基于DRASTIC的含水层脆弱性模糊评价方法与应用

通过分析目前广泛采用的DRASTIC方法存在的主要问题,将含水层脆弱性定义为模糊概念,结合模糊分析评价理论及三标度分两步的层次分析法建立了一套改进的含水层脆弱性评价模型。为测试其可靠性,分别将改进模型和传统DRASTIC模型应用于祁县东观镇含水层脆弱性评价中。研究结果表明:改进模型得到的脆弱性等级变化较后者更灵敏,分布范围及变化情况更精确,更能真实反映含水层脆弱性在空间上的连续变化,且计算简便、脆弱性分区图效果直观,丰富和完善了地下水脆弱性评价方法。     

基于GIS应用DATUW模型评价地下水环境脆弱性

地下水环境脆弱性是当前地下水研究领域中的一个热点,其评价结果对于城市规划、垃圾堆放场址建设、地下水源选取与保护等具有非常重要的作用。本文是在MapGIS平台上,基于DRASTIC评价技术,选取地下水位埋深、含水层介质、地形坡度、含水层上覆地层、单井涌水量五个因子,利用DATUW模型,评价哈尔滨市区的地下水环境脆弱性。根据评价结果,将研究区的地下水环境划分为高、中、低三个脆弱性区,并就分区结果,提出了防护建议。     

基于DRASTIC指标体系法的泰安市地下水脆弱性研究

地下水脆弱性评价是地下水保护工作的核心内容之一,针对泰安市的特点和区域特色,利用DRASTIC方法,选取地下水位埋深、净补给量、含水层介质类型、土壤介质类型、地形坡度、包气带介质类型以及含水层渗透系数7个参数为评价指标,对该地区的地下水脆弱性进行了定量评价,将泰安市地下水的脆弱性分为脆弱性高、较高、中等和低4个等级,并绘制了地下水脆弱性分区图,对该地区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较重要的参考指导作用。     

大型新生代断陷盆地的浅层地下水的脆弱性评价——以山西太原盆地为例

为开展山西太原盆地的地下水环境保护工作,在GIS平台上利用DRASTIC模型采用地下水位埋深、含水层净补给量、含水层介质、土壤介质、地形、包气带、水力传导系数7个指标评价了盆地浅层孔隙地下水的脆弱性.结果表明:太原市与介休市是盆地内地下水脆弱性最高的地区,同时也是山西省工农业最发达的地区.为解决工农业发展带来的高污染风险性与地下水环境脆弱性这一对明显的矛盾,应加强以上地区的地下水污染防治工作,在开展工作时应坚持"以预防为主,防、治结合"的原则.     

岩溶地下水脆弱性评价研究

岩溶地下水脆弱性评价是基于保护岩溶含水层从而有效地管理和利用地下水提出的有效方法和手段。岩溶含水层的特殊性导致污染物极易进入地下含水层,并在岩溶管道中快速、远距离地运移。与其他基岩第四系含水层相比,岩溶含水层的保护面临更大的挑战。介绍了地下水脆弱性的概念;以及岩溶地下水脆弱性的相关问题,并讨论了岩溶区脆弱性评价应考虑的一些问题。     

辽宁省中南部分城市地下水脆弱性评价

通过对辽中南地区的地质与水文地质条件特征、含水层的富水性、开采利用地下水现状等资料的调查和了解,利用地下水脆弱性的DRASTIC评价模型和AHP模糊评价模型,对地下水固有脆弱性的七个因素指标进行了赋值、计算。最终得出了辽宁省中南部分城市地下水脆弱性分区分为强脆弱区、较强脆弱区、中等脆弱区、弱脆弱区。     

黑龙江省黑河市地下水脆弱性评价及地下水资源保护区划

在黑河市地下水环境开发利用状况及污染情况调查的基础上,开展了该市地下水污染特征及分布规律研究.根据研究区的具体情况,选取影响地下水脆弱性的地下水埋深、地下水净补给量、含水层介质、土壤介质、地形坡度、包气带介质和水力传导系数7个参数作为评价因子,建立黑河市地下水脆弱性评价DRASTIC指标体系和评价标准,并结合MapGIS软件实现了地下水脆弱性等级分布图及地下水保护防治区划的定量化及数字化.结果表明：该区地下水脆弱性等级为Ⅲ-Ⅳ级,表明地下水容易受到污染.根据评价结果对该区进行地下水资源保护分区,并提出了防治措施.     

