The Study On Analysis About Citrus Trees Low-temperature Disaster Risk Based On GIS Technology In Zhejiang Province

This paper takes agricultural zone as theoretical foundation ,covers meteorological data which are 1971～2006 as data resource. With the supports of GIS, Analytical Hierarchy Process, the paper analyzes Citrus trees low-temperature disaster risk in Zhejiang province and obtained freezing in index. The main conclusions are as followings:(1) Citrus planting can be divided into five main producing in Zhejiang province.①Qu zhou producing, Citrus growing area is 32,600 hectares;②Tai zhou producing, Citrus growing area is 31,100 hectares;③Jin hua producing, Citrus growing area is 24,600 hectares;④Li shui producing, Citrus growing area is 13,200 hectares. Citrus plays producing divis broad,which is in central Zhejiang Province. Northern and southern part of Zhejiang Province are the non-citrus producing areas.(2) Absolute value of negative accumulated temperature in winter to decrease year by year, Since the 90s, winter phenomenon is highlights. Winter warming on the growth of citrus is pros and cons, absolute reduction of negative accumulated temperature, Citrus will be significantly shorter hibernation.Basing on Statistical analysis, the spring freeze are the most in 70's and 80's which is significantly higher than in other years. The maximum data of spring freeze in 70's. Significant climate is warming and most of the year without spring freeze date since 90's.(3) Takes extreme minimum temperature, continuous days, maximum temperature range and harmful accumulated temperature as factors of causing disaster, Between the four factors of causing disaster are obvious correlation, and the four factors of causing disaster is very representative of the province. After these four four factors of causing disaster indicators can be used to assess the degree of vulnerability of Citrus.