Contrasting definitions for the term ‘karst aquifer’

It is generally considered that karst aquifers have distinctly different properties from other bedrock aquifers. A search of the literature found five definitions that have been proposed to differentiate karst aquifers from non-karstic aquifers. The five definitions are based upon the presence of solution channel networks, hydraulic conductivities >10^?6 m/s, karst landscapes, channels with turbulent flow, and caves. The percentage of unconfined carbonate aquifers that would classify as ‘karst’ ranges from <1 to >50%.     

跨边界含水层问题研究

跨边界含水层作为地下水资源系统的一部分，涉及国家或地区之间的利益关系。文章分析了跨边界含水层问题，针对亚洲东部、中部和南部地下水系统，圈定了具有重要意义的跨国界含水层9处。对这些含水层，特别是我国边界上的黑龙江一阿穆尔河平原和伊犁河谷含水层进行了评价；对我国跨省界含水层进行了初步分析。研究跨边界含水层问题，对管理国家或地区之间共有的珍贵地下水资源，建设持久和平、共同繁荣的和谐社会具有重要的意义。     

Groundwater recharge in semi-arid carbonate aquifers under intensive use: the Estepa Range aquifers (Seville, southern Spain)

Quantifying groundwater recharge in carbonate aquifers located in semi-arid regions and subjected to intensive groundwater use is no easy task. One reason is that there are very few available methods suitable for application under such climatic conditions, and moreover, some of the methods that might be applied were originally designed with reference to non-carbonate aquifers. In addition, it is necessary to take into account the fact that, in any given aquifer, groundwater recharge is modified by the groundwater exploitation. Here we focus on four methods selected to assess their suitability for estimating groundwater recharge in carbonate aquifers affected by intensive exploitation. The methods were applied to the Estepa Range aquifers of Seville, southern Spain, which are subjected to different degrees of exploitation. Two conventional methods were used: chloride mass balance and daily soil–water balance. These results were compared with the results obtained by means of two non-conventional methods, designed for application to the carbonate aquifers of southern Spain: the APLIS and ERAS methods. The results of the different methods are analogous, comparable to those obtained in nearby non-exploited carbonate aquifers, confirming their suitability for use with carbonate aquifers in either natural or exploited regimes in a semi-arid climate.     

跨边界含水层研究

跨边界含水层作为地下水资源系统的一部分,与国际河流同样涉及国家或地区之间的利益关系。文中分析和总结了近年来对跨边界含水层研究的进展;对亚洲东部、中部和南部地下水系统进行了分析,圈定了具有重要意义的跨国界含水层9处,对这些含水层,特别是中国边界上的黑龙江—阿穆尔河平原和伊犁河谷含水层进行了评价;对中国跨省界含水层进行了初步分析。跨边界含水层问题的提出和研究,对管理国家或地区之间共有的珍贵地下水资源,建设持久和平、共同繁荣的和谐社会具有重要的意义。     

澜沧江—湄公河流域跨界含水层研究

跨界含水层由位于不同国家的含水层组成,是地下水资源系统的重要组成部分。妥善管理并公平合理地利用跨界含水层,对促进可持续发展及国家之间的睦邻友好关系有着重要意义。通过分析澜沧江—湄公河流域水文地质条件,划定流域的跨界含水层系统,并对地下水资源与环境问题进行探索,提出跨界含水层综合评价指标体系,结合澜沧江—湄公河流域4个跨界含水层相关的指标进行了综合评价。本次研究,对管理澜沧江—湄公河流域跨界含水层,建设和谐的东南亚国际环境有着重要意义。     

Sources of low-arsenic groundwater in the Bengal Basin: investigating the influence of the last glacial maximum palaeosol using a 115-km traverse across Bangladesh

