•Probabilistic assessment of hydraulic heads exceeding spring thresholds undertaken.•Measurement uncertainty incorporated into Indicator Kriging.•Spring source aquifer assessment informed through ...head-based likelihood estimates.•Areas that would benefit most from additional hydraulic head measurements identified.
Hydraulic head distributions can inform spring source-water characterisation by determining whether aquifers meet the thresholds required to sustain spring flow. Assessing hydraulic head data can be challenging in areas where data are sparsely distributed and subject to variable measurement uncertainty. Geostatistical methods can be used to estimate hydraulic head values at unmeasured locations with quantitative uncertainty estimates. While these methods have been applied extensively for hydraulic head estimation in management contexts, no studies have used these approaches for spring source-water conceptual model testing. In this study, an investigation into the hydraulic head distribution was conducted through the application of Ordinary Indicator Co-Kriging. Interpolated hydraulic head estimates were used to quantitatively assess the plausibility of source-aquifer conceptual models for the Doongmabulla Springs Complex (DSC), Queensland, Australia. The results offer insights into the likelihood of alternative source aquifers having adequate head to support flow to eight springs within the DSC. Probabilities of adequate head to support the springs ranged from 0.03 to 0.12 for the Permian Formations, compared to <0.01 to 0.49 for the Triassic Formations. Analyses indicated that the Triassic Formations are more likely to have adequate hydraulic head to support spring flow. However, significant uncertainty exists in the conceptual model assessment due to hydraulic head measurement scarcity, particularly in the vicinity of the springs. These findings have important implications given that the Permian Formations will be dewatered by the operation of the nearby Carmichael coal mine. The techniques employed here can inform conceptual model uncertainties arising from the interpretation of sparsely distributed hydraulic head datasets, a major benefit over traditional interpolation methods.
•Hydraulic head and partial derivatives simulated using Sequential Gaussian simulation.•Minima/maxima in the hydraulic head surface located and mapped stochastically.•Concavity of the hydraulic head ...surface identified and mapped.•Method provides an objective interpretation of recharge/discharge areas.
Identifying groundwater flow directions and the locations of recharge and discharge areas is critical for effective groundwater management. Groundwater flow directions, the concavity and the locations of extrema (i.e., minima and maxima) can be assessed using the first and second derivatives of the hydraulic head surface. We developed a geostatistical method to jointly simulate hydraulic head and its first and second derivatives using sequential Gaussian simulation. The derivative values were used to identify regional groundwater flow directions, and the second derivative test was used to probabilistically map the concavity and the locations of extrema in the hydraulic head surface. By comparing the mapped concavity and extrema to known features, it was possible to attribute areas of recharge and discharge to physical features of the system, such as rivers, lakes and geological outcrops. This was applied to Triassic aquifers in the Galilee Basin (Queensland, Australia) to delineate the likely recharge and discharge areas. This provided an objective assessment of likely recharge and discharge zones and their uncertainty, which is an important addition to a region where the hydrogeology has been the subject of much conjecture.
Fault-controlled springs: A review Keegan-Treloar, Robin; Irvine, Dylan J.; Solórzano-Rivas, S. Cristina ...
Earth-science reviews,
July 2022, 2022-07-00, Letnik:
230
Journal Article
Recenzirano
Odprti dostop
Springs sustain groundwater-dependent ecosystems and provide freshwater for human use. Springs often occur because faults modify groundwater flow pathways leading to discharge from aquifers with ...sufficiently high pressure. This study reviews the key characteristics and physical processes, field investigation techniques, modelling approaches and management strategies for fault-controlled spring systems. Field investigation techniques suitable for quantifying spring discharge and fault characteristics are often restricted by high values of spring ecosystems, requiring mainly non-invasive techniques. Numerical models of fault-controlled spring systems can be divided into local-scale, process-based models that allow the damage zone and fault core to be distinguished, and regional-scale models that usually adopt highly simplified representations of both the fault and the spring. Water resources management relating to fault-controlled spring systems often involves ad hoc applications of trigger levels, even though more sophisticated management strategies are available. Major gaps in the understanding of fault-controlled spring systems create substantial risks of degradation from human activities, arising from limited data and process understanding, and simplified representations in models. Thus, further studies are needed to improve the understanding of hydrogeological processes, including through detailed field studies, physics-based modelling, and by quantifying the effects of groundwater withdrawals on spring discharge.
•Fault-spring processes, investigation methods, models and management reviewed.•Long-term spring discharge and source-aquifer head data are rarely available.•Fault representation in models is improved by recent advances in popular codes.•Spring management is often hindered by poor knowledge of fault characteristics.•Further research needed to quantify aquifer-fault-spring-ecosystem relationships.
