em locais onde os dados hidrogeológicos são dispersos, escassos ou apresentam desinformação potencial. Os níveis freáticos no sul do Vale do Jordão decresceram drasticamente nas últimas três décadas, devido ao excesso de extração de águas subterrâneas para irrigação. Esse estudo apresenta um modelo numérico de águas subterrâneas local, bidimensional e transiente, utilizando o MODFLOW, para caracterizar o sistema de águas subterrâneas e o balanço hídrico no sul do Vale do Jordão. Ademais, os cenários são simulados em relação às condições hidrológicas e opções de gerenciamento, como extensão da terra arável e fechamento de poços ilegais, influenciando a projeção da extração de águas subterrâneas. Um conjunto de dados limitados, valores de literatura, pesquisas de campo, e o ‘método de requerimento de água das culturas’ são combinados para determinar as condições de contorno, parâmetros do aquífero, bem como as fontes e sumidouros. Os resultados do modelo apresentaram boa concordância entre os valores estimados e observados; as isolinhas do nível das águas subterrâneas coincidiram com o modelo conceitual e com a direção de fluxo esperada, e, em termos do balanço hídrico, os volumes de fluxo estão em conformidade com os valores da literatura. O consumo anual médio de água para irrigação foi estimado como 29 milhões de m3 e os resultados da simulação demonstraram que uma redução de 40% no bombeamento das águas subterrâneas poderiam recuperar os níveis freáticos, reduzindo a água retirada do armazenamento. Esse estudo apresenta um exemplo de como desenvolver um modelo numérico local de águas subterrâneas para apoiar estratégias de gerenciamento sob a condição de escassez de dados.

Multi-tracer approach to characterize hydraulically induced sulfate rock dissolution processes below a weir lock

Numerous damages at structures and failures of dams can be ascribed to solution processes and attendant subsidence. Leaching in gypsum-bearing layers of the Middle Triassic has induced subsidence underneath the structure of the weir Hessigheim, River Neckar. The goals of this study were to gain a better understanding of the prevailing groundwater flow processes as well as the interaction between surface water and groundwater in the area of the weir lock and to verify the success of former remediation measures. In order to attain these objectives a combined groundwater and surface water tracer test in combination with hydraulic borehole tests were performed. In addition, a study of the dissolved sulfate distribution was carried out using sampling data from 1987 to 2013. Based on the results of these methods a strongly heterogeneous aquifer with main runoff occurring in few major flow paths could be characterized. Former remediation measures showed to be successful.

Contamination risk and drinking water protection for a large-scale managed aquifer recharge site in a semi-arid karst region, Jordan