Pollution of groundwater in the Bengal Basin (Bangladesh and West Bengal, India) by arsenic (As) puts at risk the health of more than 100 million consumers. Using 1,580 borehole lithological logs and published hydrochemistry on 2,387 wells, it was predicted that low-As (<10 μg/L) groundwater exists, in palaeo-interfluvial aquifers of brown sand capped by a protective palaeosol, beneath at least 45,000 km² of the Bengal Basin. The aquifers were predicted to be at a depth of as little as 25 m below ground level (mbgl), and typically no more than 50 mbgl. The predictions were confirmed along an east–west traverse 115 km in length (i.e. across half of Bangladesh) by drilling 28 new boreholes to 91-m depth to reveal subsurface sedimentology, and by mapping As distribution in groundwater. The aquifers identified occur at typically <40 mbgl and so are accessible with local drilling methods. A protective palaeosol that caps the palaeo-interfluvial aquifers prevents downward movement into them of As-polluted groundwater present in shallower palaeo-channel aquifers and ensures that the palaeo-interfluvial aquifers will yield low-As groundwater for the foreseeable future. Their use, in place of the shallower As-polluted palaeo-channel aquifers, would rapidly mitigate the health risks from consumption of As-polluted groundwater.     

218P0测深法寻找基岩地下水实用研究

阐明了一种新的找水方法——218P₀测深法。对其操作过程和根据实测曲线识别含水层、确定含水层数、分析富水性,以及计算含水层底板埋深的方法作了分析,并对有关机理作了初步探讨。     

Key Groundwater Control Factors of Deep Buried Coalfield by Landform and Sedimentation in the Northern Ordos Basin

There were three landforms (i.e. desert, bedrock platform and loess gully) in deep-buried coalfield of northern Ordos Basin. Water inflow of working face in desert area was 1~2 orders of magnitude larger than that in other landform areas. In order to find out the key controlling factors of the directly water filled aquifers on the roof of the coal seam, we carried out research from the aspects of topography, landform and geological sedimentation. The results showed that desert landform provides abundant recharge water for underlying aquifers because of gentle topography, large precipitation infiltration coefficient, thick and water-rich quaternary system. While bedrock platform and loess gully landform were the water sources with weak recharge capacity of underlying aquifers. The sandstone-mudstone interbedding structure formed by continental deposits resulted in the absence of regional stable aquifers in Jurassic and Cretaceous strata on the roof of coal seams. Pumping tests of boreholes showed that all strata belong to weak to medium water-rich aquifers. The groundwater level of Cretaceous aquifer decreased by 20~130 m in three mines. There was a close hydraulic relationship between shallow and deep aquifers. The Mesozoic strata belonged to fluvial deposits. Qilizhen sandstone and Zhenwudong sandstone aquifers were mainly developed on the roof of the coal seam, which were characterized by thick medium-coarse sandstone sections. The geological and sedimentary conditions of direct water-filled aquifer were similar, but the amount of borehole water, cumulative pre-drainage water and water inflow from goaf in desert geomorphic area were much larger than those in bedrock platform and loess gully geomorphic area. The water-rich of the aquifer was mainly controlled by geomorphology, and the water sources of the deep aquifers were meteoric precipitation and Quaternary aquifer. In different mines with similar Quaternary conditions in Mu Us Desert, there were also great differences in the amount of borehole water, cumulative pre-drainage water and water inflow from goafs. The difference was related to the thickness and lithology of the aquifers. It reflected that the geological sedimentary conditions of the coal seam roof were also important factors to control the water-rich of the aquifers. Topography, landform and geological sedimentation were the key factors to control the water-rich of the aquifer directly and the water inflow from the working face.     

Groundwater quality of porous aquifers in Greece: a synoptic review

Greece is dependent on groundwater resources for its water supply. The main aquifers are within carbonate rocks (karstic aquifers) and coarse grained Neogene and Quaternary deposits (porous aquifers). The use of groundwater resources has become particularly intensive in coastal areas during the last decades with the intense urbanization, tourist development and irrigated land expansion. Sources of groundwater pollution are the seawater intrusion due to over-exploitation of coastal aquifers, the fertilizers from agricultural activities and the disposal of untreated wastewater in torrents or in old pumping wells. In the last decades the total abstractions from coastal aquifers exceed the natural recharge; so the aquifer systems are not used safely. Over-exploitation causes a negative water balance, triggering seawater intrusion. Seawater intrusion phenomena are recorded in coastal aquifer systems. Nitrate pollution is the second major source of groundwater degradation in many areas in Greece. The high levels of nitrate are probably the result of over-fertilization and the lack of sewage systems in some urban areas.     

