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- Title
On the Impact of Rainfall Spatial Variability, Geomorphology, and Climatology on Flash Floods.
- Authors
Saharia, Manabendra; Kirstetter, Pierre‐Emmanuel; Vergara, Humberto; Gourley, Jonathan J.; Emmanuel, Isabelle; Andrieu, Hervé
- Abstract
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. Plain Language Summary: This study aims at understanding the effects of rainfall, geomorphology, and climatology on the flash flood response at the hydrologic event scale. To investigates, these interactive processes, it uniquely gathers 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 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 the flood response. Dispersion of precipitation with respect to the stream network decreases flood severity. An improved understanding of the rainfall spatial variability at sub‐basin scale aids in identifying and mitigating flash flooding situations. Key Points: The impact of rainfall spatial variability, physiography and climatology on flood severity is empirically investigated for the first timeSeverity increases with basin slope and accumulated precipitation, and decreases with rainfall dispersion w.r.t. the flow pathBasin physiography dampens the effect of lower rainfall intensities, while higher rainfall overwhelms other factors
- Subjects
CLIMATOLOGY; GEOMORPHOLOGY; FLOODS; HYDROLOGIC models; STATISTICAL models
- Publication
Water Resources Research, 2021, Vol 57, Issue 9, p1
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1029/2020WR029124