Source vulnerability mapping in carbonate (karst) aquifers by extension of the COP method: application to pilot sites

A step from resource to source vulnerability mapping is presented, based on the European COST Action 620 approach for karst groundwater protection. Guidelines on vulnerability assessment of the horizontal groundwater flow path within the karst saturated zone (K factor) are proposed. By integrating this into the previously existing COP method for intrinsic resource vulnerability mapping, adequate source protection can be assessed. The proposed “Karst saturated zone (K) factor” assessment considers groundwater travel time (t subfactor), connection and contribution to the source (r subfactor) and active conduit or fissured network (n subfactor). The extended COP method was applied in two carbonate aquifers in southern Spain with different geological, hydrogeological and climate settings. The results are coherent with previous research results of the studied areas. Moreover, they are consistent with the occasional groundwater contamination detected in one of the springs. On the other hand, an absence of contamination, despite high risk, justifies the lower degrees of vulnerability assigned to the sources surveyed. The source vulnerability maps obtained can thus be used as a basis for the delineation of protection zones.     

Proposed method for groundwater vulnerability mapping in carbonate (karstic) aquifers: the COP method

The ‘COP method’ has been developed for the assessment of intrinsic vulnerability of carbonate aquifers in the frame of the European COST Action 620. This method uses the properties of overlying layers above the water table (O factor), the concentration of flow (C factor) and precipitation (P factor) over the aquifer, as the parameters to assess the intrinsic vulnerability of groundwater. This method considers karst characteristics, such as the presence of swallow holes (C factor) and their catchment areas as well as karstic landforms, as factors which decrease the natural protection provided by overlying layers (O factor). The P factor allows for consideration of the spatial and temporal variability of precipitation, which is considered the transport agent of contamination. Two carbonate aquifers in the South of Spain, Sierra de Líbar (a conduit flow system) and Torremolinos (a diffuse flow system), have been selected for the application and validation of the method and the results have been compared with three methods widely applied in different aquifers around the world (AVI, GOD and DRASTIC). Comparisons with these methods and validation tools (hydrogeological data and tracer test) show the advantages of the COP method in the assessment of vulnerability of karstic groundwaters.     

A simplified methodology for mapping groundwater vulnerability and contamination risk, and its first application in a tropical karst area, Vietnam

A simplified methodology for mapping groundwater vulnerability and contamination risk is proposed, and the first application of the methodology, in a mountainous tropical karst area, is presented. The test site is the Tam Duong area, one of the poorest and remotest regions in northern Vietnam. The methodology requires a minimum of input data, which makes it particularly useful for developing countries. Vulnerability is assessed on the basis of two factors, which take into account the duality of recharge processes in karst aquifer systems: the overlying layers (O) and the concentration of flow (C). The risk map is obtained by putting together the vulnerability map and a simplified hazard assessment. The resulting maps provide a basis for groundwater protection zoning and land-use planning. Tracer tests and microbiological data confirmed the vulnerability and risk assessment in the test site.     

Improved groundwater vulnerability mapping for the karstic chalk aquifer of south east England

The Cretaceous age Chalk of south east England forms an important aquifer. Within chalk the storage and transmission of groundwater is enhanced by subsurface karstic weathering. The case study presented in this paper demonstrates that current approaches to assessing groundwater vulnerability to pollution and delineating source protection zones are flawed, as they do not take proper account of the karstic nature of chalk.Improved techniques, based on understanding the geological and geomorphological controls of karst development in chalk, are proposed to overcome the shortcomings of published groundwater vulnerability maps. The results also demonstrate the inadequacies of current groundwater modelling approaches for defining source protection zones. The techniques follow European Commission research recommendations by taking account of recharge, presence of overlying cover deposits, the nature of chalk karst and the way in which it influences the flow of groundwater. The approach described allows for better informed decisions to be made about chalk aquifer management to ensure adequate protection and conservation of groundwater. For example, the published groundwater vulnerability map shows Lambeth Group deposits classified as being a minor aquifer of low groundwater vulnerability in the chosen study area. However, by applying the new techniques, they are classified as having an Aquifer Vulnerability Rating of moderate to very high, when taking the karstic development of the underlying chalk into account.     

