Jun-Zhi Wang

An analytical study on artesian flow conditions in unconfined-aquifer drainage basins

Although it has been reported that flowing artesian wells could be topographically controlled, there is no quantitative research on artesian flow conditions in unconfined aquifers. In this study, the water table, which has a lower amplitude than the land surface, is damped from the topography and used as the boundary condition to obtain the analytical solution of hydraulic head of a unit basin with a single flow system. The term artesian head is defined to characterize the condition of flowing artesian wells. The zone with positive artesian head is called artesian zone while with negative artesian head is nonartesian zone. The maximum artesian head and the size of artesian zones are found to increase with the damping factor and the anisotropy ratio, and decrease with the ratio of basin width to depth and the depth-decay exponent of hydraulic conductivity. Moreover, the artesian head increases with depth nearby the valley and decreases with depth near by the divide, and the variation rates are influenced by the decay exponent and the anisotropy ratio. Finally, the distribution of flowing artesian wells and the artesian head measurements in different depths of a borehole in a small catchment in the Ordos Plateau, Northwestern China is used to illustrate the theoretical findings. The change in artesian head with depth was used to estimate the anisotropy ratio and the decay exponent. This study opens up a new door to analyze basin-scale groundwater flow.

Field identification of groundwater flow systems and hydraulic traps in drainage basins using a geophysical method

Groundwater flow systems and stagnant zones in drainage basins are critical to a series of geologic processes. Unfortunately, the difficulty of mapping flow system boundaries and no field example of detected stagnant zones restrict the application of the concept of nested flow systems. By assuming the variation in bulk resistivity of an aquifer with uniform porosity is mainly caused by groundwater salinity, the magnetotelluric technique is used to obtain the apparent resistivity of a profile across a groundwater-fed river in the Ordos Plateau, China. Based on the variations in apparent resistivity of the Cretaceous sandstone aquifer, the basin-bottom hydraulic trap below the river has been detected for the first time, and its size is found to be large enough for possible deposition of large ore bodies. The boundaries between local and regional flows have also been identified, which would be useful for groundwater exploration and calibration of large-scale groundwater models.

