岩溶水数值模拟研究进展

本文从岩溶水赋存介质及特性出发,介绍了岩溶地下水数值模拟模型研究的国内外研究发展状况,几种常用软件特点及其应用情况,提出了岩溶水模拟研究存在的不足,并就开展进一步研究提出了相应的建议。     

渭北西部黄土塬隐伏岩溶区地下水资源评价及其开发利用研究

通过野外调查及已有资料的收集分析,划出了渭北西部黄土塬隐伏岩溶区不同类型的岩溶泉域系统,采用数值模拟技术模拟以及理论频率计算方法,计算出各泉域系统的开采资源量,提出了岩溶地下水的合理开发利用方案.     

模拟水源地开采法在岩溶水系统开采资源评价中的应用─—以丹河岩溶水系统为例

由于大规模开发岩溶地下水,出现了多个水源地之间互相干扰、保泉洪水互相矛盾等诸多环境问题。如何在这种复杂情况下科学地评价开采资源已成为亟待解决的问题。本文通过对丹河岩溶地下水系统岩溶水文地质条件的分析、概化,提出了模拟水源地开采法,即在二维数值法评价数学模型上叠加一系列的模拟开采水源地,在多种约束条件下进行岩溶地下水系统开采方案的优化,是一种经济效益显著的水资源评价方法。      

工业废渣库岩溶渗漏水动力弥散污染及其防治研究

通过对工业废渣库岩溶渗漏形式以及渗漏污染特征的探讨,根据岩溶地下水的水动力弥散条件,应用动态系统模型和水动力弥散叠加模型,模拟和预测了岩溶渗漏污染对地下水的影响,提出了污染治理措施。     

北方岩溶大泉地下水系统的圈划:以太原盆地东西山地区为例

运用地下水系统分析理论, 以山西省太原盆地东西山地区为实例, 利用GIS技术对区内岩溶大泉地下水系统进行了圈划.运用岩相古地理、地质构造和水文地质分析方法, 首次提取了研究区岩溶含水系统的区域隔水底板等高线、边山断裂两壁投影图及岩溶水系统图等定量或半定量水文地质信息, 圈划出了东西山岩溶水系统的局部饱水带、饱水带和碳酸盐岩非饱水带.研究结果表明, 西山地区兰村泉、晋祠泉属于同一个岩溶子系统; 西冶泉岩溶子系统是相对独立的岩溶水系统; 东山基岩山区大部分属于娘子关泉岩溶子系统, 且东山岩溶水子系统与盆地地下水有密切水力联系而与兰村泉-晋祠泉岩溶子系统无直接关系.这些为模拟盆地地下水系统和评价北方岩溶地下水资源提供重要的科学依据, 对前人就太原盆地边山岩溶水系统边界的确定和内部结构的划分提法有了新的认识.      

工业废渣库岩溶渗漏水动力弥散污染及其防治研究

通过对工业废渣库岩溶渗漏形式以及渗漏污染特征的探讨,根据岩溶地下水的水动力弥散条件,应用动态系统模型和水动力弥散叠加模型,模拟和预测了岩溶渗漏污染对地下水的影响,提出了污染治理措施。      

MODFLOW-CFP软件在岩溶水系统数值模拟应用中的若干关键问题

MODFLOW-CFP软件很好地解决了管道流与含水层连续介质地下水渗流的耦合问题以及管道中水流运动的层流−紊流转换问题,为岩溶管道型地下水系统的定量研究提供了一个适用的数值模拟平台,近年来也在工程实际中得到了较多的应用。为了更好地利用和推广该软件在岩溶地下水系统定量平价和研究中的应用,避免新方法在实际应用中的盲目性,文章结合MODFLOW-CFP软件自身的特点、岩溶水系统常见的水循环特征及其在实际应用中存在的一些关键问题,从地下水数值模拟的基本要求出发,探讨如何通过一些有针对性且相对比较容易开展的野外岩溶水文地质调查、降雨−流量（水位）高分辨率监测、地下水示踪试验和综合分析研究等工作,提取MODFLOW-CFP模型所需的关键结构要素、水文地质参数以及模型识别的目标函数,进而提高复杂岩溶水系统地下水数值模型的仿真度和预测精度,推动岩溶地下水定量研究的发展。     

