Modeling land suitability evaluation for wheat production by parametric and TOPSIS approaches using GIS, northeast of Iran

Abstract

Land evaluation is the process of predicting land use potential on the basis of its attributes. In the present study, the qualitative land suitability evaluation by parametric and TOPSIS models was investigated for irrigated wheat crop based on FAO land evaluation frameworks (FAO 1976a, b, 1983, 1985) and the proposed methods by Sys et al. (1991b) and Hwang and Yoon (1981) in Joveyn plain, Northeast of Iran. Some 26 land units were studied at the study area by a precise soil survey and their morphological and physicochemical properties. The climatic and land qualities/characteristics for wheat crop were determined using the tables of soil and crop requirements developed by Sys et al. (1993). An interpolation function was used to map values to scores in terms of land qualities/characteristics for the land utilization type and the evaluation was carried out according to parametric and TOPSIS models. Our results indicated that the most limiting factor for wheat cultivation in the study area was soil fertility properties. The values of land indexes by parametric model ranged from 62.71 in some parts in east and west to 87.24 in the middle parts of the study area, which categorized the plain from moderate (S2) to high (S1) suitable classes. The TOPSIS preference values for wheat cultivation in the study area varied between 0.438 and 0.916 which categorized from moderate to very high classes for wheat production. The coefficient of determination between the parametric land index values and the corresponding TOPSIS preference values revealed a high correlation (R2 = 0.961) between two models. The correlation coefficient (R2) between the parametric land indexes and TOPSIS preference values with the observed wheat yield varied between 0.943 and 0.861, respectively, which verify the validation of both models in estimating land suitability for irrigated wheat production in the study area.