基于标准化降水指数与Z指数的萍乡市干旱特征分析

Analysis of Drought Characteristics of Pingxiang City Based on SPI Index and Z Index

基于萍乡市6个监测站点1965~2013年的逐月降雨资料,结合历史干旱资料对比分析了标准化降水指数及Z指数在萍乡市干旱评估中的适用性,并从干旱频率、覆盖范围及强度角度分析了年际和季节干旱特征。结果表明,标准化降水指数在月尺度和季尺度上对萍乡市干旱识别能力优于Z指数,在年尺度上二者表现基本一致,前者更适用于分析萍乡市干旱特征;年尺度上,轻旱及中旱多发于莲花县及芦溪县南部,重旱和特旱则多发于湘东区、上栗县及芦溪县北部,干旱强度和影响范围均呈增大趋势;季尺度上,春旱多发于湘东区、莲花县,夏旱、冬旱多发于中部和东西部,秋旱则多见于湘东区、莲花县和芦溪县,四季干旱具有全域性和局域性特征且多为轻、中旱,冬旱覆盖相对均匀,其余三季干旱覆盖范围呈缩减趋势。

Based on the monthly rainfall data of six monitoring stations in Pingxiang city from 1965to 2013,the applicability of SPI index and Z index in drought assessment was analyzed by combining with the historical drought data.The annual and seasonal drought characteristics were analyzed from aspects of draught frequency,coverage range and intensity.The results show that the SPI index was better than Z index in recognizing the drought on the monthly scale and the seasonal scale,and the performance of the two was basically the same on the annual scale,and the SPI index was more suitable for analyzing drought characteristics of Pingxiang city.In annual scale,light drought and moderate drought mostly occurred in Lianhua county and the south of Luxi county,while severe drought and extreme drought mostly occurred in Xiangdong,Shangli county and northern Luxi county.The intensity and influence range of drought were increasing on the annual scale.In seasonal scale,spring drought was mainly distributed in Lianhua county,Xiangdong,summer and winter drought mostly happened in central,eastern and western,autumn drought mostly happened in Lianhua county,Luxi county and Xiangdong.The four seasons were given priority to with light and medium drought.Drought coverage in spring,summer,autumn was on the decline,while winter drought coverage was relatively uniform.