基于五元减法集对势的山东省旱情动态评价

Dynamic Evaluationand Analysis of Drought in Shandong Province Based on Five⁃Element Subtraction Set Pair Potential

为深入剖析和充分挖掘评价样本与评价等级之间的关系信息,进行区域旱情动态评价,以山东省1972—2003年历史资料作为评价样本,选取水库蓄水量距平百分率、地下水埋深、土壤含水率和降水量距平百分率4个旱情评价指标,采用基于加速遗传算法的模糊层次分析方法确定评价指标权重,通过计算评价样本的指标数联系数、指标值联系数并用最小相对熵原理得到样本的平均联系数,建立了基于集对分析五元联系数的区域旱情评价模型,从而判定山东省旱情等级,并将五元联系数的减法集对势方法应用于山东省旱情动态评价分析,诊断识别山东省旱情的主要脆弱性指标。结果表明:五元联系数旱情评价模型的旱情等级计算值与有关研究的评价结果基本一致,较为符合实际情况;在时间尺度上,山东省总体干旱频率和强度在提高,1981年、1989年、2002年发生特旱且1977—1979年、1981—1984年、1986—1989年、1991—1994年和1997—2002年均发生连续干旱;五元减法集对势诊断和识别出了导致山东省出现严重旱情的主要指标为水库蓄水量距平百分率和降水量距平百分率,地下水埋深呈波动下降趋势也是引起旱情趋于严重的一个重要原因。五元联系数减法集对势克服了常用集对势处理复杂系统的不确定性问题时出现的失真现象,内涵更加丰富,能更好地刻画系统的不确定性趋势,且计算简单、操作方便,为准确判别区域旱情动态评价等集对系统所处状态及总体发展趋势提供了新的思路和途径。

In order to deeply analyze and fully excavate the relationship between evaluation samples and evaluation grades,regional drought dynamic evaluation was carried out.Taking Shandong Province from 1972 to 2003 as samples,and four evaluation indexes were selected,including reservoir water storage level deviation percentage,groundwater depth,soil water content and precipitation level deviation percentage.Moreover,index weights were determined by fuzzy analytic hierarchy process for accelerating genetic algorithm.By calculating index number connection number and index value connection number of the samples and using the principle of minimum relative entropy to obtain the average connection number of the samples,a regional drought evaluation model based on set pair analysis five-element connection number was established to determine the drought level in Shandong Province.And then the subtractive set pair potential method of five-element connection number was applied to dynamic drought evaluation analysis and main vulnerability indexes diagnosis.The results show that calculated value of the drought grade of the five-element connection number drought evaluation model is basically consistent with the results of relevant studies,which is more in line with the actual situation.In terms of time scale,the overall drought frequency and intensity in Shandong Province ware increasing.Special drought occurred in 1981,1989,2002 and continuous drought occurred in 1977-1979,1981-1984,1986-1989,1991-1994 and 1997-2002.The main factors causing drought diagnosed by five-element subtraction set pair potential are the reservoir water storage level deviation percentage and the precipitation level deviation percentage.Groundwater depth shows a fluctuating downward trend,which is an important reason causing drought to become more severe.The five-element connection number subtraction set pair potential overcomes the distortion phenomenon when the common set pair potential is used to deal with the uncertainty issues of a complex system,and the former has richer connotation.Meanwhile,it can better depict the uncertainty trend of the system and is simple to calculate and convenient to operate.Therefore,it provides a new idea and approach for accurately judging the status and overall development trend of set pair system such as regional drought dynamic evaluation.