Hydrogeological mapping as a basis for establishing site-specific ...

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(e). Para financiar esto los consumidores pagarµn unsobreprecio de e 0.02 por m 3 de agua potable durante unperiodo de 10 aæos. Este anµlisis de la estrategia Danesapara proteger el recurso agua subterrµnea, demuestraporque la cartografía detallada, hecha con nuevos avancesen mØtodos de medición geofísica, aplicados a grandesµreas aledaæas, otorgan a la geofísica un papel altamenteimportante en el futuro de la cartografía hidrogeológica.Esto estµ ilustrado con ejemplos de cartografía geofísica agran escala y espacialmente detallada, llevados a cabo enel µrea de Aarhus.551Keywords General hydrogeology · Geophysicalmethods · Groundwater management · Groundwaterprotection · LegislationIntroductionIn 1995, increasing problems with water quality in Denmarkdue to urban development and contamination fromagricultural sources led the Minister for the Environmentto approve a 10-point plan to improve groundwater protection.One of the major initiatives was to ban the use ofpesticides which can contaminate the groundwater. Anotherwas that the Counties (the regional authorities)should draw up new water-resource protection plans. Bythe end of 1997, the 14 County Councils had classified thecountry into three types of groundwater-abstraction areas:particularly valuable, valuable, and less-valuable waterabstractionareas (Fig. 1). This classification is based onan evaluation of the size and quality of all groundwaterresources in the country.In July 1998, the Danish Parliament adopted an ambitiousplan to significantly intensify hydrogeologicalinvestigation to facilitate protection of the groundwaterresource in order to meet future water-supply challenges.Parliament decided that, in addition to being responsiblefor water-resource planning, the 14 County Councilsshould also be responsible for ensuring spatially densemapping and hydrological modelling of the water resourcesas a basis for establishing site-specific groundwaterprotection zones (Danish EPA 2000a).The mapping and planning work is to be carried outover a 10-year period and encompasses all parts of Denmarkclassified as particularly valuable water-abstractionareas. Together, these cover almost 16,000 km 2 or 37% ofthe total area of the country. The total cost of this spatiallydense mapping and planning work is estimated at aroundDKK 920 million, equivalent to 120 million euro (e,2002 prices) or e 7,500 per km 2 for a programme encompassinggeophysical profiling every 250 m, surveydrilling every 4 km 2 , water sampling and hydrologicalmodelling. During the 10-year mapping and planningperiod, Danish consumers have to pay the County Councilsa e 0.02 surcharge per m 3 of water consumed, i.e.about e 4 per family per year.Hydrogeology Journal (2004) 12:550–562Fig. 1 Groundwater classification map showing subdivision ofDenmark into particularly valuable, valuable and less-valuablegroundwater-abstraction areas in 2001. The Danish island Countyof Bornholm, which is located far from the mainland in the BalticSea south of Sweden, is shown as an inset in the upper right-handcornerPublic Water Supply Administration in DenmarkPlanning and public administration in Denmark is carriedout at three governmental levels: State, county and municipal.Legislation is passed by the State. The 14 CountyCouncils are responsible for overall administration ofwater-abstraction permits and protection of water resourcesagainst contamination. The Water Supply Act andthe Environmental Protection Act require the use ofgroundwater and surface water to be regulated throughintegrated planning and comprehensive assessment andprotection of the water resources while concomitantlyensuring water-supply needs and protection of nature andthe environment. The administration of water-abstractionpermits is regulated by the Water Resource Plan drawn upby each County Council pursuant to the Water Supply Act(Danish EPA 1999). The Water Resource Plan is theframework for the Water Supply Plan drawn up by eachof the 275 Municipal Councils (Thomsen 1997).Site-Specific Groundwater Protection Strategyand Action PlanGroundwater protection in Denmark is based on the assumptionthat the physical environment provides someDOI 10.1007/s10040-004-0345-1
552Fig. 2 Example of zonedgroundwater protection at Bederabstraction site in Aarhus Municipalitydegree of protection against anthropogenic pressures, especiallyas regards contaminants entering the subsurfaceenvironment. The fundamental concept of site-specificgroundwater protection zones is that some areas are morevulnerable to groundwater contamination than others. Thegoal is thus the subdivision of a given area according tothe different potential of the various sub-areas as regardsspecific purposes and uses. Assessment of groundwatervulnerability is described very comprehensively in theGuidebook on mapping groundwater vulnerability (Vrbaand Zaporozec 1994). The guidebook specifies the usesand limitations of groundwater vulnerability maps.The Danish site-specific groundwater protection strategyis based on three steps.1. Spatially dense hydrogeological mapping based onnew geophysical surveys, survey drilling, water sampling,hydrological modelling, etc., aimed at facilitatingthe establishment of site-specific protection zones.These zones are directed at both point sources anddiffuse sources of contamination within the wholegroundwater recharge area, and shall supplement thetraditional protection zones around the wells. Thevulnerability is interpreted in relation to the local hydrologicaland chemical conditions.2. Mapping and assessment of all past, present and possible,future sources of contamination—both pointsourceand diffuse.3. Preparation and evaluation of an action plan stipulatingpolitically determined regulations for future land useHydrogeology Journal (2004) 12:550–562within the site-specific groundwater protection zones.The action plan has to be evaluated through a publicplanning process with a high degree of transparencyand public participation. Moreover, it must include atimetable for implementation, and a description of whois responsible for implementing the plan. The protectionzones and guidelines will be used to preventgroundwater contamination from urban developmentand agricultural activities and for planning the remediationof contaminated sites.This three-step protection strategy is based on previousexperience with groundwater protection in Denmark andabroad. In some parts of Denmark, water-supply wellshave been successfully protected using two-level protectionzones directed at contamination from point sources.The protection zones encompass a 10-m-diameter protectionzone around the well indicated by a fence, and a300-m protection zone directed at point sources such asleaching of wastewater (Fig. 2). The well-site protectionzones correspond to the protection zones which have beenused for several years in countries such as Germany(DVGW 1995). In Germany, the well-site protectionzones are established as concentric circles with a radiusranging from 10 m to 2–3 km around the well. Thesezones are based on experience with the dilution anddegradation of contaminants from point sources, and theradius is fixed on the basis of the transport time and thehydraulic properties of the water-bearing layers in particular.In Denmark, the new site-specific protectionDOI 10.1007/s10040-004-0345-1
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