Precipitation-driven flood-inundation mapping of the Little Blue River at Grandview, Missouri

First posted July 26, 2021 Revised January 7, 2022 For additional information, contact: Director, Central Midwest Water Science Center U.S. Geological Survey1400 Independence Road Rolla, Missouri 65401 The Survey (USGS), in cooperation with the City of Grandview, Missouri, assessed flooding Little Blue River at Grandview resulting from varying precipitation magnitudes and durations expected land-cover changes. scenarios were used to develop a library flood-inundation maps that included 3.5-mile reach tributaries within adjacent city.A hydrologic model upper Basin hydraulic selected study constructed assess streamflow associated simulated amounts conditions. Army Corps Engineers Hydrologic Engineering Center-Hydrologic Modeling System (HEC–HMS; version 4.4.1) was simulate amount produced range rain events. Center-River Analysis (HEC–RAS; 5.0.7) then construct steady-state map areas flood inundation.Both models calibrated May 28, 2020, high-flow event peak approximating 10-percent annual exceedance probability (10-year flood-frequency recurrence interval) streamgage (USGS station 06893750). HEC–HMS streamflows design rainfall events 1- 8-hour ranging 100- 0.2-percent probability. Flood-inundation for USGS stages 17.0 feet (ft), or near bankfull, 23.0 ft, stage exceeding interval flood, using HEC–RAS model. consequence each duration-frequency value represented by 1-ft increment inundation based on generated corresponding reference streamgage.Four developed model: (1) current (2016) land cover, normal antecedent soil-moisture conditions; (2) wet (3) future (4) condition estimated anticipated development basin. All input into four moisture conditions assigned flow streamgage.