Flow and solute transport monitoring in the karst aquifer in SW Slovenia

The role of the unsaturated zone in the karst aquifer hydraulic behaviour was brought into focus in these studies of the catchment of the Hubelj spring (SW Slovenia). The variations of natural tracers in precipitation and in groundwater during a summer storm event made it possible to trace local flow and solute transport in the observed aquifer. The results produced data on the aquifer recharge, storage and discharge processes, as well as on mechanisms that affected them, which reflects a karst groundwater dynamics also at a regional scale. They point out the significance of effects of the fast preferential flow—epiflow that is the main factor controlling solute/contaminant transport towards the aquifer saturated zone. Numerous arguments indicate that the karst aquifer flow and solute transport mechanisms depend on the hydraulic behaviour of the epikarst zone.     

基于OSP的自动端元提取及混合像元线性分解

正交子空间投影(OSP)方法广泛用于目标与背景的分离之中,对于高光谱影像,OSP可用于目标提取和混合像元分解,但缺点是需要端元的先验知识。针对这一问题,基于OSP的原理提出一种自动提取端元的方法,该方法不需端元的先验知识并且不需对原始数据进行降维。实验使用由OMISⅠ和PHI获取的两组高光谱数据进行端元提取,并采用带全约束条件的最小二乘法进行混合像元分解,结果精度令人满意,证明算法进行端元自动提取的可行性。     

天津市深层淡水井的水质咸化分类——以东丽区为例

第四系第Ⅱ含水组地下水经长期开采,早已完成主固结过程;开采Ⅱ组地下水可使上覆咸水淡化越流,最终加快各类地表水的入渗,多年来在适宜地段大幅恢复Ⅱ组地下水的开采。经调查大部分水井水质恶化非含水层水质变化,绝大多数地区咸水底界没有下移趋势。笔者认为在滨海平原区能使咸、淡水保持数10万年高浓度差的粘土层,具有半透膜特性。由于部分观点与前人研究结果相左,澄清"井水咸化"与地下水咸化污染的区分就显得尤为重要。为此,将多年地下水水质调查资料进行分类,推进咸化污染机理研究推进。     

碎石土潜水含水层成井工艺研究

从北京市丰台地区第四系潜水含水层的地层岩性结构入手,分析了传统供水管井成井工艺存在的问题,详细研究介绍了孔壁坍塌填砾法成井工艺在实际水井工程项目中的成功应用,取得了较好的增加水井出水量的效果。     

Some limitations in using <Superscript>222</Superscript>Rn to assess river–groundwater interactions: the case of Castel di Sangro alluvial plain (central Italy)

²²²Rn was used to assess river–groundwater interactions within Castel di Sangro alluvial aquifer (Italy). The effectiveness of results obtained through this indicator was verified by also analyzing δ¹⁸O, major ions and temperature in both surface and groundwater, and carrying out piezometric head monitoring and discharge measurements. Hydrogeological investigations suggested that the river infiltrates into the aquifer in the south-eastern aquifer portion, while groundwater discharges into the river in the north-eastern portion. The latter phenomenon is supported by ²²²Rn data. Nevertheless, flow-through conditions cause the modelled discharge along this river reach, estimated by ²²²Rn data in a degassing-corrected two-component mixing model, to be greater than the measured discharge. Concerning river infiltration into the aquifer, δ¹⁸O, major ions and temperature data show that the river contribution is negligible in terms of aquifer recharge. Thus, the observed increase in ²²²Rn concentration in that portion of the aquifer is due to the enrichment process caused by infiltration of rainwater (²²²Rn free) which flows from the local divide area. Hence, in the study site, the use of only ²²²Rn to predict river–groundwater interactions causes some estimation inaccuracies and it must be coupled with other hydrochemical and hydrogeological parameters to gain a thorough understanding of such interactions.     

