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。     

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。     

Features of groundwaters in basins shared between Ethiopia and Kenya and the implications for international legislation on transboundary aquifers

The implementation of laws relating to transboundary aquifers necessitates field knowledge so that the laws can be coincident with reality on the ground. The definition of ‘shared aquifer’ is more complex than the mere physically shared body of groundwater flowing from country A to country B. The border between Ethiopia and Kenya is characterized by low-volume groundwater storage and low transboundary flows. However, groundwater has visible environmental, social and economic functions. The characteristics of groundwater flow and storage in aquifers shared between Ethiopia and Kenya are different from those used in setting the foundation of the international legal framework on shared aquifers. By describing the characteristics of the groundwaters that are shared between Ethiopia and Kenya, this work demonstrates that the international legal framework is inadequate when applied in this region. The main inadequacies are: (1) international law does not specify the minimum volume of transboundary flow in an aquifer for it to qualify to be treated under the law, and (2) the physical aspects of water get more emphasis than the functions of groundwater. A more adequate international legal framework would be one that considers specific types of groundwater and local needs.     

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。     

Transboundary aquifer mapping and management in Africa: a harmonised approach

Recent attention to transboundary aquifers (TBAs) in Africa reflects the growing importance of these resources for development in the continent. However, relatively little research on these aquifers and their best management strategies has been published. This report recapitulates progress on mapping and management frameworks for TBAs in Africa. The world map on transboundary aquifers presented at the 6th World Water Forum in 2012 identified 71 TBA systems in Africa. This report presents an updated African TBA map including 80 shared aquifers and aquifer systems superimposed on 63 international river basins. Furthermore, it proposes a new nomenclature for the mapping based on three sub-regions, reflecting the leading regional development communities. The map shows that TBAs represent approximately 42 % of the continental area and 30 % of the population. Finally, a brief review of current international law, specific bi- or multilateral treaties, and TBA management practice in Africa reveals little documented international conflicts over TBAs. The existing or upcoming international river and lake basin organisations offer a harmonised institutional base for TBA management while alternative or supportive models involving the regional development communities are also required. The proposed map and geographical classification scheme for TBAs facilitates identification of options for joint institutional setups.     

Hydrogeological investigation of shallow aquifers in an arid data-scarce coastal region (El Daba’a,northwestern Egypt)

Hydrogeological investigations in arid regions are particularly important to support sustainable development. The study area, El Daba’a in northwestern Egypt, faces scarce water resources as a result of reported climate change that particularly affects the southern Mediterranean coast and increases stress on the local groundwater reserves. This change in climate affects the area in terms of drought, over-pumping and unregulated exploration of groundwater for irrigation purposes. The hydrogeological investigation is based on a multidisciplinary data-layer analysis that includes geomorphology, geology, slope, drainage lines, soil type, structural lineaments, subsurface data, stable isotopes, and chemical analyses. The study area contains Pleistocene and middle Miocene marine limestone aquifers. Based on lithology and microfacies analysis, the middle Miocene aquifer is subdivided into two water-bearing zones. The area is affected by sets of faults and anticline folds, and these structures are associated with fractures and joints that increase permeability and facilitate the recharge of groundwater. Stable isotope data indicate that groundwater of both the Pleistocene and middle Miocene aquifers is recharged by modern precipitation. The high salinity values observed in some groundwater wells that tap both aquifers could be attributed to leaching and dissolution processes of marine salts from the aquifers’ marine limestone matrix. In addition, human activities can also contribute to an increase in groundwater salinity. A future water exploration strategy, based on the results from the multidisciplinary data-layer analysis, is proposed for the area. The derived scientific approach is transferable to other arid coastal areas with comparable conditions.     

