北京西南城近郊浅层地下水盐污染特征及机理分析

北京市西南城近郊是本市高硬度水主要分布区，也是北京平原区地下水主要补给区，浅层地下水水质恶化已成为影响本区经济发展的主要因素。本文通过对区内14个长期观测孔11a来水质资料的统计分析，从统计学和水化学角度分析了本区浅层地下水盐污染特征和机理。结果说明，盐污染主要是硬度升高和硝酸盐污染，而在时间和空间分布上的不均匀性，显示出污染源、污染途径及污染机理的复杂性。最主要的污染原因有：独特的水文地质条件，污灌，砂石坑垃圾回填，及区域地下水位下降。     

Hydrogeological studies for the Nubia sandstone aquifers in Garf Hussein area,Western Desert,Egypt

The lithology of the studied aquifers has an important effect on their hydrogeologic setting. Moreover, the structural patterns have their imprint on the geologic setting and consequently the hydrogeologic conditions of the area. Lake Nasser recharges the groundwater in the study area by large amount of water increasing the groundwater level. A comparison of the depth to water in the same wells at two different periods (1998 and 2014 ) shows that the depth to water increases with average rise 11.1 m during 16 years. The constructed water table map shows that the groundwater flow is mainly towards the northwest direction reflecting recharge from Lake Nasser. The hydraulic parameters of the Abu Aggag and Sabaya sandstone aquifers are determined in the present work from pumping tests. The transmissivity of the studied aquifers reflects the moderate to high potentiality. The groundwater salinity of the studied aquifers is fresh water and varies from 353 to 983 ppm (part per million) and suitable for all purposes. It increases due to the west direction coinciding with groundwater flow direction. The main result of the present study shows that the seepage water from Lake Nasser attains 17 mcm/year.     

Impact of intense exploitation on the groundwater balance and flow within Mullusi aquifer (arid zone, west Iraq)

The main results that derived from this study is the quantitative determination of subsurface water balance and the water loses along flow line during drought decade (before 2000–2009), with intense exploitation of groundwater from water wells. The hydrogeological data are presented as spatial distribution maps and three dimensional models. The results are correlated with the main hydrogeologic control points including (storage and transmissivity coefficients, groundwater depths, aquifers thickness, lateral extensions, well productivity) to determine the preferable hydrogeologic districts for development and exploitations, avoiding groundwater depletion as captured zone flow. Based on the isotope analysis of deuterium, oxygen-18, tritium, carbon-13, and carbon-14, the recharge of the aquifer is originated to direct infiltration of atmospheric water through exposure outcrops within Hauran catchments area. The isotope compositions also show that the groundwater is a mixture of an old groundwater with modern recharge in the areas adjacent to Rutba. The fact that the Mullusi aquifer is of major importance as the water supply of people in Rutba region, particularly, for increasing demand of water resources and sustainability assessment in the future, this study developed a reliable strategic suggested plan in groundwater supply, based on groundwater exploitation and amount of safe yield within Dhabaa basin.     

The karst contagion model: Synopsis and environmental implications

The contagion model of karst terrane evolution focuses on the environmental implications for a large karst depression population on the Pennyroyal Plain (southern Kentucky) and the adjacent Western Highland Rim (Tennessee) immediately south of the Mammoth Cave Plateau. In karst terranes where the contagion model applies, there is a well-defined infrastructure comprised of hydrologic, structural geologic and geomorphic interacting elements that result in clustered depressions underlain by a radial conduit system. Clusters tend to be randomly distributed and typically contain a parent depression surrounded by numerous daughters.Groundwater flow is assumed to be turbulent and confined largely to conduits that are 3-dimensionally configured between clusters in a dendritic to trellis network. Parent depressions serve as conduit nodes for collecting groundwater migrating from beneath daughter depressions.Flow velocities in the 3-dimensional cluster-cell conduits exceed those in granular media by several orders of magnitude making pathogen and chemical contaminant migration rapid. Groundwater quality assessment in karst conduit hydrogeologic settings is difficult because monitoring wells are inappropriate. Monitoring wells may have a low probability of intercepting a major conduit and therefore the sampling regime must take into consideration the pulse discharge of pollutants in karst conduits. Representative water quality data must come from springs located near the local base level.     

