Assessment of groundwater vulnerability in Mettur region, Tamilnadu, India using drastic and GIS techniques

A study was carried in Mettur taluk, Salem district of Tamilnadu, India to develop a DRASTIC vulnerability index in GIS environment owing to groundwater pollution with increasing population, industries, and agricultural activities. Seven DRASTIC layers were created from available data (depth to water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity) and incorporated into DRASTIC model to create a groundwater vulnerability map by overlaying the hydrogeological parameters. The output map indicates southwestern part of the study area with high pollution potential, northern and northwestern parts as moderate pollution potential and northeastern parts as low and no risk of pollution potential. For validating the vulnerability assessment, a total of 46 groundwater samples were collected from different vulnerability zones of the study area for two different seasons (pre- and post-monsoon) and analyzed for major anions and cations. Higher ionic concentrations were noted in wells located near highly industrialized, urbanized, and agricultural active zones. The water types represent Na–Mg–HCO₃ and Na–Cl–HCO₃ type indicating dominance of anthropogenic-related activities. Nitrate and chloride were demarcated as pollution indicators and correlated with DRASTIC vulnerability map. The results show that southwestern, northwestern, and northern parts of the study area recorded with high and moderate vulnerable zones, record higher nitrate values. In contrast to DRASTIC method predicted, low vulnerable zones show higher chloride concentration may be due to agricultural and urban development.     

Assessment of Groundwater Vulnerability in Upper Betwa River Watershed using GIS based DRASTIC Model

Groundwater, the most vital water resource being used for irrigation, domestic and industrial purposes is nowadays under severe threat of contamination. Groundwater contamination risk assessment is an effective tool for groundwater management. In the study, a DRASTIC model which is based on the seven hydrogeological parameters viz: depth of water, net-recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity was used to evaluate the groundwater pollution potentiality of upper Betwa watershed. ArcGIS was used to create the ground water vulnerability map by overlaying the seven layers. Based on groundwater vulnerability map, the watershed has been divided in three vulnerable zones viz; low vulnerability zone with 42.83 km² of area, moderate with 369.21 km² area and high having 270.96 km² of area. Furthermore, the DRASTIC model has been validated by nitrate concentration over the area. Results of validation have shown that in low vulnerable zone, no nitrate contamination has been recorded. While in the moderate zone nitrate has been found in the range of 1.6-10ppm. However, in high vulnerable zone 11-40ppm of nitrate concentration in groundwater has been recorded, which proves that the DRASTIC model is applicable for the prediction of groundwater vulnerability in the watershed and in similar areas too.     

Groundwater vulnerability assessment in the Melaka State of Malaysia using DRASTIC and GIS techniques

The present work attempts to interpret the groundwater vulnerability of the Melaka State in peninsular Malaysia. The state of groundwater pollution in Melaka is a critical issue particularly in respect of the increasing population, and tourism industry as well as the agricultural, industrial and commercial development. Focusing on this issue, the study illustrates the groundwater vulnerability map for the Melaka State using the DRASTIC model together with remote sensing and geographic information system (GIS). The data which correspond to the seven parameters of the model were collected and converted into thematic maps by GIS. Seven thematic maps defining the depth to water level, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity were generated to develop the DRASTIC map. In addition, this map was integrated with a land use map for generating the risk map to assess the effect of land use activities on the groundwater vulnerability. Three types of vulnerability zones were assigned for both DRASTIC map and risk map, namely, high, moderate and low. The DRASTIC map illustrates that an area of 11.02 % is low vulnerability, 61.53 % moderate vulnerability and 23.45 % high vulnerability, whereas the risk map indicates that 14.40 % of the area is low vulnerability, 47.34 % moderate vulnerability and 38.26 % high vulnerability in the study area. The most vulnerability area exists around Melaka, Jasin and Alor Gajah cities of the Melaka State.     

