Multi-Criteria Decision Analysis and GIS Approach for Prioritization of Drinking Water Utilities Protection Based on their Vulnerability to Contamination

This work presents the use of multi-criteria decision analysis (MCDA) as a decision tool to facilitate the process of prioritization of drinking wells that would need more protection before contamination risk. In this study, three aspects of the protection of the groundwater quality were taken into account: natural, anthropic and technical. From these aspects, elements more representative were selected, which can be quantified with available and easily accessible information. Considering those elements, selection criteria were defined which have been represented by: population distribution indicator, human development index, land use, index for aquifer vulnerability to contamination, well age and well yearly pumping rate. The developed method has been applied to drinking supply wells located in the Toluca Valley aquifer (Mexico), and implied the generation of the thematic maps of the defined selection criteria. For the MCDA, the values of each map were converted to the same scale, each criterion was weighted in function of its importance according to the objective and there were aggregated by the way of a lineal combination. The obtained result is a map that shows the level of protection priority of the supply wells. This map can offer information to the stakeholder in a relative short time and contribute to accelerate the actions aimed to protect the quality of the vital underground liquid.     

Benefit and Implementation of Groundwater Protection Zoning in South Africa

Groundwater studies in several African countries show that the contamination of water-supply aquifers is mainly due to improper placement of land-based activities such as agriculture, industries, waste disposal. In South Africa, groundwater pollution is also of increasing concern due to fast population growth and accompanying development. Groundwater protection zoning is a supplemental methodology for groundwater management that incorporates land use planning. The land is managed to minimize the potential of groundwater contamination by human activities that occur on or below the land surface. The various benefits associated with implementation of protection zoning are discussed for stakeholders such as communities, water supply companies, ecosystems and policy makers. A South African case study is presented comparing the cost of protection with the cost incurred due to the treatment of sick and dying people due to contaminated drinking water. These benefits must be communicated to the stakeholders to start the implementation at all management levels. Implementation steps of groundwater protection zones are discussed and can be tested even with low budgets and little data available. Monitoring and reassessment of protection zones are important to test the effectiveness and prove to decision makers that the money was well spent. The legal framework for implementation of groundwater protection zoning in a South African context is described, where the water law makes provision for tools like differentiated protection, licensing and recovery of cost. Challenges regarding implementation of groundwater protection are discussed with some action steps on how to move forward.     

DRASTIC地下水脆弱性评价方法及其应用——以泰国清迈盆地为例

针对泰国清迈盆地的特点和区域特色,利用DRASTIC方法对该地区的地下水脆弱性进行了定量评价,并绘制了地下水脆弱性分区图,对清迈盆地今后制订地下水资源管理、土地利用、环境保护及城市规划等政策措施具有重要的指导作用。该方法同样适用于我国广大地区的地下水脆弱性评价。     

甘肃南部武都区滑坡危险性评价

利用GIS技术分别与信息量模型和贡献权重模型结合,以甘肃南部武都区为研究区,选取高程、坡度、地质年代、河流缓冲区、土地利用和距离断层构造线距离6个评价因子进行滑坡危险性评价,得到基于2种评价模型的区划图。对比2种结果分析得出从滑坡灾害点的分布情况看,2种模型均能较好地对研究区滑坡危险性进行分区,但基于贡献权重模型得出的结果显示,中、高和极高度危险区的面积占全区总面积的82.3%,略夸大了山区滑坡灾害的危险性。结合现场实际勘察结果表明基于信息量模型得到的危险性评价结果更符合武都区的实际情况。因此,利用信息量模型与GIS技术结合对甘肃南部武都区滑坡灾害进行评价,相比贡献权重模型具有较高的准确性,为研究区滑坡的防灾减灾工作提供了参考价值。     

洪水管理、风险评估和洪泛区区划

洪水风险评估包括洪峰、洪量、水位和洪水过程.从安全角度来看,洪水风险评估对于水电工程、防洪工程的设计和运行是十分重要的.洪水管理旨在最大限度地减少洪泛区的洪灾损失,因此根据洪水发生的量级和频率进行洪水风险评估、制作洪水风险图对于洪水管理至关重要.目前在印度采取的主要防洪措施有:进行堤坝溃决风险分析、发布洪水预警、制作洪水风险图或洪灾风险图等.根据洪灾风险评估确定不同的保险费用,并据此推行防洪保险计划,可能非常有助于洪泛区的区划工作.地形等高线图是进行洪泛区区划的前提条件.根据这些图集和洪水风险评估,洪泛区能够按照区划进行开发活动的分类管理.     

