Natural background levels and threshold values for groundwater in fluvial Pleistocene and Tertiary marine aquifers in Flanders,Belgium

Aquifers from the same typology can have strongly different groundwater chemistry. Deducing the groundwater quality of less well-characterized aquifers from well-documented aquifers belonging to the same typology should be done with great reserve, and can only be considered as a preliminary approach. In the EU’s 6th FP BRIDGE project “Background cRiteria for the IDentification of Groundwater thrEsholds”, a methodology for the derivation of threshold values (TV) for groundwater bodies is proposed. This methodology is tested on four aquifers in Flanders of the sand and gravel typology. The methodology works well for all but the Ledo-Paniselian aquifer, where the subdivision into a fresh and saline part is disproved, as a gradual natural transition from fresh to saline conditions in the aquifer is observed. The 90 percentile is proposed as natural background level (NBL) for the unconfined Pleistocene deposits, ascribing the outliers to possible influence of pollution. For the Tertiary aquifers, high values for different parameters have a natural origin and the 97.7 percentile is preferred as NBL. The methodology leads to high TVs for parameters presenting low NBL, when compared to the standard used as a reference. This would allow for substantial anthropogenic inputs of these parameters.     

水质监测在识别水动力条件中的作用

水质监资料不仅可反映地下水水质的时、空变化特征，而且可提供有关地下水赋存环境、循环深度、流速、资源量组成等方面的重要信息。     

Groundwater system division and compilation of Groundwater Resources Map of Asia

Based on landform, climate, river system, geological structure and hydrogeological structure and from the perspective of systematology, the groundwater system of Asia can be divided into 36 secondary groundwater systems under 11 primary ones by the intercontinental scale. A scientific evaluation of groundwater resources in Asia can be secured using water balance method and runoff modulus method through water circulating analysis and feature study of groundwater system on the basis of groundwater system division of Asia. With natural recharge(runoff) modulus(10~4m~3/km~2·a), the total amount of water resources and those available for exploitation of primary groundwater system can be evaluated-continuous aquifers in plains and basins contain 242.465× 10~9 m~3/a of water, 169.725× 10~9 m~3/a of which is recoverable; discrete aquifers contain 186.695× 10~9 m~3/a, 130.686× 10~9 m~3/a of which is available for exploitation; other scattered aquifers contain 38.614× 10~9 m~3/a, 27.029× 10~9 m~3/a of which could be exploited. In total, there is 467.774× 10~9 m~3/a of groundwater with 327.440× 10~9 m~3/a recoverable. The groundwater map of Asia is compiled according to groundwater system division, evaluation of the total amount and aquifer types to reflect the macro features of groundwater resources in Asia, laying a scientific foundation for exploitation and management of water resources here and for avoiding disputes over groundwater resources and environment among Asian countries.     

Natural background levels for some ions in groundwater of the Campania region (southern Italy)

The aim of the study was the determination of the natural background levels (NBLs) for the ions Na⁺, Cl^?, SO₄ ^2?, As³⁺, F^?, Fe²⁺, and Mn²⁺, in some groundwater bodies of the Campania region (southern Italy). The ??Protocol to evaluate the natural background concentrations?? proposed in 2009 by ISPRA (Italian Institute for Environmental Protection and Research) has been applied to the chemical data set of groundwater of the examined groundwater bodies. These analyses have also been examined following the guidelines of the BRIDGE project (Background cRiteria for the IDentification of Groundwater thrEshold). These approaches to evaluate the Threshold Values (TVs) and the NBLs, based on probability distribution functions, have been applied in many countries by various authors during the last 5?years. Changes applied to ISPRA Protocol in this study concern mainly the preselection criteria, in particular threshold values of specific ions, deriving from the aquifers geochemical features. The preselection criteria of the ISPRA Protocol have been merged with those of the BRIDGE Project in order to define a procedure suitable for the definition of the NBLs in the examined aquifers. The NBL of fluoride for the ??Phlegrean Fields?? and the ??eastern Plain of Naples?? groundwater bodies shows values deeply exceeding the reference value (REF) of 1,500???g/L, ranging between 3,600 and 15,000???g/L. The cause of this very high fluoride content is in the natural features of the aquifers constituted by volcanic and pyroclastic rocks. The volcanic origin of the aquifers is also the reason for the high arsenic content in ??Phlegrean Fields?? groundwater. Here the NBL calculated was about 47???g/L against the drinking water standard value of 10???g/L. The widespread high content of manganese and iron for the groundwater body of the ??eastern Plain of Naples?? is due to the reducing conditions related to the extensive marshlands present in the past. The very high NBL of all the examined ions for the groundwater body of ??Ischia Island?? depends on the existence of a geothermal system.     

