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This article was downloaded by: [University of Malaya]On: 25 September 2012, At: 18:10Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Journal of Risk ResearchPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/rjrr20

GIS-based DRASTIC method forgroundwater vulnerability assessment:a reviewS.M. Shirazi a , H.M. Imran a & Shatirah Akib aa Faculty of Engineering, Department of Civil Engineering,University of Malaya, Kuala Lumpur, Malaysia

Version of record first published: 14 May 2012.

To cite this article: S.M. Shirazi, H.M. Imran & Shatirah Akib (2012): GIS-based DRASTIC method forgroundwater vulnerability assessment: a review, Journal of Risk Research, 15:8, 991-1011

To link to this article: http://dx.doi.org/10.1080/13669877.2012.686053

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GIS-based DRASTIC method for groundwater vulnerabilityassessment: a review

S.M. Shirazi*, H.M. Imran and Shatirah Akib

Faculty of Engineering, Department of Civil Engineering, University of Malaya, KualaLumpur, Malaysia

(Received 18 January 2012; final version received 29 February 2012)

Groundwater vulnerability is a burning issue all over the world due to thedeterioration of groundwater level and increasing contamination which posesserious detrimental risk to the environment. To identify this risk, extensiveresearch has been carried out to assess the groundwater vulnerability by usingdifferent methods. Generally, the process-based method, statistical method, andoverlay & index methods are used in this regard. DRASTIC method is one typeof overlay & index method for vulnerability assessment. This paper represents acomprehensive review of available literature on the applications of GeographicInformation System (GIS)-based DRASTIC method for groundwater vulnerabil-ity assessment. Also, some other types of overlay & index methods are com-pared with the DRASTIC method. This study discusses the rescaling of ratingranges and modification of DRASTIC parameters, and shows the comparison ofDRASTIC method with other vulnerability assessment methods. In addition, thisstudy identifies some research gaps on the present state of groundwater vulnera-bility assessment and proposes some research needs for further studies. Thefindings of this study indicate that the combination of GIS and DRASTIC aremore viable for groundwater vulnerability assessment. Furthermore, modifiedDRASTIC method can be used for agricultural, arid, semi-arid, and basalticregions.

Keywords: DRASTIC; groundwater; vulnerability; GIS

Introduction

Groundwater vulnerability refers to intrinsic characteristics that determine the sensi-tivity of the water to be adversely affected by an imposed contaminant load. Theanthropogenic and agricultural activities are responsible for deterioration of ground-water level and increasing vulnerability. Due to the deterioration of groundwaterlevel, sustainable development plans are needed to protect these resources (Nagesw-ara and Narendra 2006). Groundwater has a major contribution to agricultural,industrial, drinking, and other municipal uses, particularly in the region where othersources of water are lacking. To get continuous supply of water and mitigateadverse effects, it is urgent to define definite strategies and guidelines for qualitycontrol, monitoring and management of groundwater. An assessment of groundwa-ter vulnerability is the most feasible step regarding these purposes. The main con-

*Corresponding author. Email: [email protected]

Journal of Risk ResearchVol. 15, No. 8, September 2012, 9911011

ISSN 1366-9877 print/ISSN 1466-4461 online 2012 Taylor & Francishttp://dx.doi.org/10.1080/13669877.2012.686053http://www.tandfonline.com

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cept of groundwater vulnerability assessment is the areas which are more vulnerableto pollution than others (Piscopo 2001). Process-based method, statistical method,and overlay & index methods are generally used to assess groundwater vulnerabilityin many parts of the world. The limitations of process-based method are availabilityof adequate data and quality for the capture of physical, chemical and biologicalreactions which occur from the surface through the groundwater regimes. The statis-tical method includes uncertainty and tries to minimize the error and used parame-ters coefficient instead of weight. The lack of this method is proper monitoringdata. This method is only applicable to those regions where the groundwater con-tamination is governed by similar factors. Overlay & index methods are the mostsuitable method for groundwater vulnerability assessment overcoming all the limita-tions mentioned above. Some common overlay & index methods are DRASTIC,SEEPAGE, SINTACS, GOD, and EPIK, in which the DRASTIC method is themost recognized worldwide for groundwater vulnerability assessment. This methodis based on the assumption that some known major factors control the groundwatervulnerability and that those can be weighted. It is very costly and time consumingto assess groundwater vulnerability for a specific site, whereas DRASTIC method ismore economic and less time consuming to assess a wide range of regional ground-water vulnerability, overcoming sloppy, uncontrolled development of land, andundesirable activities. This method was first developed (Aller et al. 1985) for theUS Environmental Protection Agency. Then the method has been modified by manyresearchers and scientists based on geological or hydrogeological settings, climateconditions, and other special situations. Geographic Information System (GIS) is avery efficient tool for analyzing, interpreting, manipulating and incorporating thegeological, hydrogeological and geomorphological data (Anbazhagan and Nair2004; Jha and Peiffer 2006; Jha et al. 2007).

The present paper reviews the concepts, significance, and applicability of GIS-based DRASTIC method for groundwater vulnerability assessment. It enforces themodification of rating ranges of DRASTIC parameters based on geological, hydro-geological, and climatic conditions in the different parts of the world. However, thispaper emphasizes the calibration systems of DRASTIC method. Above all, theexisting gaps in the current state of knowledge on groundwater vulnerability assess-ment were required to identify for future research.

Conventional DRASTIC method

DRASTIC method generally used seven hydrogeological parameters to assessgroundwater vulnerability. The parameters were considered as depth to groundwatertable (D), net recharge (R), aquifer media (A), soil media (S), topography (T),impact of vadose zone (I) and hydraulic conductivity (C). The input informationsuch as borehole data, meteorological data, hydrological data, geology data, soildata, lithology data, contour map, and topography map were used to develop GISdatabase. The method was used to consider various circumstances such as arid orsemi-arid regions, agricultural, industrial, municipal, coastal, septic tank, and landfillareas. The parameters were rated and weighted due to their relative importance tocontamination. Weighting and rating ranges were considered from 1 to 5 and 1 to10, respectively. A multiplier defined as weight was multiplied with each parameterrating for each interval and then the products were summed up to calculate the finalDRASTIC index. This index indicated the relative degree of groundwater

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vulnerability of an area. Higher index value indicated the greater possibility of con-tamination. Final vulnerability map was generated by integrating all the thematicmaps of DRASTIC parameters through the GIS environment. ArcGIS software wasa powerful tool to generate different thematic maps, GIS database, format conver-sion, overlaying maps, integrating maps, and so on. Some extension tools (spatialanalyst, 3D analyst, and geostatistical analyst) of GIS software were extensivelyused in DRASTIC method. Many researchers and scientists assessed groundwatervulnerability based on the above concept and used the Equation (1) (Kim andHamm 1999; Ibe, Nwankwor, and Onyekuru 2001; Withowski et al. 2003; Tovarand Rodriguez 2004; De Silva and Hohne 2005; Jasrotia and Singh 2005; Shahidand Hazarika 2007; Chitsaz