Karst aquifers in semi-arid regions are particularly threatened by surface contamination, especially during winter seasons when extremely variable rainfall of high intensities prevails. An additional challenge is posed when managed recharge of storm water is applied, since karst aquifers display a high spatial variability of hydraulic properties. In these cases, adapted protection concepts are required to address the interaction of surface water and groundwater. In this study a combined protection approach for the surface catchment of the managed aquifer recharge site at the Wala reservoir in Jordan and the downstream Hidan wellfield, which are both subject to frequent bacteriological contamination, is developed. The variability of groundwater quality was evaluated by correlating contamination events to rainfall, and to recharge from the reservoir. Both trigger increased wadi flow downstream of the reservoir by surface runoff generation and groundwater seepage, respectively. A tracer test verified the major pathway of the surface flow into the underground by infiltrating from pools along Wadi Wala. An intrinsic karst vulnerability and risk map was adapted to the regional characteristics and developed to account for the catchment separation by the Wala Dam and the interaction of surface water and groundwater. Implementation of the proposed protection zones for the wellfield and the reservoir is highly recommended, since the results suggest an extreme contamination risk resulting from livestock farming, arable agriculture and human occupation along the wadi. The applied methods can be transferred to other managed aquifer recharge sites in similar karstic environments of semi-arid regions.ZusammenfassungKarstgrundwasserleiter in semiariden Gebieten sind im besonderen Maße von Oberflächenverschmutzung bedroht, vor allem während der Wintersaison, wenn extrem variabler Niederschlag von hoher Intensität vorherrscht. Eine zusätzliche Herausforderung stellt die künstliche Grundwasseranreicherung mit Niederschlagswasser dar, da Karstgrundwasserleiter eine hohe räumliche Variabilität in ihren hydraulischen Eigenschaften aufweisen. In diesen Fällen sind angepasste Schutzkonzepte erforderlich, die das Zusammenspiel von Oberflächenwasser und Grundwasser berücksichtigen. In dieser Studie wird ein kombiniertes Schutzkonzept für das Oberflächeneinzugsgebiet der künstlichen Grundwasseranreicherungsanlage am Wala Stausee und dem unterstromig gelegenen Hidan Brunnenfeld in Jordanien entwickelt. In Beiden wurden wiederholt bakteriologische Verunreinigungen festgestellt. Die Variabilität der Grundwasserqualität lässt sich durch Korrelation der Kontaminationsereignisse mit Niederschlagsereignissen und Infiltration aus dem Stausee erklären. Beides führt zu erhöhtem Abfluss im Wadi unterhalb des Stausees, hervorgerufen durch Oberflächenabfluss und Grundwasseraustritte. Ein Tracerversuch bestätigte die Infiltration des Oberflächenflusses in den Untergrund über Pools entlang des Wadi Wala. Eine intrinsische Karstvulnerabilitäts- und Risikokarte wurde entwickelt und an die regionalen Besonderheiten angepasst, um die Abtrennung des Einzugsgebiets durch den Wala Staudamm und das Zusammenwirken von Oberflächenwasser und Grundwasser zu berücksichtigen. Die Umsetzung der vorgeschlagenen Schutzzonen für das Brunnenfeld und das Reservoir wird dringend empfohlen, da die Ergebnisse ein extremes Kontaminationsrisiko durch Viehzucht, Ackerbau und menschliche Besiedlung entlang des Wadis zeigen. Die angewandten Methoden können auf andere künstliche Grundwasseranreicherungsanlagen in ähnlichen Karstgebieten semiarider Regionen übertragen werden.RésuméLes aquifères karstiques dans les régions semi-arides sont particulièrement menacés par une contamination provenant de la surface, surtout pendant les saisons hivernales où prévaut une pluviométrie extrêmement variable de fortes intensités. Un défi supplémentaire existe lorsque la gestion de la recharge par les eaux pluviales est. appliquée, car les aquifères karstiques présentent une grande variabilité spatiale des propriétés hydrauliques. Dans ces cas, des concepts de protection adaptée sont nécessaires pour traiter la question des interactions entre les eaux de surface et les eaux souterraines. Dans cette étude, une approche combinée de protection est. développée pour le bassin versant du site de recharge de l’aquifère au niveau du réservoir de Wala en Jordanie et du champ de captage d’Hidan situé en aval hydraulique, tous les deux sujets à une contamination bactériologique fréquente. La variabilité de la qualité des eaux souterraines a été évaluée en corrélant les événements de contamination avec les précipitations, et à la recharge à partir du réservoir. Les deux déclenchent une augmentation du débit de l’oued en aval du réservoir due à la génération d’un ruissellement de surface et à l’infiltration vers les eaux souterraines, respectivement. Un essai de traçage a vérifié la voie principale de