Controls on groundwater flow in the Bengal Basin of India and Bangladesh: regional modeling analysis

Groundwater for domestic and irrigation purposes is produced primarily from shallow parts of the Bengal Basin aquifer system (India and Bangladesh), which contains high concentrations of dissolved arsenic (exceeding worldwide drinking water standards), though deeper groundwater is generally low in arsenic. An essential first step for determining sustainable management of the deep groundwater resource is identification of hydrogeologic controls on flow and quantification of basin-scale groundwater flow patterns. Results from groundwater modeling, in which the Bengal Basin aquifer system is represented as a single aquifer with higher horizontal than vertical hydraulic conductivity, indicate that this anisotropy is the primary hydrogeologic control on the natural flowpath lengths. Despite extremely low hydraulic gradients due to minimal topographic relief, anisotropy implies large-scale (tens to hundreds of kilometers) flow at depth. Other hydrogeologic factors, including lateral and vertical changes in hydraulic conductivity, have minor effects on overall flow patterns. However, because natural hydraulic gradients are low, the impact of pumping on groundwater flow is overwhelming; modeling indicates that pumping has substantially changed the shallow groundwater budget and flowpaths from predevelopment conditions.     

Case studies in organic contaminant hydrogeology

The effective management of domestic solid waste and hazardous, toxic, and radioactive waste is a major problem in the area of environmental geology and water sciences over the world. This series of case studies of organic contaminants from both solid and hazardous waste disposal facilities provides examples of these problems. The facilities were investigated to determine risks and liabilities before acquisition, to determine the site hydrogeologic conditions for design of appropriate groundwater monitoring plans, and/or to determine the potential for groundwater contamination. The results of these studies and investigations by Waste Management Inc. (WMI) and its consultants have shown certain relationships in the distribution of organic pollutants to the different geologic and hydrogeologic charac teristics of each facility. In each of the case studies, all 129 priority pollutants were analyzed in private wells and/or monitoring wells at the request of regulatory agencies. The 31 volatile organic compounds (VOCs) of the priority pollutant list were the majority of the organic compounds detected and these data are evaluated in each case study. The case studies are on disposal facilities located in glacial tills, carbonaceous weathered clay soils, weathered shale, limestone bedrock, dolomite bedrock, and alluvial and sedimentary deposits. A brief discussion of groundwater quality impacts and remedial measures also is included.Presented at the Second Annual Canadian/American Conference on Hydrogeology: Hazardous Wastes in Ground Water—A Soluble Dilemma. Banff, Alberta, Canada, June 26, 1985.     

Conservation planning as an adaptive strategy for climate change and groundwater depletion in Wadi El Natrun,Egypt

In drylands, groundwater is often the sole source of freshwater for industrial, domestic and agricultural uses, while concurrently supporting ecosystems. Many dryland aquifers are becoming depleted due to over-pumping and a lack of natural recharge, resulting in loss of storage and future water supplies, water-level declines that reduce access to freshwater, water quality problems, and, in extreme cases, geologic hazards. Conservation is often proposed as a strategy for managing groundwater to reduce or reverse the depletion, although there is a need to better understand its potential effectiveness and benefits at the local scale. This study assesses the impact of water-conservation planning strategies on groundwater resources in the Wadi El Natrun (WEN) area of northern Egypt. WEN has been subjected to groundwater depletion and quality degradation since the 1990s, attributed to agricultural and industrial groundwater usage. Initiatives have been proposed to increase the sustainability of the groundwater resource in the study area, but they have yet to be evaluated. Simultaneously, there are also proposals to increase the extent of arable land and thus demand for freshwater. In this study, three water management scenarios are developed and assessed to the 2060s for their impact on groundwater resources using a hydrogeologic model. Results demonstrate that demand management implemented through an optimized irrigation and crop rotation strategy has the greatest potential to significantly reduce risk of groundwater depletion compared to the other two scenarios—“business as usual” and “30% water-use reduction”—that were evaluated.     