A critical overview of transboundary aquifers shared by South Africa

Transboundary groundwater commonly implies a body of groundwater intersected by a political border with the attendant potential threat of dispute over a shared resource. This definition is inadequate in many parts of southern Africa. Approximately 96% of South Africa’s borders are underlain by low-yielding aquifers and, coupled with a low demand for water attendant on low population density, the risk of over-pumping or pollution leading to dispute is low, and a modified understanding is required. Examples of transboundary aquifers are used to illustrate implications for policy and management of southern African transboundary groundwater resources, where transmissivities are low and, less commonly, where over-pumping may indeed be a problem. The general lack of technical cooperation, data sharing, training and research between the riparian states on hydrogeology hampers a mutual understanding of the resources. The concept of transboundary groundwater must necessarily include aquifers where little cross-border flow occurs, but where cross-border cooperation will help to ensure sustainable cooperative utilisation of shared aquifer resources. This is imperative if future disputes are to be averted. Agreement between scientists is a necessary precursor to broader transnational governance agreements in regard to shared water resources, and recent initiatives by the Orange-Senqu River Commission promise closer integration.     

Groundwater travel times for unconfined island aquifers bounded by freshwater or seawater

Analytical solutions for calculating groundwater travel times within unconfined island aquifers are given for cases of both a freshwater-bounded island (island located in a fresh water lake) and an oceanic island (freshwater contained above intrusive saltwater). The solutions apply for homogenous aquifers recharged by surface infiltration and discharged by a down-gradient, fixed-head boundary, under steady-state conditions. The solutions are given for two simple island geometries: circular islands and strip islands. A technique is also provided for comparing travel times in inland islands and oceanic islands. Travel times in oceanic islands are found to be shorter than travel times in inland islands, and travel times in circular islands are found to be longer than travel times in strip islands.     

Estimating hydraulic conductivity from specific capacity for Hawaii aquifers,USA

Site-specific relationships between specific capacity and hydraulic parameters (transmissivity and hydraulic conductivity) were investigated for volcanic rocks in Maui, Hawaii, USA. Details about well construction were commonly ignored in previous studies. To improve on such efforts, specific-capacity values were normalized by the open interval of the well. Correcting specific capacity for turbulent head losses using step-drawdown tests and including aquifer penetration length improved the correlation between specific capacity and hydraulic conductivity and reduced uncertainty in the prediction of hydraulic parameters. The relationships provide estimates of aquifer parameters with correlation coefficients between 0.81 and 0.99. The relationships for Maui can probably be extended to other Hawaii islands, given the similarity of aquifer formations and a reasonable fit to step-drawdown data from Oahu. Hydraulic conductivity was estimated from 1,257 specific-capacity values in the Hawaii’s well database. Hydraulic-conductivity estimates for dike-free volcanic rocks are consistent on different islands. For all islands, the estimates range from 3 to 8,200 m/d, with a geometric-mean and median value of 272 and 291 m/d, respectively. A geostatistical approach was applied to Maui and Oahu to generate island-wide hydraulic-conductivity maps to facilitate groundwater management efforts.     

铬污染地下水的PRB反应介质筛选及修复试验

通过实验研究筛选出一种经济可行的用于修复Cr(Ⅵ)污染地下水的PRB反应介质。实验以Cr(Ⅵ)污染地下水为研究对象,选用MB、Fe0、粉煤灰和活性炭4种材料进行PRB介质筛选的静态实验,选取处理效果好且经济的MB作为PRB反应介质进行动态修复实验。结果表明:以MB作为PRB反应介质可以使Cr(Ⅵ)的质量浓度从0.50 mg/L降低到0.05 mg/L以下,达到地下水水质Ⅲ类标准;且MB具有吸附量大、固液分离容易、无解吸、无二次污染等优点。以MB作为PRB反应介质修复Cr(Ⅵ)污染的地下水是可行的。     

太平矿暗斜井充水水源分析

在综合分析太平煤矿井水文地质条件、出水点岩性特征的基础上,通过钻孔探放、水样化验资料的对比分析,认为该矿＋700水平胶带暗斜井的间接充水水源可能来自摩梭河;基于涌水点位置与出水量,以及瞬变电磁法确定的巷道前方富水区域情况,确定了采用浅层注浆法封堵的治水方案。