Skip to main content
U.S. flag

An official website of the United States government

At-site flood frequency estimates for 64 urban streamgages in Alabama and Mississippi using data through water year 2024 (ver. 2.0, August 2026)

Published by U.S. Geological Survey | Department of the Interior | Catalog Last Checked: August 06, 2026 at 10:53 PM | Dataset Last Updated: August 04, 2026 at 12:00 AM
This dataset contains site information and results of flood frequency analysis for 64 urban streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in Alabama and Mississippi. Site information and annual peak-flow data from the 1885 - 2024 water years were obtained from the USGS National Water Information System (NWIS) database (U.S. Geological Survey, 2025). Flood frequency analysis was conducted in version 8.0.0 of USGS PeakFQ software (Siefken and others, 2024) in the R environment (R Core Team, 2024) following the guidelines set forth in Bulletin 17C (England and others, 2018) and using the approaches described in the most recent flood frequency reports for Alabama and Mississippi (Anderson, 2020 and Anderson, 2018, respectively). Site information is provided in .csv format ("AL_MS_UrbanFFreq_SiteInfo.csv"). Peak-flow ("AL_MS_UrbanFFreq_nwis_peak.txt"), specification ("AL_MS_UrbanFFreq.psf"), and output files from PeakFQ ("AL_MS_UrbanFFreq_emp.csv", "AL_MS_UrbanFFreq_lp3.csv", "AL_MS_UrbanFFreq_mgb.csv", "AL_MS_UrbanFFreq_qnt.csv", and "AL_MS_UrbanFFreq_trd.csv") are provided. Estimates of the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 annual exceedance probabilities (the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively) are in file "AL_MS_UrbanFFreq_qnt.csv". The data release was revised July, 2026. Column "index_no" was added to file "AL_MS_UrbanFFreq_SiteInfo.csv" and a description of the column was added to the metadata. The values in column "index_no" are used as the streamgage labels in Figure 1 in the related primary publication.

Resources

2 resources available

Find Related Datasets

data.gov

An official website of the GSA's Technology Transformation Services

Looking for U.S. government information and services?
Visit USA.gov