The changing role of hydrogeology in semi-arid southern and eastern Africa

Much of southern and eastern Africa is semi-arid and heavily groundwater dependent. Borehole drilling commenced over a hundred years ago with magnetic and electrical resistivity surveys for borehole siting being introduced from 1936. Formalised training of hydrogeologists led in the 1970s to an almost standard approach to hydrogeological investigation and a period of stability followed, during which some major investigations were carried out. A period of decentralisation and fragmentation has since taken place in many parts of southern and eastern Africa, and groundwater monitoring and management are inadequate in many countries. All but six of the 14 SADC (Southern African Development Community) member states reportedly have an adequate monitoring network in place. However, groundwater demand is increasing and hydrogeologists need to promote the use of appropriate methodologies as an essential part of tackling the severe issues now facing the water sector in the region.     

21世纪中叶中国需水展望

随着人口的增长和经济的高速发展,水资源短缺日益严重。利用基于宏观经济的分行业需水预测模型,对21世纪上半叶中国的需水形势进行展望。进入21世纪以后,在相当长的一段时间内,水资源紧缺仍然将困扰着我国社会经济的发展,供需矛盾有可能进一步加剧。2030年前后预计将会出现缺水的高峰,2030年后供需缺口有望减缓,到21世纪中叶实现水资源总供给和总需求的基本平衡。     

A proposal for an extended typology of groundwater habitats

Many governments now require the ecological condition of groundwater ecosystems to be considered when making policy decisions. However, groundwater habitats and communities occur at different spatial scales to those at which aquifers are managed, making their inclusion in policy decisions difficult. A system of classifying groundwater ecosystems is needed to aid this, yet such a typology is currently not available. Here, a hierarchical model for a typology of groundwater habitats is suggested, which considers three spatial scales: macro, meso, and local. On a macroscale, communities are influenced by biogeographic characteristics; at a mesoscale they are influenced by the hydrogeological type of the aquifer; and on local scale by the hydrological exchange with surface water and hence the oxygen and nutrient supply. Consequently, groundwater habitats are assumed to be defined by biogeographic particularities, the hydrogeological aquifer type and by localized hydrological exchange with surface water. By adopting a ‘groundwater habitat typology’, groundwater biologists may be able to work with hydrogeologists to assist in the sustainable management of groundwater by predicting groundwater biodiversity and the distribution of important or endangered species. The typology proposed here is a first step towards achieving this goal.     

21世纪长春市城市供水水源问题

长春市是一个水资源比较贫乏的大城市,水资源一直是困扰该市社会经济发展的主要问题。本文概述了长春市半个多世纪以来城市供水水源随着城市需水量增长而变化的历史过程,预测了21世纪前期城市的需水量,提出了解决城市供水水源的方向,对新世纪城市的供水水源与区域供水规划间的关系、水资源管理政策与法规、水资源分配原则、供水水源投资与经营等问题提出了新的思路和见解。     

"地下水科学与工程"学科形成的历史沿革及其发展前景

人类由逐水而居到凿井取用地下水是人类文明史的一大转折。和地表水相比,地下水具有分布广泛、水质良好、变化稳定、便于利用、不容易受污染等优点,因此它是理想的供水水源。地下水本身既是人类生存不可或缺的重要资源,同时也是一种地质营力、信息载体、生态环境因子和灾害因子。因此开展地下水的形成、赋存、运动规律的研究,以及合理开发、利用的工程技术、布局设计和实施等水文地质研究是一门关系到人类生活、社会需求和发展的重要学科。笔者着重论述了“地下水科学与工程”学科形成的历史是和人类社会的诞生、繁衍和发展紧密相关的。随着科学进步和国民经济的发展,该学科已从原来的基础学科逐渐向应用基础学科和应用学科相结合的方向发展。因此,今后在加强水文地质基础研究的同时,还应该十分重视满足国民经济需求和面向市场应用的研究。最后,从世界面临严重缺水和水污染的现实、科学发展的必然和国际学术组织和学者对地下水学科的重视,以及当前人才市场对该学科人才需求等方面指出,21世纪“地下水科学与工程”学科的发展具有很大的空间和十分广阔的前景。     

