Digital datasets were used to develop basin characteristics values that are used in multiple regression equations and tested for the use in predicting flow-duration curves (FDCs) in ungaged areas of Illinois and Indiana. Several basin characteristics are easily derived from StreamStats basin delineations, such as basin area and basin centroid (https://streamstats.usgs.gov/ss/). Other basin characteristics require ancillary datasets as input. The data provided through this data release are those data that have been collected, tested, and ultimately selected as a basis for FDC development. These include Soil Components (Available Water Capacity, Drainage Index, and Permeability); PRISM 3-Month Average Precipitation; Thickness and Coarseness of Quaternary Sediments; and NLCD Landcover. Illinois and Indiana have different datasets that are used in each state's StreamStats application and should not be interchanged in flow-duration curve equations. Therefore, each state has a separate child item related to this main data release. The metadata in these child items details the data sources, processes used to derive the final data layers, and attribute information.

Digital datasets were used to develop basin characteristics values that are used in multiple regression equations and tested for the use in predicting flow-duration curves (FDCs) in ungaged areas of Illinois. Several basin characteristics are easily derived from StreamStats basin delineations, such as basin area and basin centroid (https://streamstats.usgs.gov/ss/). Other basin characteristics require ancillary datasets as input. The data provided through this data release are those data that have been collected, tested, and ultimately selected as a basis for FDC development. These include Soil Components (Available Water Capacity, Drainage Index, and Permeability); PRISM 3-Month Average Precipitation; and Thickness and Coarseness of Quaternary Sediments. There are 7 grids included in the Illinois portion of this data release: Soil Drainage index (drainind), PRISM December to February Average Precipitation (prdecfeb00), PRISM September to November Average Precipitation (prsepnov00), PermBXThick equation inputs (qss_permb and qss_thick), STATSGO Permeability (statsperm), and Available Water Capacity (watcapinil). NOTE: While previous versions are available from the author, all the records in previous versions can be found in version 3.0. First posted - May 26, 2020 (available from author) Revised - February 19, 2021 (version 2.0) Revised - December 2, 2021 (version 3.0)

Digital datasets were used to develop basin characteristics values that are used in multiple regression equations and tested for the use in predicting flow-duration curves (FDCs) in ungaged areas of Illinois. Several basin characteristics are easily derived from StreamStats basin delineations, such as basin area and basin centroid (https://streamstats.usgs.gov/ss/). Other basin characteristics require ancillary datasets as input. The data provided through this data release are those data that have been collected, tested, and ultimately selected as a basis for FDC development. These include Soil Components (Available Water Capacity, Drainage Index, and Permeability); PRISM 3-Month Average Precipitation; and Thickness and Coarseness of Quaternary Sediments. There are 7 grids included in the Illinois portion of this data release: Soil Drainage index (drainind), PRISM December to February Average Precipitation (prdecfeb00), PRISM September to November Average Precipitation (prsepnov00), PermBXThick equation inputs (qss_permb and qss_thick), STATSGO Permeability (statsperm), and Available Water Capacity (watcapinil). NOTE: While previous versions are available from the author, all the records in previous versions can be found in version 3.0. First posted - May 26, 2020 (available from author) Revised - February 19, 2021 (version 2.0) Revised - December 2, 2021 (version 3.0)

Digital datasets were used to develop basin characteristics values that are used in multiple regression equations and tested for the use in predicting flow-duration curves (FDCs) in ungaged areas of Indiana. Several basin characteristics are easily derived from StreamStats basin delineations, such as basin area (https://streamstats.usgs.gov/ss/). Other basin characteristics require ancillary datasets as input. The data provided through this data release are those data that have been collected, tested, and ultimately selected as a basis for FDC development. These include PRISM 3-Month Average Precipitation, Thickness and Coarseness of Quaternary Sediments, and Soil Available Water Capacity. There are 6 continuous parameter grids (CPGs; for a definition, see https://pubs.usgs.gov/ds/412/section3.html) included in the Indiana portion of this data release: PRISM December to February Average Precipitation (prdecfeb00_cpg), PRISM September to November Average Precipitation (prsepnov00_cpg), index of permeability of Quaternary surficial sediments (qss_permb_cpg), index of permeability of Quaternary surficial sediments multiplied by their thickness (permbxthick_cpg), STATSGO Permeability (statsperm_cpg), and Available Water Capacity (watcapinil_cpg).

