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1.
Groundwater vulnerability maps were constructed for the surface water catchment area of Tanour and Rasoun spring (north-west of Jordan) using the COP and EPIK intrinsic groundwater vulnerability assessment methods. Tanour and Rasoun springs are the main water resources for domestic purposes within the study area. A detailed geological survey was carried out, and data of lithology, karst features, precipitation, vegetation and soil cover, etc. were gathered from various sources for the catchment area in order to determine the required parameters for each method. ArcGIS software was used for map preparation. In the resulting COP vulnerability map, spatial distribution of groundwater vulnerability is as follows: (1) high (37%), (2) moderate (34.8%), (3) low (20.1%), and (4) very low (8.1%). In the EPIK vulnerability map, only two out of four vulnerability classes characterize the catchment area: very high vulnerable areas (38.4%) and moderately vulnerable areas (61.6%). Due to limited soil thickness, the low vulnerability class is absent within the catchment. The high percentage of very high to moderately vulnerable areas displayed by both the COP and EPIK vulnerability assessment methods are reflected by different pollution events in Tanour and Rasoun karst springs especially during the winter season. The high sensitivity of the aquifer to pollution can be explained by different factors such as: thin or absent soil cover, the high development of the epikarst and karst network, and the lithology and confining conditions of the aquifer.  相似文献   

2.
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.  相似文献   

3.
 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  相似文献   

4.
Standardization of vulnerability maps   总被引：3，自引：0，他引：3  
Groundwater vulnerability assessment schemes are used for the estimation of potential groundwater contamination at different scales and on different administrative levels. However, the term vulnerability is not standardized and the available methods are not able to give a unique assessment of vulnerability creating thus uncertainty in the interpretation and in further application concerning decision creation processes. To judge the information of vulnerability maps certainly and to value the general trends of vulnerability assessment of different methods, four different vulnerability methods of the parametric system group have been applied on a karst area in southwestern Germany to perform a comparative assessment and correlation of these vulnerability assessment methods, namely DRASTIC, PI, EPIK, and GLA. It is shown that by means of simple statistical considerations the first highly different vulnerability maps could be made more coherent after reclassification. The reclassified vulnerability assessments show a more consistent vulnerability distribution pattern and provide the possibility of area-wide validation of the maps as the chosen vulnerability classification is theoretically connected to the mean transit time of percolation water and is largely independent of the applied vulnerability assessment method.  相似文献   

