德州市近50年来旱涝特征分析

Analysis Latter 50 Years of the Drought-flood Characteristic in Dezhou City

对德州市1951～1999a的逐年降水数据、区域旱涝灾害成灾面积及降水与成灾之间的相关性进行了统计分析。依据Z指标划分了7个旱涝等级,给出了旱涝指标与旱涝成灾面积的多年变化趋势以及它们之间的相关系数。结果表明：德州市近50a来,降水变化呈下降趋势;1975a以前偏涝,间或有旱的年份出现,极涝年份为1953、1961、1964a;1975a以后偏旱,间或有涝的年份出现,极旱年份为1981a;旱灾面积越来越大,涝灾面积越来越少,60～70年代为旱涝灾害成灾面积变化的转折点。降水指标为该市今后旱涝预测提供了可能的途径。

The precipitation and the disaster area data in Dezhou 1951～1999 and the relativity between them are analyzed. It compartmentalized seven drought-flood grades by Z-index. The perennial variety current and the interfix coefficient between precipitation and disaster area are given. It indicates that there is more and more droughty trend latter 50 years in Dezhou. In general, the majority of years are waterlogged before 1975a except few years and the years of severe flood in 1953a, 1961a and 1964a; while after 1975a, it appears contrary case and the year of severe drought in 1981a. There are more and more drought area and less and less flood area and 60～70＇s is the turning point. The precipitation index provides a possible way to forecast the drought or flood in this city.