Abstract Developing conceptual models is a critical step in hydrogeological studies that should utilise multiple lines of evidence and data types to minimise conceptual uncertainty, particularly in ...data-sparse systems. This study used new and existing major ion and isotope (O, H, Sr, C) data sets to refine a previous hydraulic-head-based conceptual model of the Galilee Basin (Australia). The analyses provide evidence for the locations of recharge and discharge areas and determine hydrochemical processes along flow paths to improve understanding of potential source waters to the Doongmabulla Springs Complex (DSC) and to infer mixing within, or exchange between aquifer units. There was good agreement between previously inferred recharge and discharge areas defined using hydraulic head data and interpretations from hydrochemical evolution along groundwater flow pathways, at least where data were available. Major ion and isotope data suggest that the DSC likely receives water from both a relatively shallow, local flow path and a deeper regional flow path. This observation is relevant to previous concerns about threats to the DSC, as mine-induced drawdown may impact the relative contributions to spring discharge from different recharge sources and aquifers. Silicate weathering in the deeper Clematis Formation and Dunda Beds, and evapotranspiration in the overlying Moolayember Formation have strong control on the total dissolved solids content. These findings suggest that the Clematis Formation and Dunda Beds are hydrochemically distinct from the Moolayember Formation, with limited exchange between these aquifers, which has important implications for model conceptualisation and ongoing monitoring of mining activities in the Galilee Basin.
Résumé L’élaboration de modèles conceptuels est une étape essentielle des études hydrogéologiques, qui doit utiliser plusieurs sources et types de données pour minimiser l’incertitude conceptuelle, en particulier dans les systèmes où les données sont rares. Cette étude a utilisé des jeux de données en ions majeurs et isotopes (O, H, Sr, C), nouvellement acquis ou existants, pour affiner un modèle conceptuel antérieur, basé sur la charge hydraulique, du bassin de Galilée (Australie). Les analyses chimiques permettent de localiser les zones de recharge et de décharge et de déterminer les processus hydrochimiques le long des axes d’écoulement et ainsi d’améliorer la compréhension de l’origine potentielle des sources du complexe de Doongmabulla (CSD) et de déduire les échanges dans et entre les unités aquifères. Il existe une bonne concordance entre les zones de recharge et de décharge précédemment définies à l’aide des données de charge hydraulique et les interprétations de l’évolution hydrochimique le long des axes d’écoulement des eaux souterraines, du moins lorsque les données sont disponibles. Les données en ions majeurs et isotopes suggèrent que le CSD est rechargé probablement par des eaux provenant à la fois d’un écoulement local relativement peu profond et d’un écoulement régional plus profond. Cette observation est pertinente compte tenu des préoccupations antérieures concernant les menaces pesant sur le CSD, car l’abaissement induit par les mines peut avoir un impact sur les contributions relatives des différentes origines d’alimentation et des différents aquifères à l’écoulement des sources. L’altération des silicates dans les formations Clematis et Dunda Beds, plus profondes, et l’évapotranspiration dans la formation Moolayember sus-jacente exercent un contrôle important sur la teneur totale en solides dissous. Ces résultats suggèrent que les formations Clematis et Dunda Beds sont hydrochimiquement distinctes de la formation Moolayember, avec des échanges limités entre ces aquifères, ce qui a des implications importantes pour le modèle conceptuel et pour la surveillance en continu des activités minières dans le bassin de Galilée.
Resumen El desarrollo de modelos conceptuales es un paso crítico en los estudios hidrogeológicos que deben utilizar múltiples líneas de evidencia y tipos de datos para minimizar la incertidumbre conceptual, particularmente en sistemas con datos escasos. En este estudio se utilizaron conjuntos de datos existentes y recientes sobre los principales iones e isótopos (O, H, Sr, C) para perfeccionar un modelo conceptual previo basado en la carga hidráulica de la cuenca de Galilea (Australia). Los análisis aportan pruebas de la ubicación de las zonas de recarga y descarga y determinan los procesos hidroquímicos a lo largo de las trayectorias de flujo para mejorar la comprensión de las posibles aguas de origen del Complejo Doongmabulla Springs (DSC) e inferir la mezcla dentro de las unidades acuíferas o el intercambio entre ellas. Se observó una buena concordancia entre las zonas de recarga y descarga previamente inferidas, definidas a partir de los datos de carga hidráulica, y las interpretaciones de la evolución hidroquímica a lo largo de las trayectorias de flujo de las aguas subterráneas, al menos en los casos en que se disponía de datos. Los datos de iones mayoritarios e isótopos sugieren que es probable que el DSC reciba agua tanto de una trayectoria de flujo local relativamente poco profunda como de una regional más profunda. Esta observación es relevante para las preocupaciones previas sobre las amenazas al DSC, ya que la reducción inducida por la explotación minera puede afectar a las contribuciones relativas a la descarga del manantial desde diferentes fuentes de recarga y acuíferos. La meteorización de silicatos en las capas más profundas de la Clematis Formation y Dunda Beds, y la evapotranspiración en la suprayacente Moolayember Formation ejercen un fuerte control sobre el contenido total de sólidos disueltos. Estos resultados sugieren que la Clematis Formation y la Dunda Beds son hidroquímicamente distintas de la Moolayember Formation, con un intercambio limitado entre estos acuíferos, lo que tiene importantes implicancias para la conceptualización de modelos y el monitoreo continuo de las actividades mineras en la cuenca de Galilea.
