Groundwater protection in fractured media: a vulnerability-based approach for delineating protection zones in Switzerland

A vulnerability-based approach for delineating groundwater protection zones around springs in fractured media has been developed to implement Swiss water-protection regulations. It takes into consideration the diversity of hydrogeological conditions observed in fractured aquifers and provides individual solutions for each type of setting. A decision process allows for selecting one of three methods, depending on the spring vulnerability and the heterogeneity of the aquifer. At the first stage, an evaluation of spring vulnerability is required, which is essentially based on spring hydrographs and groundwater quality monitoring. In case of a low vulnerability of the spring, a simplified method using a fixed radius approach (“distance method”) is applied. For vulnerable springs, additional investigations must be completed during a second stage to better characterize the aquifer properties, especially in terms of heterogeneity. This second stage includes a detailed hydrogeological survey and tracer testing. If the aquifer is assessed as slightly heterogeneous, the delineation of protection zones is performed using a calculated radius approach based on tracer test results (“isochrone method”). If the heterogeneity is high, a groundwater vulnerability mapping method is applied (“DISCO method”), based on evaluating discontinuities, protective cover and runoff parameters. Each method is illustrated by a case study.     

Groundwater resources protection and aquifer recovery in China

The groundwater resources in China and especially the northern part represent a vital water resource. Both the shallow and deep aquifers are highly overexploited in a large area of north China. The heavy overexploitation of groundwater resources is causing major environmental damage. To protect groundwater resources, several technical feasibility studies were performed. Artificial recharge using floodwater and wastewater was tried. Surface spreading systems are applicable in many areas of the Yellow River basin and Hai River basin. Deep aquifer injections were undertaken in the urban area. A far better strategy is to reduce the extraction of groundwater, especially to stop or slow down land subsidence and seawater intrusion. To address the problem of falling groundwater levels and aquifer recovery, there is a need reduce groundwater extraction and artificial recharge.     

海河流域地下水资源保护

地下水资源在海河流域至关重要的资源。海河平原的浅层和深层含水层大面积处于严重超采状态。地下水资源的的过量开采造成了严重环境问题。为了保护地下水资源，评价了可行的技术。利用洪水和废水进行人工回灌已进行了试验。在很多地区可以应用地表回灌系统，城市地区实施深层含水层的回灌。更好地策略是减少地下水的抽取量，特别是为了减缓地面沉降和海水入侵。应该联合运用减少地下水抽水量和人工回灌，以解决地下水位持续下降和含水层恢复的问题。     

Groundwater of the Gaza Strip: is it drinkable?

Groundwater from 73 municipal and 21 private wells were analyzed for Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Ni, Pb, Sr and Zn over a 3 year monitoring program in the Gaza Strip. The results show that the trace elements of the groundwater of the Gaza Strip do not generally pose any health or environmental hazard. In spite of that, only 10% of the municipal wells meet the WHO standards. Cl^-, NO ₃ ⁻ and F^- concentrations exceeded 2–9 times the WHO standards in 90% of the wells tested with maximum concentrations of 3,000, 450 and 1.6 mg/l, respectively. Several private wells should not be used for drinking purposes as the average of Zn, Cd, Pb, Fe and As was 58, 30, 270, 468 and 10 μg/l, respectively. A severe water dilemma will appear in the near future from both quality and quantity aspects.     

Groundwater chemistry within a plateau neighboring Matsumoto city,Japan

The change in groundwater chemistry along the groundwater flow path in the Matsumoto tunnel vicinity was studied, and the origin of the groundwater and dissoluted substances was determined. The relationship between the concentration of HCO₃ ^–, Ca²⁺, and Na⁺, and CO₂ gas pressure in the groundwater indicated that the HCO₃ ^–, Ca²⁺, and Na⁺ were produced by the reaction of the CO₂ gas in the groundwater and feldspar in the rocks. The relationship between the concentration of NO₃ ^– and the Eh and pH values in the groundwater indicated that in an oxidative condition, ammonia-oxidizing and nitriteoxidizing bacteria used NH₄ ⁺ and produced NO₃ ^– and H⁺, and in a reductive condition, denitrifying bacteria used NO₃ ^– and produced N₂ gas and OH^–. The stable hydrogen and oxygen isotopic ratio in the groundwater and precipitation indicated that the groundwater originated from precipitation that had fallen on the area. The concentration of³H and the stable hydrogen and oxygen isotopic ratios in the groundwater suggested that it has been getting warmer climatically for more than 60 years. The stable carbon isotopic ratio indicated that the HCO₃ ^– in the groundwater, excluding deep well water, originated from CO₂ gas produced by organic matter in the soil. The deep well water, which had a higher concentration of HCO₃ ^– than the other groundwater sampled, was thought to have acquired HCO₃ ^– though contact with rocks. The³⁶Cl/Cl ratio indicated the recharge age of the deep well water sampled at a depth of 760 m at the foot of the plateau was recent.     