Digital datasets were used to develop basin characteristics values that are used in multiple regression equations and tested for the use in predicting flow-duration curves (FDCs) in ungaged areas of Indiana. Several basin characteristics are easily derived from StreamStats basin delineations, such as basin area (https://streamstats.usgs.gov/ss/). Other basin characteristics require ancillary datasets as input. The data provided through this data release are those data that have been collected, tested, and ultimately selected as a basis for FDC development. These include PRISM 3-Month Average Precipitation, Thickness and Coarseness of Quaternary Sediments, and Soil Available Water Capacity. There are 6 continuous parameter grids (CPGs; for a definition, see https://pubs.usgs.gov/ds/412/section3.html) included in the Indiana portion of this data release: PRISM December to February Average Precipitation (prdecfeb00_cpg), PRISM September to November Average Precipitation (prsepnov00_cpg), index of permeability of Quaternary surficial sediments (qss_permb_cpg), index of permeability of Quaternary surficial sediments multiplied by their thickness (permbxthick_cpg), STATSGO Permeability (statsperm_cpg), and Available Water Capacity (watcapinil_cpg).

The U.S. Geological Survey Central Midwest Water Science Center completed a report (Over and others, 2023) documenting methods, results, and applications of an updated flood-frequency study for the State of Illinois. The study developed regional regression equations that relate the peak-flow quantiles and the basin characteristics of selected streamgages in Illinois, Indiana, and Wisconsin, based on data through water year 2017 (a water year is the period from October 1 to September 30 and is designated by the year in which it ends; for example, water year 2017 was from October 1, 2016, to September 30, 2017). The data provided through this data release are those digital datasets of basin characteristics that have been collected, tested, and ultimately selected for use in regional regression equations. These datasets consist of raster grid files for slope (slope100.zip), calculated from a published digital elevation model (DEM) (Schafer and Sharpe, 2023), soil slope (stats_slope100.zip) subsetted and resampled from Wolock (1997), a soil texture permeability index (texp_indx_rnd.zip) computed using data from Wolock (1997), land cover (nlcd16_22_23_24.zip) adapted from Yang and others (2018), a basin soil wetness measure (drclass1a.zip) computed from U.S. Department of Agriculture (USDA) (2013), and an urbanization fraction (urbthe2010.zip) computed from Theobald 2010 data (Theobald, 2005). Some basin characteristics are not included in this data release as they are easily derived from StreamStats basin delineations themselves, such as basin drainage area. The U.S. Geological Survey (USGS), in cooperation with the Illinois Center for Transportation (ICT) and the Illinois Department of Transportation (IDOT), prepared these digital datasets of basin characteristics for use in the Illinois StreamStats application (https://streamstats.usgs.gov/ss/). Two additional shapefiles are provided: a shapefile of the streamgages (IL_StreamStats_Gages.zip) and a shapefile of the associated delineated streamgage drainage basins (IL_StreamStats_DrainageBasins.zip) used in analysis (Over and others, 2023).

