LAND SUITABILITY EVALUATION FOR WHEAT CULTIVATION BY FUZZY THEORY APPROACHE AS COMPARED WITH PARAMETRIC METHOD

摘要

Nowadays infinity examples of irreparable damaging to natural resources have been occurred due to lack of attention and improper uses of soil and water. Land evaluation is a process of assessment of land performance when used for specified purposes. In other words, Land Evaluation is the estimation of the possible behaviour of the land when used for a particular purpose. The main purpose of this study is to prepare land suitability evaluation maps for Wheat using Fuzzy classification in Shavur area, Khuzestan province. In the model non-physical factors is included. The results are compared to a Crisp classification using the standard FAO framework (parametric) for land evaluation which, include non-physical parameters as well. In the present study, eight soil parameters, such as soil Texture, Wetness (ground water depth and hydromorphy ), Cation Exchange Capacity (CEC) and Exchangeable Sodium Percentage (ESP), Gypsum (%), CaCO_3 (%),Topography, Soil depth and pH values, are chosen for crop-land suitability analysis and thematic maps are developed for each of the parameters with IDW model. Different Fuzzy membership functions obtained from the literature (Con function) were employed and the weights for each parameter were calculated according to an Analytic Hierarchy Process (AHP) 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 coefficient of Kappa is used for comparing these two methods and choosing the better one. 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.