Development of a simple method for determining the influence radius of a pumping well in steady-state condition

Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a project foundation that may need lowering of groundwater level to a certain depth due to dewatering operation. In addition, this is important for hydrogeologists to determine ground water contamination flow paths and contributing recharge area for domestic water supply and aquifer management purposes. Empirical formulas that usually neglect vital parameters to determine the influence radius accurately have been traditionally utilized due to lack of adequate methods. In this study, a physically based method, which incorporates aquifer hydraulic gradient for determining the influence radius of a pumping well in steady-state flow condition, was developed. It utilizes Darcy and Dupuit laws to calculate the influence radius, where Darcy's law and Dupuit equation, in steady-state condition, represent the inflow and the outflow of the pumping well, respectively. In an untraditional manner, this method can be also used to determine aquifer hydraulic conductivity as an alternative to other pumping test methods with high degree of accuracy. The developed method is easy to use; where a simple mathematical calculator may be used to calculate the influence radius and the pumping rate or hydraulic conductivity. By comparing the results from this method with the MODFLOW numerical model outputs with different simulated scenarios, it is realized that this method is much superior and more advantageous than other commonly used empirical methods.     

A GIS enabled nested simulation-optimization model for routing groundwater to overcome spatio-temporal water supply and demand disconnects in South Texas

Groundwater, under sustainable management policies, can be an invaluable source of water to municipal, agricultural, and industrial sectors. Management, however, can be challenging given that historically, these resources have been privately owned and minimally regulated. This research details the development of a decision support system (DSS) which couples a GIS-based multi-criteria decision-making (MCDM) scheme with simulation-optimization routines to identify suitable regions for groundwater development and optimal preferences for apportioning those supplies to areas of demand in South Texas. The developed DSS consisted of three modules: (1) a GIS-based MCDM for identifying suitable locations for groundwater production; (2) a simulation-optimization model for estimating available groundwater; and (3) a transportation optimization model for redistributing the groundwater. Applying a comprehensive suite of nine exclusionary criteria in GIS resulted in only 15,304 km² (5,909 mi²) suitable for groundwater production out of the original ~50,500 km² (19,500 mi²). Two ideal sites were selected in the suitable region based on proposed major water supply projects in the study area. The projected groundwater extraction rates per month varied considerably over a year emphasizing a need for storage technologies. Furthermore, a transportation optimization model, which considered cost of storage and movement, was developed and applied to obtain the most optimal scheme to transport groundwater from potential supply centers located in Bee and Kennedy counties to projected water deficit areas of San Antonio, Laredo, and McAllen, TX, USA. Lastly, a full-factorial sensitivity analysis was carried out to check the impacts of the supply and demand factors on groundwater production and transport. Policies at the supply centers had a larger impact on the total availability of water, and policies at the demand centers had a larger impact on the total cost of the management scheme. Furthermore, an analysis of total volume stored in a storage and recovery system exhibited an inverse relationship with the groundwater development (supply side) policies and a direct relationship with the demand requirements. The developed DSS proved useful for determining the most optimal siting and distribution network for groundwater sources in South Texas.     

Hydrogeology and groundwater ecology: Does each inform the other?