The U.S. Geological Survey Central Midwest Water Science Center completed a report (Over and others, 2023) documenting methods, results, and applications of an updated flood-frequency study for the State of Illinois. The study developed regional regression equations that relate the peak-flow quantiles and the basin characteristics of selected streamgages in Illinois, Indiana, and Wisconsin, based on data through water year 2017 (a water year is the period from October 1 to September 30 and is designated by the year in which it ends; for example, water year 2017 was from October 1, 2016, to September 30, 2017). The data provided through this data release are those digital datasets of basin characteristics that have been collected, tested, and ultimately selected for use in regional regression equations. These datasets consist of raster grid files for slope (slope100.zip), calculated from a published digital elevation model (DEM) (Schafer and Sharpe, 2023), soil slope (stats_slope100.zip) subsetted and resampled from Wolock (1997), a soil texture permeability index (texp_indx_rnd.zip) computed using data from Wolock (1997), land cover (nlcd16_22_23_24.zip) adapted from Yang and others (2018), a basin soil wetness measure (drclass1a.zip) computed from U.S. Department of Agriculture (USDA) (2013), and an urbanization fraction (urbthe2010.zip) computed from Theobald 2010 data (Theobald, 2005). Some basin characteristics are not included in this data release as they are easily derived from StreamStats basin delineations themselves, such as basin drainage area. The U.S. Geological Survey (USGS), in cooperation with the Illinois Center for Transportation (ICT) and the Illinois Department of Transportation (IDOT), prepared these digital datasets of basin characteristics for use in the Illinois StreamStats application (https://streamstats.usgs.gov/ss/). Two additional shapefiles are provided: a shapefile of the streamgages (IL_StreamStats_Gages.zip) and a shapefile of the associated delineated streamgage drainage basins (IL_StreamStats_DrainageBasins.zip) used in analysis (Over and others, 2023).

The U.S. Geological Survey (USGS), in cooperation with the Illinois Center for Transportation and the Illinois Department of Transportation, prepared hydro-conditioned geographic information systems (GIS) layers for use in the Illinois StreamStats application. These data were used to delineate drainage basins and compute basin characteristics for updated peak flow and flow duration regression equations for Illinois. This dataset consists of raster grid files for elevation (dem), flow accumulation (fac), flow direction (fdr), and stream definition (str900) for each 8-digit Hydrologic Unit Code (HUC) area in Illinois merged into a single dataset. There are 51 full or partial HUC 8s represented by this data set: 04040002, 05120108, 05120109, 05120111, 05120112, 05120113, 05120114, 05120115, 05140202, 05140203, 05140204, 05140206, 07060005, 07080101, 07080104, 07090001, 07090002, 07090003, 07090004, 07090005, 07090006, 07090007, 07110001, 07110004, 07110009, 07120001, 07120002, 07120004 (0712003 was combined into this HUC), 07120005, 07120006, 07120007, 07130001, 07130002, 07130003, 07130004, 07130005, 07130006, 07130007, 07130008, 07130009, 07130010, 07130011, 07130012, 07140101, 07140105, 07140106, 07140108, 07140201, 07140202, 07140203, and 07140204.

