APPLICATION OF DRASTIC MODEL AND GIS FOR EVALUATION OF AQUIFER VULNERABILITY: STUDY CASE BARLAD CITY AREA

Iuliana Gabriela Breaban,  Madalina Paiu, University “Al.I.Cuza” Iasi,  Romania

Abstract

The aims of this study is to determinate the aquifer vulnerability using the DRASTIC method and the correlations that can be establish between this and the nitrate level present in Barlad city and surrounding villages’ wells.
Groundwater is a finite resource, which is being overexploited due to increase in demand over the years leading to decrease in its potentiality. The groundwater vulnerability to contaminants was defined as the possibility of percolation and diffusion of contaminants from the ground surface into the groundwater system. Geographic information system (GIS) has become one of the leading tools in the field of hydrogeological science that helps in assessing, monitoring, and conserving groundwater resources. The main objective is to determine susceptible zone for groundwater pollution by integrating hydrogeological layers in GIS environment.
The methodology consisted in a documentations stage, followed by a field phase consisting in collecting 94 groundwater samples from the STUDY area, analyzed in the laboratory for physico – chemical parameters.
The layers such as depth to water table, recharge rate, aquifer media, soil permeability, topography, impact of the vadose zone, and hydraulic conductivity are incorporated in the DRASTIC model using GIS techniques. The following steps were performed in order to apply the DRASTIC parameter method:
(1) the creation of a database of parameters
(2) the calculation of DRASTIC values;
(3) the construction of GIS maps for DRASTIC;
(4) the construction of a vulnerability map of groundwater
The aquifer analysis has highlighted the following: the vulnerability varies between  100÷150, being predominant the moderate and moderately-high values (120÷157) while the nitrates concentration is between 0.1 to 788 mg/l. The statistical analysis puts into evidence a powerful positive correlation between vulnerability and concentration of the nitrates in the groundwater. High nitrate concentration are present in high pollution areas as well as in moderate pollution areas. The present model can be used for assessment and management of groundwater.