Groundwater vulnerability assessment using a GIS-based DRASTIC method in the Erbil Dumpsite area (Kani Qirzhala), Central Erbil Basin, North Iraq

Groundwater vulnerability assessment is a crucial step in the efficient management of groundwater resources,especially in areas with intensive anthropogenic activities and groundwater pollution.In the present study,the DRASTIC method was applied using Geographic Information System(GIS)to delineate groundwater vulnerability zones in the Erbil Dumpsite area,Central Erbil Basin,North Iraq.Results showed that the area was classified into four vulnerability classes:Very low(16.97%),low(27.67%),moderate(36.55%)and high(18.81%).The southern,south-eastern and northern parts of the study area exhibited the highest vulnerability potential,while the central-northern,northern and north-western regions displayed the lowest vulnerability potential.Moreover,results of the single-parameter sensitivity analysis indicated that amongst the seven DRASTIC parameters,the unsaturated zone and the aquifer media were the most influencing parameters.In conclustion,the correlation of 25 nitrate concentration values with the final vulnerability map,assessed using the Pearson correlation coefficient,yielded a satisfactory result of R=0.72.

Fuzzy pattern recognition method for assessing groundwater vulnerability to pollution in the Zhangji area

Based on the widely used DRASTIC method, a fuzzy pattern recognition and optimization method was proposed and applied to the fissured-karstic aquifer of Zhangji area for assessing groundwater vulnerability to pollution. The result is compared with DRASTIC method. It is shown that by taking the fuzziness into consideration, the fuzzy pattern recognition and optimization method reflects more efficiently the fuzzy nature of the groundwater vulnerability to pollution and is more applicable in reality.

Entropy weight coefficient model and its application in evaluation of groundwater vulnerability of the Sanjiang Plain

The research of groundwater vulnerability is the basic work to protect the groundwater. For utilizing groundwater resource continuably, groundwater vulnerability evaluation is necessary. Useful reference to protect, exploit and utilize on groundwater resource are provided rationally. According to the real condition of Sanjiang Plain, the indexes system is established based on the traditional DRASTIC model. The new system includes the following seven indexes： Depth of Water, Net Recharge, Aquifer Media, Soil Media, Conductivity of the Aquifer, Land Utilizing Ratio and Populace Density. The related analysis appears that the system is rather reasonable. Because traditional methods, such as analytic hierarchy process and fuzzy mathematics theory, can＇t be avoided human interference in selection of weights, they could lead to an imprecise result. In order to evaluate the groundwater vulnerability reasonably, entropy weight coefficient method is applied for the first time, which provides a new way to groundwater vulnerability evaluation. The method is a model whose weights are insured by the calculation process, so the artificial disturb can be avoided. It has been used to evaluate the groundwater vulnerability in Sanjiang Plain. The satisfied result is acquired. Comparably, the same result is acquired by the other method named projection pursuit evaluation based on real-coded accelerating genetic algorithm. It shows that entropy weight coefficient method is applicable on groundwater vulnerability evaluation. The evaluation result can provide reference on the decision-making departments.

Assessment of shallow groundwater vulnerability in Dahei River Plain based on AHP and DRASTIC

Based on the special hydrogeological conditions of the Dahei River Plain in the Inner Mongolia area, assessment of shallow groundwater vulnerability is conducted based on DRASTIC model. Each evaluation indicator weight is determined by using analytic hierarchy process(AHP). The most important indicators are lithology in soil media and vadose zone. Assessment model of shallow groundwater vulnerability of the Dahei River plain is constructed. Distribution map of vulnerability index in this area is made with the spatial analysis function of ARCGIS. The results show that the particularly sensitive area is the piedmont of the Daqing Mountain, where the upstream place of the groundwater and the south-central place of the plain has the lowest vulnerability. The assessment results are more in accordance with the actual vulnerability conditions of this area by using analytic hierarchy process, and is helpful for groundwater protection.

