淮河流域极端降水与极端流量关系的研究

Relationship between extremes of precipitation and discharge in the Huaihe river basin

通过对淮河流域各气象站月降水和水文站月流量的广义帕累托分布(generalized ParetoDistribution)(GPD)函数拟合,分析比较了二者概率分布特征之间的异同,尤其对二者极端事件灾害风险之间的异同进行了定量化的对比分析.指出淮河流域月降水的概率函数特征在整个区域上具有相似性,接近于指数分布.而月流量相对于月降水概率分布更分散,并且其特征在流域上游和中游存在一定差异.由此发现,在水文循环过程中,淮河河流在区域尺度上可以减低由极端降水事件引发河流洪涝灾害的风险.这一作用在上游表现更为显著,往下游随着流域面积的不断扩大,这一作用逐渐减小,极端月流量事件发生的风险趋近于极端月降水事件.这一结论对于淮河流域天然河道与水利设施在淮河治理中的作用和洪涝治理规划具有参考意义.

The extreme monthly precipitation and discharge in the Huaihe river basin are fitted by the generalized Pareto distribution （GPD） function, and the fitted parameters of GPD are analyzed and compared. The characteristics of probability functions of the extreme monthly precipitation are similar in the whole Huaihe river basin, and it is denoted that the features of precipitation in Huaihe river basin are the same. And there are some differences between the upper and middle reaches in the characteristics of probability functions of the extreme monthly discharge. The curve-fitted shape parameters of the extreme monthly discharge are larger than those of the extreme monthly precipitation. It means that the return period of the extreme monthly precipitation events is longer than the return period of the extreme monthly discharge events for the same intensity. So the natural rivers and hydraulic engineering can adjust the process of natural hydrological cycle and reduce the risk of flooding disaster resulting from the extreme precipitation events in the regional scale. This effect is more significant in the upper reaches and weakens in the middle reaches as the basin area increases, and the risks of the extreme monthly discharge events and precipitation events are closer over lower reaches. This conclusion is useful for natural rivers and hydraulic engineering planning and the flood controlling in the Huaihe river basin