The known, perceived and potential relationships between hydrogeology and groundwater ecology are explored, along with the spatial and temporal scale of these relations, the limit of knowledge and areas in need of research. Issues concerned with the subterranean part of the water cycle are considered from the perspective of the biology of those invertebrate animals that live, of necessity, in groundwater and the microbiological milieu essential for their survival. Groundwater ecosystems are placed in a hydrogeological context including the groundwater evolution along a flowpath, the significance of the biodiversity and of the ecosystem services potentially provided. This is considered against a background of three major components essential to the functioning of groundwater ecosystems, each of which can be affected by activities over which hydrogeologists often have control, and each, in turn, may have implications for groundwater management; these are, a place to live, oxygen and food (energy). New techniques and increasing awareness amongst hydrogeologists of the diversity and broad distribution of groundwater ecosystems offer new opportunities to develop cross disciplinary work between hydrogeologists and groundwater ecologists, already demonstrated to be a field for collaboration with broad benefits.     

海原盆地地下水咸化特征和控制因素

地下水是海原盆地唯一的供水水源,近年来部分地区地下水溶解性总固体(TDS)增高,引起了有关部门和水文地质工作者的高度关注。通过分析69组地下水样品的水化学和氢氧稳定同位素数据,对地下水补给来源和咸化的水文地球化学过程进行了研究。结果表明:地下水TDS值198.2~6 436.4 mg/L,沿着地下水流向,咸化程度增加,水化学类型从基岩区的HCO3—Ca·Mg型演化至滞留—排泄区的SO4·Cl—Na·Mg型。地下水补给来源主要为大气降雨和基岩裂隙水侧向径流,补给源—对地下水咸化贡献较小。溶滤作用具空间差异,基岩区和补给区以碳酸盐、硅酸盐风化为主,径流区和滞留—排泄区则为蒸发岩风化,硫酸盐是地下水中阳离子的主要来源。补给水、溶滤和蒸发对第四系地下水TDS的贡献比率分别为4.8%~81.2%、11.9% ~85.9%、1.7%~29.5%,溶滤作用是控制海原盆地地下水咸化的首要因素。当地有关部门应加大对基岩泉水的综合利用,同时注意控制海原县和西安镇等地区地下水开采量,防止地下水进一步咸化。另外,在微咸水分布区可引进地下水去除硫酸盐技术,提高微咸水利用程度。     

城市水资源供需平衡及预测分析——以开封市为例

运用水资源供需平衡的基本理论,以中型城市开封市为例,借助灰色系统原理,采用定性与定量相结合的方法,在对开封市水资源供需平衡分析的基础上进行预测.通过对开封市现状年供水量与需水量统计分析,确认在超采地下水的状况下才达到该城水资源供需基本平衡.基于不同时期城市未来年份社会经济发展的预测,考虑节水技术提高和先进节水措施的应用,结合对水资源供需量的趋势分析,预测结果为2010年余水,2020年缺水,表明未来开封市水资源紧缺成为社会经济发展的"瓶颈".     

基于数值模型的地下水污染预警方法研究

地下水是中国许多城市主要的供水水源,目前中国部分城市地下水已受到不同程度的污染,导致地下水资源供需矛盾日益突出。进行地下水污染预警是保护地下水资源的一个有效措施,当前国内外相关研究刚刚起步,有关预警理论、方法和技术框架仍未形成一套完善的体系。本文简述了地下水污染预警的研究现状及存在的不足,并以中国北方某铬渣场地为例,根据当地的水文地质条件,利用数学模型建立了地下水污染预警模型,给出了不同等级的地下水污染预警分区,研究结果可为当地地下水污染防治和地下水污染控制规划提供科学依据。     

Review: Epidemiological evidence of groundwater contribution to global enteric disease, 1948–2015

