基于改进的综合气象干旱指数的洞庭湖流域干旱时空特征

Spatial and temporal patterns of droughts in Dongting Lake watershed based on improved meteorological drought composite index

运用改进的综合气象干旱指数,根据洞庭湖流域19个气象站1961—2009年的实测气象资料,运用小波理论分析洞庭湖流域发生的干旱时间差异,并对洞庭湖流域的干旱特征进行空间格局分析。结果表明:从时间格局上,洞庭湖流域发生90%以上范围的干旱周期四季依次为:春季16a,夏季13 a,秋季9 a,冬季16 a;在空间格局上,洞庭湖流域干旱发生程度整体上是以衡阳、邵阳,芷江、通道以西,石门、南县以北三个地区为中心向其四周递减;从季节尺度来看,整体上秋季干旱最为严重,冬季次之,春季干旱最轻。

Based on the improved meteorological drought composite index and measured meteorological data from 19 meteorological stations in the watershed during the period from 1961 to 2009 , the time difference of the drought development in the watershed was analyzed through wavelet analysis , and the spatial pattern of the drought characteristics were analyzed .The results show that the primary cycles of drought that occurred in more than 90%of the coverage area in the watershed were 16 years in the spring , 13 years in the summer , nine years in the autumn , and 16 years in the winter; at the spatial scale , the most severe droughts occurred in the Hengyang-Shaoyang region , the western part of the Zhijiang-Tongdao region , and the northern part of the Shimen-Nanxian region , and the degree of drought decreased in the surrounding regions;and at the seasonal scale , the most severe droughts occurred in the autumn on the whole , followed by the winter , with the most slight droughts occurring in the spring .