Evaluation Of Aquifer Vulnerability Research Articles

Protection of groundwater resources from multi-hazards: An integration of risk assessment and watershed management

The improving groundwater resource protection depends on aligning contamination risk mapping with aquifer protection measures. However, existing methods often fail to align with aquifer protection goals, hindering practical implementation. The study demonstrated integrating vulnerability assessment, hazard evaluation, and groundwater protection initiatives using an L-Matrix approach. Testing this model in a well-documented watershed with multiple hazards to illustrates its applicability, providing a reference for similar scenarios. The risk was assessed through evaluation of aquifer vulnerability, using the DRASTIC method, coupled with the evaluation of a hazard potential considering industrial, livestock/agriculture and urban infrastructure sources in separate. The L-Matrix diagrams consisted of cartesian representations of V versus H, ranging from 0 to 1, segmented into four quadrants bounded by the cut-off lines V = 0.5 and H = 0.5. The quadrants were then linked to aquifer protection measures, with site inspection (high V and H), groundwater monitoring (low V and high H), land use planning (high V and low H), and tolerable expansion of hazardous activities (low V and H). The Paraopeba River basin was used as test site. Mining areas are abundant in this basin and were allocated high values of H and low to high values of V, requesting implementation of groundwater monitoring and periodic inspection of mining sites, even more because groundwater contamination with iron could be clearly associated with the presence of mine-tailings. In the results, it was observed that the DRASTIC vulnerability map of the aquifers has a mean vulnerability around the central value (V = 0.48 ± 0.08). Regarding the distribution of hazards, the average rounds to the value for to (Hindustry = 0.41 ± 0.37, Hagriculture = 0.33 ± 0.09 and Hinfrastructure = 0.27 ± 0.14). Thus, it is noted that for industrial activities, the risk of contamination could be moderate to high, while for agricultural and livestock activities, the risk lies between low and moderate contamination impact.

Comparison of GIS-Based Intrinsic Groundwater Vulnerability Assessment Methods: DRASTIC and SINTACS

The possibility of contaminants percolating and diffusing into the groundwater system is referred to as groundwater vulnerability. When groundwater once gets polluted it is very difficult to process/clean it so, measures must be taken to assess the vulnerability of the groundwater for effective groundwater conservation and management planning. This study aims to evaluate and map the vulnerability of Raipur city using the SINTACS and DRASTIC models and to compare their effectiveness between them. To assess the hydrogeological setting and evaluate aquifer vulnerability, each model includes seven environmental parameters (aquifer hydrogeologic features, effective infiltration, topographic slope, soil media, water table depth, unsaturated conditions, and hydraulic conductivity). The parameter data sets are evaluated in a Geographical Information system (GIS) environment to get the vulnerability index (VI), the index is categorized into five classes that show low to high vulnerability. The area under the low class for DRASTIC and SINTACS is 26.14% and 20.34% respectively whereas for the highly vulnerable class it is 15.54% and 22.54% respectively of the total area. By comparing the 15-groundwater sample value of nitrate concentration on the two vulnerability maps it was found that the SINTACS method result was shown to be significantly associated with the nitrate concentration with an accuracy of 86.7 percent.

Vulnerability assessment of an aquifer in the basement complex terrain of Nigeria using ‘LAHBUD’ model

We integrated hydrogeological and hydrogeophysical parameters to evaluate aquifer vulnerability to contamination in a basement complex terrain in Nigeria. Aeromagnetic and Shuttle Radar Topography Mission (SRTM) data were used to generate the composite lineament density map. Lithology information was obtained from the existing geological map, while land-use and land-use changes were derived from the Landsat 8 imagery. We also acquired 216 vertical electrical soundings (VES) to estimate the geoelectric parameters including depth to aquifer, hydraulic conductivity, and bedrock relief maps. The information obtained from geoelectric parameters, lithology, lineament density, and land use were used as the parameters in assessing the aquifer vulnerability using multi-criteria decision analysis (MCDA) in the context of the analytical hierarchy process (AHP). The assigned weights for the various aquifer vulnerability indices are 0.4569, 0.2482, 0.1469, 0.0775, 0.0402 and 0.0303 respectively for lithology (L), depth to aquifer (A), hydraulic conductivity (H), bedrock relief (B), land-use (U) and lineament density (D). These values were normalized and used in establishing a consistency ratio of 6.94%, which is lower than 10% (recommended limit). The MCDA was used to develop the aquifer vulnerability (‘LAHBUD’) model which was used to classify the study area into very low, low, moderate, high, and very high aquifer vulnerability zones. Geochemical parameters obtained from water samples were used to validate the ‘LAHBUD’ model, and gave 81% agreement in predicting the risk level of possible contaminant influence with the conceptual model, and thus confirm the reliability of the model adopted for this study.

