Evaluation of vulnerability of aquifers by improved fuzzy drastic method: Case study: Aastane Kochesfahan plain in Iran

In this study the vulnerability of aquifer is investigated by fuzziness of the different layers. The vulnerable potential of different location within the basin by most accuracy was traced. In this method by the use of max lambda the weights of parameters were become fuzzy and quantity weights parameters has been fuzzy by the use of membership function. The quality weights were done by the discrete functions became fuzzy. The final map showed that some parts of north and northeast parts of the aquifer were most vulnerable locations. The correlation coefficient of vulnerability and nitrate concentration by standard method was estimated 49 percent and in the fuzzy method 53 percent that showed fuzzy method is more realistic. In FAHP method 13.87% of the plain area was by the low vulnerability, 11.96% by low to moderate vulnerability, 41.24% by moderate to high vulnerability, and 32.92% by high vulnerability.