عنوان مقاله [English]
Background and Objectives: The FAO framework for land suitability evaluation is the most commonly used and is based on the biophysical properties and socioeconomic parameters of lands. The FAO framework for land suitability and soil mapping application a Boolean approach that has been criticized by some of authors. Because the Boolean representations ignore the continuous nature of soil and uncertainties in measurement .Also for overcoming problems related to vagueness in definition and other uncertainties, Fuzzy set methodologies have been proposed. Analytical Hierarchy Process (AHP) calculates the needed weighting factors with the help of a preference matrix where all identified relevant criteria are compared against each other with reproducible preference factors. Finally the derivation of suitability using Fuzzy AHP method was not just based on the fuzzy membership function values, but also the weighting values allocated to any criterion. This article uses of Fuzzy–AHP methods to land suitability evaluation. The method were evaluated application a case study which model the opportunities for chickpea production under irrigation conditions in the Hashtrood region in East Azarbaijan province, IRAN.
Materials and Methods: Soil morphological and analytical data were obtained from 29 sampling profile on Chickpea farms. Then a number of relevant soil and landscape criteria were identified through the literature and their weights specified as a result of discussions with local experts. For land suitability evaluation by FAHP approach, First hierarchical structure employed, Second asymmetric and symmetric models were used for land characteristics, Third Weighting the model criteria provides relative measures of the interaction and importance of the criteria. The weights were obtained through a pairwise comparison analysis in an AHP approach in discussion with local experts, Fifth the weighted criterion layers are generated using the relative function, Finally The suitability is calculated by combining the weighted criterion layers. For assessing of accuracy of modeling, has been used matching of between suitability and actual production maps.
Results: The results indicated that cation exchange capacity (0.179), available-water-holding capacity (0.161) and soil calcium carbonate (0.143) have higher weights than other criteria and therefore they are considered as the most significant criteria in the study area. The results of the Fuzzy AHP approaches showed that no locations in the study area were mapped with a degree of suitability equal to 1. In this model, a number of locations in specific criteria were given MFs of 1 due to the strength of support they offered in the overall assessment of chickpea suitability. However, the derivation of the overall suitability using the Fuzzy AHP approach was not only based on the fuzzy membership function values but also the weighting values allocated to each criterion. The results of the Fuzzy AHP showed that the majority of the study area has membership values to the set of suitability between 0.6 and 0.7. Agreement between land suitability and actual map is 76.7; also this model has been presented good result for land suitability of chickpea in study region. The results of this work provide information to decision-makers in their land planning decisions and further work should develop trial plots to ground truth the suitability measures.
Conclusion: Fuzzy AHP approaches accommodate the continuous nature of some soil properties and produce more intuitive distributions of land Suitability Indexes.