Evaluation of aquifer vulnerability using PCA technique and various clustering methods

One of the significant challenges in applying vulnerability methods is their dependence on the same weights and ranks for each parameter. Therefore, to modify these methods, a clustering technique independent of ranks and weights and based only on the nature of data was used in the first step in this study for vulnerability mapping. Moreover, Principal Component Analysis (PCA) was employed to consider all parameters and select the effective ones. After reviewing the literature on different vulnerability assessment methods, 14 parameters involved in determining the vulnerability of the Varamin Aquifer in Iran were selected. The principal component analysis revealed that seven of them were the major ones. In the next step, the vulnerability map of the aquifer was prepared by using the C-Means, the K-Medoids, and the K-Means clustering methods. It was found that the fuzzy C-Means clustering method outperformed others with a CI of 260.

Assessment of aquifer vulnerability for pollution for middle delta in Egypt using Geographic Information System and DRASTIC technique

Egypt is one of the countries suffering from water poverty, so researches must be increased about groundwater as a clean source of water. Aquifer vulnerability has assessed using the DRASTIC method, based on a Geographic Information System (GIS) to evaluate the relative importance of the model parameters for aquifer vulnerability in middle Delta Gharbiya Governorate (Egypt). An additional objective is to demonstrate the combined use of the DRASTIC with GIS system as an effective method for groundwater pollution vulnerability. The DRASTIC model uses seven hydrological factors (Depth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and hydraulic Conductivity) to characterize the hydrogeological setting and evaluate aquifer vulnerability. A DRASTIC vulnerability map, verified by nitrate in groundwater data, shows that the defined areas are compatible with land-use data. It is concluded that these values were reclassified into four classes, low (132–146) 24%, medium (146–159) 30%, high (159–172) 35%, and very high 11%”, of the study area, respectively.

Assessment of Groundwater Pollution Vulnerability Using GIS-Based DRASTIC Model and its Validation Using Nitrate Concentration in Tandula Watershed, Chhattisgarh

ABSTRACT Effective management of groundwater resources has now become a global issue and on the other hand industrialization, deforestation and agricultural activities are potential sources of groundwater pollution. Groundwater vulnerability index assessment is an effective tool for groundwater management. In this study DRASTIC model was utilized to evaluate aquifer vulnerability of Tandula watershed, Chhattisgarh, India. Aquifer vulnerability of the study area classified into five categories such as very low (18.68%), low (23.84%), moderate (16.42%), high (23.72%) and very high (17.34%) vulnerability. To validate the DRASTIC model, nitrate concentration was selected and found that it is 82.35% accurate which reflects that, DRASTIC model is appropriate to understand groundwater pollution risk assessment. In the study area groundwater is contaminated mainly due to extensive use of fertilizer for agriculture purpose. Present study will be helpful in proper management and development of available groundwater resource in the study area.

Groundwater Vulnerability Assessment of the Tarkwa Mining Area Using SINTACS Approach and GIS

Groundwater vulnerability assessment to delineate areas that are susceptible to contamination from mining and anthropogenic activities has become an important element for resource management and landuse planning. In view of the extensive mining in the Tarkwa area, quality of groundwater has become an important issue. This study estimates aquifer vulnerability by applying the SINTACS model which uses seven environmental parameters to evaluate aquifer vulnerability and geographical information system (GIS) in the Tarkwa mining area. Sensitivity analysis has also been carried out to evaluate the relative importance of the model parameters for aquifer vulnerability. The SINTACS model results show that the intrusive rocks within the Tarkwaian and the Birimian rocks are dominated by very high vulnerability classes while the Banket Series is characterised by high vulnerability class. The Huni Sandstones have moderately high vulnerability. In addition, the Kawere Group and the Tarkwa Phyllites displayed medium vulnerability. Analysis from the variogram model shows that all parameters used in the SINTACS model have a strong spatial structure. From statistical analysis, depth to water parameter inflicted the highest impact on the vulnerability of the aquifer followed by effective infiltration, vadose zone media, soil media, aquifer media, topography and hydraulic conductivity in the order of decreasing impact. Sensitivity analysis indicated that the aquifer media, hydraulic characteristics and topography cause large variation in vulnerability index. Depth to water and effective infiltration were found to be more effective in assessing aquifer vulnerability. Keywords: Groundwater, Vulnerability, Tarkwa, SINTACS, GIS

