This metadata record describes observed and predicted baseflow recession characteristics for 300 streamflow gauges in the western United States and 282 streamflow gauges in the eastern United States. Specifically, this record describes (1) the streamflow gauge locations (west or east) in the United States (Location), (2) the U.S. Geological Survey streamflow gauge identification numbers (USGS_Site_Identifier), (3) observed regions of similar aquifer hydraulic properties (7 regions coded by color: blue, green, red, purple, grey, pink, and orange) by k-means clustering method (Observed_Class(k-means)), (4) predicted regions of similar aquifer hydraulic properties by random forest classification models (Predicted_Class(k-means)), (5) calculated long-term baseflow recession constant at streamflow gauges (Observed_a-long[ft^(-3/2)s^(-1/2)]), (6) predicted long-term baseflow recession constant by novel empirical and physical approach (Predicted_a-long(Novel)[ft^(-3/2)s^(-1/2)]), (7) predicted long-term baseflow recession constant by random forest regression (Predicted_a-long(Random_Forest_Regression)[ft^(-3/2)s^(-1/2)]), (8) calculated short-term baseflow recession constant at streamflow gauges (Observed_a-short[sft^(-6)]), (9) predicted short-term baseflow recession constant by novel empirical and physical approach (Predicted_a-short(Novel)[sft^(-6)]), (10) predicted short-term baseflow recession constant by random forest regression (Predicted_a-short(Random_Forest_Regression)[sft^(-6)]). For more details for (3) to (10), please see Eng, K., Wolock, D. M., and Wieczorek, M., 2023, Predicting baseflow recession characteristics at ungauged locations using a physical and machine learning approach. The values entered for (5) to (10) are in scientific notation, and they are character strings that will require the user to convert numeric values using methods for their software or use case. The data are in a tab-delimited text format.

This data release presents streamflow recession analyses and supporting statistics for 164 U.S. Geological Survey (USGS) streamgages located in or near the watersheds of Mobile and Perdido Bays in the south-central United States (see Tatum and others, 2024). Streamgages were selected based on a minimum of two complete decades of daily streamflow data since January 1, 1950, with the additional requirement that data coverage includes the entire 2010s decade. Daily streamflow data were retrieved on March 8, 2024 (U.S. Geological Survey, 2024). The primary output of this release, gfactor.txt, is a pipe-delimited text file containing 22 attributes and over 1,000 unique records summarizing decadal streamflow statistics for each site. Key identifying attributes include the USGS site identification number (site_no), streamgage name (station_nm), geographic coordinates (dec_lat_va, dec_long_va), contributing drainage area (CDA), and projected coordinates (xkm, ykm). Key statistical attributes consist of decadal counts of daily streamflow conditions (decreasing_count, increasing_count, nochange_count, total_count), as well as summary statistics that characterize the declining days distribution, including the 50th percentile (median), L-moments (L1, L2, T3, T4, T5), and streamflow recession indices associated with the 90th percentile (gfactor, gfactor_emp). Additional attributes capture adjusted statistics produced through a detrending procedure designed to assess and remove potential decadal biases in the declining day distribution. Core statistical computations were carried out using custom functions developed in the R environment for statistical computing (R Core Team, 2024).

This dataset contains statistical descriptions of observed daily-mean streamflow for 956 sites in the southeast United States. For each site, statistical descriptions are provided according to decade for up to six decades, beginning in 1950 (1950-59 calendar years) and ending with 2000 (2000 - 2009 calendar years) with no more than 7 missing values per year in total (continuous or noncontinuous). There are 40 statistical descriptions including 28 flow-duration curve values, 8 L-moments, and 4 describing the minimum, maximum, median flow for days not equal to zero, and number of zero-flow days. Site information is provided by decade - the number of rows per site varies from 1 to 6 depending on the number of decades with observed record available. This information was used as the response variable(s) for statistical models for estimating the same characteristics at nearly 10,000 ungaged locations throughout the southeast United States. The dataset has been provided as a shapefile and a comma-delimited file. The comma-delimited file is an exact copy of the attribute table of the shapefile.

