Updating of a DRASTIC-based Method for Specific Vulnerability Assessment in Carbonate Aquifers

Abstract

Some methodological modifications are suggested to improve a DRASTIC-based method as a reliable predictor of microbial contamination in extensively fractured and subordinately karstified carbonate aquifers. These modifications will allow a better assessment of vulnerability induced by the concentrated infiltration of surface runoff in two different scenarios: (a) when the karst system is entirely located within an unsaturated aquifer and (b) when the karst system is partially located within a saturated medium. The effectiveness of the updated method has been experimentally verified by comparing the vulnerability values with the results of a hydrogeological and microbiological study at a test site.     

华北山前平原不同含水组垂向水循环规律

地下水是华北山前平原的主要供水水源,其资源属性一直存在争议。以正定试验基地为研究区,通过分析地下水化学、氘氧同位素、14 C测年等在垂向上的变化特点,对比不同含水组地下水与大气降水的氘氧同位素含量关系,研究华北山前平原典型研究区504m深度内不同含水组地下水在垂向上的循环规律,确定360m为该区地下水含水系统的内部界限,其上构成浅层含水系统,其下构成深层含水系统。     

模糊综合评价在区域水资源承载力研究中的应用

区域水资源承载力是进行生态环境建设和确定社会经济发展方向的资源基础。阐述了水资源承载力的内涵,选取了区域水资源承载力的指标体系:人均供水量、水资源利用率、耕地灌溉率、供水模数、需水模数、生态用水率,对平坝区进行了水资源承载力模糊综合评价计算,对今后的水资源开发提供决策依据。     

Development of a Protection Strategy of Karst Limestone Aquifers: The Merida Yucatan,Mexico Case Study

In many regions karstic aquifers constitute the only available source of drinking water. Due to the high risk of contamination in these aquifers, a comprehensive groundwater protection and control system must be designed and established. It has recentlybeen proposed that Hydrogeologic Reserve Zones (HRZ) can be established as a tool for the groundwater management in these aquifers. The following approach is proposed in order to establish the HRZ in karstic aquifers: including several generalstrategies for the protection of the ground waters within them, as well as the zoning of the land use and the development of acode of practice. A general procedure is proposed for the development of code of practice for ground water protection inkarst aquifers, which is applied as a case study in Merida, Yucatan, Mexico.     

Evaluation of Groundwater Resources in Lower Cretaceous Aquifer System in Sinai

The Sinai Peninsula has an area of 61000 km² and its populationis about 325000. It is located in an arid area. Extensivedevelopment in the socio-economic, industrial and agriculturalis in process. Although Lower Cretaceous aquifer is the mostprospective aquifer in Sinai, it is not yet precisely evaluated.Spatially distributed areas of good groundwater quality suitablefor various types of development are not identified.The current article presents a comprehensive assessment of thehydrogeological information and hydrological data. Accordingly,three aquifer zones have been identified. Groundwater reserve wasestimated and groundwater balance has been developed. Developmentpotential was evaluated. Development criteria were proposed and applied.Suitable areas for domestic and irrigation purposes weredelineated. Results indicated that the aquifer contains 308 billion m³ ofgroundwater of which a considerable volume is of good quality. Bylowering the present water level some 200 meters, the aquiferyielded 3643 million m³, which is sufficient to supply thepresent rate of withdrawal for 445 years. The results are considered to be usefulfor preparing groundwater master plans in Sinai. Under the properwater management, Sinai could be self sufficient in satisfying itsdomestic water demand.     

多元因子分析模型在河流健康评价中的应用——以苏子河水质特性研究为例

为顺应河流生态可持续发展,提出健康河流、生命河流等概念,维持河流生态系统健康已经成为流域综合管理的必然趋势。综合运用水文学、水力学、泥沙地貌学和水生生态学的基本理论和方法研究河流生态健康的表征因子,确定各因子的阈值,建立流域性水体水质可续发展评价体系。以河流可持续发展为基础,引用代表性的相关指标进行筛选,对流域水质指标进行数值化分析,以苏子河流域水质特性为研究对象,选取出评估河流健康状况的环境因子,客观反映出中小河流域健康状况,为河流的可持续管理和生态环境建设提供参考。     