Evaluation of Aquifer Vulnerability by GIS Application: Case study from Asadabad, Hamadan (Western Iran)

Evaluation of Aquifer Vulnerability by GIS Application: Case study from Asadabad, Hamadan (Western Iran)

Evaluation of aquifer vulnerability in a coal mining of India by using GIS-based DRASTIC model

The objective of this study is to estimate the aquifer vulnerability in the West Bokaro coalfield, Jharkhand, India, by using a geographic information system (GIS)-based DRASTIC model. The DRASTIC model incorporates seven hydrogeological data, i.e. depth of water table, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity. The model was validated by comparing the model output (vulnerability index map) with a statistical analysis and the actual SO4 2− and Fe concentrations in the groundwater of the study area. Thirty-three well samples were collected from the West Bokaro coalfield area. These were analyzed in the laboratory to measure the level of SO4 2− and Fe in the groundwater. The GIS-based DRASTIC result showed that 0.06 % of the area fell into the low-vulnerability zone and 10.8 % fell into the moderate vulnerability zone. About 87.7 % of the study area fell into the moderate to high-vulnerability zone, and 1.4 % of the study area was classified as the highly vulnerable zone. From the vulnerability map, it was observed that some of the western part and some of the middle part of the study area lay in the high-vulnerability zone, and therefore, they were more susceptible to aquifer pollution. The geogenic and anthropogenic activities are responsible for the high vulnerability in the study area. The shallow water level, topography, high net recharge and permeable vadose zone of the area served as the major influential parameters in mapping the vulnerability. The mining and related activities are also responsible for the high aquifer vulnerability of the area. The aquifer vulnerability maps generated in this study could also be used for the management of future water resources and environmental planning in all the mining regions.

Assessing groundwater vulnerability to contamination in an arid environment using DRASTIC and GOD models

Groundwater is vulnerable to contamination by anthropological activities. Vulnerability mapping is considered as a fundamental aspect of groundwater management. The aim of this study was to estimate aquifer vulnerability by applying the DRASTIC and GOD models in Abarkooh plain, Yazd province, center of Iran. 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. GOD is an overlay and index method designed to map groundwater vulnerability over large regions based on three parameters (groundwater confinement, overlying strata, and depth to groundwater). The information layers for models were provided via geographic information system. The overlap techniques were used to provide and produce the vulnerability map of the study areas considering weight coefficients of each layer. Accuracy of the models was evaluated using linear regression between observations values of nitrate and estimated vulnerability to pollution in the measured wells. A significant correlation was observed between measured nitrate and pollution potential evaluated by DRASTIC model (P < 0.01), but no significant correlation was observed for GOD model (P < 0.05). The results showed that the DRASTIC model is better than GOD model to estimate groundwater vulnerability to pollution in the measured wells. For DRASTIC model, the correlation coefficient between vulnerability index and nitrate concentration was 68 % that was substantially higher than 28 % obtained for the GOD model. We can conclude that nitrate concentration should be a suitable parameter to investigate the accuracy of the DRASTIC and GOD models.

Integrating indicator-based geostatistical estimation and aquifer vulnerability of nitrate-N for establishing groundwater protection zones

