The Characteristic Precipitation and Land Surface Conditions that Lead to Flooding over Different Basin Sizes

Abstract:

Flooding occurs across a range of basin sizes, from small catchments to the Mississippi River, and across a range of temporal scales, from flash floods on the order of hours to several weeks. Previous research has primarily focused on scaling of flood peaks, flood processes in catchments, and diagnosis of major events. This research seeks to fill in the gaps between the different studies, by understanding flooding mechanisms across a range of drainage basin size, accounting for precipitation patterns, antecedent soil moisture, and snow. In this study, we use over 250 sub-basins in the Ohio River basin with 60 years of observed precipitation and streamflow and simulated soil moisture and snow with a land surface model. We find that large basins sizes typically have stronger correlation with longer precipitation durations rather than shorter, and vice versa. Soil moisture plays a significant role in determining flooding, but snowmelt also influences the flood generation. Finally, we identify if characteristic precipitation and antecedent moisture conditions lead to floods over different basins sizes. These results have the potential to increase our understanding of flood generation across a range of basin scales, which can then be used to better inform flood predictions under climate change.

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