Comparison of DRASTIC and DC resistivity modeling for assessing aquifer vulnerability in the central Nile Delta,Egypt

DRASTIC indexing and integrated electrical conductivity (IEC) modeling are approaches for assessing aquifer vulnerability to surface pollution. DRASTIC indexing is more common, but IEC modeling is faster and more cost-effective because it requires less data and fewer processing steps. This study aimed to compare DRASTIC indexing with IEC modeling to determine whether the latter is sufficient on its own. Both approaches are utilized to determine zones vulnerable to groundwater pollution in the Nile Delta. Hence, assessing the nature and degree of risk are important for realizing effective measures toward damage minimization. For DRASTIC indexing, hydrogeological factors such as depth to aquifer, recharge rate, aquifer media, soil permeability, topography, impact of the vadose zone, and hydraulic conductivity were combined in a geographical information system environment for assessing the aquifer vulnerability. For IEC modeling, DC resistivity data were collected from 36 surface sounding points to cover the entire area and used to estimate the IEC index. Additionally, the vulnerable zones identified by both approaches were tested using a local-scale resistivity survey in the form of 1D and 2D resistivity imaging to determine the permeable pathways in the vadose zone. A correlation of 0.82 was obtained between the DRASTIC indexing and IEC modeling results. For additional benefit, the obtained DRASTIC and IEC models were used together to develop a vulnerability map. This map showed a very high vulnerability zone, a high-vulnerability zone, and moderate- and low-vulnerability zones constituting 19.89, 41, 27, and 12%, respectively, of the study area. Identifying where groundwater is more vulnerable to pollution enables more effective protection and management of groundwater resources in vulnerable areas.     

Groundwater vulnerability and risk mapping of the Angad transboundary aquifer using DRASTIC index method in GIS environment

The protection and preservation of groundwater resources are compulsory, particularly in the arid and semiarid countries where the waters are scarce. The effects of increasing urbanization, economic development, and agricultural activities, along with the erratic and scarce rainfall, contribute to the quantitative and qualitative deterioration of these resources. This paper attempts to produce groundwater vulnerability and risk maps for the Angad transboundary aquifer using DRASTIC model. The data which correspond to the seven parameters of the model were collected and converted to thematic maps in Geographic Information System environment. The modified DRASTIC map, which is the summation of the DRASTIC index and the network fractures maps, shows two degreed of vulnerability: medium and high. This map is then integrated with a land use map to assess the potential risk of groundwater to pollution in the Angad transboundary aquifer. There are three risk zones that are identified: moderate, high, and very high.     

GIS-based DRASTIC, Pesticide DRASTIC and the Susceptibility Index (SI): comparative study for evaluation of pollution potential in the Nabeul-Hammamet shallow aquifer, Tunisia

Three vulnerability index models were applied to assess the pollution potential of Nabeul-Hammamet shallow aquifer, Tunisia: DRASTIC, Pesticide DRASTIC and the Susceptibility Index (SI). An output map layer of each one was obtained using a geographic information system (GIS). The SI layer was overlain with DRASTIC and Pesticide DRASTIC and the percentage areas of agreement and divergence in vulnerability categories were extracted. DRASTIC results suggest the aquifer has mostly low vulnerability. Pesticide DRASTIC and SI identify three vulnerability categories (low, moderate, high) in the aquifer. Published data on current chemical groundwater composition indicate that parts of the aquifer are highly contaminated, revealing that DRASTIC underestimates the risk of pollution; Pesticide DRASTIC and SI reflect this risk better. Agreement in vulnerability categories between the two last models is found for 64 % of the aquifer area. To help manage land-use allocation and prevent Nabeul-Hammamet-aquifer contamination, DRASTIC is not recommended. Pesticide DRASTIC and SI are recommended but for slightly different applications. SI helps in the monitoring of current vulnerable areas and, thus, in contamination prevention. Pesticide DRASTIC could better intervene as a criterion in a multi-criteria analysis to select the best sites for specific on-the-ground practice or future land use.     

Modelling the vulnerability of groundwater to contamination in an unconfined alluvial aquifer in Pakistan

The area of Thal Doab is located in the Indus Basin and is underlain by a thick alluvial aquifer called the Thal Doab aquifer (TDA). The TDA is undergone intense hydrological stress owing to rapid population growth and excessive groundwater use for livestock and irrigated agricultural land uses. The potential impact of these land uses on groundwater quality was assessed using a DRASTIC model in a Geographic Information System environment. Seven DRASTIC thematic maps were developed at fixed scale and then combined into a groundwater vulnerability map. The resultant vulnerability index values were grouped into four zones as low, moderate, high and very high. The study has established that 76% of the land area that is underlain by the TDA has a high to very high vulnerability to groundwater contamination mainly because of a thin soil profile, a shallow water table and the presence of soils and sediments with high hydraulic conductivity values. In addition, only 2 and 22% of the total area lie in low and moderate vulnerability zones, respectively. The outcomes of this study can be used to improve the sustainability of the groundwater resource through proper land-use management.     