The application of isotope and chemical analyses in managing transboundary groundwater resources

Managing transboundary groundwater resources requires accurate and detailed knowledge of aquifers and groundwater bodies. The Pannonian Basin is the largest intracontinental basin in Europe with a continuous succession of more than 7 km of Miocene to Quaternary sediments and with an average geothermal gradient of about 5 °C/100 m. Geographically the Pannonian basin overlaps eight countries (Hungary, Romania, Serbia, Croatia, Slovenia, Austria, Slovakia and Ukraine), so the issue of transboundary cold and thermal water resources is regionally very important. The T-JAM bilateral Hungarian–Slovenian (HU–SLO) project is the first to apply modern isotopic and chemical analyses in the characterization and correlation of a number of shared groundwater resources in the Mura-Zala Sub-basin of the Pannonian. The aims of this work were the identification of groundwater flow paths, the delineation of transboundary aquifers based on thermal and cold groundwater geochemical and isotope properties in the Mura-Zala Basin, and providing input to calibrate a hydraulic numerical model. Following a common groundwater sampling campaign, 24 cold and thermal groundwater samples from seven aquifers were collected for chemical, isotope, gas and noble gas analyses. Chemical analyses, and D, O and C isotopes were used to correlate cross border aquifers. A regional groundwater flow is hydrogeologically possible in some aquifers in the Mura-Zala Basin, and has been confirmed by hydrogeochemistry. The Újfalu (HU) and Mura (SLO) Formations are a part of the active regional thermal groundwater flow system, probably hydraulically separated from the shallower flow system of the Ptuj-Grad (SLO), Zagyva and Somló-Tihany (HU) Formations. The thermal water is of meteoric origin, reductive and alkaline. The predominant water type in the Quaternary and Pliocene aquifers is Ca–Mg–HCO₃, changing to Na–HCO₃ in the main Pannonian geothermal aquifer, and Na–Cl brine in deeper and older Miocene aquifers. Total dissolved solids and Na content generally increase with depth. Deuterium is in the range −87‰ to −75‰, ¹⁸O from −11.9‰ to −10.4‰, while ¹⁴C values are less than 6.1 pmC in the samples of the active regional thermal groundwater flow system. These and results of noble gas analyses indicate recharge during the Pleistocene interglacial period with temperatures around 6–7 °C. Regional thermal water resources are limited and environmental isotopes can be used as an early warning in the management of thermal water.     

Review on transboundary aquifers in People’s Republic of China with case study of Heilongjiang-Amur River Basin

Groundwater, as a precious resource hidden underground, is an important component of the global water system. Transboundary aquifers containing substantial amount of groundwater often carry crucial ecological and social implications. Yet, it is unfortunate that transboundary aquifers have hardly been in the forefront of political and scientific discussions, and have not received due attention by policymakers. This article attempts to summarize the investigation on the eight transboundary aquifers that China shares with the neighboring countries. An overview on the groundwater resources in China, including its distribution, exploitation and challenges is also provided. Hydrogeological condition of the Heilongjiang-Amur River Basin aquifer, which is one of the eight major aquifers, is further elaborated. Cooperative activities carried out by China and Russia on monitoring and management of this aquifer are also presented.     

Review on status of groundwater database and application prospect in deep-time digital earth plan

Groundwater is an important water resource. The total amount of active groundwater in a hydrological cycle is about 3.5 times that of the total amount of surface water. The information in the deep groundwater records the material exchange and dynamics in the earth’s evolution, which is an important aspect of the Deep-Time Digital Earth (DDE) plan. In recent years, scientists have discussed the distribution of transboundary aquifers and the environmental significance of groundwater resources through groundwater databases established by international organizations, such as the Global Groundwater Information System and the chronicles consortium, and national institutes, such as national geological surveys. The application of the groundwater database in the DDE plan, however, has been limited by the management, interactivity, and monitoring method of the groundwater data. The ability to further integrate data that are private and scattered across research institutions and individuals, while establishing an open, unified, and shared groundwater data platform, is essential to enhance our understanding of groundwater, ranging from shallow to deep water, which is a goal of the DDE plan. In this study, we introduced the current situation of groundwater database operations in domestic and international research and provided frontier research with groundwater big data. Considering the related objectives of the DDE plan and the limitations of existing groundwater databases, we proposed an improvement plan and new prospects for applying groundwater databases in the research of the deep earth.     