Multiobjective management of a contaminated aquifer for agricultural use

Planned utilization of groundwater from a contaminated aquifer requires development of management strategies that determine the spatial distribution of withdrawal for allocation, as well as for control of water quality. Minimization of groundwater allocation for different purposes, and the control of contamination in the aquifer by a specified pumping strategy constitute a management problem with two conflicting objectives. In order to demonstrate possible tradeoffs between water quality control objective and minimum groundwater withdrawal objective, a multiobjective optimization model is formulated. The solution of the model specifies a strategy to control pollution distribution in the aquifer as per agricultural needs, and also evolve an optimal allocation policy to statisfy agricultural demands. Pareto-optimal solutions representing the tradeoff between the two noncommensurate objectives are established. The formulated model uses the embedding technique for simulating the flow and the transport processes in the aquifer. The constraint method is used to transform the multiobjective optimization model into a single objective optimization model. The resulting model is solved using the exterior penalty function method in conjunction with the Hooke-Jeeves method. The proposed model is easily adoptable for various agroclimatic regions and cropping patterns. For illustrative purposes, the model is applied to a specified study area. Although solutions of the model are presented and discussed as per agricultural requirements in terms of both quality and quantity, solutions for other kinds of water demands can be obtained using the same model with minor modifications. Results show that an optimal pumping strategy can be effectively utilized for controlling contamination in the aquifer.     

内蒙古东胜煤田阿不亥普查区地下水水质评价及水化学形成机制

在了解研究区地质、水文地质条件的基础上,对区内15个潜水样品运用基于熵权的密切值法进行了水质综合评价,论述了研究区地下水赋存类型及其水化学特征,分析了其水化学形成机制,并重点利用溶液组分平衡模型计算了方解石、白云岩和石膏的饱和指数,利用质量平衡模型计算并分析了地下水成分沿流程的变化规律,定量分析了溶滤沉析作用对地下水化学成分的影响。结果表明:研究区潜水水质普遍较好,适合人类饮用。地下水水化学成分的形成与演化主要受溶滤沉析作用控制,其中方解石、白云石、石膏的沉淀作用、钾长石的溶解作用以及CO2的逸出是最主要的控制因素,同时地下水水化学成分的形成与演化还受到蒸发浓缩作用、阳离子交换作用、地下水混合作用以及人类活动的影响。     

地下水可持续开采量评价方法综述

本文评述了地下水开采量概念的发展过程,指出为实现可持续开采量的评价,国内外目前研究的焦点主要集中在可持续开采量的可更新能力、生态和环境用水约束与社会经济发展及环境保护的协调优化等方面。同位素和地球化学示踪、GIS等新技术的发展及新技术与传统评价方法的有机结合大大促进了可持续开采量评价的发展。本文着重讨论了当前水均衡法、数值模拟、同位素技术和基流分割等评价方法的优缺点,以及在实现地下水可持续开采量评价方面的进展和面临的问题,认为多种方法有机结合是未来的发展方向。     

基于熵权权重的可变模糊理论在大连市地下水水质评价中的应用

针对地下水质评价中存在的多目标性和模糊性特点,采用可变模糊集理论模型进行评价;同时基于指标权重确定的客观性,采用熵权法确定指标权重。以大连市甘井子区2007年-2011年4月的水质调查资料为评价指标集,构筑多目标可变模糊识别模型,用熵权法确定评价指标的权重。评价结果显示,研究区内整体水质处于II～III等级之间,与传统的综合指数法评价结果相对比,将熵权法与可变模糊集理论模型相结合的评价结果比较合理,可为大连市的地下水资源综合利用与管理提供水质依据。     

改进灰色聚类关联在地下水水质评价中的应用

将改进的灰色聚类关联模型应用于地下水水质评价,通过对白化函数的改进,提高了资料的信息利用程度,根据各监测点不同水质类别关联度的比较,可判断出各监测点地下水水质的优劣。东昌府区地下水水质综合评价结果表明:改进的灰色聚类关联评价方法易于掌握,评价结果可以作为地下水管理的依据,是地下水水质评价的新途径。     

基于可持续发展的区域水资源优化配置研究

运用可持续发展的水资源优化配置理论,以区域经济发展与水环境保护相协调为目标,建立地下水开采漏斗区水资源多目标优化配置模型。采用多目标遗传算法对漏斗区水资源进行合理配置。优化配置结果表明:基本解决了漏斗区供需矛盾,缓解了地下水的开采压力。     

