Applicability of knowledge-based and fuzzy theory-oriented approaches to land suitability for irrigated wheat as compared to the parametric method (A case study of Shavur in Khuzestan)

Nowadays, infinity examples of irreparable damaging to natural resources have been occurred caused by to lack of attention and improper uses of soil and water. There are many methods which could be used to protectnatural resources against these damages. Land evaluation is one of these methods which are process of assessment of land performance when used for specified purposes. The main purpose of the study is to evaluate land suitability for Wheat using Fuzzy classification in GIS environment and compare the result to parametric methods in Shavur area, Khuzestan province. First, prepare land suitability evaluation raster maps related to effective parameters in land suitability (soil Texture, Wetness, CEC and ESP, Gypsum, CaCO3, Topography, Soil depth and pH values) using ArcGIS. Then Fuzzy maps were prepared. For producing final Fuzzy maps Analytic Hierarchy Process for weights and mixing layers were applied. Climatic requirements, landscape and soil requirements for selected crop was determined based on parametric method. Parametric method results showed 26% of the area as moderately suitable, 25% as marginally suitable and 49% as unsuitable. The Fuzzy results showed 31% of the study area as highly suitable for wheat 29 % as moderately suitable, 19% as marginally suitable and 21% as unsuitable. Based on them, it has been concluded that Fuzzy method allows obtaining results that seems to be corresponded with the current conditions in the area. In parametric framework, that relies on pair wise comparisons. For Wheat using Fuzzy classification. The results are compared to a Crisp classification using the standard FAO framework for land evaluation which, include non-physical parameters as well. In the present study, eight soil parameters, such as soil Texture, Wetness, CEC and ESP, Gypsum, CaCO3, Topography, Soil depth and pH values, are chosen for crop-land suitability analysis. Different Fuzzy membership functions obtained from the literature were employed and the weights for each parameter were calculated according to an Analytic Hierarchy Process that relies on pair wise comparisons. Climatic requirements, landscape and soil requirements for selected crop was determined based on parametric method. Finally classes of land suitability provided for each Land unit. The results with the parametric method showed 26% of the area as moderately suitable, 25% as marginally suitable and 49% as unsuitable. The results with the Fuzzy theory showed 31% of the study area as highly suitable for wheat 29 % as moderately suitable, 19% as marginally suitable and 21% as unsuitable. Based on the results it has been concluded that Fuzzy method allows obtaining results that seems to be corresponded with the current conditions in the area.