中国北方岩溶水系统管理模型中处理大泉的一种方法

探讨了具有岩溶大泉的岩溶地下水系统的数值模拟与优化管理问题。首先把泉流量转换成为受控于地下水头的排泄强度，然后将它嵌入到地下水系统的数值模型之中。在优化管理模型中，将受人工开采影响而产生的泉流量的改变量作为决策变量处理，并把描述地下水头和泉流量之间数量关系的方程嵌入到管理模型中，作为等式约束。从而为具有岩溶大泉的地下水系统的数值模拟和优化管理问题的解决找到了一条有效可行的途径。     

张集水源地岩溶发育及岩溶地下水富集特征

张集水源地是岩溶地下水特大型水源地,岩溶地层发育,地下水循环交替强烈,地质构造复杂,为岩溶的发育、岩溶地下水的富集提供了良好的条件。在大量查勘研究成果的基础上,查明岩溶发育规律及岩溶水的富集特征,可为地下水资源合理开发与地质环境保护提供科学依据。     

数值模拟查明地下水系统隐伏边界位置及其性质方法探讨

本文以瓮安县老虎洞磷矿岩溶水系统为实验场,以群孔干扰抽水试验资料为依据,利用数值模拟的方法对地下水系统隐伏边界的位置和性质进行了探讨,提出了在复杂岩溶水系统利用数值模拟方法查明隐伏边界的方法。     

Geochemical investigation of groundwater in a Granitic Island: a case study from Kinmen Island,Taiwan

Kinmen Island is principally composed of low permeable granitoid and covered by a very thin sedimentary layer. Both surface and groundwater resources are limited and water demand is increasing with time. The groundwater in the granitoid has been surveyed as an alternative water source for daily use. Two to five highly fractured zones in the granitoid aquifer for each site were first determined by geochemical well logging. Accordingly, ten samples were collected from three sites. Using environmental isotopes and geochemical modeling, geochemical processes occurring due to water–rock interaction in the granitoid aquifer can be quantitatively interpreted. The stable isotopes of oxygen and hydrogen in groundwaters cluster along Taiwan’s local meteoric waterline, indicating evaporation does not have considerable effect on groundwaters. Given such a high evaporation rate for Kinmen Island, this result implies that infiltration rate of groundwater is high enough to reduce retention time through a well-developed fracture zone. NetpathXL is employed for inverse geochemical modeling. Results determine gypsum as being the major source of sulfate for deep groundwaters. The contribution from pyrite is minor. In addition, the weathering of albite to kaolinite is the dominant water–rock interaction characterizing geochemical compositions of deep groundwater in Kinmen Island.     

Geochemistry of carbon dioxide mineral waters of the Choigan natural complex (northeastern Tuva)

The abundance of various chemical elements (including trace, rare-earth, and radioactive) in the carbon dioxide mineral waters of the Choigan complex has been investigated. Three groups of waters are recognized according to the geochemical conditions and chemical composition: groundwaters of regional-jointing zone with oxidizing conditions; CO₂-enriched groundwaters of regional-jointing zone with oxidizing conditions; and groundwaters of fault zones with reducing conditions. It is shown that water–rock interaction intensified by high temperature and carbon dioxide action is the main process determining the chemical composition of groundwaters.     

Saturation of groundwaters with respect to minerals of the host rocks

Calculations of the saturation of groundwaters with respect to minerals of the rocks hosting these waters indicate that most of the analyzed groundwaters were saturates with respect to calcite, dolomite, and quartz. Brines of chloride-calcic composition were determined to be saturated with respect to calcite, whereas brines of chloride-sodic composition are saturated with respect to dolomite and quartz. The solution was simultaneously saturated with respect to six minerals for the association ankerite-calcite-dolomite-pyrite-quartz-strontianite. An increase in the number of minerals with respect to which solution is saturated is correlated with an increase in the diversity of types of groundwaters and an increase in the runoff rate. The paper proposes possible avenues for searches for relations between hydrogeological and geochemical parameters that make it possible to adapt the thermodynamic models to real geological-hydrogeological conditions. The research was centered on the testing of groundwaters for their saturation with respect to minerals of the rocks hosting these waters. This parameter plays a significant part in forming the geochemical type of natural waters because it reflects the crystallization of a mineral from a solution and, consequently, the removal of an element from the aqueous solution.     

