Evaluation of quality of groundwater in irrigation using fuzzy logic in the Bafra Plain, Northern Turkey

Abstract

The quality of groundwater plays an important role in irrigation management and planning.The most commonly used method when classifying the irrigation water quality is the UnitedStates Soil Laboratory (USSL) diagram. Fuzzy logic approach is one of the widely usedmethods produced more precise and accurate results according to the USSL diagram. A rulebased, fuzzy logic irrigation water quality (FL-IWQ) were evaluated by using electricalconductivity (EC), sodium adsorption ratio (SAR), and residual sodium carbonate (RSC)values of groundwater in irrigation, in Bafra plain. The FL-IWQ defuzzification methodscenter of area (COA), mean of maxima (MOM), least of maxima (LOM), and (SOM) wereselected and compared with quality values of groundwater in irrigation. Based on the resultsof the FL-IWQ defuzzification methods with quality values of groundwater in irrigation, thedetermination of coefficients for COA, MOM, SOM and LOM were 0.9874, 0.9755, 0,9574 and0.9453, respectively. Results obtained from FL-IWQ revealed that there has been 93% generalagreement with the results obtained from the USSL diagram and RSC classification. Thedeveloped fuzzy model produced more reliable results for groundwater in irrigation than thatof the USSL-diagram and RSC classification. The study suggests using proposed fuzzy modelas a promising alternative to the traditional ones for classifying the quality of groundwater inirrigation under uncertain conditions.