Groundwater Protection and Management Strategy in Jordan

Groundwater resources are essential in Jordan that require careful planning and management in order to sustain human socio-economic development and various ecosystems. However these vital resources are under the threat of degradation by both mismanagement and over-exploitation that leads to contamination and decline of water levels. A new by-law, which specifically addresses pollution prevention and protection of water resources used for domestic purposes through appropriate land use restriction and zoning, is currently under preparation in Jordan. This law (i.e., Groundwater Management Policy) addresses the management of groundwater resources including development, protection, management, and reducing abstraction for each renewable aquifer to the sustainable rate (i.e., safe yield). Groundwater vulnerability mapping and delineation of groundwater protection zones were implemented in different areas in Jordan in cooperation between the German Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) company and Ministry of Water and Irrigation. This paper presents the status of groundwater resources in Jordan and their major issues. It attempts to discuss the groundwater vulnerability and protection strategy and the impacts of over-exploitation on the groundwater aquifers in an integrated water resources management perspective.     

Groundwater Overexploitation Causing Land Subsidence: Hazard Risk Assessment Using Field Observation and Spatial Modelling

Hazard risk assessment of land subsidence is a complicated issue aiming at identifying areas with potentially high environmental hazard due to land subsidence. The methods of hazard risk assessment of land subsidence were reviewed and a new systematic approach was proposed in this study. Quantitative identification of land subsidence is important to the hazard risk assessment. Field observations using extensometers were used to determine assessment indexes and estimate weights of each index. Spatial modelling was also established in ArcGIS to better visualize the assessment data. These approaches then were applied to the Chengnan region, China as a case study. Three factors, thickness of the second confined aquifer, thickness of the soft clay and the annual recovery rate of groundwater level were incorporated into the hazard risk assessment index system. The weights of each index are 0.33, 0.17 and 0.5 respectively. The zonation map shows that the high, medium and low risk ranked areas for land subsidence account for 9.5?%, 44.7?% and 45.8?% of the total area respectively. The annual recovery rate of groundwater level is the major factor raising land subsidence hazard risk in approximately half of the study area.     

信息融合型页岩气开采区含水层富水性预测——以凤冈区块为例

页岩气在开采过程中不但容易污染地下水资源,而且还需要大量的水资源来保障水力压裂技术的用水量,因此预测页岩气开采区的地下水富水性对于合理保护和利用页岩气开采区的地下水资源具有重要的意义。在总结岩溶地区含水层富水性主要控制因素的基础上,利用层次分析方法(AHP)建立了融合多源信息的含水层富水性评价模型,确定了因素权重,然后利用地理信息系统(GIS)技术的信息处理和空间展示功能制作了各富水性影响因素专题图,并对各专题图进行了信息融合叠加,最终完成了凤冈页岩气开采区的含水层富水性评价预测。基于GIS技术的信息融合型含水层富水性评价方法可以有效地反映含水层富水性这一受控于多因素影响且具有非常复杂形成机理的非线性动力现象,可为页岩气开采区的地下水资源利用与保护提供依据。     

深圳河流域内陆侧洪涝风险分析

基于致灾因子、孕灾环境、承灾体与防灾减灾能力四大风险要素对深圳河流域内陆侧的洪涝风险进行分析,构建以雨、洪、潮叠加的复杂致灾因子危险性和高度城市化带来的高易损性为特征的沿海城市洪涝灾害风险评价指标体系,用层次分析法修正熵权法以确定评价指标的权重,得到洪涝的危险性风险、易损性风险和综合风险区划。结果表明：福田区西南部至罗湖区西南部是极高危险性与极高易损性的统一体,在防洪减灾中应予以较全方位的重点防护,其他低易损性且高危险性地区只需根据主导的危险性因子给予有所侧重的防护措施;构建的沿海城市洪涝灾害风险评价指标体系可为政府防灾减灾规划与防洪应急响应提供必要的参考依据,亦可为防灾资源分配和灾后恢复重建提供有效信息。     

基于GIS的南水北调东线山东段区域洪灾风险区划

针对南水北调东线山东段区域的防汛需求,主要从洪水灾害的危险性、敏感性和易损性3方面建立洪水灾害风险区划模型,综合考虑研究区域的汛期暴雨日数、暴雨强度、高程、高程标准差、河网密度、湖区缓冲区、GDP、人口密度、土地利用类型等9项影响指标,用蒙特卡罗法辅助层次分析法分析确定指标权重值,通过ArcGIS的地图代数功能对各个指标图层归一化处理,计算得到研究区域的洪水灾害风险区划图。区划结果显示:鲁南片的高风险区位于南四湖周边区域、枣庄市局部地区;鲁北片的高风险区位于聊城城区、黄河以北沿线;胶东片的高风险区位于济南市周边以及半岛东部局部地区。通过与历史洪涝灾情资料进行比对,发现上述区划结果符合灾害发生的实际情况,区划结果对南水北调东线山东段洪水防治和决策管理具有重要的参考价值。     