l’écoulement de surface dans le sous-sol par infiltration à partir des bassins situés le long de l’oued Wala. Une carte de la vulnérabilité intrinsèque du karst et de risque a été adaptée aux caractéristiques régionales et élaborée pour prendre en considération la séparation des bassins versants par le barrage de Wala et l’interaction entre les eaux de surface et les eaux souterraines. La mise en œuvre des zones de protection proposées pour le champ de captage et le réservoir est. fortement recommandée, car les résultats suggèrent un risque de contamination extrême résultant de l’élevage, de l’agriculture et des habitations le long de l’oued. Les méthodes appliquées peuvent être transférées à d’autres sites de recharge des aquifères dans des environnements karstiques similaires en régions semi-arides.ResumenLos acuíferos kársticos de las regiones semiáridas están particularmente amenazados por la contaminación desde la superficie, especialmente durante las estaciones invernales cuando prevalecen lluvias extremadamente variables de altas intensidades. Un desafío adicional se plantea cuando se aplica gestión de la recarga de aguas pluviales, ya que los acuíferos kársticos muestran una alta variabilidad espacial de sus propiedades hidráulicas. En estos casos, se requieren conceptos de protección adaptados para abordar la interacción entre el agua superficial y subterránea. En este estudio se desarrolla un enfoque combinado de protección para la cuenca superficial de un sitio de recarga del acuífero gestionado en el embalse de Wala en Jordania y el campo de pozos Hidan aguas abajo, ambos sujetos a una frecuente contaminación bacteriológica. La variabilidad de la calidad del agua subterránea se evaluó mediante la correlación de los eventos de contaminación con las precipitaciones y la recarga desde el embalse. Ambos desencadenan el aumento del flujo del wadi, río abajo del reservorio por la generación de escorrentía de superficie y filtración de agua subterránea, respectivamente. Una prueba de trazadores verificó la trayectoria principal del flujo superficial en el subsuelo por infiltración a partir de estanques a lo largo de Wadi Wala. Se adaptó un mapa de vulnerabilidad intrínseca y de riesgo kárstico a las características regionales y se desarrolló para tener en cuenta la separación de las cuencas por la presa de Wala y la interacción del agua superficial y subterránea. La implementación de las zonas de protección propuestas para el pozo y el embalse es altamente recomendable, ya que los resultados sugieren un riesgo extremo de contaminación como resultado de la ganadería, la agricultura y la ocupación humana a lo largo del wadi. Los métodos aplicados pueden ser transferidos a otros sitios gestionados de recarga de acuíferos en ambientes kársticos similares de regiones semiáridas.摘要半干旱地区的岩溶含水层特别容易受到地表污染的威胁,尤其是在极度变化的高强度降雨盛行的冬季。在应用雨水作为补给的时候还有额外的挑战,因为岩溶含水层的水文特性空间变化很大。在这些情况下,需要适合的保护概念来强调地表水和地下水的相互作用。在本研究中,对约旦Wala储水地区管理的含水层补给地地表流域及下游的Hidan井场提出了一项组合保护方法,这两个区域常常受到微生物的污染。通过污染事件与降雨以及污染与储水地补给的对比,评价了水质的变化性。两者分别通过产生地表径流和地下水渗漏导致旱谷流向下游的水流增加。示踪实验证实了地表水流从沿Wala旱谷的池塘入渗进入地下的主要通道。针对区域特征对固有的岩溶脆弱性和风险图进行了改编并改进,来说明Wala大坝的流域划分和地表水与地下水的相互作用。强烈建议在井场和储水地建立提出的保护帶,因为研究结果表明,沿旱谷的畜牧耕作、耕地农业和人类侵占致使污染风险极高。这个实用方法可应用在半干旱区域类似岩溶环境种其它管理的含水层补给场地。.ResumoAquíferos cársticos em regiões semiáridas são particularmente ameaçados por contaminação superficial, especialmente durante as estações de inverno quando prevalecem precipitações extremamente variáveis e de alta intensidade. Um desafio adicional é criado quando o gerenciamento de recarga da água da chuva é aplicado, já que os aquíferos cársticos apresentam uma alta variabilidade espacial de propriedades hidráulicas. Nestes casos, são necessários conceitos de proteção adaptados para abordar a interação entre águas superficiais e subterrâneas. Nesse estudo, desenvolveu-se uma abordagem de proteção combinada para a captação superficial na área de gerenciamento de recarga no reservatório Wala, na Jordânia, e no campo de poços Hidan, a jusante, ambos sujeitos à frequente contaminação bacteriológica. A variabilidade da qualidade das águas subterrâneas foi avaliada correlacionando os eventos de contaminação com a precipitação e recarga do reservatório. Ambos desencadeiam o aumento do fluxo do Wadi a jusante do reservatório pela geração do escoamento superficial e infiltração das águas subterrâneas, respectivamente. Um teste de traçadores verificou o caminho principal do fluxo superficial para o subsolo por infiltração de lagoas ao longo do Wadi Wala. Um mapa de vulnerabilidade intrínseca e risco do cárste foi adaptado às características regionais e desenvolvido para explicar a separação da bacia hidrográfica pela barragem de Wala e a interação entre águas superficiais e subterrâneas. A implementação das zonas de proteção propostas para o campo de poços e o reservatório é altamente recomendado, já que os resultados sugerem um risco extremo de contaminação resultante da pecuária, agricultura e ocupação humana ao

