论设计洪水计算

Research on design flood calculation

论述了作为随机现象的洪水的致灾率和风险率,以及防洪工程措施减小洪水致灾率或风险率的功能。认为防洪计算的任务是:基于洪水的统计规律,建立调洪库容-调节流量-频率(重现期)的关系,而不是直接推求洪水的多维联合分布。证明了基于概率论和数理统计的防洪计算途径理论上的正确性和实用上的不可能性,分析了同倍比法和同频率法产生的背景,通过与数理统计途径的对比,揭示了借助于"设计洪水过程线"概念建立起来的这两个方法的理论基础。指出峰量频率计算在同倍比法和同频率法中的关键作用,以及对旨在依据小样本推估无限总体统计特性的峰量频率计算,提高其成果稳定性的重要性和可能性。

Taken flood as a random phenomenon, the probability of failure due to flood and the probability of risk due to flood were discussed. To reduce them, the function of flood control engineering was also discussed. The task of flood control calculations is to establish the relations among the flood regulation storage, regulated flow and frequency （i. e. recurrence period） by means of statistical law of flood rather than the solution of the multidimensional joint distribution of the flood. The flood control calculation with probability theory and mathematical statistics is theoretically correct and practically impossible. The background of the method of enlarging by the same ratio and the method of enlarging in the same frequency was analyzed, and their theoretical bases, founding on the concept of design flood hydrograph, were revealed through the comparison with the approach of mathematical statistics. The critical role of the frequency computation of peak discharge and flood volume used in both the methods is indicated, as well as the importance and possibilities to strengthen its research, which rely on a small sample to calculate statistical characteristics of infinite population.