Globally, approximately 2.2 billion people rely on groundwater for daily consumption. It is widely accepted that groundwater is more pristine than surface water but while this assumption is frequently the case, groundwater is not ubiquitously free of contaminants; accordingly, this presumption can result in an unfounded and potentially hazardous sense of security among owners, operators and users. The current paper presents a review of published literature providing epidemiological evidence of the contribution of groundwater to global human enteric infection. An emphasis is placed on enteric pathogens transmitted via the faecal-oral route, and specifically those associated with acute gastrointestinal illness (AGI). The review identified 649 published groundwater outbreaks globally between 1948 and 2013 and several epidemiological studies that show there is an increased risk of AGI associated with the consumption of untreated groundwater. The review identified that the following five pathogens were responsible for most outbreaks: norovirus, Campylobacter, Shigella, Hepatitis A and Giardia. Crudely, the authors estimate that between 35.2 and 59.4 million cases of AGI per year globally could be attributable to the consumption of groundwater. Although groundwater is frequently presumed to be a microbiologically safe source of water for consumption, this review demonstrates that consumers served by an untreated groundwater supply remain at risk to enteric disease. The authors conclude that collaboration between microbiologists, hydrogeologists and epidemiologists is needed to better understand pathogen occurrence, persistence, detection and transport in groundwater as well as build stronger epidemiological evidence documenting the true magnitude of disease associated with groundwater globally.     

The first field-based descriptions of pumping-induced saltwater intrusion and upconing

Development of the ideas about the equilibrium between freshwater and saline water has received considerable attention in the literature, but little has been written so far about the earliest scientific works about well salinization. Based on a review of the literature from the second half of the 19th century and the early 20th century, this historical note explores how insights into groundwater abstraction and saltwater intrusion developed, and examples of the earliest field studies are provided. Fundamental research was driven by the need for increasing water supply, but the progress of science did not lead to sustainable management practices everywhere. Research outcomes were shared between scientists of different countries, marking the beginning of coastal hydrogeology as a scientific specialization in the first decade of the 20th century.     

Numerical analysis of the groundwater regime in the western Dead Sea escarpment, Israel + West Bank

Water is scarce in the semi-arid to arid regions around the Dead Sea, where water supply mostly relies on restricted groundwater resources. Due to increasing population in this region, the regional aquifer system is exposed to additional stress. This results in the continuous decrease in water level of the adjacent Dead Sea. The interaction of an increasing demand for water due to population growth and the decrease of groundwater resources will intensify in the near future. Thus, the water supply situation could worsen significantly unless sustainable water resource management is conducted. In this study, we develop a regional groundwater flow model of the eastern and southern Judea Group Aquifer to investigate the groundwater regime in the western Dead Sea drainage basin of Israel and the West Bank. An extensive geological database was developed and consequently a high-resolution structural model was derived. This structural model was the basis for various groundwater flow scenarios. The objective was to capture the spatial heterogeneity of the aquifer system and to apply these results to the southern part of the study area, which has not been studied in detail until now. As a result we analyzed quantitatively the flow regime, the groundwater mass balance and the hydraulic characteristics (hydraulic conductivity and hydraulic head) of the cretaceous aquifer system and calibrated them with PEST. The calibrated groundwater flow model can be used for integrated groundwater water management purposes in the Dead Sea area, especially within the framework of the SUMAR-Project.     

地下水的分类和基岩裂隙水的基本概念

论文深入地论述了“地下水类型”及“基岩裂隙水”这两个重要概念的认识过程。根据新近的地下水勘探资料,论文指出了目前通用的地下水介质分类存在的问题,提出了地下水介质分类的新方案和基岩裂隙水的新概念。     

常德市地下水应急水源地应急供水可行性评价及方案研究

寻找地下水应急水源地、建立应急供水机制,是城市发生日常供水障碍时保障居民用水安全、维护社会稳定的重要措施。通过分析常德市规划区水文地质条件,圈定了5个地下水应急水源地,总结了同类型城市地下水应急水源地的选址原则,并从水量、水质、开采能力3个方面对水源地进行了可行性分析。结合现有城市供水管网及地下水开采井保留情况,分别考虑了人均用水量最低标准20 L/d和一般标准50 L/d两种状态下的应急供水方案。应急供水每人20 L/d状态下,保留井的现有供水能力可以满足应急供水需求,而应急供水每人50 L/d状态下,河洑水源地和芦荻山水源地保留井的现有供水能力不足,建议增加开采井以满足应急供水需求。     

