This dataset contains predicted flow-duration curves (FDCs) for 1,378 streamgages in 19 study regions in the conterminous U.S. from mostly undisturbed watersheds using regression models constructed with four or five binary methodological choices (thus 16 or 32 methodological combinations). The predicted FDCs are presented as 27 quantiles ranging from 0.02 to 99.98 percent nonexceedance probabilities. These data are also contained within the CSV files in child item 4, "Selected regression models for predicting FDC quantiles for selected streamgages in the conterminous United States", but are separated out here to provide more convenient access in a single Excel file (predictedFDCs.xlsx). These data support a concurrent publication (Over and others, 2018).

This dataset contains selected basin characteristics from the GAGES-II dataset (https://water.usgs.gov/lookup/getspatial?gagesII_Sept2011) that were considered for use in regression equations for predicting flow-duration curves as well as additional variables that were constructed or derived from these basin characteristics. Descriptions of basin characteristics used in regression equations are provided (BCdescriptions.xlsx). Additional processing of the selected basin characteristics was done on a region-by-region basis, including deletion of variables with a large (greater than 50%) fraction of the same value (usually zero). A table indicating the basin characteristics considered for use in regression equations for each study region is provided (BCs_byRegion.xlsx). After transformation to reduce skewness and to convert to a similar range of values, these basin characteristics were used to fit regression equations for predicting FDCs. Basin characteristic selection and transformation were performed separately for each study region using all the USGS streamgages that were identified as being of “reference” quality in the GAGES-II dataset. Of the reference quality streamgages, only those having at least 10 complete water years (WYs) during the study period from WY1981 through WY2013 were used in regression model building; these are identified in the dataset. The basin characteristics are presented in their original units (unstransfBCs.new.xlsx) and as transformed (transfBCs.new.xlsx); a table specifying the transformations is provided (tranfBC_info.new.xlsx). Methods are fully described by Over and others (in review).

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.

This dataset contains the empirical flow-duration curves (FDCs) derived from complete water years of daily streamflow data for 1,378 streamgages in 19 study regions in the conterminous U.S. from October 1, 1980 through September 30, 2013 from mostly undisturbed watersheds contained in child item 1, "Daily streamflow data for selected streamgages in the conterminous United States", of this data release. The empirical FDCs are presented as 27 quantiles ranging from 0.02 to 99.98 percent nonexceedance probabilities. Because streamflow data less than 0.005 cfs are reported as zero, they are considered to be censored values. To handle these censored data values, two versions of the FDC quantiles from streamgage records were computed: (1) empFDCs.unfilled.xlsx - where the quantiles were estimated from the original data and (2) empFDCs.filled.xlsx – where the censored quantile values were filled with estimated positive values. With the method used for filling the censored quantiles, which relies on a lognormal fit to the data, occasionally the data values estimated for the largest censored values were larger than the smallest noncensored data values. This sometimes resulted in increases to the quantiles greater than the censoring level. As a result, some of the noncensored flow quantile values in the filled dataset are greater than the corresponding noncensored flow quantile values in the unfilled dataset. Methods are fully described by Over and others (2018).

This data release contains values of 29 streamflow statistics computed from modeled and observed daily streamflows from October 1, 1983, through September 30, 2016 at 1,257 streamgages in the 19 study regions defined by Falcone (2011) covering the conterminous United States. The streamflow statistics were computed at GAGES-II non-reference streamgages (Falcone, 2011), determined to be affected by only irrigation or regulation among antrhopogenic influences. At each streamgage, statistics were computed from daily streamflow observations, from daily streamflow time series computed using the National Hydrologic Model-Precipitation Runoff Modeling System (NHM-PRMS) model (the “by headwater” and "by observation" calibrations with Muskingum routing; Hay and LaFontaine, 2020), and from daily streamflow time series computed using five statistical time series models fitted to reference basins (Russell and others, 2021). The data release comprises nine .csv files. The streamflow statistics values are provided in eight of these files, one each for the observed, the two NHM-PRMS calibrations, and the five statistical time series models. The remaining file is a summary table, which provides period-of-record information for each streamgage. References cited: Falcone, J.A., 2011, GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow [digital spatial dataset]: U.S. Geological Survey Water Resources NSDI Node web page, https://water.usgs.gov/lookup/getspatial?gagesII_Sept2011. Hay, L.E., and LaFontaine, J.H., 2020, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), 1980-2016, Daymet Version 3 calibration: U.S. Geological Survey data release, https://doi.org/10.5066/P9PGZE0S. Russell, A.M., Over, T.M., Farmer, W.H., and Miles, K.J., 2021, Statistical daily streamflow estimates at GAGES-II non-reference streamgages in the conterminous Unites States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9PA9PKM.