Summary Groundwater nitrate-N contamination occurs frequently in agricultural regions, primarily resulting from surface agricultural activities. The focus of this study is to establish groundwater protection zones based on indicator-based geostatistical estimation and aquifer vulnerability of nitrate-N in the Choushui River alluvial fan in Taiwan. The groundwater protection zones are determined by univariate indicator kriging (IK) estimation, aquifer vulnerability assessment using logistic regression (LR), and integration of the IK estimation and aquifer vulnerability using simple IK with local prior means (sIKlpm). First, according to the statistical significance of source, transport, and attenuation factors dominating the occurrence of nitrate-N pollution, a LR model was adopted to evaluate aquifer vulnerability and to characterize occurrence probability of nitrate-N exceeding 0.5 mg/L. Moreover, the probabilities estimated using LR were regarded as local prior means. IK was then used to estimate the actual extent of nitrate-N pollution. The integration of the IK estimation and aquifer vulnerability was obtained using sIKlpm. Finally, groundwater protection zones were probabilistically determined using the three aforementioned methods, and the estimated accuracy of the delineated groundwater protection zones was gauged using a cross-validation procedure based on observed nitrate-N data. The results reveal that the integration of the IK estimation and aquifer vulnerability using sIKlpm is more robust than univariate IK estimation and aquifer vulnerability assessment using LR for establishing groundwater protection zones. Rigorous management practices for fertilizer use should be implemented in orchards situated in the determined groundwater protection zones.

Groundwater vulnerability assessment using SINTACS model

Groundwater has been treated as an important source of water supply due to its relatively low vulnerability to pollution in comparison to surface water, and its huge storage capacity. Because of the known health and economic impacts associated with groundwater contamination, steps to measure the vulnerability of groundwater must be taken for sustainable groundwater protection and management planning. Susceptibility of groundwater refers to the intrinsic characteristics that determine the sensitivity of the water to being adversely affected by an imposed contaminant load. The SINTACS model is the most extensively used method for identifying the areas where groundwater supplies are most vulnerable to contamination. The SINTACS model uses seven environmental parameters (water table depth, effective infiltration, unsaturated conditions, soil media, aquifer hydrogeologic characteristics, hydraulic conductivity and topographic slope) to characterize the hydrogeological setting and evaluate aquifer vulnerability. In this paper, the SINTACS model is applied for a part of Kancheepuram district, Tamil Nadu, India to generate a small-scale map of groundwater vulnerability to contamination. The whole area is classified as very low, low, moderate and high susceptibility to pollution. The model is validated with ground water quality data and results have shown strong relationship between SINTACS specific vulnerability index and nitrate-as-nitrogen concentrations. The ground water vulnerability map is developed by using the SINTACS model in a computer-based geographic information system (GIS).

An evaluation of aquifer vulnerability in two nitrate sensitive areas of Catalonia (NE Spain) based on electrical resistivity methods

The protection of groundwater has become one of the most important European environmental policies as evidenced by the Orders relating to the protection of water from contamination, Directive 2000/60/CE of the European Parliament and the European Union Council, and more concretely Directive 2006/118/118/CE, related to the protection of groundwater from pollution and degradation. Traditional methods for assessing vulnerability include soil surveys, drilling and analysis of lithology logs from wells with the objective of characterising the thickness, hydraulic properties and lateral extend of the protective layers. However, such studies can be labour-intensive and expensive. In addition, the parameters measured may have high spatial variability, which makes accurate characterization over large areas difficult. Fortunately, a numerical index of protection can be assigned from the longitudinal electrical conductance parameter derived from electrical resistivity surveys (VES, ERT or any other electrical or EM method). This can be more accurate and reliable than any other vulnerability index derived only from visual inspection or interpolated from sparse borehole data.

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.

Assessment of Aquifer Vulnerability Based on GIS and ARCGIS Methods: A Case Study of the Sana’a Basin (Yemen)

Groundwater is the main source of water in arid and semi-arid regions. Therefore, pollution of groundwater is a major issue because aquifers and the contained groundwater are inherently susceptible to contamination from wastewater and agricultural activities. Aquifer vulnerability has been assessed in the Sana’a basin using the DRASTIC method, based on a Geographic Information System (GIS). 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. A regional scale aquifer vulnerability map of the basin was prepared using overlay analysis with the aid of GIS. A DRASTIC vulnerability map, verified by data of nitrate in groundwater, shows that the defined areas are compatible with land-use data. It is concluded that 6.4% of the basin area is highly vulnerable and urgent pollution-preventions measures should be taken for every kind of relevant activity within the whole basin.