地下水环境修复评价及预测研究的重要意义

地下水作为水资源的重要组成部分,其开发利用必然会对生态环境产生巨大影响。水资源的价值是其有用性和稀缺性决定的,因此,加强对有限资源的科学、合理地评价和预测,包括对地下水资源科学、合理地评价和预测是十分必要的,已成为水资源可持续利用,人口、资源、环境和经济社会协调发展的迫切要求。     

坚持科学发展观合理开发水电资源实现地方经济可持续发展

人类社会的发展必然要消耗资源并依赖能源工业的发展,水电是可再生能源。如何把开发水电和保护环境有机地结合起来,实现“人与自然和谐相处,”就企业来讲,必须坚持科学发展观,用新的发展思路,开发水电建设,处理好企业前进道路上的各种矛盾和问题,全面提升企业在市场中的综合竞争力,实现企业健康发展,同时实现地方经济可持续发展。     

模糊可变评价模型在地下水水质评价中的应用

针对水质系统所表现出的复杂性和模糊性,采用基于模糊可变集合理论的模糊可变评价模型对地下水环境质量进行综合评价。通过科学地确定与地下水水质评价相关的各项指标处于区间值的相对隶属度和相对隶属函数,并根据二元比较模糊决策分析法计算出各指标的权重,最终得出地下水质量的级别特征值。同时,采用单项参数评价法和灰关联分析法对同一地下水水样进行水环境质量评价。结果表明,该方法不仅符合客观事物运动发展变化的自然辩证法原理,而且能够使评价结果更加合理、可信。     

Characterization of a Regional Aquifer System in the Maritimes Basin,Eastern Canada

A regional hydrogeological study was carried out in the Maritimes provinces, in one of the main aquifer systems in Canada. The study area covers a land surface of 10,500 km², of which 9,400 km² is over Carboniferous and younger rocks. The sedimentary fractured bedrock is composed of a sequence of discontinuous strata of highly variable hydraulic properties, and is overlain by a thin layer of glacial till (mostly 4 to 8 m). Depending on areas, 46 to 100% of the population relies on groundwater for water supply. Almost all residential wells are shallow (28 m on average) open holes that are cased only through the surficial sediments. This paper describes a regional hydrogeological investigation based on targeted fieldwork, the integration of a wide variety of existing multisource datasets and groundwater flow numerical modelling. The aim of this paper is to present the current state of understanding of the aquifer system in a representative area of the Maritimes Basin, along with the methodology used to characterize and analyze its distinct behaviour at the regional, local and point scales. This regional hydrogeological system contains confined and unconfined zones, and its aquifer lenticular strata extend only a few kilometers. Preferential groundwater recharge occurs where sandy tills are present. The estimated mean annual recharge rate to the bedrock aquifers ranges between 130 and 165 mm/year. Several geological formations of this Basin provide good aquifers, with hydraulic conductivity in the range of 5 × 10⁻⁶ to 10⁻⁴ m/s. Based on numerical flow modelling, faults were interpreted to play a key role in the regional flow. Pumping test results revealed that the aquifers can locally be very heterogeneous and anisotropic, but behave similarly to porous media. Work performed at the local scale indicated that most water-producing fractures generally have a sub-horizontal dip along a north-east (45°) strike.     

Groundwater quality management of a low inertia basin: Application to the San Mateo Basin,California

A two-dimensional finite element model is applied to the San Mateo Basin, California in order to investigate feasible and efficient management alternatives to enhance the basin yield and preserve the basin water quality. The model utilizes lumped approximation methods for the determination of its subsurface boundary conditions, and incorporates a variety of hydrological processes. The model solves uncoupled flow and transport equations using a nodal domain integration technique for the flow model and an integrated finite difference method for the transport model. The model incorporates the basin inputs and outputs as ocean flux, well and phreatophyte extractions, subsurface inflow, precipitation and streambed percolation. Modeling results indicate that the substained yield may be maximized by interception of ocean outflow from the basin. An improvement of about four times of the historical sustained yield was achieved. This strategy required relocation of existing wastewater recharge ponds and increasing basin extractions. In order to intercept most of the ocean outflow by increasing basin extractions, simulated subsurface seawater intrusion was observed. The water quality study indicated that the basin yield could be increased significantly by moderately relaxing the water quality criteria near the ocean.     