This data release contains 29 streamflow statistics computed from modeled and observed daily streamflows from October 1, 1983, through September 30, 2016 at 1,114 streamgages in 19 study regions covering the conterminous United States. The streamflow statistics were computed at selected GAGES-II reference streamgages (Falcone, 2011) from daily streamflow observations (Russell and others, 2020), from daily streamflow time series computed using the National Hydrologic Model-Precipitation Runoff Modeling System (NHM-PRMS) model (“by headwater” and “by observation” calibrations with Muskingum routing; Hay and LaFontaine, 2020), from daily streamflow time series computed using five statistical time series models (Russell and others, 2020), and from three direct statistical prediction methods (Over and others, unpub. data, 2020). The data release comprises twelve .csv files. The streamflow statistics values are provided in eleven of these files, one each for the observed, the two NHM-PRMS calibrations, the five statistical time series models, and the three direct statistical prediction methods. The remaining file is a summary table, which provides period-of-record information for each streamgage. References cited: Falcone, J.A., 2011, GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow [digital spatial dataset] : U.S. Geological Survey Water Resources NSDI Node web page, https://water.usgs.gov/lookup/getspatial?gagesII_Sept2011. Hay, L.E., and LaFontaine, J.H., 2020, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS),1980-2016, Daymet Version 3 calibration: U.S. Geological Survey data release, https://doi.org/10.5066/P9PGZE0S Russell, A.M., Over, T.M., and Farmer, W.H., 2020, Cross-validation results for five statistical methods of daily streamflow estimation at 1,385 reference streamgages in the conterminous United States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9XT4WSP

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).

This data set serves to archive the data, analysis and models of the associated publication entitled “Calibration of the USGS National Hydrologic Model in Ungauged Basins Using Statistical At-Site Streamflow Simulations” as published in the Journal of Hydrologic Engineering. The input data files included here as comma-separated values contain measured streamflow, streamflow simulated by the Precipitation-Runoff Modeling System calibrated to measured streamflow, streamflow simulated by the Precipitation-Runoff Modeling System calibrated to streamflow simulated by pooled ordinary kriging, and streamflow simulated by pooled ordinary kriging at 1,410 streamgage locations across the United States. These data sets, built on previously published models, are assessed in the included analysis script (R programming language) to reproduce the findings of the associated manuscript. The manuscript argues that statistically generated daily streamflow can be used to support the ability of physical models to represent hydrologic processes at ungauged locations. The objective of this study was to determine the feasibility of using simulations in place of measured streamflow to calibrate physical models in ungauged basins. Calibrating with statistically simulated streamflow produced performances within 23% of applications with knowledge of at-site measurements. Furthermore, statistically generated streamflows produced accurate timing information, which, when combined with alternative data sets (e.g., evapotranspiration, recharge, etc.), can be used to improve representation of hydrologic processes at ungauged locations.

This data release contains trend results computed on the basis of modeled and observed daily streamflows at 502 reference gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Modeled daily streamflows were computed using the deterministic Precipitation Runoff Modeling System (PRMS), and five statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-Correlation Drainage Area Ratio (MCDAR), Ordinary Kriging of the logarithms of discharge per unit area (OKDAR), Nearest-Neighbor nonlinear spatial interpolation using flow duration curves (NNQPPQ), and Map-Correlation nonlinear spatial interpolation using flow duration curves (MCQPPQ). Observed daily streamflow data for the study gages were retrieved from the National Water Information System (NWIS). Study gages were selected from among Hydro-Climatic Data Network 2009 (HCDN-2009) gages in the GAGES-II dataset considered to be minimally affected by regulation, diversion, mining, or other anthropogenic activities. Results include trends in annual and monthly means, annual percentiles (1, 5, 10, 25, 50, 75, 90, 95, 99), annual 1-day high, 3-day high, and 7-day low, and annual snowmelt-related runoff timing for a subset of snowmelt dominated basins. Bias and volumetric efficiency statistics between observed and modeled streamflows also are provided.

This dataset contains a zipped file (dailyQs.zip) of daily streamflow data for 1,378 streamgages in 19 study regions in the conterminous U.S. from October 1, 1980 through September 30, 2013 from mostly undisturbed watersheds. USGS streamgages that were identified as being of “reference” quality in the GAGES-II dataset (https://water.usgs.gov/lookup/getspatial?gagesII_Sept2011) and had at least 10 complete water years (WYs) during the study period from WY1981 through WY2013 were selected. Daily streamflow data were retrieved from the National Water Information System (NWIS) on April 18, 2016. This dataset also contains an Excel file (compWYs.xlsx) indicating for each WY during the study period whether a streamgage had a complete streamflow record (no missing values) during that year. Only complete WYs of daily streamflow data during the study period from the selected streamgages were used to compute the empirical FDC quantiles to which regression equations were fitted. These data support a concurrent publication (Over and others, 2018).