Hazard and risk intensity maps for water-bearing units: a case study

Fresh groundwater from intergranular and carbonate aquifers are considered as the valuable resources for domestic, agricultural and industrial water supplies of the Iraqi Kurdistan Region. A comprehensive approach to groundwater protection using the intrinsic vulnerability, hazard and risk intensity mapping was proposed by the European COST Action 620. The current article applied all the components of the above mentioned Pan-European approach to assess the risk harmfulness in the Sulaimani sub-basin by combining hydrogeological parameters using the DRASTIC system and the hazard components by taking the product of the weighted hazard value (H_I), the ranking factor (Q_n) and the reduction factor (R_f). The hazard map was constructed from twenty-six hazard feature types of the point, line and polygon. Their distributions, extents and of harmfulness degrees vary sharply from one place to another. Results of the risk intensity map divided the area into five classes as “no or very low, low, moderate, high and very high” risk zones. Fortunately, the majority of the area of interest is classified as very low to low contamination potential due to the limited impact of hazards as well as low groundwater vulnerabilities. The zones with moderate-risk potentials clustered in industrialized areas.     

青木关岩溶槽谷地下水水源地固有脆弱性评价

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。我国西南岩溶区大多数地区缺少应有的地下水保护带,地下水比较容易受到污染。通过采用改进的斯洛文尼亚模式,考虑四个因子:覆盖层(O)、径流特征(C)、降雨条件(P)、岩溶发育程度(K),对重庆市青木关岩溶槽谷地下水水源地的固有脆弱性进行了定量评价。结果表明:流域范围内12.6%为高脆弱性地区;43%为中等脆弱性;44.4%为低脆弱性区域。消水洞及周边100m和消水河及其两边10m,以及岩溶管道发育地区为高脆弱性区。大部分岩溶区为中等脆弱性区。砂岩地区为低脆弱性地区。评价结果与实际吻合。该评价结果为各级决策部门合理规划利用和保护地下水资源提供简单明了的科学依据。该方法对于川东岩溶槽谷地区脆弱性评价有推广价值。      

Karst morphology and groundwater vulnerability of high alpine karst plateaus

High alpine karst plateaus are recharge areas for major drinking water resources in the Alps and many other regions. Well-established methods for the vulnerability mapping of groundwater to contamination have not been applied to such areas yet. The paper characterises this karst type and shows that two common vulnerability assessment methods (COP and PI) classify most of the areas with high vulnerability classes. In the test site on the Hochschwab plateau (Northern Calcareous Alps, Austria), overlying layers are mostly absent, not protective or even enhance point recharge, where they have aquiclude character. The COP method classifies 82% of the area as highly or extremely vulnerable. The resulting maps are reasonable, but do not differentiate vulnerabilities to the extent that the results can be used for protective measures. An extension for the upper end of the vulnerability scale is presented that allows identifying ultra vulnerable areas. The proposed enhancement of the conventional approach points out that infiltration conditions are of key importance for vulnerability. The method accounts for karst genetical and hydrologic processes using qualitative and quantitative properties of karst depressions and sinking streams including parameters calculated from digital elevations models. The method is tested on the Hochschwab plateau where 1.7% of the area is delineated as ultra vulnerable. This differentiation could not be reached by the COP and PI methods. The resulting vulnerability map highlights spots of maximum vulnerability and the combination with a hazard map enables protective measures for a manageable area and number of sites.     