北京市平谷盆地地下水三维数值模拟及管理应用

为缓解北京城区的用水紧张问题,平谷区建立了王都庄和中桥两个应急水源地。持续过量的开采导致盆地内水位急剧下降。为研究大规模开采对平谷盆地地下水系统的影响,并分析不同地区的开采潜力,本文建立了合理刻画三维地下水流动特征的数值模型,对五种不同的开采方案进行模拟。模拟结果表明,丰水条件下地下水位回升明显,王都庄水源地补给条件优越,尤其是盆地上游地区,具有更大的开采潜力;而盆地中下部应适当限制开采,避免水位下降过快。高仿真的数值模型可作为强有力的管理辅助工具,为地下水资源分析及合理利用提供科学的技术支持。     

Socio-hydrogeology and low-income countries: taking science to rural society

Rural societies in low-income, high-population countries often faces scarcity of water of suitable quality for domestic use and agriculture. Hydrogeologists should therefore orientate their research work towards solving practical problems and impart basic knowledge about the hydrogeology of local watersheds to the village councils and communities so as to ensure their participation in better management of groundwater resources. Such cooperation between the hydrogeologists and villagers is the foundation of socio-hydrogeology, which aims at broader dissemination of information and discussions with hydrogeologists at village meetings regarding watershed management such as recharge augmentation, groundwater quality issues and prudent use of groundwater. Socio-hydrogeology implies improved accessibility of rural society to hydrogeological experts and better communication through the use of more appropriate and understandable language.     

常德市地下水应急水源地应急供水可行性评价及方案研究

寻找地下水应急水源地、建立应急供水机制,是城市发生日常供水障碍时保障居民用水安全、维护社会稳定的重要措施。通过分析常德市规划区水文地质条件,圈定了5个地下水应急水源地,总结了同类型城市地下水应急水源地的选址原则,并从水量、水质、开采能力3个方面对水源地进行了可行性分析。结合现有城市供水管网及地下水开采井保留情况,分别考虑了人均用水量最低标准20 L/d和一般标准50 L/d两种状态下的应急供水方案。应急供水每人20 L/d状态下,保留井的现有供水能力可以满足应急供水需求,而应急供水每人50 L/d状态下,河洑水源地和芦荻山水源地保留井的现有供水能力不足,建议增加开采井以满足应急供水需求。     

Locating suitable sites for the construction of subsurface dams using GIS

Subsurface dams constitute an affordable and effective method for the sustainable development and management of groundwater resources when constructed on suitable sites. Such dams have rarely been constructed in crystalline rock areas and to best of our knowledge, geographic information system (GIS) has never been used in any methodology for locating suitable sites for constructing these dams. This paper presents a new methodology to locate suitable sites for the construction of subsurface dams using GIS software supported by groundwater balance modelling in a study area Boda-Kalvsvik, Sweden. Groundwater resources were calculated based on digitized geological data and assumptions regarding stratigraphic layering taken from well archive data and geological maps. These estimates were then compared with future extractions for domestic water supply using a temporally dynamic water balance model. Suitability analyses for subsurface dams were based on calculated topographic wetness index (TWI) values and geological data, including stratigraphic information. Groundwater balance calculations indicated that many of the most populated areas were susceptible to frequent water supply shortages. Of the 34 sub-catchments within the study area: ten were over-extracted, nine did not have any water supply demand at all, one was self-sufficient and the remaining 14 were able to meet the water supply demand with surplus storage capacity. Six suitable sites for the construction of subsurface dams were suggested in the vicinity of the over-extracted sites based on suitability analysis and groundwater balance estimates. The new methodology shows encouraging results for regions with humid climate but having limited natural water storage capacities. The developed methodology can be used as a preliminary planning step for subsurface dam construction, establishing a base for more detailed field investigations.