RETRACTED ARTICLE: Development prospects of groundwater resources in an elliptical shape island,Union Territory of Lakshadweep,India

A major problem of the islanders is the availability of fresh water for drinking purpose. Groundwater is the only source of fresh water for the islanders. The demand for groundwater is increasing very year due to growing population and urbanization. A proper understanding of the groundwater condition is important in order to meet this increasing demand and to formulate future development and management strategies. It is in this context, principal hydrogeologic units; water table fluctuation pattern, general groundwater potential, existing groundwater withdrawal structures and draft, water quality, etc. have been studied in an elliptical shape Andrott Island of Union Territory of Lakshadweep, India, through field investigation and secondary data collection. Groundwater occurs under phreatic condition and seawater is in hydraulic continuity with the groundwater as evidenced by the tidal influence in almost all the wells. Groundwater level fluctuation due to seasonal variation varies from 0 to 0.542 m depending on the distance of the well from the coast. Depth to groundwater level varies from less than 1.234 to 3.520 m depending on the topography. Groundwater level fluctuation is due to the combination of factors like rainfall, tidal activities, sub-surface runoff, and draft. Large diameter dug wells are the main groundwater extraction structures in this island. There are 2,143 dug wells with almost each family having its own well and the density of the dug wells is about 437/km². The stage of groundwater development is estimated as 37% and hence “Safe” for further groundwater development in this island. However, considering the very limited fresh-water resources and also the growing demand for groundwater, various management strategies such as rainwater harvesting, artificial recharge of groundwater, public participation in water conservation and wise use of groundwater, etc., have been suggested.     

内蒙古翁牛特-库伦一带严重缺水区找水研究

翁牛特-库伦一带为西辽河平原周边的严重缺水区,区内地形、地貌及地质构造条件复杂,找水难度较大.在该区找水过程中充分利用了前人资料,综合研究区域水文地质条件及地下水的补径排规律,合理采用遥感、物探等各方面的新技术、新方法.主要寻找断层带脉状水、碳酸岩类裂隙溶洞水、古河道砂砾石松散岩类水等.通过两年的工作,为地方成井7眼,总涌水量达3464.91m³/d,缓解了部分地区的人畜饮用水紧张状况,起到了典型的示范作用.     

The application of satellite differential SAR interferometry-derived ground displacements in hydrogeology

The application of satellite differential synthetic aperture radar (SAR) interferometry, principally coherent (InSAR) and to a lesser extent, persistent-scatterer (PSI) techniques to hydrogeologic studies has improved capabilities to map, monitor, analyze, and simulate groundwater flow, aquifer-system compaction and land subsidence. A number of investigations over the previous decade show how the spatially detailed images of ground displacements measured with InSAR have advanced hydrogeologic understanding, especially when a time series of images is used in conjunction with histories of changes in water levels and management practices. Important advances include: (1) identifying structural or lithostratigraphic boundaries (e.g. faults or transitional facies) of groundwater flow and deformation; (2) defining the material and hydraulic heterogeneity of deforming aquifer-systems; (3) estimating system properties (e.g. storage coefficients and hydraulic conductivities); and (4) constraining numerical models of groundwater flow, aquifer-system compaction, and land subsidence. As a component of an integrated approach to hydrogeologic monitoring and characterization of unconsolidated alluvial groundwater basins differential SAR interferometry contributes unique information that can facilitate improved management of groundwater resources. Future satellite SAR missions specifically designed for differential interferometry will enhance these contributions.     

Recharge and discharge controls on groundwater travel times and flow paths to production wells for the Ammer catchment in southwestern Germany