Hydrochemistry of a complex volcano-sedimentary aquifer using major ions and environmental isotopes data: Dalha basalts aquifer, southwest of Republic of Djibouti

In the Republic of Djibouti (Horn of Africa), fractured volcanic aquifers are the main water resources. The country undergoes an arid climate. Alluvial aquifers exist in the wadis (intermittent streams) valleys and, in relation with volcanic aquifers, form complex volcano-sedimentary systems. Due to increasing water demands, groundwater resources are overexploited and require a rigorous management. This paper is focused on the Dalha basalts aquifer, located in the Dikhil area (Southwest of Djibouti). This aquifer is of vital importance for this area. Hydrochemical data and isotopic tracers (¹⁸O and ²H) were used to identify factors and phenomena governing the groundwater’s mineralization. The Piper diagram shows complex water types. Results from multivariate statistical analyses highlight three water families according to their locations: (1) groundwater characterized by low ionic concentrations located at the wadis zones; (2) groundwater characterized by moderate salinity and (3) highly mineralized waters mainly flowing in the eastern and central part of the study area, in volcanic aquifers. Results from scatter plots, especially Na versus Cl and Br versus Cl, suggest that the origin of more saline waters is not from dissolution of halite. The δ¹⁸O and δ²H data indicate that the groundwater flowing in the alluvial aquifer is of meteoric origin and fast percolation of rainwater occurs in the volcanic aquifers. These findings provide a preliminary understanding of the overall functioning of this complex volcano-sedimentary system. Additional investigations (pumping tests, numerical modeling) are in progress to achieve a more comprehensive understanding of this system.     

Hard-rock aquifers in tropical regions: using science to inform development and management policy

An overview of progress during the past 30 years in the hydrogeologic understanding of groundwater in hard-rock aquifers of tropical regions is presented. Geographically, the paper concentrates upon and contrasts Tropical Africa and Peninsular India, where very extensive areas of weathered hard-rock aquifers occur, but its conclusions are more widely applicable. This scientific understanding forms the basis for a critical discussion of key policy issues for the development and management of the water resources of these aquifers, given their major importance for economical and sustainable water-supply provision, in the context of efforts to achieve the UN Millennium Development Goals for rural drinking water and improved livelihoods.     

The fountains of Pretoria

The occurrence of groundwater in South Africa is to a very large degree limited to a surficial zone of weathered and fractured hard rock formations. Primary aquifers include narrow strips of alluvium along certain river stretches and to Cenozoic coastal deposits. Coupled with a rainfall that is well below the world average, South Africa is therefore poorly endowed with large springs. These are almost totally confined to karst areas.     

Groundwater status and associated issues in the Mekong-Lancang River Basin: International collaborations to achieve sustainable groundwater resources

Groundwater is an important and readily available source of fresh water in the Mekong-Lancang River Basin. With a rapid population growth and increasing human activities, an increasing number of countries in the Mekong-Lancang River Basin are experiencing depleted and degraded groundwater supplies. In transboundary river basins, such as the Mekong-Lancang River, prioritizing the use of the shared aquifer by one riparian government may affect the opportunities of other riparian governments and lead to potential water conflicts between neighboring countries. To promote the sharing of strategies and information for the sustainable and equitable use of water resources of the shared basin, international collaborative workshops on groundwater resources have been organized for all Mekong-Lancang River countries. These workshops provide an opportunity to communicate and discuss nationally sensitive issues on groundwater by the associated countries, with topics covering multiple aspects of groundwater, such as the groundwater status in the basin, quality issues, water use conflicts, hydrological information gaps, management policies and capacity building for successful water resource management. Consensus has been reached by all countries on the importance of catchment-based groundwater management and the need for close communication among the countries. Strategies for managing transboundary aquifer issues must foster international collaboration based on the regional network, influence national networks and enhance the capacity to building maps and monitoring systems based on associated databases. The sustainability of water resources cannot be achieved without the integrated involvement and contributions by multiple countries and various stakeholders. Therefore, collaborative workshops provide a great opportunity to further our understanding of the hydrologic processes of the Mekong River Basin, share the benefits of the aquifer and provide a strategy and vision for sustainable water resource management in the Mekong-Lancang River countries.     