5.
Vulnerability maps illustrate the potential threat of contaminants to groundwater and can be considered as important tools for land-use planning and related legislation. For karst areas with characteristic preferential infiltration conditions, vulnerability maps are also excellent tools for source and resource protection. However, the resulting qualitative maps are often inconsistent and even contradictive and thus might lead to inconclusive vulnerability assessments. The results of a validation of vulnerability maps produced using four different methods, DRASTIC, GLA, PI and EPIK, are reported for a karst area in southwest Germany. By means of measured hydraulic and transport parameters of the geological sequence, numerical simulations were used based on a conceptual model for the area under study. The mean transit time through the unsaturated zone (resource protection) was used as the validation parameter. The study demonstrates that the highest level of accuracy is achieved with the GLA- and PI methods. Both DRASTIC and EPIK are not able to incorporate highly variable distributions and thickness of cover sediments and their protective properties in the respective mapping procedure. Thus, vulnerability maps produced with DRASTIC, EPIK, and related methods should be used with care when employed in vulnerability assessments for land use planning and related decision-making.
Résumé  Les cartes de vulnérabilité illustrent la menace potentielle des contaminants envers les eaux souterraines, et peuvent être considérées comme des outils importants en matière d'aménagement foncier et de réglementation associée. Sur les domaines karstiques, caractérisés par des conditions d'infiltration préférentielle, ces cartes sont également d'excellents outils de protection des sources et des ressources. Cependant, les cartes qualitatives résultantes sont généralement incohérentes voire contradictoires, et peuvent par là-même mener à des évaluations de vulnérabilité peu concluantes. La présente étude expose les résultats de validation de cartes de vulnérabilité produites selon quatre méthodes différentes (DRASTIC, GLA, PI et EPIK), dans le cas d'un domaine karstique du sud-est de l'Allemagne. Par le biais des paramètres de transport et hydrauliques mesurés sur la séquence géologique, des simulations numériques basées sur un modèle conceptuel du secteur d'étude ont été utilisées. Les temps de transit moyens à travers la zone non saturée (protection de la ressource) ont été utilisés comme paramètres de validation. L'étude démontre que le niveau maximum de précision est obtenu par les méthodes GLA et PI. Dans la phase de cartographie, les méthodes EPIK et DRASTIC sont incapables d'intégrer une forte variabilité dans les distributions et les épaisseurs de sédiments de couverture, ainsi que dans leurs potentiels de protection. Aussi, les cartes de vulnérabilité produites par les méthodes DRASTIC et EPIK doivent être utilisées avec précaution dans le cadre des évaluations de vulnérabilité à but décisionnaire pour les aménagements fonciers.
Resumen  Los mapas de vulnerabilidad ilustran la amenaza potencial de contaminantes para el agua subterránea y pueden ser considerados herramientas importantes para planeamiento del uso de la tierra y legislación relacionada. Para áreas cársticas con sus características condiciones de infiltración preferencial, los mapas de vulnerabilidad son también excelentes herramientas para protección de fuentes y recursos. Sin embargo, los mapas cualitativos resultantes son frecuentemente inconsistentes y hasta contradictorios y por lo tanto podrían conducir a evaluaciones de vulnerabilidad no concluyentes. Los resultados de una validación de mapas de vulnerabilidad producidos usando cuatro métodos diferentes, DRASTIC, GLA, PI y EPIK, son presentados aquí para un área cárstica en Alemania suroccidental. Se usaron simulaciones numéricas usando parámetros hidráulicos y de transporte medidos de la secuencia geológica y basándose en un modelo conceptual del área en estudio. El tiempo promedio de tránsito a través de la zona no saturada (protección del recurso) fue utilizado como el parámetro de validación. El estudio demuestra que el máximo nivel de precisión es alcanzado con los métodos GLA y PI. DRASTIC y EPIK no fueron capaces de incorporar distribuciones altamente variables ni espesor de sedimentos de cubierta y sus propiedades protectivas en el respectivo procedimiento de elaboración de mapas. Por lo tanto los mapas de vulnerabilidad producidos con DRASTIC, EPIK y métodos relacionados deberían ser usados con cuidado cuando se usen en evaluaciones de vulnerabilidad para planeamiento del uso de tierra y toma de decisiones relacionadas.
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6.
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  相似文献   

7.
For good management of groundwater resources, and to comply with European and national regulations, a detailed understanding of an aquifer’s hydraulic setting is required. In order to better characterize a sandy aquifer that is affected by diffuse pollution (Brévilles spring catchment, Val d’Oise, France), and to quantify the transfer time in the saturated zone, a multi-tracer test involving a new technique, the ‘finite volume point dilution method’, has been performed in natural flow conditions. In November 2005, injections of four different tracers took place in four piezometers involving different locations and depths in the aquifer. Recovery of the tracers was observed at two different places near the aquifer outlet. A particularly long and unusual monitoring exercise (27 months) demonstrated the existence of several different velocities within the sandy layer, which seems to be linked to the decrease of hydraulic conductivity with depth. The new insight and parameter quantification brought by interpretation of these tests contribute to a better characterization of the saturated zone. The particularly long-term monitoring exercise also gives new information to understand and forecast the trend and persistence of groundwater contamination by pesticides in the catchment.  相似文献   

