闽北山洪致灾临界雨量重现期分布及山洪风险分析

Distribution of Critical Precipitation Return Period of Mountain Flood in Northern Fujian and Analysis of Flood Risk

根据山洪发生时的降水资料、洪水淹没记录和地理信息资料,利用二维水动力模型＂Floodarea＂,计算闽北山洪6h致灾临界雨量;根据多年降水资料,计算闽北气象站各重现期6h最大降水量,并利用ArcGIS进行区域插值计算.结果表明,闽北6h最大降水量高值区位于西部、东部和中南部部分地区;山洪低致灾等级临界雨量相当于5年以内重现期的6h最大降水量,多数为1年;中致灾等级临界雨量相当于2-5年重现期的6h最大降水量,少数为1年;多数山洪沟高致灾等级临界雨量相当于5年以上重现期的6h最大降水量,少数2年以内.天气背景分析表明,闽北地区短历时强降水主要由锋面暴雨和台风暴雨引起.

For the area of Northern Fujian,with local data of precipitation,flood water depth,digital elevation model date（DEM）over the hydrodynamic model＂Floodarea＂,the study works out the 6-hour critical precipitation of mountain flood.Based on historical data of the meteorological station,the maximums of 6-hour precipitation amount,at various return periods,are figured out,and interpolates these results,by the means of Kriging,into the area of Northern Fujian.The results show that：1）the high-value areas of the maximum of 6-hour precipitation are around the west,east and parts of southern central of Northern Fujian;2）the low grade critical precipitation of mountain flood amounts to the maximums of 6-hour precipitation of return periods of less than 5a,and most for 1year;3）the medium grade critical precipitation matches the return periods of 2—5a,and few for 1year;4）the high grade one matches the return periods of 5aabove,and few for 2year or less.According to the synoptic analysis,the heavy rainfalls of short lifetime are mainly caused by the frontal rainstorms or typhoons.