Abstract:

Cultivated land suitability evaluation of the plateau is an important prerequisite to promote the planning of regional agricultural development and the construction of food security system. This paper takes cultivated land of 18 counties in the Yarlung Zangbo River, Nyangqu River and Lhasa River (YNL) region of Tibet as the object of evaluation. The fuzzy weight of evidence model is introduced to screen out nine factors included in the four aspects of topography, climate, soil and water conditions as evidence layers, calculate the fuzzy weight of evidence of factor layer, and finally synthesize parameters of all factor layers to calculate posterior probability weight and revise it to format a distribution map of cultivated land suitability. The study shows that: 1) 80.83% of the known suitable points are above moderately suitable level in the grading figure of modified posterior probability, reflecting a high coherency, which indicates that the fuzzy weight of evidence connecting with modified posterior probability can evaluate the suitability of cultivated land scientifically and effectively. 2) Fuzzy weight of evidence model, which is both data-driven and knowledge-driven, can give full play to the prior knowledge and the role of objective laws. It can also increase the intervention of knowledge by the membership function, effectively using the experience of experts, which, to some extent, avoids arbitrariness in selecting indicators and determining the weight in the knowledgedriven method and overcomes the weakness of purely data-driven method. 3) Highly suitable, moderately suitable, generally suitable and unsuitable culti-vated land in the study area cover 213200 hm² of cultivated land, accounting for 32.03%, 31.94%, 27.19% and 8.84% respectively, which corresponds to the spatial distribution. This can optimize the scale and layout of cultivated land and also can be used in the practice of cultivated area on the plateau to promote the rational utilization and management of cultivated land.

Key words: cultivated land suitability evaluation, modified posterior probability, the YNL region, Tibet, fuzzy weight of evidence, land use