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Evaluating Potential Contamination of Groundwater by DRASTIC (Case Study: Plain Mahidasht Kermanshah)
Sh Gorgani, A Bafkar, Se Fatemi,
Volume 9, Issue 4 (3-2017)
Abstract

Background and Objective: There are major mobile and non-mobile pollution sources due to human activities that can influence aquifers and reduce groundwater quality. Vulnerability assessment is an inexpensive procedure in to identify areas prone to the pollutants. Identification of these sources is essential in water resources management. Mahidasht Plain is one of the important regions of Kermanshah province and plays a significant role in the production of agricultural products. Water supply for agriculture may be at risk due to the indiscriminate withdrawal of groundwater resources of the plains, the recent droughts and potable water requirements. Therefore, analysis and evaluation of the area helps to make better decisions on proper management and control of water pollution.

Materials and Methods: Vulnerability, which is defined as the sensitivity of groundwater quality to pollution load, was applied and determined using intrinsic features of the aquifer. In this study, we have studied inherent vulnerability of the Mahidasht aquifer against pollution by using DRASTIC model and GIS. Seven parameters for the zoning of aquifer vulnerability was used in the DRASTIC method, including depth to the water table, net recharge, aquifer material, soil type, topography, impact of vadose zone and hydraulic conductivity. These parameters were prepared as seven layers of information in Arc GIS10 Software. The data collected for the purpose of this study were taken fromwells log, 44 piezometer in the area, pumping experiments and three rain-gauge stations. The layers prepared in Arc GIS10 software were weighted, ranked and eventually integrated.

Results: The DRASTIC index calculated for the plain ranged from 34 to 120 units. On this basis and according to the standards listed for DRASTIC index, the aquifer was in a vulnerable group with a low or no risk.

Conclusion: DRASTIC model output showed an inherent vulnerability of the aquifer. The model can be used as a primary tool in the development and management of water resources in the future. In addition, this model is not able to produce information about amount and type of pollutants. Therefore, it is recommended to examine the salinity zoning in the future research due to less rainfall and decreasing underground water level and consequently the higher probability of salinity in underground water. Additionally, the domestic and industrial wastewater, sewage irrigation and the fraction used for groundwater recharge should be considered in order to validate the results of Drastic model.


Prediction of groundwater pollution potential using the DRASTIC index and annual time series analysis (case study: Plain Mahidasht Kermanshah)
Sh Gorgani, A Bafkar, Se Fatemi,
Volume 10, Issue 3 (12-2017)
Abstract
Background and Objective: Rainfall and groundwater level are important parameters of DRASTIC index, thus their time-series were examined using time series analysis for Mahidasht plain vulnerability in Kermanshah Province.
Materials and Methods: DRASTIC model is a quantitative model that seven parameters for transfer of pollution are considered including depth of water table, net recharge, aquifer, soil, topography, unsaturated environment and hydraulic conductivity. The data was prepared in seven-layer information in Arc GIS10 software. After integration, weighting and ranking, DRASTIC index for the region was estimated between 34 and 120. Precipitation is an uncertainty factor in water projects. Precipitation is the origin of other uncertainties such as surface runoff, recharge, and water balance.  Underground water level and recharge are main factors in the DRASTIC model that are considered as component hydrological variables and time series, thus, they were analyzed and forecasted using stochastic methods on the horizon in 2032.
Results: Finally, selection of the data predicted in 2032 and the creation of dual new depth to the water table and recharge, as well as the weighting and ranking of the repeated placement in the DRASTIC model, another vulnerabilities map is prepared in which the index DRASTIC was 34 to 110 units.
Conclusion: Results showed that due to further decrease of water table and reduced rainfall, DRASTIC index will be less in the next 18 years (2014-2032).
 

Determination of vulnerability of aquifer Ardebil using DRASTIC method in GIS
K Jafari, N Hafezi Moghaddas, Ar Mazloumi, A Ghazi,
Volume 12, Issue 3 (12-2019)
Abstract
Background and Objective: Groundwater resources are the most valuable resources of each country. Development of agricultural activities in Ardabil plain and over-use of fertilizers and pesticides, improper disposal of municipal sewage and industrial areas are responsible for groundwater pollution. Clean-up of groundwater resources is very difficult and expensive. One of suitable method in preventing groundwater contamination is determination of the vulnerable zones of an aquifer to manage water resources and sustainable development. 
Materials and Methods: In this study for determining of vulnerability of aquifer Ardebil, information of 52 observational wells, 43 pumping tests, average of annual precipitation of 8 stations, 45 logs of exploration wells, land use map, topographic map and geological map have been gathered. Then, data layers of groundwater depth (D), Recharge (R), Aquifer media (A), Soil media (S), topography (T), impact of vadose zone (I) and hydraulic conductivity of aquifer (C) were prepared and overlaid based on DRASTIC method in ArcGIS software.
Results: Zoning map of DRASTIC method showed that DRASTIC index varied between 63 to 195 units. Areas with high vulnerability potential were characteristic with shallow depth groundwater, coarse-texture soil, thin soil and gentle topographic slope. Accuracy of the zoning map was evaluated by nitrate concentration map which showed the increase of DRASTIC index with nitrate concentration.
Conclusion: Northwestern and central parts of the Ardabil plain showed high vulnerability. The results of this study could help to reduce the environmental impact of contaminants on groundwater resources of the study area in future.
 

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