Groundwater resources and development in China

Since the establishment of new China, great attention has been paid by the government to the investigation of groundwater resources. On the basis of regional hydrogeological mapping covering most parts of the territory, an overall evaluation of groundwater resources in China is about 872 billion m³/a, in which the amounts of pore water, fissure water, and karst water are calculated separately, and the consumption of groundwater is also accounted for. Much prospecting work has been carried out for the development of well irrigation as well as the urban water supply of industrial cities. This extensive work has provided a scientific basis for the rational development and utilization of groundwater resources. According to statistics, 11.3 million ha of arable land are irrigated with water from wells, and the annual exploitation of underground water has reached 40 billion m³. In 27 cities of North China, the output of groundwater reached 6.86 million m³/d, which amounted to 87% of the total water consumed. The distribution and different hydrogeological characteristics of groundwater resources in various regions are discussed in this article, including some environmental hydrogeological problems related to the exploitation and utilization of groundwater. In short, it is evident that groundwater resources play a significant role in both urban and rural water supply, and promote the development of agriculture and industries in China.     

河流与地下水关系的演化及若干科学问题

河流和地下水之间存在着密切的水力联系和频繁的转化关系。近几十年来,受自然因素和人类活动的影响,河流与地下水之间的转化关系趋于复杂化,引起水循环的变化,诱发了一系列生态环境负效益,使水资源及生态问题突显,其中河流与地下水关系及其演化是河流与地下水相互作用中重要问题之一,是属于河流维持机理与地下水可再生能力的基础研究内容。笔者在对河流与地下水转化关系类型划分的基础上,依据室内和野外试验资料,结合地质、水文地质条件,分析了各类型的渗流特征和影响河流与地下水关系演化的因素;从国内外研究现状出发,分析了当前该领域存在的不足和急待解决的有关科学问题,为定量模拟和评价河流与地下水的演化关系提供了科学依据。     

水文地质概念模型的水动力场研究方法——"流场分析法"

水文地质概念模型建立的正确与否是地下水资源评价计算的关键,水文地质概念模型的水动力场研究方法——“流场分析法”是以地下水动力学和水均衡原理为基础,通过对水头函数的时空分布特征分析,判断出地下水系统的结构和功能,据此,科学概化出地下水系统的水文地质概念模型,为地下水资源的正确评价计算奠定基础。     

邯邢煤田岩浆岩侵入体的水文地质意义

邯邢煤田煤系及其上覆地层中常有岩浆岩侵入体穿插。通过调查研究发现：侵入体的大小不同，其对地下水影响表现不一；区域上的岩体使地下水运动受阻隔，而穿插于煤系地层中的薄层岩脉则往往形成含、储水空间，成为导水通道；而且岩浆岩体的存在对地下水的化学成分还有一定的影响。因而，认识和分析岩浆岩侵入体的水文地质意义，对于客观分析煤（井）田的水文地质条件，尤其对矿井生产中防治水工作具有积极的意义。     

辽宁省中南部分城市地下水脆弱性评价

通过对辽中南地区的地质与水文地质条件特征、含水层的富水性、开采利用地下水现状等资料的调查和了解,利用地下水脆弱性的DRASTIC评价模型和AHP模糊评价模型,对地下水固有脆弱性的七个因素指标进行了赋值、计算。最终得出了辽宁省中南部分城市地下水脆弱性分区分为强脆弱区、较强脆弱区、中等脆弱区、弱脆弱区。     