Hydrochemistry and isotope geochemistry as tools for groundwater hydrodynamic investigation in multilayer aquifers: a case study from Lomellina, Po plain, South-Western Lombardy, Italy

A multicriteria approach in studying hydrodynamics of a multilayer aquifer system has been used in the Lomellina region (Northern Italy). It involves the reconstruction of the hydrogeological framework coupled to the definition of the hydrochemical and isotopic features of the aquifers. A shallow phreatic aquifer, reaching depths of about 60–80 m from the surface, and deeper aquifers containing confined groundwater, were distinguished. Groundwater generally shows mineralisation decreasing with depth; dissolved ions depict calcium-bicarbonate hydrochemical facies and stable isotopes define the recharge mechanisms, the origin of groundwater, and the hydraulic confinement of deep aquifers. The phreatic aquifer is fed by local infiltration and by streams and irrigation channels. Tritium and Carbon-14 groundwater dating indicate long residence times (on the order of thousands of years) for confined aquifers. The confined aquifers show essentially passive hydrodynamic conditions and maintain a higher piezometric level than the phreatic aquifer. This inhibits the possibility of recent water penetrating far below the surface. The hydrogeological setting of the Lomellina region displays features which are common to other sectors of the Po plain. As a consequence, the results of this study, although conducted on a restricted area, are highly illustrative of groundwater hydrodynamics in large sedimentary aquifers.     

基于岩相的鄂尔多斯白垩系盆地含水层系统的结构研究

依据岩性岩相研究、孔隙度研究、物探测井解译等成果,对鄂尔多斯白垩系盆地含水层系统的结构进行了划分与研究。结果表明：盆地北部沙漠高原区为单一结构,表现为强富水与中等富水含水层在垂向上叠置与组合,无区域性连续稳定的隔水层,由下到上构成含水统一体;南部黄土高原区为多层结构,表现为含水层与隔水层上下叠置,垂向水文地质分层明显;盆地南、北含水层结构的结构类型明显不同。利用孔隙度、渗透系数、单位涌水量3个参数,对含水层的富水性级别进行了划分,盆地中共划分出7个强富水含水层、7个中等富水含水层和2个弱富水含水层。盆地南、北比较,北部含水层孔隙度大,富水性强,地下水主要富集于盆地北部地区。垂向上比较,盆地北部由上到下,孔隙度由大变小,富水性由强变弱,地下水主要富集于浅层和中层;南部上部罗汉洞组和下部洛河组孔隙度较大,富水性好,中部环河组相对较差,地下水主要富集于罗汉洞组和洛河组。     

大陆岛地下水动力学特征—以湛江东海岛为例

东海岛是一具有独特水文地质条件的大陆岛,浅层含水层与大陆以浅海湾相隔,中深层承压水含水层与大陆地下水系统紧密相连。为了深入地认识大陆岛地下水水动力学特征,以湛江东海岛为例,阐述了其水文地质条件,并分析了东海岛浅、中、深层地下水的流场和动态特征。分析结果表明,东海岛为一个典型且独特的大陆岛,岛内和大陆的部分浅层含水层由湛江湾相隔,岛内中、深层含水层和大陆中、深层含水层通过湛江湾相连,且具有统一的水位分布,并保持着密切的水力联系,岛内中、深层地下水由南向北径流补给湛江市区的降落漏斗中心;滨海及海水区域浅层含水层及其下伏的粘土层构成了防止海水入侵中、深层地下水的保护层;浅层地下水流场基本保持天然状态,水位动态特征主要为入渗径流型,水位变化与降雨量相关;中、深层地下水流场以人工流场为主,地下水由南向北径流,水位动态类型主要为开采动态型,水位变化主要受到开采量变化的影响;在近海岸地区,地下水动态表现为潮汐效应型,在潮汐作用下,地下水位动态具有周期性。     

Assessment of groundwater dynamics in Quaternary aquifers of the Phrae Basin,northern Thailand,using isotope techniques

Hydrogeology Journal - The Quaternary sequences in the Phrae Basin, northern Thailand, can be classified into three aquifers based on depth. The groundwater dynamics and recharge of these aquifers...     