我国水污染状况与防治

我国东部近岸海洋,部分江河、湖泊,许多城市邻近地区的地下水污染呈不断发展与恶化态势,造成部分城市和村镇供水水质下降,有的甚至发生供水危机。及时加强水体污染控制与治理已成为迫切的任务。     

Groundwater protection in Mediterranean countries after the European water framework directive

The European Water Framework Directive (WFD) has driven the protection of groundwater and characterization of water bodies. Development of appropriate and efficient approaches which consider the special features of the hydrologic regime is essential. The results of different projects that have been carried out to integrate characterization and protection of water bodies are summarized herein. In the Les eaux de la Mediterranée (AQUAMED) Project, applicability to the Mediterranean Region of guidelines provided by the European Commission to facilitate the WFD implementation has been verified. The Background criteria for the identification of groundwater thresholds (BRIDGE) Project developed a methodology to establish threshold values of pollutants contributing to the chemical status of groundwater bodies. This method has been applied to pollutants used to classify groundwater bodies as at risk of not achieving objectives of the WFD. Selected features of protection areas for drinking water and safeguard zones are analyzed, as well as the possibility of using wellhead protection areas.     

山东省地下水资源及其潜力评价

通过对山东省水文地质条件、地下水赋存特征、地下水开采现状及其动态特征进行系统研究的基础上,计算评价了全省地下水天然补给资源量、可开采资源量、开采程度和剩余可开采资源量。论述了地下水开采资源潜力的计算评价原则和判别标志,确定了全省主要的地下水资源潜力分布区。     

桩孔内反复抽排地下水诱发地面塌陷成因分析及防治对策

某大桥位于贵州省中部一岩溶槽准谷内,上覆第四系土层厚3～12m,下伏基岩为灰岩和白云岩,地下水埋深0～2m,采用人工挖孔桩基础,以中等风化基岩作为地基持力层,设计86根桩,桩间距3～10m,施工期间,由于反复抽排地下水导致场地周边出现多处岩溶塌陷。本文在实地调查的基础上论述了其形成机制,并对类似工程提出了防治对策。     

区域地下水环境监测与未来发展的思考

文章指出了我国地下水环境面临的严峻形势,分析了国内地下水监测体系存在的问题。以北京地区为例,回顾了地下水监测的历史和发展过程,介绍了北京地区1:5万精度的立体分层区域监控网和地下水污染源监控网。针对北京在南水进京和京津冀协同发展的新水情条件下,提出了地下水环境监测网未来发展的对策与建议,指出必须要对监测网定期优化(包括点位密度、监测频率、测试组分)、搭建数据共享平台、争取尽快立法,以确保这项工作顺利开展。     

水源热泵系统中地下水流贯通及其对温度场的影响

利用含水层储能的一般特点,提出流贯通;分析流贯通和热贯通的相互作用、相互影响及对工程实际的意义;并基于地下水水热运移的基本原理,建立地下水流动和热量输运的耦合数值模型。在此基础上对沈阳某场地水源热泵工程的运行进行流场及温度场的数值模拟分析,给出产生流贯通的依据,即利用水力坡度定量的判断流贯通发生与否;当水力坡度变化非常小、可忽略不计时,认为含水层出现流贯通;进而研究抽、灌量对流贯通的影响,发现抽、灌量越大,则出现流贯通时间越短;而大量的抽、灌量更容易发生流贯通,进而会引起热贯通的发生。在实际工程中可降低抽、灌水量,在条件许可的情况下可提高抽、灌井的间距,并可在抽、灌井运行一个周期后调整抽灌井位置,以减少热贯通的发生。     

关于贵州地下水类型和含水岩组划分及其与地下水资源量计算关系的思考

正确划分地下水含水岩组和地下水类型,对较为准确的计算地下水资源量具有重要意义。但在目前实际工作中,地下水含水岩组和地下水类型的划分存在一定误区,导致地下水资源量计算成果较为粗放,以至于还可能给地下水的开发利用带来障碍。笔者认为,间互状不纯碳酸盐岩类归属于基岩裂隙水含水岩组较恰当,其所含地下水类型归属于基岩裂隙水更合适。在计算间互状不纯碳酸盐岩类地下水资源量时,宜扣除泥岩、粉砂岩和页岩的分布面积。     

德阳市城区地下水位动态特征及成因分析

根据监测孔资料对德阳市区地下水位动态类型划分,分析其水位动态特征表明：德阳市区地下水是降水入渗型、沿岸型、开采型、灌溉型综合而成。地下水受河流切割,旌湖上、下游拦河坝蓄水,北郊水厂、二重厂一工农村一带为集中开采区,绵远河一带开采强度的不稳定性、西北侧区域地下水径流补给,季节降雨等综合因素的影响,其中降水和开采因素是地下水位动态变化的主要因素。这些因素使得德阳市区地下水位和降落漏斗呈复杂多变势态,地下水流场在不同区段亦表现出明显的差异。     

关中盆地地下水特殊脆弱性及其评价

关中盆地浅层地下水面状硝酸盐污染严重,以"三氮"为主要污染物.分析了地下水特殊脆弱性内涵,以及地下水本质因素、人为因素及污染物特殊因素等对脆弱性的影响,并从中选取13个评价因子.将包气带"三氮"迁移转化过程数值模拟结果耦合到脆弱性评价模型中,使过程模型与评价模型结合起来,再结合GIS技术,对地下水特殊脆弱性进行了评价.结果表明,易引起地下水"三氮"的地区主要分布在渭河中下游冲积平原、黄土台塬洼地、以及渭河南岸西安一带小于20 m厚的黄土台塬等地区.从2001年关中盆地地下水"三氮"污染分布来看,这些地区地下水硝酸盐已出现大面积超标,评价结果与地下水实际"三氮"污染情况基本吻合.     

