SGER: Anatomy of the 2008 Iowa Flood: Exploring the Interplay Between Successive Storms and Basin Drainage Topology

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Preliminary analysis of the storms preceding the recent Eastern Iowa floods have revealed that there was no single, extreme storm that was responsible for the flood conditions. Instead, the effect of a sequence of storms compounded, affecting locations along the larger rivers in the basin. We propose to investigate: (1) the link between the characteristics of the storms (or group of storms) that caused the floods along the Iowa River; (2) how storm properties are related to flooding as a function of basin scale, following insights from a new geophysical theory of floods; and (3) whether the methodologies developed here can be extended to other large basins using the Hydro?]NEXRAD radar?]rainfall dataset.The urgency of our proposal lies in the pressing need to understand the causes and far?]reaching effects of the 2008 Iowa flood. Undoubtedly, local authorities and communities will be looking to our research facility, IIHR?]Hydroscience and Engineering at The University of Iowa, to analyze the flooding events and offer guidance in adopting measures to prevent or mitigate the effect of future floods. While this proposal addresses a very recent, ongoing natural disaster, it is grounded in our collective, sustained work on the geophysical theory of floods.Intellectual Merit: Over the past 20 years, scientists at the University of Colorado, The University of Iowa, and other institutions have collaborated on a new theory of floods. Recent advances in this theory have revealed the important role played by the self?]similar structure of the river network in determining the magnitude of peak flows. In particular, flow aggregation patterns imposed by the presence of the river network provide explicit guidelines to understand the genesis of extreme flooding events similar to the ones in Eastern Iowa in June 2008. This framework allows rapid and physically meaningful analysis of flood events across a range of spatial scales, without the need to resort to rainfall?]runoff model calibration.Broader Impacts: This work could potentially change the concept of Probable Maximum Precipitation and Probable Maximum Flood and their use in engineering design. The analysis will also offer significant insight into our globally changing climate.