A theoretical analysis of basin-scale groundwater temperature distribution

The theory of regional groundwater flow is critical for explaining heat transport by moving groundwater in basins. Domenico and Palciauskas’s (1973) pioneering study on convective heat transport in a simple basin assumed that convection has a small influence on redistributing groundwater temperature. Moreover, there has been no research focused on the temperature distribution around stagnation zones among flow systems. In this paper, the temperature distribution in the simple basin is reexamined and that in a complex basin with nested flow systems is explored. In both basins, compared to the temperature distribution due to conduction, convection leads to a lower temperature in most parts of the basin except for a small part near the discharge area. There is a high-temperature anomaly around the basin-bottom stagnation point where two flow systems converge due to a low degree of convection and a long travel distance, but there is no anomaly around the basin-bottom stagnation point where two flow systems diverge. In the complex basin, there are also high-temperature anomalies around internal stagnation points. Temperature around internal stagnation points could be very high when they are close to the basin bottom, for example, due to the small permeability anisotropy ratio. The temperature distribution revealed in this study could be valuable when using heat as a tracer to identify the pattern of groundwater flow in large-scale basins. Domenico PA, Palciauskas VV (1973) Theoretical analysis of forced convective heat transfer in regional groundwater flow. Geological Society of America Bulletin 84:3803–3814RésuméLa théorie du flux souterrain régional est indispensable pour expliquer le transport de chaleur par mouvements d’eau souterraine dans les bassins. Domenico et Palciauskas (1973), pionniers dans l’étude du transport convectif de chaleur dans un bassin simple, assumaient que la convection avait une faible influence sur la redistribution des températures dans un aquifère. De plus, il n’y a pas eu de recherche se focalisant sur la distribution des températures près des zones de stagnation entre différents systèmes de flux. Dans cet article, la distribution des températures dans un bassin simple est réexaminée et de plus, celle d’un bassin complexe avec des systèmes de flux imbriqués est explorée. Dans ces deux bassins pour lesquels la distribution de la température due à la conduction est comparée, la convection entraine une baisse de température dans la plus grande partie du bassin à l’exception d’un petit secteur proche de la zone de décharge. Il existe une anomalie de hautes températures près du point de stagnation en fond de bassin où deux systèmes de flux convergent du fait d’un faible degré de convection et une distance de trajet importante. Par contre, il n’y a pas d’anomalie près du point de stagnation de fond de bassin lorsque deux systèmes de flux divergent. Dans le bassin complexe, il y a également une anomalie de fortes températures vers le point de stagnation interne. La température vers le point interne de stagnation peut être très élevée lorsqu’ils sont proches du fond du bassin du fait, par exemple, d’un faible rapport d’anisotropie de la perméabilité. La distribution de la température montrée dans cette étude peut être intéressante lorsque l’on utilise la chaleur comme un traceur pour identifier les schémas de circulation des flux souterrains dans de grands bassins. Domenico PA, Palciauskas VV (1973) Theoretical analysis of forced convective heat transfer in regional groundwater flow (Analyse théorique du transfert de chaleur par convection sous contraintes dans l’écoulement régional d’eaux souterraines). Geological Society of America Bulletin 84:3803–3814ResumenLa teoría del flujo regional de agua subterránea es crítica para explicar el transporte del calor por movimiento del agua subterránea en cuencas. El estudio pionero de Domenico y Palciauskas (1973) sobre transporte convectivo de calor en una cuenca simple asumió que la convección tenía una influencia pequeña en la redistribución de la temperatura en el agua subterránea. Más aún, no ha habido ninguna investigación enfocada en la distribución de la temperatura alrededor de las zonas de estancamiento entre los sistemas de flujo. En este trabajo, se reexamina la distribución de la temperatura en la cuenca simple y se explora dicha distribución en una cuenca compleja con sistemas de flujo anidados. Comparada con la distribución de la temperatura debido a la conducción, la convección en ambas cuenca lleva a temperaturas más bajas en la mayor parte de la cuenca excepto para una parte pequeña cercana a la zona de descarga. Existe una anomalía de alta temperatura alrededor del punto de estancamiento en el fondo de la cuenca donde dos sistema de flujo convergen debido a un bajo grado de convección y a una gran distancia de tránsito, pero no existe anomalía alrededor de un punto de estancamiento en el fondo de la cuenca donde dos sistemas de flujo divergen. En la cuenca compleja, también existen anomalías de alta temperatura alrededor de puntos internos de estancamiento. La temperatura alrededor de los puntos internos de estancamiento podría ser muy alta cuando ellos están cercanos al fondo de la cuenca, por ejemplo, debido a una baja relación entre permeabilidad y anisotropía. La distribución de temperatura revelada en este estudio podría ser valiosa al utilizar el calor como un trazador para identificar el esquema del flujo de agua subterránea en cuencas a gran escala. Domenico PA, Palciauskas VV (1973) Theoretical analysis of forced convective heat transfer in regional groundwater flow (Análisis teórico de la transferencia de calor por convección forzada en el flujo regional de agua subterránea). Geological Society of America Bulletin 84:3803–3814摘要区域地下水流理论对解释盆地内依靠地下水流动的热量传输过程至关重要。Domenico 和 Palciauskas (1973年)对一个简单盆地进行热对流传输的开拓性研究中, 假定对流对地下水温度的再分布影响很小。此外,对水流系统中滞流区周围的的温度分布还没有研究过。本文中,重新研究了简单盆地的温度分布规律,并对拥有多级次水流系统的复杂盆地进的温度分布规律开展了研究。在这两种盆地中,与传导造成的温度分布相比,除了排泄区附近很小一片区域外,对流将会使流域大部分地区的温度偏低。在两个水流系统汇聚的盆地底部驻点周围,由于对流程度较低及流动距离很长,存在着一个高温异常,但在两个水流系统分岔的盆地底部驻点周围,没有高温异常。在复杂盆地中,内部驻点周围也有高温异常。当内部驻点靠近盆地底部时,例如,由于渗透性各向异性比值很小,其周围的温度可能非常高。在利用温度作为示踪剂确定大尺度盆地地下水水流模式时,本研究所揭示的温度分布规律非常有价值。Domenico PA, Palciauskas VV (1973年),Theoretical analysis of forced convective heat transfer in regional groundwater flow (区域地下水流中强迫性对流热量转移的理论分析)。美国地质学会学报 84:3803–3814ResumoA teoria do fluxo de água subterrânea regional é crítica para explicar o transporte de calor através do movimento da água subterrânea nas bacias. O estudo pioneiro de Domenico e Palciauskas (1973) sobre transporte de calor convectivo numa bacia simples assumiu que a convecção tem uma influência diminuta na redistribuição da temperatura da água subterrânea. Para além disso, não tem havido pesquisa vocacionada para a distribuição de temperatura em redor de zonas de estagnação dentro dos sistemas de fluxo. Neste documento, a distribuição de temperatura na bacia simples é reexaminada e é explorada a mesma situação numa bacia complexa com sistemas de fluxo aninhados. Em ambas as bacias, em comparação com a distribuição de temperaturas devidas a condução, a convecção leva a temperaturas mais baixas na maior parte das bacias, exceto em pequenas zonas próximas das áreas de descarga. Existe uma grande anomalia de alta temperatura em redor do ponto de estagnação na base da bacia, onde dois sistemas de fluxo convergem devido ao baixo grau de convecção e à longa distância de circulação, mas não há anomalia em redor do ponto de estagnação da base da bacia onde os dois sistemas de fluxo divergem. Na bacia complexa existem também anomalias de alta temperatura em redor de pontos de estagnação internos. A temperatura em redor de pontos de estagnação internos pode ser muito elevada quando estes estão próximos da base da bacia, por exemplo devido a pequenos efeitos anisotrópicos na permeabilidade. A distribuição de temperatura revelada neste estudo pode ser valiosa quando se usa o calor como traçador para identificar o padrão de fluxo da água subterrânea em bacias a grande escala. Domenico PA, Palciauskas VV (1973) Theoretical analysis of forced convective heat transfer in regional groundwater flow [Análise teórica de transferência de calor convectivo forçado em fluxos regionais de água subterrânea]. Geological Society of America Bulletin 84:3803–3814