基于DRASTIC方法的乌鲁木齐市平原区地下水脆弱性评价

乌鲁木齐市位于西北干旱地区,地下水人均资源量严重不足,制约了城市经济和资源环境的协调发展。本次评价采用国内外应用成熟的DRASTIC方法,评价乌鲁木齐市浅层地下水脆弱性,首先对7个指标进行评分,建立符合研究区的DRASTIC评分体系,得到研究区DRASTIC模型的7个指标的评分图,然后利用ArcGis10.2软件的图层空间分析平台,结合评价结果做出了相应的脆弱性分区图。结果显示,乌鲁木齐市内乌鲁木齐河谷区及北部五一农场地段的地下水脆弱性为中—高等,主导因素为含水层介质类型为砂岩、砂砾石等透水性较好的地层,地下水埋深较小,地层渗透系数较高;位于市区南部的柴窝堡—乌拉泊村、永丰乡及北部的三坪农场至大草滩区域地下水脆弱性中等,其余地段地下水脆弱性低。     

石家庄城市区地下水脆弱性评价研究

本文通过系统分析石家庄城市区水文地质条件,采用DRASTIC法,选取了地下水位埋深、净补给量、含水层介质、土壤介质、地形、包气带介质和渗透系数共七项影响因子对石家庄城市区地下水脆弱性进行了评价。结果表明,石家庄市地下水最脆弱的地带位于滹沱河河道及其一、二级阶地范围内,符合实际。本研究还提出了在进行地下水脆弱性评价过程中应重视脆弱性的相对性,要根据研究区的实际情况对影响因子进行分级和量化。     

松花江佳木斯段潜水脆弱性评价

鉴于松花江流域地下水的重要性和当前污染,运用改进的DRASTIC模型,对松花江佳木斯段5～10 km范围内潜水进行了脆弱性评价。选取净补给量、包气带介质、含水层厚度、地下水水位埋深、土地利用类型、污染源影响和地下水开采模数建成评价指标体系;采用层次分析法确定各指标权重,结合GIS技术实现了脆弱性分区,并将结果与地下水质评价结果进行对比;最后通过敏感度分析讨论了所选指标的合理性。结果表明:地下水脆弱性相对较低和低脆弱区共占研究区面积的82.76%;较高和高的区域仅占8.13%,主要分布在七水厂、江北水源地以及污染强度较大的点源污染周围。地下水埋深、包气带岩性和地下水开采模数是对潜水脆弱性影响最大的因素。评价结果比较真实地反映了松花江佳木斯段潜水脆弱性状况,对城市规划建设和地下水资源的可持续利用具有指导意义。     

滹滏平原地下水系统脆弱性最佳地下水水位埋深探讨

笔者以滹滏平原为研究区, 采用统计分析的方法, 分析了地下水防污性与地下水资源脆弱性随地下水位埋深之间的变化关系。结果表明, 当地下水位埋深增大时, 地下水防污性增强的地区, 地下水资源脆弱性也增高;通过二者之间变化关系, 认为受地下水位埋深制约及地下水位埋深对二者的不同影响, 存在使地下水系统脆弱性最佳的地下水位埋深区间;通过地下水位埋深对地下水防污性与地下水资源脆弱性影响及其制约关系, 确定滹滏平原淡水区和咸水区地下水系统脆弱性最佳地下水位埋深分别为27~30 m和15~19 m。     