Sensitivity analysis for the EPIK method of vulnerability assessment in a small karstic aquifer, southern Belgium

Applying the EPIK parametric method, a vulnerability assessment has been made for a small karstic groundwater system in southern Belgium. The aquifer is a karstified limestone of Devonian age. A map of intrinsic vulnerability of the aquifer and of the local water-supply system shows three vulnerability areas. A parameter-balance study and a sensitivity analysis were performed to evaluate the influence of single parameters on aquifer-vulnerability assessment using the EPIK method. This approach provides a methodology for the evaluation of vulnerability mapping and for more reliable interpretation of vulnerability indices for karst groundwater resources. Received, March 1999/Revised, December 1999, February 2000/Accepted, February 2000     

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。     

Intrinsic vulnerability of Coteţul Dobreştilor karst aquifer (Bihor Mountain, Romania)

The evaluation of the vulnerability of the karst aquifer and the source in the Coteţul Dobreştilor system was performed on the basis of geological, hydrogeological and pedological data. The methods proposed in the Final Report of COST Action 620 were used. The available field data resulted in assessing the parameters P, I and in characterizing the saturated aquifer karstic network parameter (K). The soil cover over the carbonate deposits is generally shallow and easily bypassed by the superficial flow, the protection of the karstic aquifer and the source thus being minimal.     

Water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method)

 Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland. Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of Hydrogeology of the Neuchatel University to develop a new groundwater protection-zones strategy in karst environment. This approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes. Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover, (3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely. This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred. These applications resulted in recommend new boundaries for the karst water supplies protection-zones. Received: 27 October 1997 · Accepted: 4 July 1998     

PaPRIKa: a method for estimating karst resource and source vulnerability��application to the Ouysse karst system (southwest France)

The intrinsic vulnerability mapping method, PaPRIKa, is proposed as a common basis for karst groundwater protection in France. PaPRIKa is a specialized method for studying karst aquifers, derived from updating the RISKE and EPIK methods. Both the structure and functioning of karst aquifers are considered in order to develop a resource and source-vulnerability mapping method. PaPRIKa means Protection of aquifers from the assessment of four criteria: P for protection (considering the most protective aspects among parameters related to soil cover, unsaturated zone and epikarst behavior), R for rock type, I for infiltration and Ka for karstification degree. The Ouysse karst system, located in the Causses area in southwest France, is one of the nine pilot sites where this method was tested and standardized. The specificities of the Ouysse system such as the size of the catchment area, the spatial variability of the karst network development, the thick infiltration zone and the system??s dual character (both karst and non-karst areas), have provided a valuable field of application. The vulnerability of the resource was assessed for the entire catchment area, while source-orientated cartography was attempted for the catchment areas of the three different capture works used for drinking water.     

基于COP方法的徐州城市规划区内岩溶水脆弱性评价

基于欧洲模式中针对岩溶含水层脆弱性的评价方法—COP法,根据区内实际水文地质条件,建立徐州城市规划区岩溶水脆弱性评价模型。评价结果表明,脆弱性级别高区、脆弱性级别较高区占徐州城市规划区总面积的23.12%、13.73%;脆弱性级别中等区占总面积的7.85%;脆弱性级别较低区和低区分别占总面积的11.57%、43.73%。总体来看,区内岩溶含水层脆弱性整体较低,不容易被污染;脆弱性高区主要分布在基岩裸露区及其周围地区。     

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。     

Groundwater vulnerability assessment of the SW Trans-Danubian Central Range, Hungary

 The most important karst water reservoir of Hungary is found in the SW Trans-Danubian Central Range, selected as test area for the proposed "system approach" and the application of GIS/ARC-INFO to vulnerability mapping. In addition, a case-study exemplifies the particularities of regional karst-aquifer vulnerability, and moreover the interpretation of data and maps from the very same point of view. The work has resulted in plotting an atlas to be a useful tool in the hands of land-users and waste-disposal managers, helping them to prevent groundwater deterioration. Received: 22 July 1996 · Accepted: 12 September 1997     