This dataset contains statistical descriptions of observed daily-mean streamflow for 956 sites in the southeast United States. For each site, statistical descriptions are provided according to decade for up to six decades, beginning in 1950 (1950-59 calendar years) and ending with 2000 (2000 - 2009 calendar years) with no more than 7 missing values per year in total (continuous or noncontinuous). There are 40 statistical descriptions including 28 flow-duration curve values, 8 L-moments, and 4 describing the minimum, maximum, median flow for days not equal to zero, and number of zero-flow days. Site information is provided by decade - the number of rows per site varies from 1 to 6 depending on the number of decades with observed record available. This information was used as the response variable(s) for statistical models for estimating the same characteristics at nearly 10,000 ungaged locations throughout the southeast United States. The dataset has been provided as a shapefile and a comma-delimited file. The comma-delimited file is an exact copy of the attribute table of the shapefile.

This dataset provides numerical and categorical descriptions of 48 basin characteristics for 956 basins with observed streamflow information at U.S. Geological Survey (USGS) streamflow-gaging stations. Characteristics are indexed by National Hydrography Dataset (NHD) version 2 COMID (integer that uniquely identifies each feature in the NHD) and USGS station number for streamflow-gaging station. The variables represent mutable and immutable basin characteristics and are organized by characteristic type: physical (5), hydrologic (6), categorical (12), climate (6), landscape alteration (7), and land cover (12). Mutable characteristics such as climate, land cover, and landscape alteration variables are reported in decadal increments (for example, average percent forest for the decade 1950-1959, 1960-1969, etc). The majority of basin characteristics in this dataset were calculated using divergence-routing methods and are often referred to as “network-accumulated”. This method uses a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the values derived from the reach catchment scale (Schwarz, G.E., and Wieczorek, M.E., 2018, Database of modified routing for NHDPlus version 2.1 flowlines: ENHDPlusV2_us: U.S. Geological Survey data release, https://doi.org/10.5066/P9PA63SM ). In four instances, values are also provided for the entire catchment above a site and area designated using the “CAT_” prefix.

This dataset provides numerical and categorical descriptions of 48 basin characteristics for 956 basins with observed streamflow information at U.S. Geological Survey (USGS) streamflow-gaging stations. Characteristics are indexed by National Hydrography Dataset (NHD) version 2 COMID (integer that uniquely identifies each feature in the NHD) and USGS station number for streamflow-gaging station. The variables represent mutable and immutable basin characteristics and are organized by characteristic type: physical (5), hydrologic (6), categorical (12), climate (6), landscape alteration (7), and land cover (12). Mutable characteristics such as climate, land cover, and landscape alteration variables are reported in decadal increments (for example, average percent forest for the decade 1950-1959, 1960-1969, etc). The majority of basin characteristics in this dataset were calculated using divergence-routing methods and are often referred to as “network-accumulated”. This method uses a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the values derived from the reach catchment scale (Schwarz, G.E., and Wieczorek, M.E., 2018, Database of modified routing for NHDPlus version 2.1 flowlines: ENHDPlusV2_us: U.S. Geological Survey data release, https://doi.org/10.5066/P9PA63SM ). In four instances, values are also provided for the entire catchment above a site and area designated using the “CAT_” prefix.

These data include base flow separation estimates for 64 USGS streamflow gages in the Lake Superior watershed from 1945 to 2020, shapefiles of the gaging stations and watersheds for each gaging station, and a zipped folder of graphics of the base flow separation results. The base flow separation estimates were calculated using the U.S. Geological Survey Groundwater Toolbox (Barlow and others, 2014) for any complete water years of record for these gages from 1945 to 2020. The shapefile of the gaging stations includes the starting and ending years of data for each station, the number of years of record. The watersheds shapefile includes the source for the watershed delineation, the watershed area, and the number of upstream and(or) downstream gaging stations on the same river system. If there are upstream gaging stations in the river system, the watershed delineated is only the incremental part of the watershed between gaging stations. The baseflow separation estimates for each gaging station include daily, monthly, and annual output from the Groundwater Toolbox for six estimation methods included in the software (full references are available in Barlow and others, 2014): the baseflow Index-Standard method, HySep Fixed Interval, HySep Local Minimum, HySep Sliding Interval, baseflow Index-Modified, PART, and BFLOW. A summary of the annual baseflow estimates for all the gaging stations using all the methods is provided also is included in this data release. This data release is one of three child items under the overall data release at https://doi.org/10.5066/P9084UKQ.

