Floods of May and June 2008 in Iowa

Abstract

An unusually wet winter and spring of 2007 to 2008 resulted in extremely wet antecedent conditions throughout most of Iowa. Rainfall of 5 to 15 inches was observed in eastern Iowa during May 2008, and an additional 5 to 15 inches of rain was observed throughout most of Iowa in June. Because of the severity of the May and June 2008 flooding, the U.S. Geological Survey, in cooperation with other Federal, State, and local agencies, has summarized the meteorological and hydrological conditions leading to the flooding, compiled flood-peak stages and discharges, and estimated revised flood probabilities for 62 selected streamgages. Record peak discharges or flood probabilities of 1 percent or smaller (100-year flooding or greater) occurred at more than 60 streamgage locations, particularly in eastern Iowa. Cedar Rapids, Decorah, Des Moines, Iowa City, Mason City, and Waterloo were among the larger urban areas affected by this flooding. High water and flooding in small, headwater streams in north-central and eastern Iowa, particularly in June, combined and accumulated in large, mainstem rivers and resulted in flooding of historic proportions in the Cedar and Iowa Rivers. Previous flood-peak discharges at many locations were exceeded by substantial amounts, in some cases nearly doubling the previous record peak discharge at locations where more than 100 years of streamflow record are available.

Phytoestrogens and Mycotoxins in Iowa Streams: An Examination of Underinvestigated Compounds in Agricultural Basins

“…4a; Table 3). This temporal pattern of higher concentrations occurred during the early growing season (June) despite potential dilution from extreme flooding conditions that persisted across Iowa (Buchmiller and Eash 2010; Holmes et al, 2010). The ratio of DEA to ATZ (deethylatrazine to atrazine ratio [DAR]) provides a general indication of ATZ residence time (Adams and Thurman, 1991).…”

“…3 In particular, the March sampling captured runoff conditions (Fig. 3) associated with the melting of an above normal snowpack (Buchmiller and Eash, 2010; Holmes et al, 2010). In addition, the June sampling captured record flooding conditions (Fig.…”

“…In addition, the June sampling captured record flooding conditions (Fig. 2 and 3) that persisted across much of Iowa (Buchmiller and Eash, 2010; Holmes et al, 2010), with many of the sampling sites approaching or exceeding the 0.2% flood probability.…”

“…Substantially lower isoflavone concentrations were observed in the June collection. This was likely due to a combination of the flushing of chemical residues from the system during the previous period of snowmelt conditions and subsequent spring rainfall runoff, the early plant stage occurring at this time of the growing season, and the extreme flooding conditions (Buchmiller and Eash, 2010; Holmes et al, 2010) that persisted across Iowa at this time. The median streamflow of sampled sites increased by over an order of magnitude during June from the previous sampling period in March (Table 1).…”

Inundation Mapping Initiatives of the Iowa Flood Center: Statewide Coverage and Detailed Urban Flooding Analysis

“…Record-setting stream discharges were observed at approximately 30 of Iowa's 140 USGS stream gages. Peak discharges at nine gage locations were estimated to exceed the 500-year event, most notably at Cedar Rapids, shown in Figure 4 [31]. At present, no official estimates of damages sustained by the state of Iowa as a result of the 2008 floods exist, but preliminary estimates range from $8B to $10B, nearly equaling damages sustained by Iowa from the 1993 floods [32].…”