鄂尔多斯盆地北部深埋区“地貌—沉积”控水关键要素研究

鄂尔多斯盆地北部深埋煤田区地表主要有沙漠、基岩台地和黄土沟壑等地貌类型,沙漠区工作面涌水量比其他地貌区大1~2个数量级。为了查清煤层顶板直接充水含水层补给水源、导水通道和充水强度的控制要素,从地形地貌和地质沉积方面开展了研究,结果表明:沙漠地貌地势平缓,降水入渗系数大,第四系厚度大、富水性强,为下伏含水层提供了丰富的补给水源;基岩台地和黄土沟壑地貌,地形起伏大,降水入渗系数极小,浅部地层富水性极弱,是下伏含水层补给能力较弱的水源。陆相沉积形成的砂泥岩互层结构,不存在区域性稳定隔水层,各层段均属于弱-中等富水性含水层,3个矿井的白垩系含水层水位下降了20~130 m,证明浅部与深部含水层存在较密切的水力联系。煤层顶板主要发育七里镇砂岩和真武洞砂岩含水层,为厚度较大的中粗砂岩段,直接充水含水层地质沉积条件相似,但是沙漠区工作面顶板钻孔水量、累计预疏放水量和采空区涌水量均远大于其他地貌区,直接充水含水层富水性主要受地貌控制,深部含水层的水源为大气降水和第四系含水层。沙漠地貌区的不同矿井,工作面顶板钻孔水量、累计预疏放水量、采空区涌水量也存在较大差异,该差异与直接充水含水层厚度和岩性等有关,反映了地质沉积条件也是控制含水层富水性的重要因素。地形地貌和地质沉积是控制直接充水含水层富水性和工作面涌水量的关键要素。     

Study of subsurface geology in locating arsenic-free groundwater in Bengal delta,West Bengal,India

Over a large area of the Bengal delta in West Bengal, India, arsenic distribution patterns in groundwater were studied. One hundred and ten boreholes at different target locations were made, subsurface sediments were logged and analysed, and arsenic values in sediments vis-à-vis groundwater were compared. The study elucidates the subsurface geology of the western part of Bengal delta and characterises the sediments that were intersected in different boreholes with contrasting values of arsenic in groundwater. It reveals an existence of multiple aquifers stacked over each other. Depending on the color and nature of aquifer-sands and their overlying clay beds six aquifer types (Type-1 to Type-6) are classified and described. Sediment-arsenic for all the varieties of aquifer sands are near similar but the groundwater-arsenic of these six aquifers varies widely. Type-2 and Type-5 aquifers host arsenic-contaminated groundwater whereas the other four aquifers are arsenic-free. Type-2 and Type-5 aquifers are capped by a grey to dark grey soft organic matter-rich clay unit which makes these aquifers semi-confined to leaky-confined. These contribute in releasing arsenic from the sediments. The results of this study are employed in a proposed georemedial measure against this hazardous toxic element.     

Rare earth elements in groundwater from different Alpine aquifers

Rare earth elements (REE) were determined in 39 groundwater samples collected at 14 sites under low- and high-flow conditions. Water samples derived from aquifers hosted in crystalline, molasse, flysch, carbonate and evaporite rocks located in Western Switzerland. The concentration of REE in groundwater circulating in different rocks showed large variations: lowest concentrations (ΣREE≤10 ng/L) occurred in groundwater from evaporite aquifers; highest concentrations (ΣREE up to 516 ng/L) were observed in carbonate aquifers, although REE in these waters do vary under different hydrological conditions; groundwater from other aquifers had ΣREE from 10 to 100 ng/L. Distinct REE signatures were observed in waters draining specific rocks. The REE patterns in groundwater from crystalline, molasse and flysch aquifers showed heavy-REE enrichment at different degrees. Groundwaters circulating in crystalline rocks were distinguished by negative anomalies in Ce and Eu, whereas those from carbonate aquifers were nearly flat with ΣREE and the magnitude of negative anomaly in Ce is likely to be controlled by iron concentrations. The REE-Post-Archean Australian Shales (PAAS) normalized patterns appear useful to recognize the aquifer type and suggest the possibility to use the REE as geochemical tracers.     