泸西喀斯特断陷盆地地表水与地下水流域边界与水动力性质

在详细调查基础上,采用系统科学及水文地质分析方法,依据地形地貌、地层岩性、地质构造、示踪试验、地下水排泄基准面、喀斯特发育条件及发育规律等剖析论证流域边界,并通过钻探及示踪试验进行验证。研究结果:（1）对泸西喀斯特断陷盆地南东部的水系统边界向北移进行了修正,证实了三塘一带深部不发育的喀斯特是地下水分水岭边界,使得泸西喀斯特断陷盆地流域的径流系统和边界圈化更加准确;（2）泸西喀斯特断陷盆地流域地表水、地下水转化频繁,地表水径流特征主要以小江河在水库、河流、伏流间的径流转化过程为体现,地下水在侵溶山区接受大气降水补给后,上层径流以泉、暗河的形式在泸西盆地底面排泄后转化成地表水,最终汇集于盆地南部、通过工农隧洞及落水洞排向小江,而下层径流则以小江水面为基准,通过深层径流排泄。      

从施工水文地质勘查孔看乌鲁木齐北部平原水质及变化

通过水文地质钻探,抽水试验、样品分析等手段,结合前人资料,查明了乌鲁木齐北部平原内水文地质岩性结构、地下水分布状态,不同富水地段含水层特征参数等,并对地下水水质进行了评价。结果显示:评价区内赋存丰富的第四系松散岩类孔隙水,由单一结构潜水向双层或多层结构潜水、承压水演变。评价区潜水和浅层承压水质量等级为Ⅳ类或Ⅴ类,超标项目主要为硫酸盐、溶解性总固体、总硬度,较深层承压水质量等级为Ⅱ类。评价区浅层的潜水或承压水水质较差,较深层的承压水可作为理想的饮用水源。     

塔里木盆地区域地下水环境同位素特征及其意义

以大量水环境同位素样品测试结果为依据,对塔里木盆地的区域水环境同位素特征进行了分析,得出了一些有意义的认识:(1)塔里木盆地不同14C年龄的地下水的δD、δ18O值差异不明显,反映了水资源形成区在最后冰期和冰后期气温相差不大,推测是由于新构造运动使山体隆升,同一位置因高程变化产生的气温变化弥合了气候的变化,这一特征使我们难以运用δD-δ18O关系区别古水(冰期)与现代水(冰后期)。(2)在δD-δ18O关系图上,沿大气降水线可把盆地内主要河流及其补给形成的地下水大致圈定在3个域内,这3个域的区别不是大气环流作用的结果,而是河流源区山脉高程效应的反映。(3)与西北内陆盆地其他大型河流比较,阿克苏河流域下游承压自流水的14C年龄小得多,这是由阿克苏河径流量大、下游为河槽洼地、不完全具备山前倾斜平原水文地质特征等决定的。阿克苏河下游承压水水循环交替迅速,开发潜力较大,在西北内流盆地中是一个特例。(4)塔克拉玛干沙漠第四系松散层地下水主要是从盆地南缘侧向补给的,在沙漠腹地由深部向浅部顶托排泄。盆地内深层油田水处于高度封闭的滞留状态,与上部松散沉积层地下水之间基本没有联系。     

Assessment of groundwater circulation in La Gomera aquifers (Canary Islands, Spain) from their hydrochemical features