哈尔滨市地下水的易污性评价及计算机编图

介绍了目前在国际上采用的地下水的易污性评价方法－DRASTIC评价方法，用与地下水有关的多因子－地下水的埋深，含水层的净补给，岩性，土壤类型，地形，渗流区介质，水力传导系数等7个相关因子对地下水进行评价，并结合GIS地理信息系统对哈尔滨市地下水的易污性进行评价，编制了哈尔滨市地下水的易污图，为今后地下水资源管理，土地利用，城市环境管理者等进一步制定管理方针政策提供了重要的依据。     

地下水防污性能评价方法探讨

地下水防污性能评价是环境规划和决策的有用工具,国外已有许多研究,也提出了各种计算防污性能指数模型。文中着重介绍使用最广泛的DRASTIC模型,并指出其不足之处。根据中国情况,提出用DRTA模型评价潜水的防污性能,用DLCT模型评价承压含水层的防污性能。DRTA模型包含有地下水埋深、包气带评分介质、包气带评分介质的厚度和含水层厚度4 个因子;DLCT模型包含有承压含水层埋深、隔水层岩性、隔水层的连续性和隔水层厚度4个因子。     

Assessment of aquifer vulnerability to contamination in Khanyounis Governorate, Gaza Strip—Palestine, using the DRASTIC model within GIS environment

Groundwater is a very important natural resource in Khanyounis Governorate (the study area) for water supply and development. Historically, the exploitation of aquifers in Khanyounis Governorate has been undertaken without proper concern for environmental impact. In view of the importance of quality groundwater, it might be expected that aquifer protection to prevent groundwater quality deterioration would have received due attention. In the long term, however, protection of groundwater resources is of direct practical importance because, once pollution of groundwater has been allowed to occur, the scale and persistence of such pollution makes restoration technically difficult and costly. In order to maintain basin aquifer as a source of water for the area, it is necessary to find out, whether certain locations in this groundwater basin are susceptible to receive and transmit contamination. This study aims to: (1) assess the vulnerability of the aquifer to contamination in Khanyounis governorate, (2) find out the groundwater vulnerable zones to contamination in the aquifer of the study area, and (3) provide a spatial analysis of the parameters and conditions under which groundwater may become contaminate. To achieve that, DRASTIC model within geographic information system (GIS) environment was applied. The model uses seven environmental parameters: depth of water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity to evaluate aquifer vulnerability. Based on this model and by using ArcGIS 9.3 software, an attempt was made to create vulnerability maps for the study area. According to the DRASTIC model index, the study has shown that in the western part of the study area the vulnerability to contamination ranges between high and very high due to the relatively shallow water table with moderate to high recharge potential, and permeable soils. To the east of the previous part and in the south-eastern part, vulnerability to contamination is moderate. In the central and the eastern part, vulnerability to contamination is low due to depth of water table. Vulnerability analysis of the DRASTIC Model indicates that the highest risk of contamination of groundwater in the study area originates from the soil media. The impact of vadose zone, depth to water level, and hydraulic conductivity imply moderate risks of contamination, while net recharge, aquifer media, and topography impose a low risk of aquifer contamination. The coefficient of variation indicates that a high contribution to the variation of vulnerability index is made by the topography. Moderate contribution is made by the depth to water level, and net recharge, while impact of vadose zone, hydraulic conductivity, soil media, and Aquifer media are the least variable parameters. The low variability of the parameters implies a smaller contribution to the variation of the vulnerability index across the study area. Moreover, the “effective” weights of the DRASTIC parameters obtained in this study exhibited some deviation from that of the “theoretical” weights. Soil media and the impact of vadose zone were the most effective parameters in the vulnerability assessment because their mean “effective” weights were higher than their respective “theoretical” weights. The depth of water table showed that both “effective” and “theoretical” weights were equal. The rest of the parameters exhibit lower “effective” weights compared with the “theoretical” weights. This explains the importance of soil media and vadose layers in the DRASTIC model. Therefore, it is important to get the accurate and detailed information of these two specific parameters. The GIS technique has provided an efficient environment for analysis and high capabilities of handling large spatial data. Considering these results, DRASTIC model highlights as a useful tool that can be used by national authorities and decision makers especially in the agricultural areas applying chemicals and pesticides which are most likely to contaminate groundwater resources.     