This data release (DR) is the update of the U.S. Geological Survey - ScienceBase data release Bera (2023), with the processed data for the period October 1, 2021, through September 30, 2022. This data release describes the watershed data management (WDM) database SC22.WDM. The precipitation data are collected from a tipping-bucket rain-gage network and the hydrologic data (stage and discharge) are collected at USGS streamflow-gaging stations in and around Salt Creek watershed in DuPage County, Illinois, as described in Bera (2014). Hourly precipitation and hydrologic data for the period October 1, 2021, through September 30, 2022, are processed following the guidelines described in Bera (2014) and Murphy and Ishii (2006) and appended to SC21.WDM and renamed as SC22.WDM. Meteorological data (wind speed, solar radiation, air temperature, dewpoint temperature, and potential evapotranspiration) are copied from ARGNXX.WDM and appended to SCXX.WDM. XX represents last two digits of a water year (WY). A WY is the 12-month period, October 1 through September 30, in which it ends. Errors have been found in each of ARGNXX.WDM prior to WY23. SCXX.wdm contains erroneous meteorological data and related flag values until WY21 thereby. Meteorological data (wind speed, solar radiation, air temperature, dewpoint temperature, and potential evapotranspiration) from January 1, 1997, through September 30, 2022, are copied from ARGN23.WDM and uploaded to SC22.WDM. Bera (2024) describes the processing of the meteorological data in the database file ARGN23.WDM and Bera (2023) describes the processing of SC21.WDM. Data in dataset number (DSN) 107 and 801–810 are used in comparisons of precipitation data. DSN 107 contains hourly precipitation data collected at Argonne National Laboratory at Argonne, Illinois. DSN 801-810 contains the processed Next Generation Weather Radar (NEXRAD)-multisensor precipitation estimates (MPE) data from 10 NEXRAD–MPE subbasins in the Salt Creek watershed as described in Bera and Ortel (2018). Data in these DSNs are not quality-assured and quality-controlled. The data are downloaded and uploaded daily into a WDM database that is used for the real-time streamflow simulation system. Data from DSN 107 and 801-810 are copied from this WDM and stored in SC22.WDM. DSN 107 and 801-810 are updated with the data through September 30, 2022. Data in DSN 5400 (water-surface elevation at the quarry) and 5700 (water surface elevation at Thorndale) are copied and updated through September 30, 2022, similarly (Murphy and Ishii, 2006). The complete list of missing precipitation data periods and the nearby stations used to fill in those missing periods from October 1, 2021, through September 30, 2022, is given in Table1.csv. This file is in the comma separated values (CSV) file format and can be downloaded from this landing page. The list of snow affected days of precipitation data and the missing and estimated period of the stage and flow data in SC22.WDM database during the period October 1, 2021, through September 30, 2022, are given in the USGS annual Water Data Report at https://waterdata.usgs.gov/nwis. To open the WDM database SC22.WDM user needs to install Sara Timeseries Utility, listed in the section "Related External Resources" on this page. Table1.csv can be opened with any text editor or Microsoft Excel. References Cited: Bera, M., 2024, Meteorological Database, Argonne National Laboratory, Illinois: U.S. Geological Survey data release, https://doi.org/10.5066/P146RBHK. Bera, M., 2023, Watershed Data Management (WDM) Database (SC21.WDM) for Salt Creek Streamflow Simulation, DuPage County, Illinois, January 1, 1997, through September 30, 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9TFCGQU. Bera, M., and Ortel, T.W., 2018, Processing of next generation weather radar-multisensor precipitation estimates and quantitative precipitation forecast data for the DuPage County streamflow simulation system: U.S.

This data release contains the input used and the output files interpreted in the publication "Refinement of a Regression-Based Method for Prediction of Flow-Duration Curves of Daily Streamflow in the Conterminous United States". This data release contains daily streamflow data for 1,378 streamgages in 19 study regions in the conterminous U.S. (CONUS) from October 1, 1980 through September 30, 2013 from mostly undisturbed watersheds. This data release also contains the empirical flow-duration curves (FDCs) derived from this daily streamflow data, presented as 27 quantiles ranging from 0.02 to 99.98 percent nonexceedance probabilities. Selected basin characteristics from the GAGES-II dataset (https://water.usgs.gov/lookup/getspatial?gagesII_Sept2011) were transformed to reduce skewness and to convert to a similar range of values and then used, directly or in the construction of additional variables, to fit regression equations for predicting FDCs. Basin characteristic selection and transformation was performed separately for each study region. The basin characteristics considered for use in candidate regression models are presented in their original units and as their transformed values; a table specifying the variable transformations is also provided. To each group of gaged basins in each region with one basin left out, a regression model selection procedure, with four or five binary methodological choices thus 16 or 32 methodological combinations, was applied to select the best regression model for each contiguous group of FDC quantiles (called here a “flow regime”). This data release provides the definitions of the selected flow regimes, the regression model parameters, goodness-of-fit statistics of the fitted models, and predicted FDCs for the gaged basin that was left out for the selected FDC regression models for each of the methodological combinations.