La Gomera (Canary Islands, Spain) does not show water scarcity like other islands of the Archipelago. However, the study of its aquifers is paramount as nearly 60 % of the water supplies are covered with spring water. According to the currently accepted hydrogeological model, La Gomera presents an upper aquifer consisting of perched groundwater bodies. Below this hydrogeological unit, the General Saturated Zone or basal groundwater is placed. The model also establishes the presence of flows through them. Many perched groundwater bodies are located under Garajonay National Park where most of the springs are found. Therefore, if upper and lower aquifers are truly connected and new wells are built, the new extractions could affect Garajonay ecosystems. With the aim of identifying spring groups and related potential areas of water transfer, hydrochemical and statistical analyses (principal component analysis and cluster analysis) have been applied. This study shows the great compositional variability of groundwaters, precluding the identification of spring groups, hydrochemical patterns and, therefore, the transfer areas with no possibility of assessing the potential impact of a water demand increase on the Garajonay National Park ecosystems from the present data. Only the springs belonging to group II of the cluster analysis could indicate a transfer area. The lack of conclusive results could be due to: (1) great compositional variability of volcanic materials; (2) unequal influence of marine aerosols; (3) irregular distribution of rainfall; (4) different grades of soils development; and (5) the occurrence of partially disconnected water bodies giving as a result a complex hydrogeological system.     

Hydrogeological analysis and salvage of a deep coalmine after a groundwater inrush

This paper presents a case history of the permanent salvage of the Sanhejian Coalmine in China after a sudden groundwater inrush, which includes emergency responses, hydrogeological analyses, and design and performance of bulkheads. The inrush accident occurred in October 2002 in the mined-out area with a high water pressure of 7.6 MPa and a high water temperature of 51°C. The emergency response quickly followed up to provide the time required to perform a detailed hydrogeological analysis to identify the source and pathway of groundwater. The Sanhejian Coalmine is geologically located in the Tengxian anticline hydrogeological setting. The Sunshidian fault, the northern boundary of the mine, was assumed impermeable in the original hydrogeological report. After the accident and hydrogeological analysis, this assessment was revised and the fault was considered to be permeable. The Sunshidian fault connects the strata in the mine and the excellent water-productive Middle Ordovician Majiagou Formation in the core of the Tengxian anticline. It was concluded that the water inrush was from the underlying Ordovician karst aquifer and the pathway was a hidden tectonic structure in the strata overlying the aquifer. This assessment served as the guideline for salvaging the mine in this project. After a detailed technical and economic analysis, a concrete bulkhead design was selected from several alternatives including dewatering and surface grouting. The performance of the bulkheads has been sufficient for the last 6 years since their construction. This case history shows that the hydrogeological analysis plays an essential role in successfully salvaging the coalmine from the water inrush by identifying the source and pathway of groundwater.     

The cenozoic aquifer system of the Lower Tagus Basin: a description of the hydrogeological situation in the Almada region (Portugal)

A conceptual hydrogeological model of the Mio-Pleistocene deposits in the Almada region, located in the Cenozoic aquifer system of the Lower Tagus Basin (Portugal), has been developed. Though numerous studies have been conducted on its geological features, there have not been enough hydrogeological investigations to define the origin, flow path and the groundwater quality and to understand the coexistence of overlapped interacting aquifers. Therefore, a study is presented here on the occurrences and features of groundwater resources in the Almada region based on an inventory in the field (wells, springs and boreholes), physical and chemical analyses, geologic setting, and tectonic and geomorphologic observations. This aquifer system has long been a source of concern because of the high level of extraction over the last few decades, as well as the progressive degradation of the water quality. Available groundwater resources have been affected by intensive agricultural and industrial activity, as a consequence of incorrect or non-existent hydrogeological knowledge.     

Environmental tracers and indicators bringing together groundwater,surface water and groundwater-dependent ecosystems: importance of scale in choosing relevant tools

Groundwater–surface water (GW–SW) interactions cover a broad range of hydrogeological and biological processes and are controlled by natural and anthropogenic factors at various spatio-temporal scales, from watershed to hyporheic/hypolentic zone. Understanding these processes is vital in the protection of groundwater-dependent ecosystems increasingly required in water resources legislation across the world. The use of environmental tracers and indicators that are relevant simultaneously for groundwater, surface water and biocenoses–biotope interactions constitutes a powerful tool to succeed in the management task. However, tracer type must be chosen according to the scale of interest and tracer use thus requires a good conceptual understanding of the processes to be evaluated. This paper reviews various GW–SW interaction processes and their drivers and, based on available knowledge, systemises application of conservative tracers and semi-conservative and reactive environmental indicators at different spatial scales. Biocenoses–biotopes relationships are viewed as a possible transition tool between scales. Relation between principal application of the environmental tracers and indicators, examples and guidelines are further proposed for examining GW–SW interactions from a hydrogeological and biological point of view by demonstrating the usability of the tracers/indicators and providing recommendations for the scientific community and decision makers.     

