Contribution of the Sensitivity Analysis in Groundwater Vulnerability Assessing Using the DRASTIC and Composite DRASTIC Indexes

Abstract

Abstract. The present study estimates Kerman–Baghin aquifer vulnerability by applying the DRASTIC and composite DRASTIC (CDRASTIC) indexes. The factors affecting the transfer of contamination, including the water table depth, soil media, aquifer media, the impact of the vadose zone, topography, hydraulic conductivity, and land use, were ranked, weighted, and integrated using a geographical information system (GIS). A sensitivity test has also been performed to specify the sensitivity of the parameters. The study results show that the topographic layer displays a gentle slope in the aquifer. The majority of the aquifer covered irrigated field crops and grassland with a moderate vegetation cover. In addition, the aquifer vulnerability maps indicate very similar results, recognizing the northwest parts of the aquifer as areas with high and very high vulnerability. The map removal sensibility analysis (MRSA) revealed the impact of the vadose zone (in the DRASTIC index) and hydraulic conductivity (in the CDRASTIC index) as the most effective parameters in the vulnerability evaluation. In both indexes, the single-parameter sensibility analysis (SPSA) showed net recharge as the most effective factor in the vulnerability estimation. From this study, it can be concluded that vulnerability maps can be used as a tool to control human activities for the sustained protection of aquifers.

Evaluation of groundwater vulnerability to pollution using DRASTIC, composite DRASTIC, and nitrate vulnerability models

“…In this index, each factor is rated on a In the DRASTIC index formula, the letters in the abbreviation include a short form of the factors influencing the DRASTIC model. Also, "r" and "w" refer to points and weights for each factor, respectively (22). The rankings and weights of the factors are shown in Table 2.…”

“…The relative humidity is 36% and the average temperature is a maximum of 37°C and a minimum of -1°C. And the height of this area is 1730 meters above sea level (22).…”

“…This factor controls the flow of groundwater in the aquifer (22). To prepare this layer, the information of the well drilling logo, which was obtained from the KWRO, was used.…”