Assessment of the levels of coastal marine pollution of Chennai city,Southern India

The levels of hydrological pollution of Chennai coastal zone in the southeastern part of India have been increased in the recent years by an uncontrolled disposal of wastewater and pollutants due to human activities. This study gave a special emphasis on the determination of the levels of pollution, the identification of vulnerable zones and providing some probable remedial measures for severely impacted coastal zone of Chennai city. During the period from September to November 2002, sampling was carried out along the shore in two traverses running in the seaside (surf zone) and landside (coastal aquifer). When sampling efforts took place the middle of the above period experienced a monsoonal storm over Chennai coast that significantly influenced large variations in the pollution level at both traverses in seaside and landside. Analysis of physical, chemical and biological parameter determinations indicated that the concentrations of dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients (nitrate, nitrite and phosphate), turbidity, maximum probable number (MPN) and chlorophyll a (Chl a) reached notably high levels at all sample locations before monsoonal storm prevailed over these areas during October 2002, which resulted in large fresh water input to the coastal system reducing the levels of pollution to some extent. Analysis of water samples collected during November apparently indicated that the concentrations of above parameters attained abnormal level and often exceeded the permissible limit of international standards. The concentrations of trace/toxic metals such as manganese, copper, nickel, lead, cadmium and cobalt also reached very high levels as a result of their sub-aqueous disposal to these areas, leading to further habitat and ecological destruction. On the other hand, analysis of groundwater samples collected from coastal aquifer for determination of certain chemical parameters such as Ca²⁺/Mg²⁺, Cl⁻/(CO²⁻ ₃+HCO ₃ ^-) and the ratio of total alkalinity (TA) and total hardness (TH) revealed that coastal groundwater appeared to be severely contaminated by saltwater intrusion as a result of overexploitation and enormous pressure imposed by monsoonal storm of October. Higher concentrations of toxic elements, for example, lead, nickel, cobalt and cadmium from the influence of industrial wastes and contaminated coastal waters, were also found to deteriorate the quality of coastal aquifer system. Based on detailed examination, four sites including Cuvum estuary, Adyar estuary, Kannikoil and Bharathiyar nagar are identified as highly venerable zones because of receiving a large quantity of municipal and industrial wastes. To reduce severe pollution levels in these areas it is therefore necessary to design and construct the submarine pipeline system to transport and disperse such a large quantity of waste materials to the deep open ocean areas.     

农业生态系统对气候变化的脆弱性评价——以河北省农业综合开发项目区为例

选取河北省农业综合开发项目区农业生态系统作为研究对象,将其划分为2个一级区8个亚区。通过采用实地调查与专家推荐的方法,确定了河北省农业对气候变化的脆弱性评价体系;采用专家打分和层次分析法完成了现状条件下农业对气候变化的脆弱性评价。评价结果表明坝上高原和冀西北山间盆地亚区农业对气候变化非常脆弱,山麓平原亚区农业对气候变化较为适中,滨海平原亚区农业对气候变化脆弱性逐渐变缓。评价结果基本上反映出河北省农业开发项目区生态系统气候脆弱性现状的一个大致轮廓,可供进一步研究借鉴和参考。     

华县地下水水化学特征及水质评价

为了查明华县地下水水化学特征,以及地下水的水质情况,采用统计分析法对研究区15个水样点的水化学指标进行较为全面的研究,获得地下水的水化学特征,并选取模糊数学法对其进行水质评价.研究结果表明:研究区地下水基本满足生活饮用水的标准.在各个指标中,pH、HCO3-、Ca2+三项指标的含量相对较稳定,而Cl-、SO42-、K++Na+、Mg2+的变异系数介于30％～100％之间,显示出中等变异性.地下水的水化学类型以HCO3·SO4-Ca·Na+K和HCO3-CI·Mg为主.水质评价结果显示研究区地下水水质总体状况较好,多为Ⅰ类水和Ⅱ类水,可以饮用.通过计算可以看出模糊数学法的计算过程较为麻烦,但其综合考虑了评价因子对水体的污染程度大小,以及水质分级的模糊性,评价结果更加客观、有效、符合实际.