Travel times and flow paths of groundwater from its recharge area to drinking-water production wells will govern how the quality of pumped groundwater responds to contaminations. Here, we studied the 180 km² Ammer catchment in southwestern Germany, which is extensively used for groundwater production from a carbonate aquifer. Using a 3-D steady-state groundwater model, four alternative representations of discharge and recharge were systematically explored to understand their impact on groundwater travel times and flow paths. More specifically, two recharge maps obtained from different German hydrologic atlases and two plausible alternative discharge scenarios were tested: (1) groundwater flow across the entire streambed of the Ammer River and its main tributaries and (2) groundwater discharge via a few major springs feeding the Ammer River. For each of these scenarios, the groundwater model was first calibrated against water levels, and subsequently travel times and flow paths were calculated for production wells using particle tracking methods. These computed travel times and flow paths were indirectly evaluated using additional data from the wells including measured concentrations of major ions and environmental tracers indicating groundwater age. Different recharge scenarios resulted in a comparable fit to observed water levels, and similar estimates of hydraulic conductivities, flow paths and travel times of groundwater to production wells. Travel times calculated for all scenarios had a plausible order of magnitude which were comparable to apparent groundwater ages modelled using environmental tracers. Scenario with groundwater discharge across the entire streambed of the Ammer River and its tributaries resulted in a better fit to water levels than scenario with discharge at a few springs only. In spite of the poorer fit to water levels, flow paths of groundwater from the latter scenario were more plausible, and these were supported by the observed major ion chemistry at the production wells. We concluded that data commonly used in groundwater modelling such as water levels and apparent groundwater ages may be insufficient to reliably delineate capture zones of wells. Hydrogeochemical information relating only indirectly to groundwater flow such as the major ion chemistry of water sampled at the wells can substantially improve our understanding of the source areas of recharge for production wells.     

Assessing the impacts of sea-level rise and precipitation change on the surficial aquifer in the low-lying coastal alluvial plains and barrier islands,east-central Florida (USA)

A three-dimensional variable-density groundwater flow and salinity transport model is implemented using the SEAWAT code to quantify the spatial variation of water-table depth and salinity of the surficial aquifer in Merritt Island and Cape Canaveral Island in east-central Florida (USA) under steady-state 2010 hydrologic and hydrogeologic conditions. The developed model is referred to as the ‘reference’ model and calibrated against field-measured groundwater levels and a map of land use and land cover. Then, five prediction/projection models are developed based on modification of the boundary conditions of the calibrated ‘reference’ model to quantify climate change impacts under various scenarios of sea-level rise and precipitation change projected to 2050. Model results indicate that west Merritt Island will encounter lowland inundation and saltwater intrusion due to its low elevation and flat topography, while climate change impacts on Cape Canaveral Island and east Merritt Island are not significant. The SEAWAT models developed for this study are useful and effective tools for water resources management, land use planning, and climate-change adaptation decision-making in these and other low-lying coastal alluvial plains and barrier island systems.     

Saltwater intrusion in coastal regions of North America

Saltwater has intruded into many of the coastal aquifers of the United States, Mexico, and Canada, but the extent of saltwater intrusion varies widely among localities and hydrogeologic settings. In many instances, the area contaminated by saltwater is limited to small parts of an aquifer and to specific wells and has had little or no effect on overall groundwater supplies; in other instances, saltwater contamination is of regional extent and has resulted in the closure of many groundwater supply wells. The variability of hydrogeologic settings, three-dimensional distribution of saline water, and history of groundwater withdrawals and freshwater drainage has resulted in a variety of modes of saltwater intrusion into coastal aquifers. These include lateral intrusion from the ocean; upward intrusion from deeper, more saline zones of a groundwater system; and downward intrusion from coastal waters. Saltwater contamination also has occurred along open boreholes and within abandoned, improperly constructed, or corroded wells that provide pathways for vertical migration across interconnected aquifers. Communities within the coastal regions of North America are taking actions to manage and prevent saltwater intrusion to ensure a sustainable source of groundwater for the future. These actions can be grouped broadly into scientific monitoring and assessment, engineering techniques, and regulatory approaches.     

指示娘子关泉群水动力环境的水化学—同位素信息分析

本文依据宏量组分、微量元素和氢氧同位氧组成监测资料，分析了娘子关泉群水动力环境及其水文地质演化趋势。除国家和城西泉主要排泄局部流动系统的地下水外，其它各泉均为不同空间尺度流动系统地下水混合、排泄之产物。在人类活动影响下，娘子关泉群水质恶化，流量衰减，水帘洞、程家泉断流，城西、坡底泉也面临断流之危险。目前抽取的水帘洞泉的水资源量组成已与五龙泉和苇泽关泉相似，以区域和中间流动系统地下水为主。     

Numerical groundwater-flow modeling to evaluate potential effects of pumping and recharge: implications for sustainable groundwater management in the Mahanadi delta region,India

Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997–2006, followed by validation (2007–2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.     

