山洪灾害临界雨量研究综述

A review of rainfall thresholds for triggering flash floods

临界雨量是一个关键的山洪灾害预警指标。按其技术原理将临界雨量推求方法划分为数据驱动的统计归纳法和基于灾变物理机制的水文水力学法分别进行评述,并介绍了临界雨量指标的两个拓展:动态临界雨量和暴雨临界曲线,综述了临界雨量不确定性分析的研究进展。通过综述发现:中国目前主要应用的是较简单的统计归纳法;临界雨量推求主要考虑前期降雨量(前期土壤饱和度)和时段累积降雨量两个因素的影响或仅后者一个;临界雨量指标难以反映山洪灾害的规模;考虑临界雨量不确定性有助于提高预警质量,但如何充分考虑其影响仍然是一个挑战。

The rainfall threshold is an important indicator of flash flood conditions. In this study, the existing methods for computing rainfall thresholds are divided into two categories and reviewed on the basis of their technical principles. The two categories include the data-driven statistical and inductive methods and the physical process-based hydrologic hydraulic methods. As expansions of rainfall thresholds, the dynamie rainfall threshold and the storm critical curve are also introduced and discussed together with advances in uncertainty analysis of rainfall thresholds. In our review, the statistical and inductive methods have been more widely accepted in China. Moreover, antecedent rainfall （or ante- cedent soil saturation） and cumulative rainfall at particular time intervals are the two governing factors commonly con- sidered in the calculation of rainfall thresholds. Cumulative rainfall may be the loneliness factor to be considered at times. Further, it is found that the rainfall threshold conveys poorly the magnitude of flash flooding. Understanding of the uncertainty in rainfall threshold calculations would be helpful for the improvement of flash flood warnings. However, how to incorporate the uncertainty into the decision-making proeess still remains a major challenge.