土地生态安全预警的惩罚型变权评价模型及应用——以淮安市为例

Application of an Evaluation Model Based on Punishing Variable Weight for Early Warning of Land Ecological Security

日益严重的土地生态问题对人类的生存形成了很大威胁,并直接影响着人类社会的可持续发展。维护土地生态安全最有效办法就是及时发现土地生态安全危险事件的发展趋势并进行预警。针对以往常权评价难以体现土地生态安全预警中动态性要求的缺陷,本文将变权理论引入土地生态安全预警研究,结合层次分析法得到的基础权和预警指标值的动态发展趋势构建了土地生态安全预警的惩罚型变权模型,并用该模型对淮安市1996年-2010年土地生态安全警情变动趋势进行了综合评价和深入分析。结果表明惩罚型变权评价模型能够对基础权重做出局部调整以使评价结果更符合土地生态安全预警的动态性要求,1996年-2005年间淮安市土地生态安全的总体水平也由于自然、社会和经济因素三方面协同作用稳定处于轻警区间并有所提升,而且这一趋势将延续到2006年-2010年。

Land ecosystems have been suffering increasingly serious degradation and destruction resulting from irrational development modes and intensifying human activities,which even threatens human’s survival.Early warning is generally considered one of the most effective ways to maintain land ecological security,which can eliminate land ecological crises at the early stage. Dynamic characteristics of early warning for land ecological security require an immediate review and foreseeing on land ecological crises.Aiming at overcoming the drawbacks of the model with constant weights that is not able to well reveal dangerous factors,the authors introduced the variable weight theory to early warning of land ecological security in the present paper.First,a warning index system of land ecological security can be established and the warning limit for each index can be determined.Second,Forecasting values of the warning indices can be estimated for further warning.Third,the‘basic weight’can be determined by certain methods,such as analytic hierarchy process（AHP）.Fourth,the basic weight of each warning index in corresponding periods can be appropriately adjusted to a higher level in that actual values of the index were relatively lower than that at the denial level.At the last,a comprehensive evaluation value can be calculated using the specified index value and variable weight in conjunction with the punishing variable weight model.A lower comprehensive evaluation value would result in a lower actual value and a higher variable weight,which is the principle of the‘punishing variable weight’.The authors applied the punishing variable weight model to Huai’an City,Jiangsu Province.Variation trends in land ecological security for the city during the period 1996-2010 were systematically evaluated and analyzed using the punishing variable weight model.Results showed that the variable weight value of the warning index was higher than its basic weight;however,its corresponding comprehensive evaluation value was found to be lower than that from the basic weight evaluation.Furthermore, the changing range of the weight was different in terms of basic weights.The general level of land ecological security of Huai’an City during 1996-2005 was shown to be relatively steady on the interval of high warning,which was caused by combined effects of natural factors,social factors and economic factors.However,some values with regard to human activity factors lay in the interval of moderate warning primarily owing to the increasing occupation of cultivated land through construction activities and to decreases in pollutant disposal levels as well.If relevant departments could take more positive and effective measures in protecting cultivated land,reducing emissions of pollutants,promoting social equality and balancing regional development,the land ecological security conditions would be continued and even increase during the period 2006-2010.