历史时期以来汉江上游洪涝灾害研究

通过对汉江上游历史时期以来(208BC-2010AD)历史资料的搜集和整理,运用最小二乘法、小波分析和克里格插值等方法,对该区域洪涝灾害等级、时间(阶段、季节、周期等)和空间变化规律及成因进行了研究。结果表明,近2 220a间,汉江上游共发生洪涝灾害336次,平均6.6a发生1次,集中发生在夏秋季节(5-9月份)。该区域洪涝灾害划分为轻度洪灾、中度洪灾、重度洪灾和特大洪灾,分别占洪涝灾害总数的24.7%,29.5%,40.5%和5.3%。小波分析显示各级洪灾分别存在2~5a,38~40a,120a,160a的周期。洪涝灾害发生频率的变化呈现波动上升趋势,大致可分为3个阶段,清代道光年间前期、清代光绪年间和民国后期至20世纪末为洪涝灾害多发期。洪涝灾害空间分布差异明显,以安康盆地为中心向南、向北、向东、向西递减,存在两个高频中心和两个低频中心。大气环流异常,特殊地形条件,河流本身的水系特征,河道的弯曲程度及人类活动的影响是造成该区域洪涝灾害频发的主要原因。

Flood Disaster in Upper Reaches of Hanjiang River During Historical Period

The historical data about flood disaster was collected,reorganized and analyzed in upper reaches of Hanjiang River during the historical period(208BC-2010AD).By using least squares method,wavelet analysis,and the Kriging interpolation,the times when flood disaster occurred(stage,seasons,cycles,etc.),the spatial variation and the causes of flood disaster were studied.The results showed that,during the past 2 220years,the flood disaster mainly occurred in the summer and Autumn(May to September)by 336times with a frequency of once every 6.6years in the upper reaches of Hanjiang River.The flood disaster could be divided into 4classes,mild,middle,great and serious floods,and each class accounted for 24.7%,29.5%,40.5% and 5.3%in the total numbers of floods,respectively.Wavelet analysis showed that,the period of each class was 2~5a,38~40a,120a,and 160a,respectively.The floods showed an increasing trend,and could be broadly divided into three stages.There were three flood-prone periods,the early Qing Dynasty of Emperor Daoguang's Reign,Qing Dynasty of Emperor Guangxu's Reign,and the Late Republic to the end of the 20th century.Flood disasters varied significantly at spatial scale,which were declined from Ankang Basin to periphery,and there are two high-frequency centers and two low-frequency centers.Atmospheric circulation anomalies,special terrain conditions,the river's water system characteristics,the degree of bending of the river and the impact of human activities are the main causes of flood disasters in this region.