The U.S. Geological Survey (USGS), in cooperation with the Oklahoma Water Resources Board, produced this data release that includes vector and raster geographic information systems layers used in the analysis and publication of a mean annual runoff and annual runoff variability map for 1940–2007 for Oklahoma. The data release covers all 69 8-digit hydrologic units with at least 1 square mile of area in Oklahoma; those 8-digit hydrologic units contain 2,870 12-digit hydrologic units that provided the geographic framework for the analysis described in the companion map report (USGS Scientific Investigations Map 3482). The mean annual runoff and annual runoff variability values presented in this data release are most representative of runoff conditions in rural, unregulated drainage basins at the 12-digit hydrologic-unit scale. As drainage basins increase in size, they are more likely to be (1) regulated by large dams or irrigation practices, (2) augmented by substantial groundwater contributions, and (3) monitored by streamgages with long period of record. Methods for computing or estimating runoff for gaged basins generally rely on the streamgage record when sufficient data are available. For an ungaged stream reach between two streamgages, the drainage-area-ratio method, rather than the GIS layers in this data release, can be used to obtain a more accurate mean annual runoff or annual runoff variability estimate. The drainage-area-ratio method, which assumes that streamflow generally increases in proportion to increased drainage area, equates the ratio of streamflow at two stream locations to the ratio of the respective drainage areas. The layers were developed by using regression equations formulated on streamgage data for the entire period of record through 2007, but those equations are biased to the period 1940–2007 when streamgages became more numerous and distributed across Oklahoma. Therefore, the data layers are likely most representative of runoff conditions during the period 1940–2007. Because runoff is a function of climate variables that can change over time, caution is warranted when using the information in this data release to project mean annual runoff and annual runoff variability conditions beyond 2007.

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.

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.

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.

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.