跨界含水层研究现状与展望

随着人口的激增和水资源压力的不断增大,跨界含水层在地下水利用和供水安全保障方面处于越来越重要的位置。目前,围绕跨界含水层主要开展了以下三个方面的工作:联合国教科文组织国际水文计划联合其他相关机构,对世界各主要大洲进行了跨界含水层的标示及划分工作;在总结完善相关跨界含水层法律条文的基础上,联合国国际法委员会于2008年向联合国大会上提交了跨界含水层草案条款,该项草案条款的出台对共享含水层各国开发和管理地下水具有重要的指导意义;在联合国教科文组织及其他机构的推动下,各大洲已逐步开展对跨界含水层的研究,并建立了相关的合作机构。分析表明,跨界含水层的研究需要相关国家间的进一步协商与合作。     

Evaluation of groundwater dynamics and quality in the Najd aquifers located in the Sultanate of Oman

The Najd, Oman, is located in one of the most arid environments in the world. The groundwater in this region is occurring in four different aquifers A to D of the Hadhramaut Group consisting mainly of different types of limestone and dolomite. The quality of the groundwater is dominated by the major ions sodium, calcium, magnesium, sulphate, and chloride, but the hydrochemical character is varying among the four aquifers. Mineralization within the separate aquifers increases along the groundwater flow direction from south to north-northeast up to high saline sodium-chloride water in aquifer D in the northeast area of the Najd. Environmental isotope analyses of hydrogen and oxygen were conducted to monitor the groundwater dynamics and to evaluate the recharge conditions of groundwater into the Najd aquifers. Results suggest an earlier recharge into these aquifers as well as ongoing recharge takes place in the region down to present day. Mixing of modern and submodern waters was detected by water isotopes in aquifer D in the mountain chain (Jabal) area and along the northern side of the mountain range. In addition, δ²H and δ¹⁸O variations suggest that aquifers A, B, and C are assumed to be connected by faults and fractures, and interaction between the aquifers may occur. Low tritium concentrations support the mixing assumption in the recharge area. The knowledge about the groundwater development is an important factor for the sustainable use of water resources in the Dhofar region.     

Pumping from unconfined aquifers of limited saturated thickness with reference to wellpoints and horizontal wells

Groundwater in unconfined aquifers of limited saturated thickness can be a valuable resource but frequently it is not developed because conventional boreholes are unsuitable. However, successful exploitation of shallow unconfined aquifers has been achieved using either a line of wellpoints or horizontal wells extending for more than 100 m. The flow processes by which wellpoints and horizontal wells collect water from unconfined aquifers are explored by developing conceptual and computational models. Several representative examples are considered and it is found that similar discharges occur if the wellpoints are closely spaced. The sensitivity of the yield to physical dimensions of the wells and aquifers is explored; the impact of alternative aquifer parameters is also examined. Results from these computational models are used to identify the causes of air entry into wellpoint systems; the prevention of air entry into horizontal wells is also considered. This evaluation demonstrates that wellpoint systems and horizontal wells can efficiently abstract water from unconfined aquifers of limited saturated thickness provided that precautions are taken to prevent air entry.     

钻井冲洗液对水井出水量影响规律的模拟试验研究及其应用

钻井冲洗液是影响水井出水量的主要因素之一。通过室内模拟试验，发现了不同钻井冲洗液类型和不同洗井方法对含水层渗透性的影响规律，找到了既有较好护壁性又对含水层有较小封堵作用且封堵后易于冲洗的冲洗液，并对聚合物在含水层中的作用机理进行了初步探讨。同时介绍了两个应用实例。