Combining AHP and genetic algorithms approaches to modify DRASTIC model to assess groundwater vulnerability: a case study from Jianghan Plain,China

Accurate identification of vulnerability areas is critical for groundwater resources protection and management. The present study employed the modified DRASTIC model to assess the groundwater vulnerability of Jianghan Plain, a major farming area in central China. DRASTICL model was developed by incorporating the land use factor to the original model. The ratings and weightings of the selected parameters were optimized by analytic hierarchy process (AHP) method and genetic algorithms (GAs) method, respectively. A combined AHP–GAs method was proposed to further develop this methodology. The unity-based normalization process was employed to categorize the vulnerability maps into four types, such as very high (>0.75), high (0.5–0.75), low (0.25–0.5), and very low (<0.25). The accuracy of vulnerability mapping was validated by Pearson’s correlation coefficient between vulnerability index and the nitrate concentration in groundwater and analysis of variance F statistic. The results revealed that the modified DRASTIC model had a large improvement over the conventional model. The correlation coefficient increased significantly from 41.07 to 75.31% after modification. Sensitivity analysis indicated that the depth to groundwater with 39.28% of mean effective weight was the most critical factor affecting the groundwater vulnerability. The developed vulnerability model proposed in this study could provide important objective information for groundwater and environmental management at local level and innovation for international researchers.     

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.     

Intrinsic and specific vulnerability of groundwater in central Spain: the risk of nitrate pollution

The intrinsic vulnerability of groundwater in the Comunidad de Madrid (central Spain) was evaluated using the DRASTIC and GOD indexes. Groundwater vulnerability to nitrate pollution was also assessed using the composite DRASTIC (CD) and nitrate vulnerability (NV) indexes. The utility of these methods was tested by analyzing the spatial distribution of nitrate concentrations in the different aquifers located in the study area: the Tertiary Detrital Aquifer, the Moor Limestone Aquifer, the Cretaceous Limestone Aquifer and the Quaternary Aquifer. Vulnerability maps based on these four indexes showed very similar results, identifying the Quaternary Aquifer and the lower sub-unit of the Moor Limestone Aquifer as deposits subjected to a high risk of nitrate pollution due to intensive agriculture. As far as the spatial distribution of groundwater nitrate concentrations is concerned, the NV index showed the greatest statistical significance (p?<?0.01). This new type of multiplicative model offers greater accuracy in estimations of specific vulnerability with respect to the real impact of each type of land use. The results of this study provide a basis on which to guide the designation of nitrate vulnerable zones in the Comunidad de Madrid, in line with European Union Directive 91/676/EEC.     

Evaluation of aquifers vulnerability to contamination in the Yarmouk River basin, Jordan, based on DRASTIC method

The existing different human activities and planned land uses put the groundwater resources in Jordan at considerable risk. There are evidences suggesting that the quality of groundwater supplies in north Jordan is under threat from a wide variety of point and non-point sources including agricultural, domestic, and industrial. Vulnerability maps are designed to show areas of greatest potential for groundwater contamination on the basis of hydrogeological conditions and human impacts. DRASTIC method incorporates the major geological and hydrogeological factors that affect and control groundwater movement: depth to groundwater (D), net recharge (R), lithology of the aquifer (A), soil texture (S), topography (T), lithology of vadose zone (I), and hydraulic conductivity (C). The main goal of this study is to produce vulnerability maps of groundwater resources in the Yarmouk River basin by applying the DRASTIC method to determine areas where groundwater protection or monitoring is critical. ArcGIS 9.2 was used to create the groundwater vulnerability maps by overlaying the available hydrogeological data. The resulting vulnerability maps were then integrated with lineament and land use maps as additional parameters in the DRASTIC model to assess more accurately the potential risk of groundwater to pollution. The general DRASTIC index indicates that the potential for polluting groundwater is low in the whole basin, whereas the resulting pesticide DRASTIC vulnerability map indicates that about 31% of the basin is classified as having moderate vulnerability, which may be attributed to agricultural activities in the area. Although high nitrate concentrations were found in areas of moderate vulnerability, DRASTIC method did not depict accurately the nitrate distribution in the area.     