浅层地下水化学成分特征及成因分析

以淮南市浅层地下水为研究对象,采集样品130个样品,利用多种方法测试了21种水样指标。统计其化学组分,划分了水化学类型,分析了硬度与Ca^2＋／Na^＋,Mg^2＋／Na^＋,TDS和ES之间关系,并对地下水中重金属元素与常规组分的相关性进行了探讨。最后得出,淮南市区浅层地下水属于弱酸-弱碱性淡水,水体硬度大,水化学类型以Na^＋ - Ca^2＋ - HCO3^- - Cl^-为主;Cl^-、F^-、SO4^2-和氨氮超标不高,重金属超标高于其它组分,是影响地下水水质主要因素之一。另外随着TDS增加,Cl^-、SO4^2- 含量增大等。     

地下水工程学的内涵及其发展前景

地下水工程学的研究范围很广,它包括地下水资源勘察、地下水的取水工程、地下水的监测、地下水回灌、地下水的防排工程、地下水污染修复工程、防海水入侵工程、地下水资源的管理与评价、地下水工程项目的招投标、设计、施工与监理等领域。与专门水文地质学相比,它具有研究领域更广、与其它学科联系更密切等特点,有望成为应用水文地质学方面研究范围最广的一门新兴学科。     

中国北方第四系地下水同位素分层及其指示意义

中国北方第四系地下水中的D, 18O, 3H和14C含量存在明显的分层现象, 这种现象与末次冰期以来的古气候变化有着较好的对应性, 反映了全新世和末次冰期气候条件的差别以及地下水不同的形成机制.深层地下水为晚更新世末次冰期时期形成, 其δ(D) 和δ(18O) 值与全新世补给形成的浅层地下水相比, 分别贫4× 10-3~ 16× 10-3和1× 10-3~ 2× 10-3, 说明末次冰期时期年均气温较低.古地下水中D和18O的大陆梯度与全新世以来地下水中的梯度基本相同, 说明在过去30000a来尽管气温发生变化, 但中国北方大陆的大气循环模式没有发生实质性的改变.地下水同位素分层现象反映了3种不同的补给机制及参与现代水循环程度.这些信息对大陆尺度上的水循环研究和地下水的可持续开发利用有着重要的意义.      

Prediction of river bank erosion and protection works in a reach of Chenab River,Pakistan

The impacts of floods on river bank erosion are generally significant in the alluvial river reaches. This paper presents the prediction of the river bank erosion along the right bank in the reach of Chenab River (starting from downstream of Marala Barrage) where excessive erosion had been reported. The bank erosion is predicted due to flow/flood events of 2010 by coupling the output from the two-dimensional numerical model to the excess shear stress approach. The predicted bank erosion was compared with the one estimated from Landsat images. The Landsat ETM+ images were processed in the ArcGIS software to assess the external bank erosion. The results show that the excess shear stress approach underpredicts the bank erosion. Therefore, the erodibility coefficient was modified by forcing the best agreement between predicted and estimated (i.e., from Landsat images) bank erosion which was used for further analysis. The results reveal that coupling the output from the numerical model to the excess shear stress approach (by modifying the erodibility coefficient) predicts the river bank erosion with a reasonable level of accuracy, thus helpful to identify the locations for the protection works. The predicted river bank erosion presents good coefficient of determination (R²) of 0.82 when compared with the estimated bank erosion from Landsat images. The findings of the present study will help to implement the river protection works at the identified locations in the selected reach of River Chenab and will also act as a guideline for similar river reaches.     

Groundwater characteristics within loessic deposits: the coastal springs of Los Acantilados,Mar del Plata,Argentina

The urban growth of the southern neighborhoods of Mar del Plata City provoked significant changes in the groundwater balance of the loessic sequences. These regional loessic levels with a significant portion of volcanic ash layers were reported subject to fluoride and nitrate concentrations. Residential houses pump from sands located 70 m depth and withdraw the sewages to depths less than 5 m. These effects cause significant local and seasonal (summer) increments of the water table outcropping via springs at certain unconformities of the coastal cliffs. A mathematical model was applied to analyze the water level lowering at the productive levels, while there is a decrease in the quality of the upper levels subject to waste discharges. Much of this groundwater flow is concentrated in unconformities between different types of sediments. Human activities have affected the aquifer dynamics increasing the groundwater pumping rates and the return velocity of the sewages. This should be considered in the management strategies of coastal hydric resources.