哈尔滨市及周边地区地下水易污性评价

在哈尔滨城市地质调查项目实测的地质、水文地质资料的基础上,利用DRASTIC方法,选择地下水埋深、净补给量、含水层介质、包气带影响等7个参数作为评价指标,建立哈尔滨地区地下水易污性评价体系,编制哈尔滨地区地下水易污性分区图。研究表明,哈尔滨地区地下水易污性较高的区域占17.1%,主要分布在松花江两岸,为地下水污染的高风险地区,应列为地下水资源管理重点防护区域。     

A GIS-based DRASTIC model for assessing groundwater vulnerability in the Ordos Plateau, China

Groundwater plays a key role in arid regions as the majority of water is supplied by it. Groundwater pollution is a major issue, because it is susceptible to contamination from land use and other anthropogenic impacts. A study was carried out to build a vulnerability map for the Ordos Plateau using the DRASTIC model in a GIS environment. The map was designed to show the areas of the highest potential for groundwater pollution based on hydrogeological conditions. Seven environmental parameters, such as depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone media, and hydraulic conductivity of the aquifer, were incorporated into the DRASTIC model and GIS was used to create a groundwater vulnerability map by overlaying the available data. The results of this study show that 24.8 % of the study area has high pollution potential, 24.2 % has moderate pollution potential, 19.7 % has low pollution potential, and the remaining 31.3 % of the area has no risk of groundwater pollution. The regional distribution of nitrate is well correlated with the DRASTIC vulnerability index. In contrast to this, although the DRASTIC model indicated that the western part had no risk, nitrate concentrations were higher in some of these areas. In particular, higher nitrate concentrations were recorded along river valleys and around lakes, such as the Mulin River valley. This is mainly caused by the intensive agricultural development and favorable conditions for recharge along river valleys.     

Assessing groundwater vulnerability and its inconsistency with groundwater quality,based on a modified DRASTIC model: a case study in Chaoyang District of Beijing City

Depth to water, net recharge, aquifer media, soil media, topography, impact of the vadose zone media, and hydraulic conductivity of the aquifer (DRASTIC) model based on a geographic information system (GIS) is the most widely adopted model for the evaluation of groundwater vulnerability. However, the model had its own disadvantages in various aspects. In this work, several methods and the technologies have been introduced to improve on the traditional model. The type of the aquifer was replaced by the thickness of the aquifer, and the index of topography was removed. The indexes of the exploitation of the groundwater and the type of land use that reflected the special vulnerability were added to the system. Furthermore, considering the wideness of the study area, the fixed weights in the DRASTIC model were not suitable. An analytic hierarchy process (AHP) method and an entropy weight (Ew) method were introduced to calculate the weights of parameters. Then, the Spearman Rho correlation coefficients between IVI and the Nemerow synthetical pollution index (NI) of the groundwater quality were significantly improved, after the four steps of modification. The level differences with little gaps between Nemerow comprehensive pollution indexes and groundwater vulnerability occupied the proportion of the area from 75.68 to 84.04%, and finally, a single-parameter sensitivity analysis for the two models was used to compute the effective weights of these parameters. By comparison, the DRMSICEL model seems to perform better than the DRASTIC model in the study area. And the results show discrepancies between the vulnerability indices and groundwater quality as indicated by existence of vulnerable areas with bad water quality and vice versa.     