水-岩相互作用研究的回顾与展望

总结了2 0世纪5 0年代末以来的水-岩相互作用研究历史, 初步划分为3个阶段: 第一阶段, 5 0年代末— 70年代初; 第二阶段, 70年代初— 80年代末; 第三阶段, 80年代末至今.近年来, 环境问题在水-岩相互作用研究中占的比重越来越大, 也使水-岩相互作用研究获得了更大、更持续的发展空间.简要回顾了地下水成因和地壳中水的地球化学循环, 控制水的化学成分的地球化学过程, 以及水-岩相互作用与地质灾害等方面的重大研究成果.认为有望取得创新成果的领域包括: 地下水地质作用及其资源环境效应, 地下水环境演化与全球变化, 和极端条件下的水-岩相互作用研究.      

Groundwater origin and flow along selected transects in Ethiopian rift volcanic aquifers

The disruption of lithologies by cross-cutting faults and the variability in volcanic structures make the hydrogeology of the rifted volcanic terrain in Ethiopia very complex. Along two transects, selected due to their hydrogeologic characteristics, groundwater flow, depth of circulation and geochemical evolution have been conceptualized. The groundwater flow continuity between the high rainfall plateau bounding the rift and the rift valley aquifers depends principally on the nature of the bounding faults. Up to 50% of recharge to the rift aquifers comes from the plateau as groundwater inflow where the rift is cross cut by transverse fault zones. Recharge from the mountains is found to be insignificant where the rift is bounded by marginal grabens; channel loss and local precipitation are the principal sources of recharge to the rift aquifers in such cases. At a regional scale, there is a clear zonation in the geochemical compositions of groundwaters, the result of aquifer matrix composition differences. The environmental isotope results show that the majority of the aquifers contain modern groundwaters. In a few localities, particularly in thermal groundwaters representing deeper circulation, palaeo-groundwaters have been identified. Deeper groundwaters in the rift floor have a uniform ¹⁴C age ranging between 2,300 and 3,000 years.     

Water-rock interaction and chemistry of groundwaters from the Canadian Shield

The chemical and isotopic compositions of groundwaters in the crystalline rocks of the Canadian Shield reflect different degrees of rock-water interactions. The chemistry of the shallow, geochemically immature groundwaters and especially of the major cations is controlled by local rock compositions, whereby dissolution reactions dominate. Conservative constituents, such as chloride and bromide, however, are not entirely a result of such reactions but appear to be readily added from leachable salts during the initial stages of the geochemical evolution of these waters. Their concentration changes little as major cations increase, until concentrations of Total Dissolved Solids (TDS) reach 3000 to 5000 mg 1^?1. The isotopic composition of these shallow waters reflects local, present day precipitations.In contrast to the shallow groundwaters, the isotopic and chemical compositions of the deep, saline waters and brines are determined by extensive, low-temperature rock-water interactions. This is documented in major ion chemistries, ¹⁸O contents and strontium isotopic compositions. These data indicate that the deep brines have been contained in hydrologically isolated “pockets”. The almost total loss of primary compositions make discussions on the origin of these brines very speculative. However, all brines from across the Canadian Shield have a very similar chemical composition, which probably reflects a common geochemical history. The concentrations of some major and most minor elements in these fluids appear to be governed by reactions with secondary mineral assemblages.     

Hydrogeochemistry of Roccamonfina volcano (Southern Italy)