8.
Karst aquifers represent important water resources in many parts of the world. Unfortunately, karst aquifers are characterised by high contamination risks. This paper presents a travel time based method for the estimation of karst groundwater vulnerability. It considers (1) physics-based lateral flow within the uppermost weathered zone (epikarst) in a limestone-dominated region and (2) high velocities of vertical infiltration at discrete infiltration points (e.g. sinkholes) or lines (e.g. dry valleys, faults). Consequently, the Transit Time Method honours the actual flow path within the unsaturated zone of a karst aquifer system. A test site in Northern Jordan was chosen for the demonstration of the assessment technique, i.e. the catchment area of the Qunayyah Spring north of the capital Amman. The results demonstrate that zones of highest vulnerability lie within valleys and nearby main fault zones. It also reveals that regions, categorised as protected areas by other methods due to thick unsaturated zones, contribute to a major degree to the total risk.  相似文献   

9.
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.  相似文献   

10.
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.  相似文献   

11.
岩溶地下水系统防污性能评价方法   总被引：9，自引：0，他引：9  
岩溶水系统结构复杂,不同类型岩溶区具有不同的岩溶水文地质特征,其地下水系统防污性能评价必须采用不同指标体系的评价模型。本文在对不同类型岩溶区发育特征分析基础上,分别就现有评价模型在不同类型岩溶区的适应性进行了分析,认为:埋藏型岩溶区可采用专门用于承压含水层防污性能评价的PTHQET模型进行评价,而对于补给区局部裸露的浅埋藏性岩溶区建议采用COP模型进行评价;EPIK模型适用于南方裸露岩溶区;北方裸露型岩溶区因表层岩溶带发育程度弱,亦可采用COP模型进行评价。针对覆盖型岩溶的特殊性,在欧洲模型基础上提出了PLEIK评价模型,评价因子包括保护性盖层(P)、土地类型与利用程度(L)、表层岩溶带发育强度(E)、补给类型(I)和岩溶网络发育情况(K);突出了P(保护性盖层)和L(土地利用类型)两个因子的作用,并赋予各因子比欧洲模型更丰富的内涵,同时采用多种可替代参数确定各因子量值,最后给出了防污性能指数计算方法与分级标准。  相似文献   