An aquifer vulnerability assessment of the Benin Formation aquifer,Calabar, southeastern Nigeria,using DRASTIC and GIS approach

An aquifer vulnerability of the Benin Formation aquifer (Calabar, southern Nigeria) has been assessed using a combination of DRASTIC index and GIS technology. The assessment was necessitated by the fact that uncontrolled disposal of domestic, industrial and agricultural wastes have caused groundwater contamination. Therefore, prevention of contamination, monitoring and management of the aquifer was urgently required to increase the efficient use of the current water supplies. The DRASTIC method uses seven parameters (depth to groundwater table, net recharge, aquifer media, soil media, topography, influence of vadose zone and hydraulic conductivity), which were used to produce vulnerability maps. The drastic vulnerability index ranged between 124 and 170. The vulnerability map shows that the aquifer is highly vulnerable in southeastern parts of the area covering about 22 %. The medium vulnerability area covers about 56.8 % of Calabar extending from the southwest to northern parts. 21.2 % of the area covering the central and northern parts the area lies within the low vulnerability zone. The present industrial and activities are located in the eastern and western parts, which falls within the low-medium vulnerability areas. Documented nitrate concentration in hand-dug wells and boreholes are in agreement with vulnerability zones. Sensitivity analysis was performed to evaluate the sensitivity of each parameter between map layers such that subjectivity can be reduced to an extent and new weights computed for each DRASTIC parameter. As management options sensitive areas, especially in the southern parts of Calabar area, should be protected from future development.     

CAD-DRASTIC: chloride application density combined with DRASTIC for assessing groundwater vulnerability to road salt application

Road salt is pervasively used throughout Canada and in other cold regions during winter. For cities relying exclusively on groundwater, it is important to plan and minimize the application of salt accordingly to mitigate the adverse effects of high chloride concentrations in water supply aquifers. The use of geospatial data (road network, land use, Quaternary and bedrock geology, average annual recharge, water-table depth, soil distribution, topography) in the DRASTIC methodology provides an efficient way of distinguishing salt-vulnerable areas associated with groundwater supply wells, to aid in the implementation of appropriate management practices for road salt application in urban areas. This research presents a GIS-based methodology to accomplish a vulnerability analysis for 12 municipal water supply wells within the City of Guelph, Ontario, Canada. The chloride application density (CAD) value at each supply well is calculated and related to the measured groundwater chloride concentrations and further combined with soil media and aquifer vadose- and saturated-zone properties used in DRASTIC. This combined approach, CAD-DRASTIC, is more accurate than existing groundwater vulnerability mapping methods and can be used by municipalities and other water managers to further improve groundwater protection related to road salt application.     

Assessing Groundwater Resource Vulnerability by Coupling GIS-Based DRASTIC and Solute Transport Model in Ajmer District,Rajasthan

Groundwater aquifer vulnerability has been assessed by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination using GIS-based DRASTIC model along with solute transport modeling. This work demonstrates the potential of GIS to derive a vulnerability map by overlying various spatially referenced digital data layers (i.e., depth to water, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity) that portrays cumulative aquifer sensitivity ratings in Kishangarh, Rajasthan. It provides a relative indication of groundwater aquifer vulnerability to contamination. The soil moisture flow and solute transport regimes of the vadose zone associated with specific hydrogeological conditions play a crucial role in pollution risk assessment of the underlying groundwater resources. An effort has been made to map the vulnerability of shallow groundwater to surface pollutants of thestudy area, using soil moisture flow and contaminant transport modeling. The classical advection-dispersion equation coupled with Richard’s equation is numerically simulated at different point locations for assessing the intrinsic vulnerability of the valley. The role of soil type, slope, and the land-use cover is considered for estimating the transient flux at the top boundary from daily precipitation and evapotranspiration data of the study area. The time required by the solute peak to travel from the surface to the groundwater table at the bottom of the soil profile is considered as an indicator of avulnerability index. Results show a high vulnerability in the southern region, whereas low vulnerability is observed in the northeast and northern parts. The results have recognized four aquifer vulnerability zones based on DRASTIC vulnerability index (DVI), which ranged from 45 to 178. It has been deduced that approximately 18, 25, 34, and 23% of the area lies in negligible, low, medium and high vulnerability zones, respectively. The study may assist in decision making related to theplanning of industrial locations and the sustainable water resources development of the selected semi-arid area.