VULNERABILITY ANALYSIS OF UNDERGROUND AQUIFERS TO CONTAMINATION USING THE DRASTIC METHOD AND RISK DETERMINATION

Groundwater represents an important component in the supply of freshwater in several regions around the world. The contamination of these waters is a worrisome problem in the management of water resources. Since underground aquifers are vulnerable to contamination by human and industrial activities, including land use, the diagnosis associated with land use is critical for environmental management. The present study was carried out in the Uberaba sandstone formation, in which the vulnerability of the subterranean aquifers was determined using the DRASTIC method, by evaluating the interaction between the use and occupation of the land using a geographic information system. Thus, the risk of contamination of the underground aquifer was determined by evaluating the land use with the water quality and fertility. The tool applied in the present study proved effective for the diagnosis, management and action planning in the short and long term, with the intention of preserving these natural resources.

Mapping Intrinsic Vulnerability to Pollution Using the DRASTIC Method in the Temara Groundwater (Northwestern Morocco)

the DRASTIC method was chosen because it can be adapted to different environments and because it combines the seven criteria that directly influence groundwater: depth, recharge, geology, soil, slope, unsaturated zone and conductivity. Located in the North West of Morocco, the Temara aquifer is a very important water resource, but it is overexploited and deteriorated as never before. This issue is of concern to decision-makers in the field of water management. The objective of this work is to create a map of vulnerability to pollution by the Bay of Geographic Information Systems (GIS) and the DRASTIC model. Thus, the highest vulnerabilities are located around the drinking water treatment plant of Ain Atiq, at the mouth of the Bouregreg River and scattered in places throughout the study area. The results of the physico-chemical analysis showed compatibility with the results of the DRASTIC model.

Assessment of the Vulnerability of the Shallow Aquifer of the City of Sarh in Chad, using the Drastic Approach

The demography (3.4%) and the development of anthropic activities in the city of Sarh, constitute a risk of groundwater pollution. That is why a vulnerability map is determined to contribute to the protection of groundwater resources against possible pollution for future decision and allocation of land and activities. The present study interested the city of Sarh and had the objective to elaborate a vulnerability map to pollution by applying the DRASTIC method. The data required for this study are summarized in seven critical factors specific to the model applied (depth of the water table, net recharge, aquifer lithology, soil type, topography (slope), unsaturated zone lithology and hydraulic conductivity). They were acquired from several sources and converted by the GIS into thematic maps. For each critical parameter, a coefficient and a weight were assigned according to its importance in the DRASTIC model. The resulting map shows three classes of vulnerability; 36% of the Sarh region has very low vulnerability, 35% has low vulnerability and 29% has medium vulnerability.

Groundwater Vulnerability potential and Health-risk assessment related to nitrate and nitrite in drinking water in Azna-Aligudarz Plain

Background: In the Azna-Aligudarz plain, the drinking water is mainly supplied from groundwater. Therefore, it is necessary to estimate the concentration of nitrate and nitrite and determine the groundwater vulnerability potential and related risks in the plain to guarantee the health of consumers. Materials and Methods: The vulnerability potential of the studied plain to pollutants was investigated by the drastic method. To estimate the concentration of nitrate and nitrite, 25 water wells in the study area were sampled within 2018-2019 and analyzed by standard method. Human health risk related to groundwater in the study area was assessed using the USEPA (the United States Environmental Protection Agency) index. Results: The results of the DRASTIC method demonstrated that 45% and 65% of the region has a high (southern part of the plain) and a medium vulnerability potential (northern part of the plain), respectively. According to the obtained results, nitrate in Chaqataram and Ashrafabad villages with 56 and 65 mg/liter, respectively, and nitrite in groundwater of Chamzaman, Aliabad, and Darreh Bagh villages with 3.5, 3.3, and 3.4 mg/liter, was higher than the standard of World Health Organization. According to the health risk assessment results, 83%, 8%, and 4% of children, women, and men are prone to health threats due to nitrate concentration (HQ>1). The accuracy of the vulnerability results was confirmed by calibrating the results of the health risk assessment and the results of the nitrate map. Conclusion: As e evidenced by the obtained results, improper use of nitrate chemical fertilizers and unsafe disposal of human wastewater (urban and rural) is the main cause of increased nitrate and nitrite concentrations in agricultural lands. Based on the results of the present study, the use of contaminated drinking wells is not recommended and continuous monitoring of drinking wells in the study area is essential to protect the health of consumers, especially children.

A GIS-based Assessment of the Vulnerability to Potential Pollution of the Alluvial Aquifer of Aousja-Ghar El Melh (North-East of Tunisia) Using the Parametric Method DRASTIC

The phreatic aquifer of Aousja-Ghar El Melh (governorate of Bizerta, northeast of Tunisia), has a great economic weight as it is tightly linked to irrigation and domestic consumption. The aquifer area is found mostly in agricultural zones where more and more chemical fertilizers are being used. Such chemical fertilizers, alongside industrial zones discharges appearing for the last 25 years, put at risk ground waters quality. The DRASTIC method has been applied to study the extent to which the aquifer has been affected by generic pollutants. This method hinges on GIS techniques. The result suggests a map with evidence for three degrees of vulnerability: low, moderate, and high. Evidence shows the predominance of moderate vulnerability in most of Aousja-Ghar El Melh aquifer, which occupies an area of 45%. Low and high groundwater vulnerability occupy 28% and 27% of the total surface of the studied area, respectively.