江汉平原旱涝时空分布特征

THE FEATURES OF SPATIAL AND TEMPORAL DISTRIBUTION OF DROUGHTS AND FLOODS IN JIANGHAN PLAIN

利用历史旱涝资料向现代降水资料，总结了江汉平原旱涝时空分布特点：（１）旱涝多发且涝多于旱。旱涝在年际上分配不均，年旱涝等级序列呈现２年、５～６年、２２年、４０年左右变化准周期。旱涝还存在持续性和转换性特点。（２）旱涝在季节上有集中性，夏季夏涝最多，秋旱多于春旱，而春涝多于秋涝，夏秋连旱亦多发。另外，夏季洪涝与秋冬干旱在一定程度上相关。（３）旱涝在空间分布上略有差别，北京及东北京旱较多，而南部涝较多，各季节旱涝频率在区域上亦有差异。

According to the historical flood-drought records and present precipitation data, the features of spatial and temporal distribution of droughts and floods in Jianghan Plain were summarized as follows: (1) Both droughts and floods occurred frequently, and floods were more frequent than droughts; the floods and droughts were not evenly distributed in years; the array of interannual drought-flood grade showed periods of 2,5～6,22,and 40 years. (2) Droughts and floods might occur all the year round, but most frequently in summer, and droughts in autumn were more frequent than those in spring, floods in spring were more frequent than those in autumn; continuous droughts in summer and autumn were also frequent. In addition, autumn and winter droughts interrelated with summer floods to certain degree. (3) Flood-drought frequencies varied with regions, being more droughts in the north and the northeast than in the south, but more floods in the south than in the north, and the frequency of floods and droughts in each season varied also with the region.