A new approach for vulnerability assessment of coastal aquifers using combined index.

A new approach, developed for coastal aquifers, consists of determination of saltwater-freshwater interface as well as obtaining map of groundwater vulnerability, for which a number of methods have been provided, including index method and numerical modelling. In the previous studies, the common vulnerability methods such as DRASTIC have not took the coastal regions into account, or that method of GALDIT, proposed for coastal regions, assumed the saltwater intrusion fixed. The vulnerability of coastal aquifer is determined in two distinct regions (coastal and non-coastal areas) using two distinct methods (Index and Numerical modelling) and finally they are combined together. The results of this study in coastal aquifer in north of Iran suggest that due to overexploitation, the intrusion of saltwater from coastline into centre of aquifer is as deep as 720 m, inducing very high vulnerability in coastal regions. The correlation of DRASTICSea method with qualitative parameter is obtained 68%. [ABSTRACT FROM AUTHOR]