Modelling an inland Delta aquifer system to evolve pre-development management schemes: a case study in Upper Thamalakane River valley, Botswana, southern Africa

 Groundwater modelling studies have been found to be a potential tool in planning the pre-development management of groundwater resources in newly developing aquifer systems. One such study was attempted in Upper Thamalakane River valley, Okavango Delta, Botswana (southern Africa). There are three major aquifers separated by two aquitards in the valley portion. The top two aquifers are freshwater bearing zones and the bottom one is saline. The hydrological set-up of the basin is complex, as the groundwater flow directions are opposite in the upper-unconfined and in the lower-confined aquifers. A preliminary multilayer model was developed for this aquifer system by making use of only available data. The hydrodynamic behavior was then studied under two prediction scenarios to evolve appropriate management decisions for locating the well field (large diameter wells) in the upper aquifer by making use of induced river infiltration during the flood season. The aquifer response for variable river-flow conditions was studied and the induced river infiltration was quantified. Received: 27 August 1998 · Accepted: 8 March 1999     

Insights into palaeorecharge conditions for European deep aquifers

Climatic instability during the late Pleistocene has been reflected in the pattern of groundwater recharge. This report summarizes palaeoclimate knowledge during the late Weichselian in Europe. During this period the majority of northern Europe was covered by thick ice sheets and permafrost, preventing aquifers from recharging. In contrast, southern Europe was generally free of these palaeoclimatic features. Palaeoclimatic information has been combined with isotope data to better understand the palaeorecharge conditions and recharge timing across the European continent. The ¹⁸O and ²H relationship shows latitudinal plus climatic influences. Radiocarbon data show that while southern European aquifers have generally been recharged continuously during the last 40,000 years, northern European aquifers typically show a recharge gap during the Last Glacial Maximum. Areas that underwent continuous recharge during the entire late Pleistocene period can also be distinguished from areas where recharge to aquifers was prevented during the Last Glacial Maximum. Finally, several examples are presented of melt-water recharge or subglacial recharge. The identification of such diversity in the groundwater palaeorecharge in Europe is of great importance for modellers developing management schemes for groundwater resources.     

Legal challenges to the management of transboundary watercourses in Central Asia under the conditions of Eurasian Economic Integration

Worldwide experience has shown that interstate economic integration can help states in strengthening of management of transboundary waters and international water law serves as a reference for developing of relevant interstate cooperation. Transboundary waters in Central Asia play important role in the economic cooperation among riparian states, including those who are members of the Eurasian Economic Union (EAEU). At the current stage of transboundary waters management in Central Asia, the obsolete legal status is evident. The international water law sources developed under the United Nations’ auspices have no binding application due to luck of formal membership of the EAEU states in these treaties. Also the regional set of regulations, especially for the Aral Sea Basin, needs further enhancement and more efficient implementation. The bilateral interstate regulatory framework of the managemennt of waters shared by EAEU states in Central Asia requires development of additional rules to enable better accommodation of challenges existing in terms of the current interstate cooperation. Having said that can one further assume that EAEU could serve as a new legal framework for more effective cooperation on transboundary watercourses in Central Asia? The answer might be yes, but… the current stage of the legal framework for cooperation on transboundary waters within the EAEU requires sufficient enhancements in terms of developing its legal and institutional framework. The first condition for EAEU to serve as framework for cooperation on transboundary waters of Central Asia is to strengthen the regulatory framework for the cooperation of EAEU member states regarding environmental issues in general and transboundary water relations in particular, able to accommodate two main goals: environmental protection on the one hand and economic development on the other hand. The EAEU legal framework shall also lead to improvement of existing institutional cooperation and a dispute settlement mechanism on transboundary waters shared by the member states of the EAEU.     