Assessment of groundwater vulnerability to pollution in Dire Dawa,Ethiopia using DRASTIC

Assessment of groundwater vulnerability to pollution is an effective tool for the delineation of groundwater protection zones. DRASTIC approach was used to determine vulnerability zones in Dire Dawa groundwater basin, a semiarid region of Ethiopia. Maps of the seven DRASTIC parameters were prepared. GIS-ArcView was used for mapping and performing weighted-overlay analysis. The result of the analysis indicated that eastern part of the study area, in which Dire Dawa town is located, is highly vulnerable. A low aquifer vulnerability class was determined for the western portion of the study area as a result of greater groundwater depths, higher relative soil-clay content, and relatively low recharge rates for this area. The area between the two zones is of medium vulnerability. Observed nitrate concentrations in boreholes are in accordance with the vulnerability map. Some of the boreholes in the Sabian well field (Dire Dawa area) already deliver groundwater with nitrate levels significantly exceeding health standards set by the World Health Organization, while boreholes in the western part (low vulnerability zone) contain almost no nitrate. The result of this study is useful for risk assessments and for the development of effective groundwater management strategies for this region and others like it.     

Groundwater pollution risk mapping for the Eocene aquifer of the Oum Er-Rabia basin, Morocco

Sustainable development requires the management and preservation of water resources indispensable for all human activities. When groundwater constitutes the main water resource, vulnerability maps therefore are an important tool for identifying zones of high pollution risk and taking preventive measures in potential pollution sites. The vulnerability assessment for the Eocene aquifer in the Moroccan basin of Oum Er-Rabia is based on the DRASTIC method that uses seven parameters summarizing climatic, geological, and hydrogeological conditions controlling the seepage of pollutant substances to groundwater. Vulnerability maps were produced by using GIS techniques and applying the “generic” and “agricultural” models according to the DRASTIC charter. Resulting maps revealed that the aquifer is highly vulnerable in the western part of the basin and areas being under high contamination risk are more extensive when the “agricultural” model was applied.     

An extension to the DRASTIC model to assess groundwater vulnerability to pollution: application to the Haouz aquifer of Marrakech (Morocco)

An extension to the DRASTIC model is proposed in order to assess aquifer vulnerability to pollution. In contrast to the DRASTIC model, which considers the unsaturated and saturated zones together and computes a global intrinsic vulnerability index, the suggested approach discriminates between the aquifer vertical vulnerability (a concept related to the pollutant percolation) and the groundwater susceptibility (a concept that depends on the behaviour and uses of the groundwater). This approach is applied to the Haouz aquifer (Morocco) that supplies water to the Marrakech area. This aquifer is widely overexploited and there is evidence that the groundwater quality is threatened by various sources of pollution. Evaluation of the vertical vulnerability indicates that the aquifer mainly presents a moderate-to-weak vertical vulnerability. The zones potentially most favourable to pollutant percolation are mainly located in Central Haouz, along or near the surface wadis. The aquifer susceptibility is high in places located near the N’Fis, Baaja and Issil wadis. Everywhere else, low-to-moderate susceptibility is observed. This new approach therefore enables areas of vertical vulnerability and areas of susceptibility to be delineated separately. As a result, it constitutes a valuable decision-making tool for optimising the management of aquifer water resources and land-use planning.     

Aquifer vulnerability assessment using the DRASTIC model at Russeifa landfill,northeast Jordan

