Hi you can proceed by analyzing hydrochemical composition, ionic ratios (Na+/Cl–, Ca2+/Cl–, Mg2+/Cl–, SO42-/Cl- and especially Br–/Cl– molar ratios; Ca2+/Mg2+ weight ratio; and chloride concentrations) and calcite-saturation index (SIcalcite) of seawater and groundwater from selected wells. Also, isotope analysis of (2H/18O, 3H, 14C, 34S).

Chloride/Br ratios are used to determine the causes of groundwater salinisation for water.

Do you can red this paper:                                                                                     Determination of Seawater Intrusion via Hydrochemicals and Isotopes in Bafra Plain, Turkey. DOI: 10.1007/s11269-012-0112-3

Thank you sending me this paper