12.
Groundwater from karst aquifers is an important drinking water resource, which is, however, particularly vulnerable to contamination. Karst aquifers consequently need special protection. This paper discusses the concept of groundwater vulnerability mapping and the special characteristics of karst aquifers that are relevant in this context. On this basis, a new method of groundwater vulnerability mapping is proposed—the PI method. It can be applied for all types of aquifers, but provides special tools for karst. Vulnerability is assessed as the product of two factors: protective cover (P) and infiltration conditions (I). The method was first applied and compared with two other methods (EPIK and the German method) in a test site in the Swabian Alb, Germany. The results obtained with the different methods are discussed and an outlook on the role of vulnerability maps within an overall groundwater protections scheme is given.
Resumen Las aguas subterráneas en medios kársticos suponen un recurso importante para uso de boca, pero es particularmente vulnerable a la contaminación, por lo que los acuíferos kársticos requieren una protección especial. Este artículo discute el concepto de cartografía de vulnerabilidad de las aguas subterráneas y las características propias de los acuíferos kársticos que son relevantes en este contexto. Con esta base, se propone un nuevo método para cartografiar la vulnerabilidad de las aguas subterráneas, denominado "PI". Puede ser aplicado a todo tipo de acuíferos, pero proporciona herramientas especiales en medios kársticos. Se establece la vulnerabilidad como resultado de dos factores: la cubierta protectora y las condiciones de infiltración. El método ha sido aplicado por vez primera y comparado con otros dos enfoques (EPIK y el método alemán) en un emplazamiento ubicado en Swabian Alb (Alemania). Se discute los resultados obtenidos con estos métodos y se incide en cuál es el papel que desempeñan los mapas de vulnerabilidad en el contexto de los esquemas generales de protección de las aguas subterráneas.
Résumé L'eau souterraine des karsts est une importante ressource d'eau potable, cependant particulièrement vulnérable à la pollution. C'est pourquoi les aquifères karstiques nécessitent une protection particulière. Ce papier discute le concept de cartographie de la vulnérabilité de l'eau souterraine et les caractéristiques particulières des aquifères karstiques qui sont concernés dans ce contexte. Sur cette base, une nouvelle méthode de cartographie de la vulnérabilité de l'eau souterraine est proposée: la méthode PI. Elle peut être appliquée à tous les types d'aquifères, mais fournit des outils spécifiques au karst. La vulnérabilité est évaluée comme étant le produit de deux facteurs: les conditions de couverture protectrice (P) et d'infiltration (I). La méthode a été mise en oeuvre pour la première fois et comparée à deux autres méthodes (EPIK et la méthode allemande) sur un site test du Jura souabe (Allemagne). Les résultats obtenus avec les différentes méthodes sont discutés et le rôle des cartes de vulnérabilité dans un schéma général de protection des eaux souterraines est passé en revue.
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13.
Five different methods for assessing intrinsic aquifer vulnerability were tested in a case study and their results compared. The test area was a slightly karstified district in the Condroz region of Belgium. The basin covers about 65 km2 and the karst aquifer provides a water-supply of about 28,000 m3d-1. The methods tested were: EPIK (Doerfliger et al. 1999), DRASTIC (Aller et al. 1987), 'German method' (von Hoyer and Söfner 1998), GOD (Foster 1987) and ISIS (Civita and De Regibus 1995). The results are compared and critically examined. From the analysis, it seems that reducing the number of parameters is unsatisfactory, due to the variety of geological conditions. The various methods produce very different results at any given site. As only physically-based methods can be checked for their reliability, it is clear that future vulnerability mapping techniques must incorporate such methods.  相似文献   

14.
This paper shows the results of a comparative study involving application of the vulnerability mapping methods known as AVI, GOD, DRASTIC and EPIK to a pilot carbonate massif in southern Spain, namely the Torremolinos aquifer. The main objectives of the study were to determine which methods are most suitable for diffuse flow carbonate aquifers such as in southern Spain, and to evaluate variations in the degree of vulnerability associated to the rainfall variations that normally occur in a Mediterranean climate. According to three of the above methods, the aquifer is moderately vulnerable, but the AVI method evaluated it as highly vulnerable—this, however, is improbable. The vulnerability maps reflect the great importance of geology-related parameters (mainly those concerned with lithology) and, to a lesser degree, that of the depth of the groundwater table which is related to the rainfall. After this latter parameter, it is possible to distinguish between humid and dry climatic situations; thus, vulnerability increases in a humid year, especially according to the GOD and AVI methods. In conclusion, the GOD method seems the most adequate of the methods applied in this work for vulnerability mapping of diffuse flow carbonate aquifers in the Mediterranean domains.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
Analysis of the maximum discharge of karst springs   总被引：2，自引：0，他引：2  
Analyses are presented of the conditions that limit the discharge of some karst springs. The large number of springs studied show that, under conditions of extremely intense precipitation, a maximum value exists for the discharge of the main springs in a catchment, independent of catchment size and the amount of precipitation. Outflow modelling of karst-spring discharge is not easily generalized and schematized due to numerous specific characteristics of karst-flow systems. A detailed examination of the published data on four karst springs identified the possible reasons for the limitation on the maximum flow rate: (1) limited size of the karst conduit; (2) pressure flow; (3) intercatchment overflow; (4) overflow from the main spring-flow system to intermittent springs within the same catchment; (5) water storage in the zone above the karst aquifer or epikarstic zone of the catchment; and (6) factors such as climate, soil and vegetation cover, and altitude and geology of the catchment area. The phenomenon of limited maximum-discharge capacity of karst springs is not included in rainfall-runoff process modelling, which is probably one of the main reasons for the present poor quality of karst hydrological modelling. Electronic Publication  相似文献   