Groundwater is inherently susceptible to contamination from anthropogenic activities and remediation is very difficult and expensive. Prevention of contamination is hence critical in effective groundwater management. In this paper an attempt has been made to assess aquifer vulnerability at the Russeifa solid waste landfill. This disposal site is placed at the most important aquifer in Jordan, which is known as Amman-Wadi Sir (B2/A7). The daily-generated leachate within the landfill is about 160 m³/day and there is no system for collecting and treating this leachate. Therefore, the leachate infiltrates to groundwater and degrades the quality of the groundwater. The area is strongly vulnerable to pollution due to the presence of intensive agricultural activity, the solid waste disposal site and industries. Increasing groundwater demand makes the protection of the aquifer from pollution crucial. Physical and hydrogeological characteristics make the aquifer susceptible to pollution. The vulnerability of groundwater to contamination in the study area was quantified using the DRASTIC model. The DRASTIC model uses the following seven parameters: depth to water, recharge, aquifer media, soil media, topography, impact on vadose zone and hydraulic conductivity. The water level data were measured in the observation wells within the disposal site. The recharge is derived based on precipitation, land use and soil characteristics. The aquifer media was obtained from a geological map of the area. The topography is obtained from the Natural Resources Authority of Jordan, 1:50,000 scale topographic map. The impact on the vadose zone is defined by the soil permeability and depth to water. The hydraulic conductivity was obtained from the field pumping tests. The calculated DRASTIC index number indicates a moderate pollution potential for the study area.     

A GIS-based DRASTIC model for assessing shallow groundwater vulnerability in the Zhangye Basin,northwestern China

Groundwater vulnerability is a cornerstone in evaluating the risk of groundwater contamination and developing management options to preserve the quality of groundwater. Based on the professional model (DRASTIC model) and geographical information system (GIS) techniques, this paper carries out the shallow groundwater vulnerability assessment in the Zhangye Basin. The DRASTIC model uses seven environmental parameters (depth to water, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity) to characterize the hydrogeological setting and evaluate aquifer vulnerability. According to the results of the shallow groundwater vulnerability assessment, the Zhangye Basin can be divided into three zones: low groundwater vulnerability risk zone (risk index <120); middle groundwater vulnerability risk zone (risk indexes 120–140) and high risk zone (risk index >140). Under the natural conditions, the middle and high groundwater vulnerability risk zones of the Zhangye Basin are mainly located in the groundwater recharge zones and the important cities. The high, middle and low groundwater vulnerability risk zones of the Zhangye Basin cover around 17, 21 and 62% of study area, respectively.     

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.     

Development of a GIS-based catastrophe theory model (modified DRASTIC model) for groundwater vulnerability assessment

This study developed a new paradigm for groundwater vulnerability assessment by modifying the standard DRASTIC index (DI) model based on catastrophe theory. The developed paradigm was called the catastrophe theory-based DI (CDI) model. The proposed model was applied to assess groundwater vulnerability to pollution index (GVPI) in Perak Province, Malaysia. The area vulnerability index was modeled by considering the DRASTIC multiple vulnerability causative factors (VCFs) obtained from different data sources. The weights and ranking of the VCFs were computed by using the inner fuzzy membership mechanism of the CDI model. The estimated vulnerability index values of the CDI model were processed in a geographic information system (GIS) environment to produce a catastrophe theory–DRASTIC groundwater vulnerability to pollution index (CDGVPI) map, which demarcated the area into five vulnerability zones. The produced CDGVPI map was validated by applying the water quality status–vulnerability zone relationship (WVR) approach and the relative operating characteristic (ROC) curve method. The performance of the developed CDI model was compared with that of the standard DI model. The validation results of the WVR approach exhibits 89.29% prediction accuracy for the CDI model compared with 75% for the DI model. Meanwhile, the ROC validation results for the CDI and DI models are 88.8% and 78%, respectively. The GIS-based CDI model demonstrated better performance than the DI model. The GVPI maps produced in this study can be used for precise decision making process in environmental planning and groundwater management.     

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。     

Groundwater vulnerability and risk mapping of the Hajeb-jelma aquifer (Central Tunisia) using a GIS-based DRASTIC model

The aim of this study is to elaborate a synthetic document for the assessment of groundwater vulnerability to pollution in the Hajeb-Jelma aquifer. The specific object is to incorporate the Geographical Information System (GIS) to generate groundwater vulnerability and risk maps with DRASTIC model. Indeed, GIS could help to make the results of a complicated model more clear through visual representation, providing an applicable tool for decision makers. The vulnerability map of Hajeb-Jelma watershed shows three classes: moderate, high and very high depending on the intrinsic properties. The risk map shows a very high risk dependant on hydrogeological characteristics, land use and human impacts in major part of the Hajeb-Jelma region. These maps could serve as a scientific basis for sustainable land use planning and groundwater management in the Hajeb-Jelma region.