GMS在双城市城区地下水资源评价中的应用

根据双城市水文地质条件建立了概念模型,应用GMS软件建立了研究区地质结构模型及地下水数值模拟模型。考虑自然条件以及开采量的影响,设计6种方案对研究区地下水流进行预报,结果显示以设计开采量对水源地进行开采,水源地投产10年后最大中心水位降深不会超过最大允许降深。     

Groundwater flow and capture zone analysis of the Central Passaic River Basin, New Jersey

Delineating capture zones of pumping wells is an important part of safe drinking water and well protection programs. Capture zones or contributing areas of a groundwater extraction well are the parts of the aquifer recharge areas from which the wells draw their water. Their extent and location depend on the hydrogeologic conditions such as groundwater recharge, pumping scenario and the aquifer properties such as hydraulic conductivity, porosity, heterogeneity of the medium and hydraulic gradient. Different methods of delineation can be used depending on the complexity of the hydrogeologic conditions. In this study, a 3-dimensional transient numerical MODFLOW model was developed for the Central Passaic River Basin (CPRB), and used with a MODPATH particle tracking code to determine 3-dimensional transient capture zones. Analytically calculated capture zones from previous studies at the site were compared with the new numerically simulated capture zones. The study results revealed that the analytical solution was more conservative, estimating larger capture zones than the numerical models. Of all the parameters that can impact the size, shape and location of a capture zone, the hydraulic conductivity is one of the most critical. Capture zones tend to be smaller in lower hydraulic conductivity areas.     

敦煌月牙泉湖水位持续下降原因及对策分析

在分析月牙泉湖水文地质条件的基础上，依据实际调查资料和前人研究成果，定量分析了月牙泉湖水位持续下降的原因，认为地表水开采量的不断增加和水资源利用率的不断提高所引起的区域性地下水位持续下降是月牙泉湖水位下降的主要原因，超采地下水所引起的储存资源的减少是导致月牙泉湖地下水位下降的次要原因。遏止月牙泉湖水位继续下降并逐步回升的关键是增加湖区上游地下水的补给量和减少党河灌区开采量，为此提出了农业节水和引哈济党二种治理方案，但就月牙泉湖水位恢复速度和时间及取得的社会、生态及经济效益而言，引哈济党方案优先。     

北京地区地下水源热泵利用现状及存在问题

本文综合国内外地下水源热泵研究现状,通过对北京地区地下水源热泵利用现状调查分析,重点分析了地下水水源热泵利用过程中存在的不能完全回灌、回灌水温差过大、水井布设不合理等问题。结合北京平原区第四系水文地质条件,分析了不同含水层结构下如何合理布设地下水源热泵系统的用水井,尽量避免水源热泵系统的使用对地下水的影响。     

Postaudit evaluation of conceptual model uncertainty for a glacial aquifer groundwater flow and contaminant transport model

Numerical groundwater flow and contaminant transport modeling incorporating three alternative conceptual models was conducted in 2005 to assess remedial actions and predict contaminant concentrations in an unconfined glacial aquifer located in Milford, Michigan, USA. Three alternative conceptual models were constructed and independently calibrated to evaluate uncertainty in the geometry of an aquitard underlying the aquifer and the extent to which infiltration from two manmade surface water bodies influenced the groundwater flow field. Contaminant transport for benzene, cis-DCE, and MTBE was modeled for a 5-year period that included a 2-year history match from July 2003 to May 2005 and predictions for a 3-year period ending in July 2008. A postaudit of model performance indicates that predictions for pumping wells, which integrated the transport signal across multiple model layers, were reliable but unable to differentiate between alternative conceptual model responses. In contrast, predictions for individual monitoring wells with limited screened intervals were less consistent, but held promise for evaluating alternative hydrogeologic models. Results of this study suggest that model conceptualization can have important practical implications for the delineation of contaminant transport pathways using monitoring wells, but may exert less influence on integrated predictions for pumping wells screened over multiple numerical model layers.