18.
A systematic approach for identifying mineral exploration target areas from reconnaissance stream sediment data without sufficient a-priori control information has been demonstrated in a portion of western Albay Province in the southern Bicol Peninsula of the Philippines. The approach involved devising a rapid method of catchment basin mapping using a geographic information system (GIS) so that the areal influence of the catchment basins may be incorporated in the geochemical data analysis. Areal proportions of mapped rock units occurring in the sample catchment basins and observed Mn and Fe contents in stream sediments are used as independent variables in multiple regression analysis to predict element contents in stream sediments related to lithologic and chemical controls. The predicted element contents are filtered-out from the original data to leave residuals in which the effects of other factors (e.g., mineralization) may be seen. A simple correction for the effects of downstream dilution is applied; this allows for the different sizes of the sample catchment basins so that positive geochemical residuals are enhanced. The inter-relationship of the different positive residuals in ‘highly enriched’ samples are investigated through principal components analysis to determine and quantify an ‘anomalous geochemical signature’. Lastly, the ‘anomalous geochemical signature’ is integrated with ‘proximity’ to faults/fractures to determine favourable target areas. For the test region, the lithologic controls explain between 80% and 100% of the variability in most of the elements studied. Chemical controls account for generally less than 5% of the variability in the data. Most of the dilution-corrected residuals reveal high relative enrichment in certain areas underlain by andesite and/or diorite. An anomalous Cu-Mg-Fe-Zn geochemical signature is disclosed by the principal components analysis of the dilution-corrected residuals in ‘highly enriched’ samples. Most sample catchment basins defined by this ‘anomalous geochemical signature’ pertain to areas underlain by andesitic rocks. Integration of the ‘anomalous geochemical signature’ and ‘proximity’ to faults/fractures reveals that some of these anomalous sample catchment basins are favourable target areas. These areas are interpreted to contain andesite-hosted stockwork or stringer zones that once formed part of a complete stratigraphic sequence of a volcanogenic massive sulphide occurrence. The results demonstrate the usefulness and ability of the procedures followed to extract significant anomalies from the reconnaissance geochemical data without the benefit of sufficient a-priori control data to aid in anomaly recognition. Similar procedures could also be applied elsewhere.  相似文献   

19.
The Supramonte limestone complex, of Jurassic–Cretaceous age, lies within the municipal borders of Urzulei, Oliena and Orgosolo (north-central Sardinia). For the most part, the Supramonte groundwater drains towards the outcrops in the northernmost part of the massif. A minor, almost negligible quantity of water drains towards a series of outcrops along the edge of the carbonate structure, with numerous subaerial and submarine springs. The groundwater in the entire system represents one of the most important water resources in Sardinia, especially for drinking purposes. Taking into consideration the development of karst cavities, permanent groundwater reserves were cautiously estimated to be at least 144 Mm3. Intrinsic vulnerability to pollution has been assessed by means of the EPIK method.  相似文献   

20.
Temperature distribution in karst systems: the role of air and water fluxes   总被引：3，自引：0，他引：3  
A better understanding of heat fluxes and temperature distribution in continental rocks is of great importance for many engineering aspects (tunnelling, mining, geothermal research, etc.). This paper aims at providing a conceptual model of temperature distribution in karst environments which display thermal ‘anomalies’ as compared with other rocks. In temperate regions, water circulation is usually high enough to ‘drain‐out’ completely the geothermal heat flux at the bottom of karst systems (phreatic zone). A theoretical approach based on temperature measurements carried out in deep caves and boreholes demonstrates, however, that air circulation can largely dominate water infiltration in the karst vadose zone, which can be as thick as 2000 m. Consequently, temperature gradients within this zone are similar to the lapse rate of humid air (～0.5 °C 100 m?1). Yet, this value depends on the regional climatic context and might present some significant variations.  相似文献   

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