Author(s): Larry J. Weber, Iris Brenner, Antonio Arenas Amado

Linked Author(s): Larry J. Weber, Iris Brenner, Antonio Arenas Amado

Keywords: Stochastic Storm Transposition; Physically-based watershed modeling;

Abstract: On June 13th, 2008 after many days of rain, the Cedar River flooded the city of Cedar Rapids at 5.8 meters above flood stage, making its largest flood in the historic record and exceeding the 500 year flood level. To study the effect of varying storm intensities and placements on the day before the peak, we transposed real storms that occurred elsewhere in the Midwest into a physically-based model of the lower part of the Cedar River watershed. By overwriting meteorological radar data from 2008 on June 12th, we were able to simulate the effects of a variety of storm events. We established that a rainfall event with 43 millimeters of accumulation across the watershed (a 2 year return period) on June 12, 2008 would have created a significantly larger flood than the 2008 event. Traditionally, storm scenarios for flood modeling consist of engineered design storms, which are uniformly applied in the study area. By modeling the effects of physically complex storm events that actually happened elsewhere in the region, we can simulate rainfall scenarios that more closely reflect natural phenomena. This study demonstrates the potential for the application of storm transposition in hydrologic modeling and flood impact studies.

DOI: https://doi.org/10.3850/38WC092019-1647

Year: 2019