These data include base flow separation estimates for 64 USGS streamflow gages in the Lake Superior watershed from 1945 to 2020, shapefiles of the gaging stations and watersheds for each gaging station, and a zipped folder of graphics of the base flow separation results. The base flow separation estimates were calculated using the U.S. Geological Survey Groundwater Toolbox (Barlow and others, 2014) for any complete water years of record for these gages from 1945 to 2020. The shapefile of the gaging stations includes the starting and ending years of data for each station, the number of years of record. The watersheds shapefile includes the source for the watershed delineation, the watershed area, and the number of upstream and(or) downstream gaging stations on the same river system. If there are upstream gaging stations in the river system, the watershed delineated is only the incremental part of the watershed between gaging stations. The baseflow separation estimates for each gaging station include daily, monthly, and annual output from the Groundwater Toolbox for six estimation methods included in the software (full references are available in Barlow and others, 2014): the baseflow Index-Standard method, HySep Fixed Interval, HySep Local Minimum, HySep Sliding Interval, baseflow Index-Modified, PART, and BFLOW. A summary of the annual baseflow estimates for all the gaging stations using all the methods is provided also is included in this data release. This data release is one of three child items under the overall data release at https://doi.org/10.5066/P9084UKQ.

This dataset includes four tables related to annual trends in streamflow metrics at 599 reference streamgages in the conterminous United States for the period 1955-2014. Reference streamgages are defined here as gages with drainage basins that are minimally impacted by anthropogenic effects such as reservoirs or urbanization. The four tables are: 1) computed annual values for 16 streamflow metrics, 2) trend estimates for the 16 streamflow metrics for the period 1955-2014, 3) metric names and definitions, and 4) location information (latitude and longitude) for the 599 sites. The computed annual values for the 16 streamflow metrics are: low flow magnitude, low flow frequency, low flow duration, high flow magnitude, high flow frequency, high flow duration, skew, daily rises, Spring low flow percentage, Spring high flow percentage, Summer low flow percentage, Summer high flow percentage, Fall low flow percentage, Fall high flow percentage, Winter low flow percentage, and Winter high flow percentage. The annual flow metrics were estimated by Eng and others (2017) from daily streamflow records at the 599 reference streamgages. Sen slope trend values and confidence intervals for the 16 flow metrics for the period 1955-2014 were computed from the annual time series using the non-parametric Theil-Sen approach (Sen, P., 1968). In addition to the Sen slope, the median value for each metric for the period 1955-2014, the percentage change in each metric over the period 1955-2014, and a percentage change class for each metric also are reported.

This dataset includes four tables related to annual trends in streamflow metrics at 599 reference streamgages in the conterminous United States for the period 1955-2014. Reference streamgages are defined here as gages with drainage basins that are minimally impacted by anthropogenic effects such as reservoirs or urbanization. The four tables are: 1) computed annual values for 16 streamflow metrics, 2) trend estimates for the 16 streamflow metrics for the period 1955-2014, 3) metric names and definitions, and 4) location information (latitude and longitude) for the 599 sites. The computed annual values for the 16 streamflow metrics are: low flow magnitude, low flow frequency, low flow duration, high flow magnitude, high flow frequency, high flow duration, skew, daily rises, Spring low flow percentage, Spring high flow percentage, Summer low flow percentage, Summer high flow percentage, Fall low flow percentage, Fall high flow percentage, Winter low flow percentage, and Winter high flow percentage. The annual flow metrics were estimated by Eng and others (2017) from daily streamflow records at the 599 reference streamgages. Sen slope trend values and confidence intervals for the 16 flow metrics for the period 1955-2014 were computed from the annual time series using the non-parametric Theil-Sen approach (Sen, P., 1968). In addition to the Sen slope, the median value for each metric for the period 1955-2014, the percentage change in each metric over the period 1955-2014, and a percentage change class for each metric also are reported.