Anthropization of groundwater resources in the Mediterranean region: processes and challenges

A comprehensive overview is provided of processes and challenges related to Mediterranean groundwater resources and associated changes in recent decades. While most studies are focused thematically and/or geographically, this paper addresses different stages of groundwater exploitation in the region and their consequences. Examples emphasize the complex interactions between the physical and social dimensions of uses and evolution of groundwater. In natural conditions, Mediterranean groundwater resources represent a wide range of hydrogeological contexts, recharge conditions and rates of exploitation. They have been actively exploited for millennia but their pseudo-natural regimes have been considerably modified in the last 50 years, especially to satisfy agricultural demand (80% of total water consumption in North Africa), as well as for tourism and coastal cities. Climate variability affects groundwater dynamics but the various forms of anthropization are more important drivers of hydrological change, including changes in land use and vegetation, hydraulic works, and intense pumpings. These changes affect both the quantity and quality of groundwater at different scales, and modify the nature of hydrogeological processes, their location, timing, and intensity. The frequent cases of drastic overexploitation illustrate the fragility of Mediterranean groundwater resources and the limits of present forms of management. There is no easy way to maintain or recover sustainability, which is often threatened by short-term interests. To achieve this goal, a significant improvement in hydrogeological knowledge and closer collaboration between the various disciplines of water sciences are indispensable.     

中国地下水污染修复方法和技术应用展望

[研究目的]:中国地下水污染调查和修复日益受到科学界的重视,了解和掌握地下水污染修复方法和技术有助于对污染场地进行科学修复.[研究方法]:本文在系统分析国内外地下水污染修复案例的基础上,对中国地下水污染修复现场实施的技术方法进行总结.[研究结果]:结合中国区域经济发展特征和地下水污染调查评价成果认为,复杂的水文地质条件...     

Groundwater investigation in the southern part of Gabes using resistivity sounding, southern Tunisia

The groundwater hydrogeology of southern Tunisia emphasizes two main groundwater bodies so-called Zeuss-Koutine and south Gabes. These groundwater bodies yielding economically important storage of useful water present complex internal architecture and heterogeneity allowing exchange flows throughout permeable or/and fractured bodies. A geophysical survey using resistivity soundings was carried out along this area to describe in detail the field structure and the 3D extent of these groundwater bodies by the hydrogeological new data and detailed subsurface mapping based on resistivity sounding and seismic data. This survey discusses also the potentialities of some permeable layer in water storage and purposes potential favorable areas for optimum groundwater mining.     

珠江流域地下水资源评价及问题分析

本文在梳理流域地下水资源评价现状及历史的基础上,讨论了水资源评价方法和分区原则,将珠江流域划分为129个四级地下水系统,以地下水系统为评价单元,在充分考虑不同水文地质参数的基础上,分析评价地下水资源量及存在的问题,讨论珠江流域三级阶地不同水流运动特征,阐述了评价的精度以及水利工程对地下水循环的影响。通过本次评价,珠江流域地下水天然资源量1374.16亿m~3,可开采量为578.7亿m~3,开发利用率仅10.01%。珠江流域跨度较大,水动力特征迥异:上游云贵高原深切峡谷区、中游桂中峰丛洼地区、下游冲洪积平原区,据不完全统计,珠江流域蓄水量大于100万m~3的水库32座,水利工程的修建以及水库对水资源调蓄和分配给地下水资源评价带来一定困难,不同部委对地表水和地下水概念上的分歧导致二者间流域边界不一致以及流域水资源评价结果的差异,为此提出了解决问题的建议,以期为地下水开发利用与治理保护服务。