摘要 发展概念模型是水文地质研究中至关重要的步骤, 应利用多重证据和不同类型的数据来尽量减少概念模型的不确定性, 特别是在数据稀少的系统中。本研究使用了新的和现有的主要离子和同位素 (氧、氢、锶、碳) 数据集, 来细化澳大利亚迦利利盆地之前基于水头数据的概念模型。通过分析确定了补给区和排泄区的位置, 并确定了沿水流路径的水化学过程, 以提高对Doongmabulla Springs Complex(DSC)潜在水源的理解, 并推断含水层内部的混合或不同含水层之间的交换。至少在有数据的地方, 之前基于水头数据定义的补给和排泄区域与沿地下水流动路径的水化学演变的解释之间, 有很好的一致性。主要离子和同位素数据表明, DSC很可能同时接受来自较浅的局部水流路径和更深的区域水流路径的水补给。这一观察与先前对DSC潜在威胁的担忧相关, 因为矿业开采可能会影响不同补给源和含水层对泉水排泄的相对贡献。更深层Clematis组和Dunda Beds的硅酸盐风化作用, 以及上覆Moolayember组的蒸散发作用, 对总溶解固体含量有重要控制作用。这些发现表明, Clematis组和Dunda Beds在水化学上与Moolayember组明显不同, 这些含水层之间的交换有限, 这对于概念模型的构建和对Galilee盆地矿业活动的持续监控具有重要的意义。
Resumo O desenvolvimento de modelos conceituais é uma etapa critica em estudos hidrogeológicos que devem utilizar múltiplas linhas de evidencia e tipos de dados para minimizar a incerteza conceitual, particularmente em sistemas com dados esparsos. Este estudo utilizou conjuntos de dados novos e existentes de íons maiores e isótopos (O, H, Sr, C) para refinar um modelo conceitual anterior baseado em carga hidráulica da Bacia da Galileia (Australia). As análises forneceram evidências das localizações das áreas de recarga e descarga e auxiliaram na determinação dos processos hidroquímicos ao longo dos caminhos de fluxo, melhorando assim a compreensão das potenciais fontes de água do Complexo de Nascentes de Doongmabulla (CND) e dos processos de mistura e/ou troca entre as unidades aquíferas. Houve uma boa concordância entre as áreas de recarga e descarga previamente inferidas usando dados de carga hidráulica, e as interpretações da evolução hidroquímica ao longo dos caminhos de fluxo das águas subterrâneas, pelo menos onde haviam dados disponíveis. Os dados de íons maiores e isótopos sugerem que o CND provavelmente recebe água tanto de um caminho de fluxo local relativamente raso quanto de um caminho de fluxo regional mais profundo. Esta observação é relevante para preocupações anteriores sobre ameaças ao CND, uma vez que o rebaixamento induzido por minas pode impactar as contribuições relativas de diferentes fontes de recarga e aquíferos para a descarga de nascentes. O intemperismo de silicatos nas formações mais profundas (Formação Clematis e Dunda Beds), e o efeito da evapotranspiração na Formação Moolatember sobrejacente têm forte controle sobre o conteúdo total de sólidos dissolvidos. Estas descobertas sugerem que a Formação Clematis e as Dunda Beds são hidroquimicamente distintas da Formação Moolayember, com trocas limitadas entre estes aquíferos, o que tem implicações importantes para a conceitualização do modelo e para o monitoramento das atividades mineiras em andamento na Bacia da Galileia.
Developing conceptual models is a critical step in hydrogeological studies that should utilise multiple lines of evidence and data types to minimise conceptual uncertainty, particularly in ...data-sparse systems. This study used new and existing major ion and isotope (O, H, Sr, C) data sets to refine a previous hydraulic-head-based conceptual model of the Galilee Basin (Australia). The analyses provide evidence for the locations of recharge and discharge areas and determine hydrochemical processes along flow paths to improve understanding of potential source waters to the Doongmabulla Springs Complex (DSC) and to infer mixing within, or exchange between aquifer units. There was good agreement between previously inferred recharge and discharge areas defined using hydraulic head data and interpretations from hydrochemical evolution along groundwater flow pathways, at least where data were available. Major ion and isotope data suggest that the DSC likely receives water from both a relatively shallow, local flow path and a deeper regional flow path. This observation is relevant to previous concerns about threats to the DSC, as mine-induced drawdown may impact the relative contributions to spring discharge from different recharge sources and aquifers. Silicate weathering in the deeper Clematis Formation and Dunda Beds, and evapotranspiration in the overlying Moolayember Formation have strong control on the total dissolved solids content. These findings suggest that the Clematis Formation and Dunda Beds are hydrochemically distinct from the Moolayember Formation, with limited exchange between these aquifers, which has important implications for model conceptualisation and ongoing monitoring of mining activities in the Galilee Basin.
