基于 SPI 指数与 R／S 分析的曲靖市干旱特征研究

摘要

Using the monthly mean rainfall data during 1960 to 2009 from typical hydrological station in Qujing City ,Yunnan Province ,calculated the multi time scale standardized precipitation index (SPI ) and analyzed the temporal and spatial change characteristics of drought distribution and drought grade in recent 50 years in Qujing City .On this ba-sis ,using the rescaled range analysis method (R/S ) calculated the Hurst index and researched the rule of drought disas-ter in Qujing City .The research showed that :The Qujing City was the drought frequently occurred region ,in whole year at least one-third of the months will been occurred different degree drought disaster .The H values at different time scale of SPI index were total greater than 0 .5 .It explained that the drought disaster in Qujing City had long period memory , and the greater time scale ,the stronger long term memory .Therefore ,the overall trend of drought in future in Qujing City will be associated with the past characteristic ,had the self similarity and the cycle of drought disaster was 15 to 17 years .It was the basic consistent with the actual situation in the Qujing City .%利用云南省曲靖市典型水文站1960—2009年的月平均降水量数据资料，计算多时间尺度标准化降水指数（SPI ）值，分析了曲靖市近50 a的干旱分布和干旱等级的时空变化特点。在此基础上，利用重标极差分析法（R／S分析法）计算Hurst指数，对曲靖市发生干旱灾害的规律进行研究。研究表明，曲靖市是干旱频发地区，全年平均至少有1／3的月份会发生不同程度的干旱灾害，不同时间尺度SPI指数的H值均大于0．5，说明曲靖市干旱灾害具有长期记忆性，且时间尺度越大，这种长期记忆性越强。因此，曲靖市干旱未来的总体趋势将与过去特征相关，具有自相似性并且发生干旱灾害的周期在15～17 a之间，这与曲靖市的实际情况基本一致。