Groundwater vulnerability assessment for the Banyas Catchment of the Syrian coastal area using GIS and the RISKE method

Vulnerability assessment to delineate areas that are more susceptible to contamination from anthropogenic sources has become an important element for sensible resource management and landuse planning. This contribution aims at estimating aquifer vulnerability by applying the RISKE model in Banyas Catchment Area (BCA), Tartous Prefecture, west Syria. An additional objective is to demonstrate the combined use of the RISKE model and a geographical information system (GIS) as an effective method for groundwater pollution risk assessment. The RISKE model uses five environmental parameters (Rock of aquifer media, Infiltration, Soil media, Karst, and Epikarst) to characterize the hydro-geological setting and evaluate aquifer vulnerability. The elevated eastern and low western part of the study area was dominated by high vulnerability classes, while the middle part was characterized by moderate vulnerability classes. Based on the vulnerability analysis, it was found that 2% and 39% of BCA is under low and high vulnerability to groundwater contamination, respectively, while more than 52% and 5% of the area of BCA can be designated as an area of moderate and very high vulnerability to groundwater contamination, respectively. The GIS technique has provided an efficient environment for analyses and high capabilities of handling a large amount of spatial data.

Evaluation of aquifer vulnerability and the protective capacity in some oil producing communities of western Niger Delta

Oil spills have become a major environmental hazard constituting serious social problems in Nigeria, especially in the oil producing communities. The spills contaminate the aquifer if the subsurface layers are not protected. Geoelectric technique of geophysical investigation has been used to evaluate the protective capacity of six oil producing communities: Oleh, Olomoro, Uzere, Afiesere, Ekakpamre and Uvwiamuge in the western Niger Delta. A total of 139 vertical electrical sounding (VES) using the Schlumberger electrode configuration were occupied in these communities. The longitudinal conductance maps delineated areas with poor (<0.1 mho), weak (0.1–0.19 mho), moderate (0.2–0.69 mho) and good protective capacity (0.7–4.9 mho). The study has shown that the protective capacity of most parts of the communities studied is poor with Uvwiamuge and Ekakpamre communities not protected hence the aquifer in these oil producing communities are vulnerable to contamination by hydrocarbon in the event of pollution. Hence proper environmental protection measures have been suggested to safeguard the aquifer from pollution by hydrocarbon in the event of spillage.

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 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.

Characterization of maximum infiltration areas using GIS tools

The main goals of this study are the identification of maximum infiltration areas and the evaluation of aquifer vulnerability in order to delineate a protection strategy for municipal water supplies. A two-step methodology is implemented in Geographic Information System (GIS): (i) in the first step, hydrogeological parameters are classified by grades of infiltration and combined to delimit the most favourable aquifer recharge areas; (ii) in the second step, infiltration potential map obtained in previous step are merged with the hydrostatic water level depth layer and a final map indicator of aquifer vulnerability to potential contamination is presented. This methodology was implemented in ArcGis 8.2 software and applied to Seixal Municipality, an urban/industrial area near the capital of Portugal, Lisbon, where negative impact on groundwater resources is a major concern.

A GIS-based DRASTIC model for assessing aquifer vulnerability in Kakamigahara Heights, Gifu Prefecture, central Japan

Vulnerability assessment to delineate areas that are more susceptible to contamination from anthropogenic sources has become an important element for sensible resource management and land use planning. This contribution aims at estimating aquifer vulnerability by applying the DRASTIC model as well as utilizing sensitivity analyses to evaluate the relative importance of the model parameters for aquifer vulnerability in Kakamigahara Heights, Gifu Prefecture central Japan. An additional objective is to demonstrate the combined use of the DRASTIC and geographical information system (GIS) as an effective method for groundwater pollution risk assessment. 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. The western part of the Kakamigahara aquifer was dominated by “High” vulnerability classes while the eastern part was characterized by “Moderate” vulnerability classes. The elevated north-eastern part of the study area displayed “Low” aquifer vulnerability. The integrated vulnerability map shows the high risk imposed on the eastern part of the Kakamigahara aquifer due to the high pollution potential of intensive vegetable cultivation. The more vulnerable western part of the aquifer is, however, under a lower contamination risk. In Kakamigahara Heights, land use seems to be a better predictor of groundwater contamination by nitrate. Net recharge parameter inflicted the largest impact on the intrinsic vulnerability of the aquifer followed by soil media, topography, vadose zone media, and hydraulic conductivity. Sensitivity analyses indicated that the removal of net recharge, soil media and topography causes large variation in vulnerability index. Moreover, net recharge and hydraulic conductivity were found to be more effective in assessing aquifer vulnerability than assumed by the DRASTIC model. The GIS technique has provided efficient environment for analyses and high capabilities of handling large spatial data.