The effects of spatial variability of rainfall, geomorphology, and climatology of precipitation and temperature on the hydrologic response remain poorly understood. This study characterizes the catchment response in terms of a variable called flashiness, that describes the severity of the flood response as the rate of rise of the unit discharge. It overcomes limitations of prior works based on limited case studies or simulations by gathering information on basins of widely varying characteristics and by using a high-resolution rainfall and flooding event data set spanning 10 years over the Continental United States. The objective is to develop a robust understanding of how rainfall spatial variability influences flash flood severity and to assess its contribution relative to basin physiography and climatology. This study explores the first-order dependencies as well as the variability in these relationships and investigates the complex interactions using a multi-dimensional statistical modeling approach. The results confirm that the spatial organization of rainfall influences the basin response on par with geomorphology and climatology. Basin physiography dampens the effect of lower rainfall intensities, while higher rainfall overwhelms other factors and primarily contributes to flashiness. Dispersion of precipitation with respect to the flow path decreases flood severity. An improved understanding of sub-basin scale rainfall spatial variability aids in developing a robust flash flood severity index to identify and mitigate flash flooding situations as well as identifying basins which could most benefit from distributed hydrologic modeling.

中文翻译：

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降雨空间变异性、地貌学和气候学对山洪暴发的影响

降雨的空间变异性、地貌、降水和温度的气候学对水文响应的影响仍然知之甚少。本研究根据称为闪蒸的变量来表征集水区响应，该变量将洪水响应的严重程度描述为单位流量的上升速率。它通过收集具有广泛不同特征的流域的信息并使用跨越美国大陆 10 年的高分辨率降雨和洪水事件数据集，克服了基于有限案例研究或模拟的先前工作的局限性。目标是深入了解降雨空间变异如何影响山洪暴发的严重程度，并评估其相对于流域地貌和气候学的贡献。本研究探讨了这些关系中的一阶依赖关系和可变性，并使用多维统计建模方法研究了复杂的相互作用。结果证实，降雨的空间组织与地貌和气候一样影响流域响应。流域地貌抑制了较低降雨强度的影响，而较高的降雨压倒了其他因素，主要是造成闪光。降水相对于流动路径的分散降低了洪水的严重程度。更好地了解子流域尺度降雨空间变异性有助于开发强大的山洪严重程度指数，以识别和减轻山洪暴发情况，以及确定最能从分布式水文建模中受益的流域。