海岸带风暴潮减水的统计分析

在青岛大港观测站连续30年实测资料的基础上,按照年、季、月等时段分别抽样,对风暴潮减水进行了长期统计分析.考虑到海岸地区风暴潮减水的诱因不同,在一维复合极值分布的基础上,提出了"组合分布法".新方法探讨了假设所有数据源于同一分布而产生的重现值估计误差.与年极值法和阈值法的计算结果进行了比较,说明以往算法得到的重现值偏低,并给出了青岛地区受季节变化影响的风暴减水设计重现值.统计表明,青岛大港春、秋、冬季均有风暴减水发生.由于寒潮大风是其产生的主导因素,以冬季的极值减水序列为样本,所得重现值与考虑季节变化得到的重现值相当.说明在实际工程区域,选取主要天气形势产生的水文要素为样本,替代所有观测数据,使统计计算得以简化的做法是可行的.

Statistical analysis of negative storm surge in coastal zone

Thirty years of negative storm surge data measured from Qingdao Dagang Tidal Station are selected to set up different statistical samples according to time division, such as year, season or month. Owing to different reasons of negative storm surge, the Combined Distribution Method is presented based on one-dimensional compound extreme distribution. This paper examines the errors in estimating the return values, which result from the assumption that the whole individual data must have a common parent distribution.Comparison shows that the traditional method under-estimates the return values. The return values of negative storm surge in Qingdao area are given with combined distribution method under the consideration of seasonal variation. The statistical results also show that the negative storm surges occur in spring, autumn, and winter at Dagang, Qingdao. Because the most frequently occurred negative storm surges are caused by cold waves, this paper shows that it is feasible to estimate the return values of the negative storm surge by sampling from dominant climate rather than from the climates occurred all the year around.