Scaling Approach to Hydrologic Extremes and Their Dependence on Climate and Basin Characteristics

目前估计极端降水和洪水关系的主要方法是对历史数据的经验曲线拟合和基于经验模型的数值模拟。如果估计非常罕见的事件或气候变化和人类干预对这些极端事件的影响，这两种方法都不准确。不准确的根源在于，在缺乏理论或物理基础的情况下，远远超出历史数据范围的外推变得高度不确定。这些经验关系中有许多是幂型的，反映了观测到的水文事件的尺度不变性质。该项目将使用缩放或分形方法来解决从有限的水文极端数据中推断的问题。将开发一类新的降雨和宽度函数模型，该模型具有这些数量在自然界中观察到的简单和多尺度特性，并将通过广泛的数据分析进行验证。这些模型将多尺度和脉冲叠加两种基本方法结合起来。该项目的最后阶段将包括在气候和流域特征方面对降雨和流域响应进行参数化，利用它们来评估峰值降水和洪水事件对气候、流域特征和人为干预的敏感性。提高对降雨-洪水关系的认识对处于危险中的地区和人民有很大的好处，并将推动最先进的技术。＊＊＊

9612531 Bras The prevalent approaches to estimating extreme precipitation and flood relationships are empirical curve fitting to historical data and numerical simulation also based on empirical models. Both methods become inaccurate if very rare events or the impact of climatic variations and human interventions on such extremes are estimated. The source of the inaccuracy is that, in the absence of a theoretical or physical basis, extrapolation far beyond the range of the historical data becomes highly uncertain. A large number of these empirical relations are of the power-type that reflect the scale-invariant properties of the observed hydrologic event. This project will use a scaling or fractal approach to the problem of extrapolation from limited data of hydrologic extremes. A new class of rainfall and width functions models will be developed which posses the simple- and multi-scaling properties observed in nature for these quantities and that will be validated through extensive data analysis. These models will combine two basic approaches, the multi-scaling and the pulse superposition. The final phase of the project will include the parameterization of rainfall and basin response in terms of climate and catchment characteristics, using them to assess the sensitivity of peak precipitation and flood events to both natural changes in the climate, basin characteristics, and human intervention. Improving the understanding of the rainfall-flood relationship is of great benefit to areas and people at risk and will advance the state-of-the-art. ***