贵州织金县城岩溶地下水脆弱性评价

本文在全面分析织金县城地下水岩溶流域的水文地质、岩溶地质特征的基础上,参照有关评价的理论数据提出了适合该区域的地下水脆弱性评价系统与DRKST模型,并结合GIS空间分析功能对岩溶流域地下水脆弱性进行了评价,对规划织金县城的建设和发展,具有较大的参考价值。     

地下水污染脆弱性评价方法

地下水污染脆弱性是指污染物自顶部含水层以上某一位置到达地下水系统中某一特定位置的趋势和可能性,进一步分为固有脆弱性和特殊脆弱性。地下水污染脆弱性受地下水流系统和地球化学系统的影响和控制。其主要评价方法有主观分级评价法、统计或基于过程的评价法和综合评价法三大类。中国地下水污染脆弱性评价已有很好的工作基础,评价工作中应以地下水系统为单元,以饮用水井、集中供水水源地、区域含水层系统的补给区为重点保护目标,评价方法应综合区域地下水流系统的过程分析和指数评价方法,并利用已有的区域水质资料进行检验,增强评价结论的科学性和可靠性。     

西辽河平原(内蒙古部分)地下水固有脆弱性评价

在西辽河平原地下水资源评价的基础上,选取影响西辽河平原固有脆弱性的最主要的7个影响因子,利用GIS平台的空间分析功能,将研究区划分为14365个评价单元,运用基于DRASTIC的模糊综合评价方法对该区的地下水固有脆弱性进行了综合评价,并绘制了脆弱性分布图。评价结果表明西辽河平原(内蒙古部分)地下水脆弱性存在3个分区:大部分地区为地下水稍易污染区;南部的黄土地区为地下水稍难污染区;而西辽河和乌尔吉木伦河的中上游为地下水相对略易污染区。评价结果对该区地下水资源保护、防止地下水污染具有指导作用。     

娘子关泉域岩溶水脆弱性模糊综合评价

地下水脆弱性评价是区域地下水资源管理和保护的重要手段之一,针对娘子关泉域岩溶水的特殊性,基于欧洲脆弱性评价方法,选择包气带厚度、入渗补给量、包气带岩性、岩溶含水层的导水性能(泉水响应)四个因子,采用模糊综合评价法评价地下水脆弱性,并且绘制地下水脆弱性分区图。评价结果表明,极易污染区主要分布在娘子关泉群出露的地区,即泉源处;极难污染区主要分布在盂县—阳泉—平定—昔阳—和顺一带以西地区,寿阳县大部分地区。评价结果在合理制定保护娘子关泉域方面具有一定的参考价值。     

Comparative application of two methods (COP and PaPRIKa) for groundwater vulnerability mapping in Mediterranean karst aquifers (France and Spain)

A comparative test of two vulnerability mapping methods (COP and PaPRIKa) specifically dedicated to for karst aquifers was carried out on two Mediterranean carbonate aquifers. The vulnerability maps obtained for each aquifer present important differences. To identify and determine the origin of these differences, the results were statistically analyzed using sensitivity analysis, coefficients of determination and scatter graphs. In addition, the global vulnerability (Gv) parameter was used to measure the general vulnerability of the aquifer and to compare the results obtained. This statistical analysis led us to conclude that the main cause of differences between these two methods used to assess aquifer vulnerability lie in the relative importance of the parameters employed in calculating the vulnerability index. For the PaPRIKa method, the variable related to infiltration (slope and karst features) has the most influence, with less weight being assigned to the protective capacity of layers overlying the aquifer. For the COP method, the most influent variable is defined by the layers overlying the aquifer, together with infiltration characteristics, determined by the relative importance of different forms of infiltration in each aquifer. The vulnerability mappings performed using the COP method present greater coherence with the known hydrogeological behavior of the study areas, especially the Spanish aquifers. Nevertheless, further hydrogeological investigations are needed, such as ones to validate the obtained vulnerability maps.