Land suitability evaluation in Qinghai-Tibet Plateau based on fuzzy weight of evidence model

With the rapid development of industrialization and urbanization in China, arable land resources are still continuing to be occupied, leading to the intensification of conflicts between an increasing population and decreasing arable land resources. Thus, how to exploit and use the reserve resources of arable land in the Qinghai-Tibet Plateau has attracted much more attention under the serious situation of protecting arable land. But it is the necessary prerequisite to carry out a study on natural suitability evaluation before the exploitation and utilization of reserved arable land. This paper took the reserved arable land of 18 counties in the "Three Rivers" Area region of Tibet as an example. Eight factors of landform, climate, soil and water, that is, slope, elevation, slope direction, temperature, rainfall, soil depth, organic matter content, and distance to water area, were adopted as evaluation factors. The fuzzy weight of evidence model, which is both knowledge and data driven, was employed to get the grade of natural suitability evaluation of reserve resources of arable land, which was then compared with the result evaluated by a comprehensive index model. Evaluation results showed as follows: first, 99.38% of "reference objects" of the arable land are above the third grade on the basis of five suitability grades in total, which means that the fuzzy weight of evidence model could evaluate the natural suitability of reserved arable land effectively. Second, compared with the evaluation results of a comprehensive index model, 90.83% of the arable land resources are above the third grade, which shows the fuzzy weight of evidence model is more objective and reasonable than the comprehensive index model in this case. And it also overcomes the subjective arbitrariness in weight determination and the computation complexity by various natural conditions. Third, 11 434.1 km2 of reserved arable land had suitable natural quality, among which grade 1, 2, 3, 4, and 5 accounted for 9.6%, 5.5%, 38.6%, 22.8%, and 23.4% respectively. And we suggest that Shigatse, Konggar, Chanang, Lhaze, Nedong, Lhasa, and Bainang counties should be the main areas for exploitation of reserved arable land in the future.