Evaluation of a GIS-Based Integrated Vulnerability Risk Assessment for the Mancha Oriental System (SE Spain)

It is widely recognized that groundwater-vulnerability maps are a useful tool for making decisions on designating pollution-vulnerable areas, in addition to being a requirement of European Directive 91/676/EEC. This study addressed the vulnerability of the Mancha Oriental System (MOS) to groundwater contamination with an integrated Generic and Agricultural DRASTIC model approach. In the MOS, groundwater is the sole water resource for a total population of about 275,000 inhabitants and for 1,000 km² of irrigated crops. DRASTIC vulnerability maps have been drawn up for two different years (1975 and 2002) in which the potentiometric surface has dropped dramatically (80 m in some areas) due to the considerable expansion of irrigated croplands. The quality of available resources has also deteriorated due to the agricultural practices and the discharge of wastewater effluents. Vulnerability maps are used to test the data on nitrate, sulphate, and chloride contents in groundwater in the Central and El Salobral-Los Llanos hydrogeologic domains of the MOS for 2002. Regardless of the method applied, the dramatic alteration in land use leads to a change in the DRASTIC index and vulnerability to groundwater contamination decreases for the study period. Vulnerability in the MOS increases in areas where the irrigation return flow is notable. The lack of a statistical correspondence between the DRASTIC index and the spatial distribution of nitrate, chloride, and sulphate contents and the distribution of the pollution load suggest that this method does not accurately assess the risk of the MOS to groundwater pollution.     

考虑库水位及降雨联合作用的云阳县区域滑坡危险性评价

危险性评价是区域滑坡灾害风险评价及风险管控工作中的关键内容。以三峡库区重庆市云阳县为例,首先利用逐步判别法从初始指标体系中筛选关键指标体系(坡度、高程、剖面曲率、地形湿度指数、岩土体类型、植被覆盖度和距道路距离),并基于逻辑回归模型完成全区滑坡易发性区划;然后以距水系5 km范围将研究区划分为非库岸区和库岸区,对非库岸区考虑不同降雨重现期下的滑坡时间概率,对库岸区考虑不同库水位状态与不同降雨重现期下的滑坡时间概率;最后综合时间概率和易发性结果得到云阳县区域滑坡灾害危险性区划图。研究结果表明:区内滑坡主要发育在强降雨+低库水位状态工况下;云阳县滑坡较高危险区及高危险区占研究区总面积的52.7%,主要沿长江干流及其支流水系展布,分布在城镇周边等人类工程活动开发程度较大的建设用地区域。研究成果对于提高危险性评价结果的精度和发展滑坡灾害风险评价理论具有借鉴价值。     

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.     

A GIS-based DRASTIC Model for Assessing Aquifer Vulnerability in Kherran Plain, Khuzestan, Iran

The Kherran plain is located in the northeast of Ahwaz in Khuzestan Province, Iran. The state of groundwater pollution is a critical issue with increasing population and agricultural development in Iran. For this reason, vulnerability assessment is an important factor in any policy making decision in any part of country. Focusing on this issue, the article attempts to presents a groundwater vulnerability map for the Kherran plain. The map designed to show areas of highest potential for groundwater pollution based on hydro-geological condition and human impacts. Seven major hydro-geological factors (Depth to water table, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone and hydraulic Conductivity) were incorporated into DRASTIC model and geographical information system (GIS) was used to create a groundwater vulnerability map by overlaying the available hydro-geological data. The output map shows that the west and southwest of the aquifer are under medium vulnerability while small areas on northwest and east of the study area have no risk to pollution. Other parts of aquifer have low vulnerability. For testing of the vulnerability assessment, 27 groundwater samples were collected from the different vulnerability zones of the study area. The chemical analysis results show that the southwest and west parts of aquifer (moderate vulnerability zones) have higher nitrate concentration relative to the rest of aquifer, that are located in low vulnerability zone.     

Assessment of Agricultural Drought Vulnerability in the Guanzhong Plain,China

The Guanzhong Plain, as an important traditional agricultural area, is suffering from high frequency droughts and a trend towards more serious drought. In this paper, eight factors, precipitation, evapotranspiration, surface water availability, depth to groundwater, well yield capacity, slope, potential water storage of soil, and GDP from agriculture, are integrated into an index to represent drought vulnerability based on the overlay and index method. In this approach, according to the internal connections between factors, precipitation and evapotranspiration are integrated into the moisture index, and depth to groundwater and well yield capacity are integrated into groundwater availability. To improve the rationality and accuracy, normalization is employed to assign rating values, and the analytic hierarchy process is introduced into the weighting scheme. Two local drought monitoring datasets endorses the results of the model. The map removal sensitivity analysis indicates the vulnerability index has low sensitivity in removing each layer. The single-parameter sensitivity analysis indicates the major contribution to the vulnerability index is meteorology followed by groundwater availability and surface water availability. The vulnerability map shows the low vulnerability coincides roughly with irrigation districts on the terraces and floodplains. The northwest tableland generally has moderate vulnerability, due largely to inefficient groundwater withdrawal. The high vulnerability is concentrated at the peripheries of the plain, where agriculture is generally rain-fed without irrigation and groundwater support, and land is rugged with high slopes.     

