Rule-based fuzzy system for assessing groundwater vulnerability

Parallel to industrial growth and ever increasing use of agrichemicals, environmental resources have been affected and deteriorated by generated pollutants. Groundwater, an important source of fresh water, has not been immune from contamination. Recognition of groundwater vulnerability to pollution will help in managing groundwater quality conflicts. The DRASTIC model (where D=depth to groundwater; R=net recharge; A=aquifer media; S=soil type; T=topography; I=impact of vadose zone; and C=hydraulic conductivity of the aquifer) has been used extensively for assessing the vulnerability of groundwater. It employs a linear combination of some intrinsic properties of aquifers to develop a vulnerability index. As there is no clear boundary for the set of vulnerable aquifers, groundwater vulnerability can be addressed through fuzzy set theory instead of classical set theory. In this study, benefiting from a fuzzy system and a conscious knowledge base, a regional-scale model is developed for groundwater vulnerability assessment that employs DRASTIC parameters. A comparison between, the output of the fuzzy model and the DRASTIC index is accomplished. The ability of the fuzzy system to cope with the modeling of a nonlinear system and presentation of the output of the fuzzy system in the framework of a geographical information system, are highlighted.