Application of Fuzzy-Delphy approach to a part of Horand lands suitability evaluation for irrigated wheat

Land suitability evaluation is one of basic efforts to sustainable managements of any region. Shortcomings in traditional land suitability evaluation assessments have drawn the attention of this field users to use of artificial intelligence and multi-criteria decision making methods. Subsystems of mentioned methods alone or in the combination with each other were used to increase accuracy of evaluation, simplify of calculations and achievement of useful side results. Fuzzy-Delphi approach is one of discussed methods that in this study, its efficiency has been measured behind investigating of Horand region potential for irrigated wheat production.

In this study, 662 ha of lands in Horand region were selected in the form of 12 land units and after completing the climate, landscape and soil database, the Fuzzy-Delphi method was applied to qualitative and quantitative land suitability evaluation of irrigated wheat. The qualitative evaluation was done by land index determination and the quantitative one was completed based on predicted yield which calculated by combination of archived potential yield from Agro-ecologic method with soil index. In this regard, the Delphi method was used to select and determine weights of the factors which are involved in the evaluation based on the experts’ opinion and were validated by Kendall coefficient. The properties matrix which obtained from fuzzyization of land properties with kandel membership function were combined with weight matrix and leads to suitability matrix. The suitability zoning of the study area were identified according to suitability classes which were determined based on resulted soil and land index from defuzzification of suitability matrix with triangle Tnorm way. Validation of Fuzzy-Delphi method was done by conventional statistical tests.

According to experts’ opinion, the 8 properties (Climate, slope, texture, calcium carbonate equivalent, gypsum, EC, drainage and flooding) of studied lands with Entisols and Inceptisols, were selected for land suitability evaluation that climate and gypsum have had maximum and minimum weight respectively, that its accuracy was confirmed by an incompatibility rate of 0.07. The conformed suitability evaluation showed S1 to S3 classes by qualitative and quantitative methods for irrigated wheat utilization type with limitation of slope, salinity, texture and gypsum. Difference of land units classes in qualitative and quantitative methods was seen only in one land unit which quantitative one take lower class. According to mean management index of 0.73, the middle management level was estimated for region. Chi-square value of 1.32, r2 0.91, RMSE 2.1% and GMER 1.34 obtained in the validation of Fuzzy-Delphi method.

Applying main agricultural lands users opinions in selecting and valuating land suitability evaluation parameters, combination of characterize weight with their rating and also considering intermediate classes, identified as the main advantages of the studied model over traditional methods that introduced the fuzzy-Delphi approach as an efficient method based on estimation of the land potential. The reliability of mentioned approach was confirmed by checked statistical accuracy and validity although with little over estimation. Beside main finding of this research work, coordination of qualitative and quantitative suitability evaluation with discussed approach, possibility of ranking the land limitation remove by sub data and also, pay attention to the land suitability class along with the management index for future land management planning are the cases that can be useful for researchers and executive experts. However, in order to find other capabilities of the model and recommending its use at the wide level, it is suggested to run this new model in different areas for various utilization types.