This is the first hydro-geochemical investigation carried out on the Roccamonfina Volcanic Complex groundwaters. The chemistry of Roccamonfina waters is defined by water–rock and water–rock–gas interactions. In fact, interactions between rocks of the first eruptive high-K formations and circulating groundwaters are recognized by high K concentrations. On the other hand, inverse concentration of calcium versus alkali metals is related to two different rock interactions occurring in different areas of the volcano: (a) within the caldera where groundwaters flow within latite and pyroclastic formations releasing calcium, and (b) similarly at the base of the volcano where groundwaters flowing from surrounding carbonates got strongly enriched in Ca. These geochemical processes are also associated with K (SE of caldera) and Mg/Ca (in sites located at the NE base of the volcano) decrease. Completely different dynamics occurs at Riardo groundwaters (SE). Here waters are the result of a mix between the Roccamonfina deep aquifer and the carbonate aquifer of the Riardo plain. Rich-CO₂ emissions make these waters strongly mineralized. Minor elements show a similar geochemical behavior of major ions and are crucial defining interactions processes. The evolution of Roccamonfina groundwaters is also evident along the simultaneous enrichment of Ba, Sr, and Ca. Ba increase is the result of deep local carbonate alteration enhanced by CO₂ emissions and, the lower Sr/Ca ratio, from 10 to 2 (ppb/ppm), is also due to the same process. In the light of our results the Roccamonfina aquifer can be schematically divided into two main reservoirs: (a) a superficial aquifer which basically follows the volcanic structure morphology and tectonics and (b) a deeper reservoir, originating within the oldest Roccamonfina volcano ultra potassic lavas and then flowing into the carbonate aquifers of the neighboring plain. Eventually, the chemistry of the Roccamonfina aquifer does not show any specific and visible pollution, contrary to what happens in the volcano surrounding plains. In fact, only 14% of the samples we collected (206) show a NO₃ content >30 mg/l. These sites are all located at the base of the volcano, near the plain.     

Groundwater in-situ generation of aquatic humic and fulvic acids and the mineralization of sedimentary organic carbon

In this paper the groundwater in-situ generation of dissolved organic carbon (DOC) is discussed based on the origin of groundwaters, their physico-chemical and isotopic properties, chemical composition and the dissolved inorganic carbon (DIC) concentration and its ¹³C content. Three aquifer systems are investigated. Two of these have relatively well defined hydrological and geochemical conditions (Fuhrberg and Munich) and are used as reference systems. The third aquifer (Gorleben) is a complex system containing DOC concentrations up to 200 mg C/L in deep groundwaters. From this aquifer system 19 groundwaters from different hydrogeochemical conditions are analyzed. The in-situ generation of DOC is found to occur in conjunction with the microbiologically mediated mineralization of sedimentary organic carbon (SOC). Thereby, SO₄ is reduced and phosphate is released into the groundwater. Where SO₄ is depleted, the mineralization of SOC occurs via fermentation, resulting in CH₄ generation.     

Hydrogeochemical genesis of groundwaters with abnormal fluoride concentrations from Zhongxiang City,Hubei Province,central China

The groundwaters from Zhongxiang City, Hubei Province of central China, have high fluoride concentration up to 3.67 mg/L, and cases of dental fluorosis have been found in this region. To delineate the nature and extent of high fluoride groundwaters and to assess the major geochemical factors controlling the fluoride enrichment in groundwater, 14 groundwater samples and 5 Quaternary sediment samples were collected and their chemistry were determined in this study. Some water samples from fissured hard rock aquifers and Quaternary aquifers have high fluoride concentrations, whereas all karst water samples contain fluoride less than 1.5 mg/L due to their high Ca/Na ratios. For the high fluoride groundwaters in the fissured hard rocks, high HCO₃ ⁻ concentration and alkaline condition favor dissolution of fluorite and anion exchange between OH⁻ in groundwater and exchangeable F⁻ in some fluoride-bearing minerals. For fluoride enrichment in groundwaters of Quaternary aquifers, high contents of fluoride in the aquifer sediments and evapotranspiration are important controls.     

Saline groundwater seepage zones and their impact on soil and water resources in the Spicers Creek catchment,central west,New South Wales,Australia

Saline seepage zone development and hence dryland salinity is a major environmental problem which many arid to semiarid landscapes in Australia are experiencing. Due to the geological complexity of the regional aquifer system and the heterogeneous nature of the local groundwater system, each groundwater seepage zone in the Spicers Creek catchment, central west, New South Wales, Australia possesses different mechanisms which control its development. Saline seepage zones have formed adjacent to a fault zone, and two experimental sites were established through these groundwater discharge zones to understand geochemical processes which have led to the development of soil sodicity, gully erosion and the flushing of salts into the surface water systems. Seepage zone groundwaters contain a distinctive geochemical signature with elevated concentrations of Na, Cl, HCO₃, Ca, Sr, B, As and Li. The mixing of deep saline groundwaters together with ion exchange processes lead to a distinctive seepage zone groundwater chemistry being developed. Altering the landscape features within this rural groundwater system has developed water toxicity for crops, soil sodicity leading to land degradation, and waterlogging problems.