Contribution of the Sensitivity Analysis in Groundwater Vulnerability Assessing Using the DRASTIC Method: Application to Groundwater in Dabou Region (Southern of Côte d’Ivoire)

The groundwater constitutes the main source of drinking water for the populations in the Dabou region which is marked by a multiplication of socio-economic activities. The quality of groundwater is increasingly tested by diverse sources of pollution caused by these human activities. In order to preserve their quality against any form of contamination, the present study aims to assess the groundwater vulnerability in this region and to highlight the relative importance of hydrogeological parameters which will be taken into account in this assessment. The assessment of the intrinsic vulnerability is to identify the most sensitive zones in order to prevent the groundwater pollution risks on the surface of the ground. To do it, the DRASTIC method is applied through a GIS. The GIS has also used to perform sensitivity analysis through the map removal and the single-parameter sensitivity analysis tests. The indexes calculated for the DRASTIC vulnerability map vary from 95 to 187 of the North towards the South. This vulnerability map presents four classes: very high (26.22%) in the South and the East, high (37.71%) in the Center, the North-East and the North-West, moderate (34.73%) to the North and the West and low (1.34%) in the North. The DRASTIC vulnerability map is heavily influenced by the impact of vadose zone and the depth to water table according to the first test. For the second test, it is the impact of vadose zone, the aquifer media and the soil media which have a more significant impact on the vulnerability map. Both sensitivity analysis tests confirm that the impact of vadose zone therefore sediment type is more implied in this assessment of the groundwater vulnerability in the Dabou region.

Application of GIS and DRASTIC Modeling for Evaluation of Groundwater Vulnerability near a Solid Waste Disposal Site

The study aims at evaluating the groundwater vulnerability to contamination in the vicinity of a solid waste disposal site, Njelianparamba, a municipal dumping site in Kozhikode, Kerala, India, using DRASTIC model using Geographic Information System environment. Vulnerability maps are intended to show areas of most potential to groundwater contamination on the basis of hydrogeological conditions and human impacts. The DRASTIC model consists of seven hydrogeological parameters that affect groundwater quality. The ESRI GIS software, Arc Map 10.1 was used to create the groundwater vulnerability map by overlaying the seven layers. The resulting vulnerability map was then validated using chemical and bacteriological analysis of samples collected from nearby wells of the dumping site to assess the area which is of more potential risk to pollution. According to the vulnerability map, the study area was divided into three vulnerability classes ranging between a minimum value of 120 and a maximum value of 243. The vulnerability classes are moderate vulnerable, high vulnerable and very high vulnerable. The vulnerability map revealed that the eastern and south eastern portion of Njelianparamba dump site was very highly vulnerable to groundwater contamination. This is probably due to the lower sloped terrains towards the eastern portion which allows percolation of contaminants into the groundwater.

Groundwater Vulnerability Assessment for the Corridor Wellfield Using DRASTIC and Modified DRASTIC Models: A Case Study of Eastern Jordan

Groundwater vulnerability maps were created for the Corridor wellfield (~300 km2) in the eastern Jordan using the DRASTIC and modified DRASTIC groundwater vulnerability assessment models. The study area is considered as one of the most important well fields therein providing partially three governorates with the needed drinking water. Detailed geological and hydrogeological parameters as well as the land-use map of the area were obtained from various sources to utilize both models. ArcGIS software was used for calculations and maps preparation. As a result, the generic DRASTIC vulnerability index ranges between 109 and 168. Thus, two vulnerability classes were observed, moderate (9.9%) and high (90.1%) vulnerability classes. On the other hand, the modified DRASTIC model (risk map) is taking into account the land-use map classes in the study area. The output risk map reveals two main classes, the moderate and high-risk areas. The moderate-risk areas occupy 9.3% of the total volume of the study area while the high-risk areas are 90.7%. Due to the high depth to groundwater within the area (between 90 m and 390 m), the depth to groundwater intervals was modified in the model to become more comfortable with the situation in Jordan. The high percentage of the high vulnerable areas against pollutants reflects the need to do more investigation for the studied area.

Assessment of Groundwater Vulnerability in Northern Babylon Governorate, Iraq

Groundwater is one of the main resources from the earth, especially for arid or semiarid countries. For this reason, it is very important to keep it unpolluted. Drastic Model is one of the widely used models to detect groundwater vulnerability to the contaminants that are found on ground surface. In this model, it is assumed that the vulnerability of the groundwater is affected by seven hydrological parameters. They are: depth from the surface ground to groundwater, net recharge into the aquifer from the surface, aquifer media, soil media, area topography, impact of vadose zone and aquifer hydraulic conductivity. In this study, the DRASTIC model was applied on the northern part of Babylon governorate in Iraq, to predict the vulnerability of Groundwater in that area. The results indicate that the vulnerability is very low to low grade.