REFLECT,a Decision Support System for Harmonizing Spatial Developments with Groundwater Resources

A sustainable drinking-water supply requires durable securing of the resource. With an increase in spatial pressure, the need is increasing to prioritize measures based on the vulnerability of the resources and the impact of surrounding land use functions. This is especially challenging in the Province of Overijssel with groundwater abstraction sites in vulnerable Pleistocene sandy soils and increasing spatial pressure from both agricultural and urban areas. The governance of the groundwater abstractions in the Province of Overijssel is based on a combination of precaution and a risk-based approach. The Province has adopted REFLECT to assess the risks of spatial developments. REFLECT is a negotiation support system that gives an overview of the vulnerability of the groundwater abstractions and risks of several land use functions on the groundwater quality. REFLECT has been used to obtain the current risk scores of all drinking water abstractions in the Province and following the EU Water Framework Directive. Spatial insight of risks was used to identify and target measures reducing these risks. Moreover, REFLECT has been applied to decide on a local spatial development near an abstraction. Knowledge of the impact of land use changes on groundwater quality helped the municipality harmonizing the spatial plan with the interest of the drinking water abstraction and creating a step-forward in the protection level of the abstraction site. These applications illustrate that REFLECT is an instrument that fits well within risk-based groundwater governance which aims at safeguarding of the public water supply by harmonizing land use functions.     

中国洪水灾害危险程度区划

洪灾的含义包括洪水和灾害两个方面。本文从气象、径流和地形三因素考虑，采用成因分析的方法，制成了洪水危险程度区划图。以耕地和人口为经济因素指标，考虑洪水造成的灾害，制作成洪灾危险程度区划图。本文制作的区划图是客观的，已得到了一些领域专家的认可，可以作为防洪规划等宏观决策的依据。     

天津市平原区第Ⅰ含水岩组地下水脆弱性评价研究

地下水脆弱性分区评价是合理开发利用地下水资源、防止地下水污染的重要基础性工作。传统的DRASTIC方法对评价参数赋予固定的经验性权重,存在一定缺陷。采用熵权法与层次分析法相结合的方法,对权重确定方法加以改进,并以易受污染的天津市平原区第Ⅰ含水岩组地下水为研究对象开展实例研究。改进权重的DRASTIC方法突出了影响程度大、原始数据较分散的净补给量、地下水埋深和包气带类型三项评价参数的权重值,剔除了影响不大且各评价单元原始数据相差很小的坡度参数。结果表明,天津市平原区第Ⅰ含水岩组地下水较低脆弱性分区、中度偏低脆弱性分区、中度偏高脆弱性分区、较高脆弱性分区和高脆弱性分区的面积比例分别为1.3%、22.3%、42.6%、31.2%、2.6%,具体分布与实际情况吻合较好。改进权重的DRASTIC方法可同时兼顾指标数据的分布特点和权重的经验性取值,对开展地下水脆弱性评价具有参考价值。     

The Combined Use of Groundwater Quality,Drawdown Index and Land Use to Establish a Multi-Purpose Groundwater Utilization Plan

Groundwater is abundant and widely used for household consumption, irrigation, and aquaculture in the Lanyang Plain in northeastern Taiwan. However, it is subject to contamination by various anthropogenic activities and natural processes, as well as overexploitation, which has led to land subsidence in the eastern coastal area of this plain. It is becoming increasingly urgent to establish a sound plan for groundwater resource management in the Lanyang Plain to ensure the safe and sustainable use of groundwater to meet demands. The aim of this study is to develop a sound management plan for multipurpose groundwater utilization in the Lanyang Plain. This plan is developed with consideration of the quality and quantity of groundwater, as well as current land use practices. First, the groundwater quality parameters are spatially mapped followed by geographic determination of regions where groundwater quality is safe for different purposes, based on the water quality criteria for drinking, irrigation, and aquaculture. Subsequently, the drawdown index, defined as the ratio of the actual groundwater utilization rate to the transmissivity, is determined for each cell and low drawdown index regions are identified geographically. Information about regions where groundwater quality is safe for different purposes and the regions where the drawdown index is low is integrated to create a map which can be used for the production of a sound management plan for multi-purpose groundwater utilization in the Lanyang Plain. Comparisons between our newly created map and current land use for farmlands and fishponds can provide a basis to review the current land use practices in these regions.