应用Z指数方法判断南方季节性干旱的结果分析

Analysis of Seasonal Drought Applying Z-index Method in South China

应用"Z指数法"来判断"土壤-作物"系统法所确定的干旱事件并进行对比分析得出:两种方法的指标既相互联系又存在差异。桃源县1960～2001年27次中等和中等以上干旱事件中一致率为29 6%,基本一致率为44 5%,错误率为25 9%,"一致"的个例多出现在60年代,"基本一致"多出现在70～80年代,"错误"多出现在90年代;两者在夏季发生的旱灾中一致性较好,秋季一般,冬季较差;重灾一致性较好,中、轻灾一致性较差;用"土壤-作物"系统法指标判断干旱,重旱约每3年一遇、中旱约1 9年一遇;用Z指数方法标准判断,重旱每7年一遇、中旱约2 1年一遇。

The Zindex method was applied to judge the drought grades of 27 moderate or upward droughts determined by the 'soilplant' system method during 1960～2001 in Taoyuan County, Hunan Province Comparison results of two methods showed that the indices calculated by two methods were relative, but different from each other The ratio of consistency between both methods was 296%, basic consistency of 445% and wrong of 259% In which the droughts of 'consistency' happened in 1960s, 'basic consistency' in 1970s or 1980s, 'wrong' in 1990s The consistency of the calculated results by two methods was high for summer droughts, moderate for autumn droughts and low for winter droughts The better consistency was obtained in calculating heavy drought By comparing drought frequency using two methods, it concluded that the heavy droughts occurred every 3 years by 'soilplant' system method and every 7 years by Zindex method, while for moderate drought the frequency was 19 years by 'soilplant' system method and 21 years by Zindex method