Research On The Evaluation Of Land Ecological Security In Dali City Based On OWA

With the increase of population,urbanization and industrialization,human growth of the scope and intensity of land use,the contradiction between people and land have become increasingly prominent.Accompanied with the ecological problems of soil erosion,loss of biodiversity,soil and vegetation destruction,land desertification,land quality decline and a series of increasingly serious,more and more domestic scholars focus on ecological land safely.Dali city is at combinative department of Yunnan-Kweichow Platea and Hengduan mountains.With the complex diversiform,the mountainous area accounts for 70% of the city’s total land area,flat land available resources are very limited.So the mountain town and low hilly land development has become the inevitable trend of future development,and it will have a significant impact on the land ecological system.With the problem of fragile ecosystem and frequent geological disaster,it’s necessary to evaluate the situation of land ecological security.This paper combine the ordered weighted average(OWA)model with GIS software,then the multi-criteria evaluation method was applied to land ecological security in Dali through IDRISI.The main contents are as follows:(1)The land ecological security evaluation index system is set up from the natural ecological factors、environmental factors、landscape factors.(2)Normalizes the data from the geospatial data cloud、the second land survey and other research of Dali such as vegetation coverage、geological disasters and soil conservation,then translate the result into raster file.(3)The criteria weights and order the weight of each index is determined according to the analytic hierarchy process(AHP)and fuzzy quantization method.(4)Seven different decision risk coefficients of the land ecological security evaluation results are obtained by using block MCE of IDRISI.The results show that:(1)Due to the decision risk can be adjusted,the land ecological security evaluation result based on OWA-GIS is more flexible than the traditional evaluation method.(2)To get more true and effectively results,decision makers have to select different risk according to the actual situation and planning purposes.When the decision makers are willing to assume greater risk,they can make the risk coefficient 2 or 10.When the decision makers think the all the index are equally important,they can make the risk coefficient 1.When the decision makers want to avoid risk,they can make the risk coefficient 0.5.When the risk coefficient becomes 0.0001、0.1 and 1000,the result is extreme and has no practical significance.(3)By contract,we find that,in general,when the risk coefficient is 1 or 2,the land ecological security situation of the plain area of the west of Erhai is best,Taiyi village is the worst,and others is better.When the risk coefficient is 10,the land ecological security situation of Dali improved apparently,especially the Taiyi village.When the risk coefficient is 0.5,the land ecological security situation of the plain area of the west of Erhai directly transforms from early warning to serious warning.