Peak-flow frequency analysis for two selected streamgages in the Fourmile Creek Basin in central Iowa, based on data through water year 2018

This data release presents peak-flow frequency analyses by the U.S. Geological Survey that were based on methods described by Eash and others (2013) for streamgages 05485605 Fourmile Creek near Ankeny, Iowa, and 05485640 Fourmile Creek at Des Moines, Iowa. These methods are used to provide estimates of peak-flow quantiles for 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs). Annual peak-flow data used in the peak-flow frequency analysis for these streamgages were retrieved from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2020) and used with USGS flood-frequency analysis software PeakFQ (Veilleux and others, 2014). This data release contains annual peak-flow data (fourmile_ffa_2018_WATSTORE.txt), PeakFQ specifications (fourmile_ffa_2018.psf), and a series of tables describing the methods and results of the peak-flow frequency analysis (fourmile_ffa_2018.xlsx). References Cited: Eash, D.A., Barnes, K.K., and Veilleux, A.G., 2013, Methods for estimating annual exceedance-probability discharges for streams in Iowa, based on data through water year 2010: U.S. Geological Survey Scientific Investigations Report 2013-5086, 63 p. with appendix., http://pubs.usgs.gov/sir/2013/5086/. U.S. Geological Survey, 2020, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed June 20, 2020, at https://doi.org/10.5066/F7P55KJN. Veilleux, A.G., Cohn, T.A., Flynn, K.M., Mason, R.R., Jr., and Hummel, P.R., 2014, Estimating magnitude and frequency of floods using the PeakFQ 7.0 program: U.S. Geological Survey Fact Sheet 2013–3108, 2 p., https://dx.doi.org/10.3133/fs20133108.