Results of weighted least-squares (WLS) regression for 42 USGS streamgages in urban areas in Alabama and Mississippi

This dataset contains results of weighted least-squares (WLS) regression for 42 streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) on urban streams in Alabama and Mississippi. WLS regression was used to relate drainage area and the percentages of the drainage basins of the streamgages in developed land use (the sum of classes 21-24 from the 2011 National Land Cover Database; Homer and others, 2015) to previously published estimates of streamflows corresponding to the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 annual exceedance probabilities (AEPs; Wagner, 2025). From this regression, equations were developed that can be used to predict streamflows corresponding to the eight selected AEPs at ungaged locations on urban streams (percent developed land use greater than 20%) in the study area. Drainage area and the percentages of the drainage basins in developed land use were generated using version 1.5.1 of the batch processor in the USGS StreamStats application (U.S. Geological Survey, 2025). Geographic Information System (GIS) shapefiles of points representing the locations of the streamgages snapped to the stream grids for StreamStats ("AL_MS_UrbanFFreq_sites.zip") and the polygons representing the streamgage basins ("AL_MS_UrbanFFreq_basins.zip") are included in this dataset. Standard errors of prediction of the regression equations ranged from 23.1 percent for the 0.04 AEP (the 25-year flood) to 36.1 percent for the 0.002 AEP (the 500-year flood). WLS regression was conducted using version 3.0 of USGS weighted regression (WREG) software (Farmer, 2019; Eng and others, 2009). The input and output files from WLS regression in WREG are located within the "WREG.zip" folder. The input files are a text file of basin characteristics for all 42 selected streamgages in the study area ("AL_MS_SiteInfo.txt") and the peak-flow ("AL_MS_UrbanFFreq_nwis_peak.txt") and specification ("AL_MS_UrbanFFreq.psf") files from at-site flood-frequency analysis in version 8.0.0 of USGS PeakFQ software. The following WREG output files are located in the "WLS_output" directory in sub-directories by AEP: "coef.txt," "CoVarMat.txt," "FitandResid.txt," "modelInput.txt," "outputRaw.rda," "PerformanceMetrics.txt," "ResLevInf.txt," and "Weighting.txt". USGS site information, values of the basin characteristics, WLS estimates of streamflows corresponding to the selected AEPs and their variances, and the residual from WLS regression are in file "WLSresults.csv". The regression equations for each AEP and their associated performance metrics are in file "RegressionEquations.csv".

[
  "010:12"
]

[
  "geospatial"
]