Extreme Flood Response: The June 2008 Flooding in Iowa

Abstract

The authors examine the hydroclimatology, hydrometeorology, and hydrology of extreme floods through analyses that center on the June 2008 flooding in Iowa. The most striking feature of the June 2008 flooding was the flood peak of the Cedar River at Cedar Rapids (3964 m 3 s 21 ), which was almost twice the previous maximum from a record of 110 years. The spatial extent of extreme flooding was exceptional, with more U.S. Geological Survey stream gauging stations reporting record flood peaks than in any other year. The 2008 flooding was produced by a sequence of organized thunderstorm systems over a period of two weeks. The authors examine clustering and seasonality of flooding in the Iowa study region and link these properties to features of the June 2008 flood event. They examine the environment of heavy rainfall in Iowa during June 2008 through analyses of composite rainfall fields (15-min time interval and 1-km spatial resolution) developed with the Hydro-NEXRAD system and simulations using the Weather Research and Forecasting Model (WRF). Water balance analyses of extreme flood response, based on rainfall and discharge observations from basins with extreme flooding, suggest that antecedent soil moisture plays a diminishing role in flood response as the return interval increases. Rainfall structure and evolution play a critical and poorly understood role in determining the scaling of flood response. As in other extreme flood studies, analyses of the Iowa flood data suggest that measurement errors can be significant for record discharge estimates.

The role of storm scale, position and movement in controlling urban flood response

“…The largest overlap in storm events, 69 %, is found for the two largest basins, 48.5 and 111.1 km 2 in size. This confirms results reported by Smith et al (2013b) and Zhou et al (2017), who also found markedly different rainfall climatologies for flood-producing storms in basins of different size.…”

Analyzing the effects of excess rainfall properties on the scaling structure of peak discharges: Insights from a mesoscale river basin

“…The derivation of equation (13) is based on the hydraulic-geometric properties of channel networks [Mantilla, 2007]. We used spatially and temporally constant values for [Mutel, 2010;Smith et al, 2013] that occurred in the Iowa River basin using the Stage-IV radarrainfall product [Kitzmiller et al, 2013] as input. The results clearly show that the model can reasonably reproduce observed streamflow time series across a range of spatial scales and, as a result, the spatial scaling property of peak discharges.…”

Remote sensing-based characterization of rainfall during atmospheric rivers over the central United States

“…Lavers and Villarini (2013) showed that more than 60% of the annual maximum floods during 1979-2011 period were associated with ARs over much of the central United States, with seven out of the ten largest floods associated with these storms. Moreover, ARs are the mechanisms responsible for some of the most devastating flooding events over this region in recent decades, including the floods of July 1993 (Dirmeyer and Kinter, 2009), June 2008 floods over eastern Iowa (Budikova et al, 2010;Smith et al, 2013), May 2010 flood in Nashville (Tennessee) and surrounding areas (Moore et al, 2012), and the flood of April 2013 over Chicago and eastern Iowa (Campos and Wang, 2015;Nayak et al, 2016).…”