Two-dimensional unsteady state HEC–RAS model to create flood-inundation maps for selected reaches of the Sabinal River and the West Sabinal River near Utopia, Texas, 2021

This data release documents the digital data used to produce flood-inundation maps for a range of gage heights (stages) for the Sabinal River near Utopia, Tex. The simulated flood-inundation maps correspond to a range in stage from 11 to 28 feet (ft) at U.S. Geological Survey (USGS) streamgage 08197970 Sabinal River at Utopia, Tex. at intervals of 0.5-ft. The maps were created for a 10-mile reach of the Sabinal River from USGS streamgage 08197936 Sabinal River below Mill Creek near Vanderpool, Tex., at the upstream boundary of the study reach, to USGS streamgage 08197970 Sabinal River at Utopia, Tex. (hereinafter referred to as the “Utopia gage”), at the downstream boundary of the study reach, and 7-mile reach of the West Sabinal River and were created by the USGS in cooperation with the Bandera County River Authority and Groundwater District and with the Texas Water Development Board. Stage data are collected every 5 minutes and used for estimating areas of inundation near the Utopia gage; the stage data are available from the USGS National Water Information System (NWIS) online database at https://dx.doi.org/10.5066/F7P55KJN (gage information are also directly accessible at https://waterdata.usgs.gov/nwis/). The companion interpretive report (larger work citation) accompanying these digital data is Choi, N., 2023, Flood-inundation maps created using a synthetic rating curve for a 10-mile reach of the Sabinal
River and a 7-mile reach of the West Sabinal River near Utopia, Texas, 2021 (ver 2.0, September 2023): U.S. Geological Survey Scientific Investigations Report 2023–5001, 18 p., https://doi.org/10.3133/sir20235001.
Flood profiles were computed for the stream reach by means of a two-dimensional unsteady state diffusion wave model, Hydrologic Engineering Center's River Analysis System (HEC–RAS; Davidian, 1984; U.S. Army Corps of Engineers, 2016a, b, c). The model results were validated using a synthetic stage-discharge relation at the Utopia gage; the synthetic rating curve was developed based on a regional regression equation by Asquith and others (2013). Detailed information about the methods and data used for this analysis are provided in the companion interpretive report. The flood-inundation maps can be accessed through the Interagency Flood Risk Management Flood Decision Support Toolbox website at https://webapps.usgs.gov/infrm/fdst/.