A numerical study on the occurrence of flowing wells in the discharge area of basins due to the upward hydraulic gradient induced wellbore flow

Ministry of Education Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China Yellow River Engineering Consulting Co., Ltd. (YREC), Jinshui Road 109, Zhengzhou, Henan 450003, China Correspondence Xiao‐Wei Jiang, Ministry of Education Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China. Email: jxw@cugb.edu.cn

An analytical study on three‐dimensional versus two‐dimensional water table‐induced flow patterns in a Tóthian basin

Although it has been increasingly acknowledged that groundwater flow pattern is complicated in the three-dimensional (3-D) domain, two-dimensional (2-D) water table-induced flow models are still widely used to delineate basin-scale groundwater circulation. However, the validity of 2-D cross-sectional flow field induced by water table has been seldom examined. Here, we derive the analytical solution of 3-D water table-induced hydraulic head in a Tothian basin and then examine the validity of 2-D cross-sectional models by comparing the flow fields of selected cross sections calculated by the 2-D cross-sectional model with those by the 3-D model, which represents the “true” cases. For cross sections in the recharge or discharge area of the 3-D basin, even if head difference is not significant, the 2-D cross-sectional models result in flow patterns absolutely different from the true ones. For the cross section following the principal direction of groundwater flow, although 2-D cross-sectional models would overestimate the penetrating depth of local flow systems and underestimate the recharge/discharge flux, the flow pattern from the cross-sectional model is similar to the true one and could be close enough to the true one by adjusting the decay exponent and anisotropy ratio of permeability. Consequently, to determine whether a 2-D cross-sectional model is applicable, a comparison of hydraulic head difference between 2-D and 3-D solutions is not enough. Instead, the similarity of flow pattern should be considered to determine whether a cross-sectional model is applicable. This study improves understanding of groundwater flow induced by more natural water table undulations in the 3-D domain and the limitations of 2-D models accounting for cross-sectional water table undulation only.