Correlating Global Precipitation Measurement satellite data with karst spring hydrographs for rapid catchment delineation

To protect karst spring water resources, catchments must be known. We have developed a method for correlating spring hydrographs with newly available, high-resolution, satellite-based Global Precipitation Measurement data to rapidly and remotely locate recharge areas. We verify the method using a synthetic comparison of ground-based rain gage data with the satellite precipitation data set. Application to karst springs is proven by correlating satellite data with hydrographs from well-known springs with published catchments in Europe and North America. Application to an unknown-catchment spring in Pennsylvania suggests distant recharge, requiring a flow path that crosses topographic divides, as well as multiple lithologies, physiographic provinces, and tectonic boundaries. Although surprising, this latter result is consistent with published geologic/geophysical, monitoring well, and stream gage data. We conclude that the method has considerable potential to improve the speed and accuracy of catchment identification and hydrodynamic characterization, with applications to water resource protection and groundwater exploration, among others.

Subsurface Flow and Sulfate Dissolution Response to the Construction and Restoration of the River Weir in Hessigheim, Germany

The construction of the combined ship lock weir in Hessigheim, Germany, created a river stage difference of more than 6 m and intensified subsequently the surface–subsurface water exchange and modified the natural subsurface flow field. In the sulfate-bearing hydrogeological setting, increased infiltration and intensified subsurface flow triggered related dissolution processes. Soon after construction, the structure started suffering from subsidence due to progressive leaching and demanded extensive grouting. In the course of approximately 25 years, groundwater heads and subsurface sulfate concentrations responded distinctively to grouting campaigns. The analysis confirms that as a result of its high solubility and altered hydrogeological conditions, gypsum karst develops on a human rather than on a geological time scale. Grouting measures considerably slowed down these processes, however, at the cost of subsurface flow field variations which will ultimately transfer the zone of enhanced dissolution.

Grundwasser - Mensch - Ökosysteme : 25. Tagung der Fachsektion Hydrogeologie in der DGGV 2016, Karlsruher Institut für Technologie (KIT), 13.-17. April 2016

Das Thema dieses Tagungsband lautet „Grundwasser, Mensch und Okosysteme“. Die vielfaltigen Aspekte dieses Themas werden in 13 thematischen Sessions und im Forum Junger Hydrogeologen intensiv diskutiert. Abgerundet wird das Programm durch drei spannende Keynote Lectures und eine popularwissenschaftliche Abendveranstaltung sowie Fortbildungskurse am Tag vor der Konferenz und Exkursionen im Anschluss an die Tagung.1 RWTH Aachen University, Department of Engineering Geology and Hydrogeology, Aachen, Germany 2 Vrije Universiteit Brussel (VUB), Department of Fundamental Electricity and Instrumentation, Brussels, Belgium 3 Vrije Universiteit Brussel (VUB), Department of Hydrology and Hydraulic Engineering, Brussels, Belgium 4 Helmholtz Centre for Environmental Research UFZ, Department of Hydrogeology, Leipzig, Germany