Groundwater age dating and recharge mechanism of Arusha aquifer,northern Tanzania: application of radioisotope and stable isotope techniques

The continuous abstraction of groundwater from Arusha aquifers in northern Tanzania has resulted in a decline in water levels and subsequent yield reduction in most production wells. The situation is threatening sustainability of the aquifers and concise knowledge on the existing groundwater challenge is of utmost importance. To gain such knowledge, stable isotopes of hydrogen and oxygen, and radiocarbon dating on dissolved inorganic carbon (DIC), were employed to establish groundwater mean residence time and recharge mechanism.¹⁴C activity of DIC was measured in groundwater samples and corrected using a δ¹³C mixing method prior to groundwater age dating. The results indicated that groundwater ranging from 1,400 years BP to modern is being abstracted from deeper aquifers that are under intensive development. This implies that the groundwater system is continuously depleted due to over-pumping, as most of the sampled wells and springs revealed recently recharged groundwater. High ¹⁴C activities observed in spring water (98.1?±?7.9 pMC) correspond with modern groundwater in the study area. The presence of modern groundwater suggests that shallow aquifers are actively recharged and respond positively to seasonal variations.     

从黑河流域地下水年龄论其资源属性

地下水资源的可持续性是当前干旱区流域水资源管理的首要问题之一 ,我国西北内陆干旱区地下水的可持续开发必须首先要了解地下水系统的更新能力 ,地下水的放射性同位素测年可以提供系统循环时间和更新能力的重要信息。本文利用地下水中放射性氚 (3H )和碳 (1 4C)测年方法 ,计算黑河流域地下水的年龄 ,进而讨论地下水的更新性。结果表明 :潜水年龄多数小于 5 0 a,具有可再生的资源的属性 ,其中山前戈壁带和张掖盆地细土平原潜水地下水年龄小于 4 0 a,为 196 3年以来补给。酒泉东盆地排泄区承压含水层中地下水的年龄为 2 338～5 5 6 9a,额济纳附近的深层承压含水层中 ,地下水的年龄为 5 4 86～ 86 30 a,地下水资源更新性较差。但是张掖盆地河流附近深层承压地下水年龄小于 5 0 a,具有一定的更新性。上述认识不仅对黑河流域水资源管理和生态环境建设具有重要意义 ,而且对西北类似的内流盆地的地下水系统的研究有着借鉴意义     

Residence times of shallow groundwater in West Africa: implications for hydrogeology and resilience to future changes in climate

Although shallow groundwater (<50 mbgl) sustains the vast majority of improved drinking-water supplies in rural Africa, there is little information on how resilient this resource may be to future changes in climate. This study presents results of a groundwater survey using stable isotopes, CFCs, SF₆, and ³H across different climatic zones (annual rainfall 400–2,000 mm/year) in West Africa. The purpose was to quantify the residence times of shallow groundwaters in sedimentary and basement aquifers, and investigate the relationship between groundwater resources and climate. Stable-isotope results indicate that most shallow groundwaters are recharged rapidly following rainfall, showing little evidence of evaporation prior to recharge. Chloride mass-balance results indicate that within the arid areas (<400 mm annual rainfall) there is recharge of up to 20 mm/year. Age tracers show that most groundwaters have mean residence times (MRTs) of 32–65 years, with comparable MRTs in the different climate zones. Similar MRTs measured in both the sedimentary and basement aquifers suggest similar hydraulic diffusivity and significant groundwater storage within the shallow basement. This suggests there is considerable resilience to short-term inter-annual variation in rainfall and recharge, and rural groundwater resources are likely to sustain diffuse, low volume abstraction.     

Analysis on exploitation status,potential and strategy of groundwater resources in the five countries of Central Asia

As an important part of water resources of the five countries of Central Asia, groundwater resources give critical supports to the regional economic development. Accompanied by rapid economic development, the demand of groundwater is increasing. As a result, the governments are paying more attention to groundwater resource development and utilization. However, there are noticeable issues and contradictions in water resource exploration in these countries. To be more specific, these countries lack the studies in development potential and conception planning, thus influencing the sustainable groundwater development. This paper mainly discusses groundwater development problems in the five countries of Central Asia, and briefly introduces volumes and distribution of transboundary groundwater. In addition, it analyzes the current exploitation status of groundwater and studies the potential in utilizing the resource. Most importantly, it proposes creative ways to address groundwater development issues: To make best of the resource, international cooperation is required.