The Assessment of Groundwater Vulnerability Due to Leaching of Chemicals: The Review of Attenuation Factor

To assess the groundwater vulnerability due to leaching of chemicals, the groundwater system in the unsaturated zone is characterized by conceptual models that are further extended and refined with more detailed mathematical models to understand the governing physical processes in detail. However, due to lack of data and uncertainty level, an intermediate transition through index based models is researched. The attenuation factor (AF) approach, which works under the assumption that the chemicals degrade following a first-order kinetics and determines the fraction of the chemicals that goes to groundwater table, is one of the index based models that has been widely used due to its simplicity. Therefore, the objective of this paper is to review the research works done using the AF approach, to outline the future research needs. Furthermore, the mathematical implementation of the AF approach and the associated uncertainty levels is explained through an example and MATLAB source code.

In-situ nitrogen fate in the vadose zone of different soil types and its implications for groundwater quality in the Huaihe River Basin,China

This paper focused on nitrate fate in the vadose zone(VZ)and its implications for groundwater vulnerability under different soil types in the agricultural area of Huaihe River Basin,China.Isotopic compositions of nitrate(δ15N andδ18O)along with NO3-and Cl-concentrations were determined in the VZ-shallow groundwater continuum beneath silty-loam and silty-clay-loam,which are distinctive in texture and organic carbon(OC).In the soil zone(<1 m in depth),measuredδ18O-NO3-suggested the ubiquitous of nitrification regardless of soil types.In the subsoil zone(>1 m in depth),however,the concurrent enrichment ofδ15N-NO3-andδ18O-NO3-indicated the occurrence of denitrification,which showed a dependence on subsoil properties.Specifically,during wheat and maize land uses,denitrification removed as much as 76%-88%of the total nitrate where the subsoil was dominated by stratified OC-rich silty-clay-loam.In contrast,only 0%-28%of the nitrate was degraded via denitrification where the subsoil was composed of uniform,OC-depleted silty-loam.Furthermore,inactive denitrification and higher permeability in the silty-loam VZ implied higher groundwater vulnerability.This observation was consistent with the fact that groundwater NO3--N concentration beneath silty-loam(11.24 mg L-1)was over two times higher than that of the silty-clay-loam(5.32 mg L-1),where stricter fertilization management and conservation strategies should be applied to protect groundwater quality.

Fuzzy Logic Implementation of Vulnerability Assessment in a Coastal Aquifer of Northern Sicily

Aquifers can be defined as complex ecological systems. Their description is closely influenced by geometrical and geological parameters, which portray the hydrogeological behaviour of underground systems. This paper reports a contribution to assessing groundwater contamination risk in a particular Sicily sector, where deterministic approaches have methodically assessed and mapped vulnerability and quality of groundwater. In detail, in the coastal area of Acquedolci (Northern Sicily), already intensely surveyed in the frame of interdisciplinary projects on geological risk, implementing models and systems have been experimented, also considering fuzzy logic. Cartography issues are here presented and compared, with particular regard to the effect of stochastic hydrogeological elements (i.e. “depth to water”), locally characterized by variability for simultaneous climate, overdraft, irrigation and sea encroachment. The authors show how fuzzy logic, applied to vulnerability settings, contributes to a better comprehension of the passive scenery offered by aquifers in Acquedolci Sicily area.

