This data set consists of digital county boundaries for Oklahoma. The boundaries were derived from U.S. Geological Survey 1:100,000-scale Digital Line Graph data sets. Two attributes are associated with each county polygon. The first is the FIPS code and the second is the county name.

These geospatial data sets consist of precipitation stations used in a regional precipitation frequency analysis for Oklahoma. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Three different rain gage networks provided the data (15-minute, 1-hour, and 1-day). Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Precipitation annual maxima (depths) were determined from the station data for each duration for 110 15-minute stations (used for 15-, 30-, and 60-minute durations), 141 hourly stations (used for 1-, 2-, 3-, 6-, 12-, and 24-hour durations), and 413 daily stations (used for 1-, 3-, and 7-day durations). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma" by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232. Depth-duration-frequency estimates and interpolated surface values are included in the point attribute tables. One geospatial data set is provided for each of the 12 durations.

These geospatial data sets consist of precipitation stations used in a regional precipitation frequency analysis for Oklahoma. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Three different rain gage networks provided the data (15-minute, 1-hour, and 1-day). Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Precipitation annual maxima (depths) were determined from the station data for each duration for 110 15-minute stations (used for 15-, 30-, and 60-minute durations), 141 hourly stations (used for 1-, 2-, 3-, 6-, 12-, and 24-hour durations), and 413 daily stations (used for 1-, 3-, and 7-day durations). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma" by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232. Depth-duration-frequency estimates and interpolated surface values are included in the point attribute tables. One geospatial data set is provided for each of the 12 durations.

These geospatial data sets consist of precipitation stations used in a regional precipitation frequency analysis for Oklahoma. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Three different rain gage networks provided the data (15-minute, 1-hour, and 1-day). Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Precipitation annual maxima (depths) were determined from the station data for each duration for 110 15-minute stations (used for 15-, 30-, and 60-minute durations), 141 hourly stations (used for 1-, 2-, 3-, 6-, 12-, and 24-hour durations), and 413 daily stations (used for 1-, 3-, and 7-day durations). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma" by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232. Depth-duration-frequency estimates and interpolated surface values are included in the point attribute tables. One geospatial data set is provided for each of the 12 durations.

These geospatial data sets consist of contours derived from surface grids of precipitation depths for seven frequencies at 12 durations used in a regional precipitation frequency analysis for Oklahoma. Eighty-four depth-duration-frequency contour maps were produced from precipitation-station data. The contour interval varies from 0.05 to 0.5 inch. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma," by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232.

These geospatial data sets consist of contours derived from surface grids of precipitation depths for seven frequencies at 12 durations used in a regional precipitation frequency analysis for Oklahoma. Eighty-four depth-duration-frequency contour maps were produced from precipitation-station data. The contour interval varies from 0.05 to 0.5 inch. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma," by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232.

These geospatial data sets consist of contours derived from surface grids of precipitation depths for seven frequencies at 12 durations used in a regional precipitation frequency analysis for Oklahoma. Eighty-four depth-duration-frequency contour maps were produced from precipitation-station data. The contour interval varies from 0.05 to 0.5 inch. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma," by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232.

These geospatial data sets consist of surface grids of precipitation depths for seven frequencies at 12 durations used in a regional precipitation frequency analysis for Oklahoma. Eighty-four depth-duration-frequency surfaces were interpolated from precipitation-station data. The grid-cell spacing is 2,000 meters. Each depth-duration-frequency surface was interpolated using the same interpolation function and parameters. Data were used from precipitation gage stations with at least 10 years of record within Oklahoma and about 50 kilometers into bordering states. Data were analyzed for seven frequencies (expressed as recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and 60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and 7-days). Statistical methods were used to estimate precipitation depths for each duration-frequency at each station. These station depth-duration-frequency estimates were interpolated to produce continuous grids with grid-cell spacing of 2,000 meters. Contour lines derived from these surfaces (grids) were used to produce the maps in the "Depth-Duration Frequency of Precipitation for Oklahoma," by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S. Geological Survey Water-Resources Investigations Report 99-4232. These geospatial data sets may be used to determine an interpolated value of depth-duration-frequency of precipitation for any point in Oklahoma.

This digital-map data set consists of a grid of mean annual precipitation, in inches, based on the period 1961-90, for Oklahoma. The data set was derived from the PRISM (Parameter-elevation Regressions on Independent Slopes Model) mean annual precipitation grid for the United States, developed by Daly, Neilson, and Phillips (1994, "A statistical-topographic model for mapping climatological precipitation over mountainous terrain:" Journal of Applied Meteorology, v. 33, no. 2, p. 140-158). The precipitation grid was used to develop peak-flow regression equations by Tortorelli, (1997, "Techniques for estimating peak-streamflow frequency for unregulated streams and streams regulated by small floodwater retarding structures in Oklahoma," U.S. Geological Survey Water-Resources Investigations Report 97-4202.)

This digital-map data set consists of a grid of mean annual precipitation, in inches, based on the period 1961-90, for Oklahoma. The data set was derived from the PRISM (Parameter-elevation Regressions on Independent Slopes Model) mean annual precipitation grid for the United States, developed by Daly, Neilson, and Phillips (1994, "A statistical-topographic model for mapping climatological precipitation over mountainous terrain:" Journal of Applied Meteorology, v. 33, no. 2, p. 140-158). The precipitation grid was used to develop peak-flow regression equations by Tortorelli, (1997, "Techniques for estimating peak-streamflow frequency for unregulated streams and streams regulated by small floodwater retarding structures in Oklahoma," U.S. Geological Survey Water-Resources Investigations Report 97-4202.)