甘肃省强降水变化特征

利用甘肃省1960~2011年逐日降水量及1984~2011年暴洪灾害的灾情资料,分析了甘肃省强降水变化特征及其对社会经济的影响。结果表明:(1)近52 a来,甘肃省降水量整体上呈逐年减少趋势,空间上由东南向西北递减;(2)河西年降水在1986年以后均匀度明显下降,而河东在20世纪70年代后期降水时间分布很不均匀、80年代后期较均匀,其它时间变化不大;河西5~9月降水在20世纪80年代后期到90年代前期分布最不均匀,河东20世纪90年代后期到21世纪初期降水不均匀性有所增加,此后逐渐减小;(3)河西西部一直是近50 a甘肃降水量分布最不均匀的地区,20世纪70年代及21世纪以来不均匀度明显较高;(4)20世纪80年代以来,甘肃河西强降水明显增加,而河东在21世纪初有短时段的增加,2008年以后又逐渐减少;(5)甘肃省暴洪灾害的频次及其造成的直接经济损失均呈增加趋势,而因暴洪灾害造成的死亡人数在减少,2009年以后略有增加。

Variation Characteristic of Heavy Rainfall in Gansu Province

Based on daily precipitation data during 1960-2011 and flood disasters data in Gansu Province during 1984-2011,the spatial and temporal distributions of heavy rainfall and its impact on social economy were analyzed. The results were as follows：（ 1）The annual precipitation in Gansu showed a declining trend from 1960 to 2011 as a whole,and the precipitation decreased gradually from southeast to northwest.（ 2） The evenness of precipitation in time domain in Gansu Province was different during 1962-2001,and that in Hexi was distinctly lower than that in Hedong. The evenness in annual rainfall in Hexi region decreased obviously since1986,and the rainfall from May to September from the late 1980s to the early 1990s was the most uneven,while the temporal distribution in annual rainfall of Hedong region was uneven in the late 1970s and even in the late 1980s,and the unevenness of rainfall from May to September from the late 1990s to the early 21st century increased.（ 3） The temporal distribution of rainfall in western Hexi was always the most uneven in Gansu Province in the past 50 years,and the unevenness of rainfall in the 1970s and the 2000s was higher significantly.（ 4） Since the 1980s,heavy rainfall in Hexi region increased significantly,while that in Hedong region had a briefly increase in the early 21st century,and dropped again since 2008.（ 5） The frequency of flash flood and the direct economic losses caused by flash flood disasters in Gansu Province showed a increasing trend,and the death persons caused by flash flood declined,but rose slightly after 2009.