Environmental Effects of Groundwater Development in Xuzhou City, China

Xuzhou City is located in the most northwestern portion of Jiangsu Province, P. R. China. Karst groundwater in the Ordovician and Cambrian Limestone aquifers is the main source of water supply. There are 527 wells in urban areas to exploit the karst groundwater, yielding up to 35 000 m^3 per day. After 1978, urbanization and industrialization of Xuzhou City have continued at a greatly accelerated pace; the population increased from 670 700 （1978） to 1 645 500 （2002）, its GDP from 0.71 × 10^9 $ to 42.7× 10^9 $ and the urban area from 184 km^2 to 1,038 km^2 （built-up city area from 41.3 km^2 to 81.9 km^2）. The volume of karst groundwater withdrawal increased yearly before the operation of a supply plant of surface water in 1992, from 3.85x 10^7 m^3（1978） to 1.34× 10^8 m^3 （1991） and now maintained at 0.1× 10^9 m^3 （2002）. Intensive overexploitation of karst groundwater has caused a continuous descending of the piezometric level and the area of the depression cone increases year after year. These changes have increased the vulnerability of the karst groundwater system and have induced environmental problems such as depletion of water resources, water quality deterioration, groundwater contamination and karst collapse. The largest buried depth of karst groundwater is up to 100 m in the dry season in some areas, while 66 exhausted wells have been abandoned. A change in the thickness of the unsaturated zone due to the drawdown of the piezometric level has caused a change of the chemical environment which has an impact on the physical state and major chemical compositions in groundwater. The contents of Ca^2＋, Mg^2＋, NO3^-, SO4^2- and C1^- in karst groundwater has increased significantly, total hardness （CaCO3 content） rises annually in most pumping wells and exceeds the Standard of Drinking Water of P.R. China. Point source pollution and belt-like pollution along the rivers has caused water quality deterioration. The sudden loss of buoyant support due to rapid drawdown of the piezometric level has induced 7 karst collapses to form 17 pits and has caused an estimated US$ 10 million economic loss. These problems have influenced the quality of development in the city.

Assessment of groundwater contamination risk in an agricultural area in north Italy

In the present study a specific approach is followed,considering the Pesticide DRASTIC and Susceptibility index(SI)methods and a GIS framework,to assess groundwater vulnerability in the agricultural area of Albenga,in north Italy.The results indicate"high"to"very high"vulnerability to groundwater contamination along the coastline and the middle part of the Albenga plain,for almost 49%and 56%of the total study area for Pesticide DRASTIC and SI methods,respectively.These sensitive regions depict characteristics such as shallow depth to groundwater,extensive deposits of alluvial silty clays,flat topography and intensive agricultural activities.The distribution of nitrates concentration in groundwater in the study area is slightly better correlated with the SI(0.728)compared to Pesticide DRASTIC(0.693),thus indicating that both methods are characterized by quite good accuracy.Sensitivity analysis was also performed to acknowledge statistical uncertainty in the estimation of each parameter used,assess its impact and thus identify the most critical parameters that require further investigation in the future.Depth to water is the parameter that exhibited the largest impact on the Pesticide DRASTIC vulnerability index followed by the impact of the vadose zone and topography.On the other hand,the SI method is more sensitive to the removal of the topography parameter followed by the aquifer media and the depth to water parameters.

Assessment of recharge capacity potential of groundwater using comparative multi-criteria decision analysis approaches

Groundwater resources have always been some of the most valuable resources of human settlements.Climate changes and ever-increasing water demands registered in the last century have led to diminishing levels of groundwater reserves,as well as reduced recharging potential.Therefore,in order to use groundwater aquifers in a sustainable manner,it is required to identify areas with higher replenishing potential.The current study addresses the issue of generating a map for identifying differently ranked groundwater recharging potential values,in the aquifers of the Moldavian Plain region,Romania.For the purpose of conducting the analysis,maps were created through GIS based multi-criteria Analytic Hierarchy Process(AHP)and Catastrophe Theory(CT),with seven relevant,thematic,spatial layers:precipitation distribution,lithological strata,soil texture,declivity,drainage density,land use and the distribution of groundwater level tendencies.The results of the two methods of analysis are similar.Prediction differences are of maximum 3%,in the case of extreme classes(very bad and very good)and in the case of middle classes the deviation is not greater than 0.4%.Following the validation of the results generated by the two methods that were applied,it was observed that the predictions offered by CT are more accurate.This aspect can be based on the fact that the main factors that contribute to the prediction are different.This type of workflow emphasizes the necessity of implementing appropriate groundwater management plans for mitigating reservoir scarcity/depletion,and recommending sustainable solutions for future groundwater exploitation practices.