Evaluation of drinking water quality of Ardabil plain aquifer by cokriging and fuzzy logic

In arid and semi arid regions like Iran، exploitation and allocation of groundwater resources have a great importance. In this study، the methods of cokriging and fuzzy logic have been used for qualitative classification of groundwater in Ardabil plain for drinking purpose. Thus، qualitative data related to the TDS، TH، pH، Ca2+، Mg2+، Cl-، Na+ and SO42- parameters of seventy-six wells were used. This study included two stages that in the first one distribution of these parameters by cokriging interpolation method (for each point of the plain) has been derived. Then in the second stage، these interpolated data have been used as fuzzy logic inputs. The qualitative spatial distribution map of plain was generate with identifying membership functions for each of parameters in three classes “Desirable”، “Acceptable” and “Not-acceptable” and with fuzzy attitudinal to drinking water quality standard. In general، to classify groundwater quality، 105 rules were specified. According to obtained results، 3. 5، 68 and 28. 5 percents of Ardabil plain area have Desirable، Acceptable and Not-acceptable quality respectively، for dinking. This spatial distribution map can help a lot for exploitation of groundwater resources and offers a good insight of groundwater qualitative trend in this study area.