This dataset is part of the National Water Census ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of total flow and snowmelt for each hydrologic unit are added to the already released estimates of actual evapotranspiration, snowpack water-equivalent storage, soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset and associated Watershed Boundary Dataset (WBD) snapshot. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. Users are advised to ignore the first two years of the simulations to account for model initialization.

For background on source data and generation of these water budget variables, see nhru_hru_outflow.csv and nhru_snowmelt.csv from:

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

The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. The HUC12 version is the one included with WBD snapshot associated withe NHDPlus v2.1. All code used for conversions are published by Blodgett (2020) referenced below.

Summary of files included:
1) hu12_ids.csv.zip - twelve digit hydrologic unit (HUC12) code identifiers used in all files.
2) timesteps.csv.zip - timesteps used in all files.
3) nhm_total_flow_timeseries.csv.zip - One HUC12 per row, one date per column, version of total flow data.
4) nhm_snowmelt_timeseries.csv.zip - One HUC12 per row, one date per column, version of snowmelt data.

This data release compliments the following related data releases:

Actual evapotranspiration and snowpack water equivalent storage:
Blodgett, D.L., 2020, Twelve-digit hydrologic unit actual evapotranspiration and snowpack water equivalent storage from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System 1980-2016: U.S. Geological Survey data release, https://doi.org/10.5066/P9IH7CB8.

Soil moisture and recharge:
Blodgett, D.L., 2019, Twelve digit hydrologic unit soil moisture and recharge from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System: U.S. Geological Survey data release, https://doi.org/10.5066/P9ZZAWK4.

Streamflow:
Russell, A.M., Over, T.M., and Farmer, W.H., 2018, Statistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9DPSY6G.

Precipitation:
https://www.sciencebase.gov/catalog/item/52a7bed0e4b0de1a6d2dd0fd
Thornton, P.E., Thornton, M.M., Mayer, B.W., Wei, Y., Devarakonda, R., Vose, R.S., and Cook, R.B., 2017, Daymet—Daily surface weather data on a 1-km grid for North America, Version 3: ORNL DAAC website, accessed March 8, 2017, at https://doi.org/10.3334/ORNLDAAC/1328.

This dataset is part of the National Water Census Water Budget Estimation and Evaluation Project's ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of actual evapotranspiration and snowpack water equivalent storage are added to the already released estimates of soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. For background on source data and generation of these water budget variables, see nhru_pkwater_equiv.csv and nhru_hru_actet.csv from: Hay, L.E., 2019, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), by HRU Calibrated Version: U.S. Geological Survey data release, https://doi.org/10.5066/P9NM8K8W The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. All code used for conversions are included as an attachment to this data release. Summary of files included: 1) hu12_ids.csv - twelve digit hydrologic unit (HUC12) code identifiers used in all files 2) timesteps.csv - timesteps used in all files. 3) nhm_eta.nc - NetCDF version of actual evapotranspiration data 4) nhm_eta_grid.csv - One timestep per row version of actual evapotranspiration data 5) nhm_eta_timeseries.csv - One HUC12 per row version of actual evapotranspiration data 6) nhm_snowpack.nc - NetCDF version of snowpack water equivalent data 7) nhm_snowpack_grid.csv - One timestep per row version of snowpack water equivalent data 8) nhm_snowpack_timeseries.csv - One HUC12 per row version of snowpack water equivalent data 9) scripts.zip - A reproducible R workflow to create outputs implemented with the drake package This data release compliments the following related data releases. Soil moisture and recharge: Blodgett, D.L., 2019, Twelve digit hydrologic unit soil moisture and recharge from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System: U.S. Geological Survey data release, https://doi.org/10.5066/P9ZZAWK4. Streamflow: Russell, A.M., Over, T.M., and Farmer, W.H., 2018, Statistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9DPSY6G. Precipitation: https://www.sciencebase.gov/catalog/item/52a7bed0e4b0de1a6d2dd0fd

This dataset is part of the National Water Census Water Budget Estimation and Evaluation Project's ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of actual evapotranspiration and snowpack water equivalent storage are added to the already released estimates of soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. For background on source data and generation of these water budget variables, see nhru_pkwater_equiv.csv and nhru_hru_actet.csv from: Hay, L.E., 2019, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), by HRU Calibrated Version: U.S. Geological Survey data release, https://doi.org/10.5066/P9NM8K8W The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. All code used for conversions are included as an attachment to this data release. Summary of files included: 1) hu12_ids.csv - twelve digit hydrologic unit (HUC12) code identifiers used in all files 2) timesteps.csv - timesteps used in all files. 3) nhm_eta.nc - NetCDF version of actual evapotranspiration data 4) nhm_eta_grid.csv - One timestep per row version of actual evapotranspiration data 5) nhm_eta_timeseries.csv - One HUC12 per row version of actual evapotranspiration data 6) nhm_snowpack.nc - NetCDF version of snowpack water equivalent data 7) nhm_snowpack_grid.csv - One timestep per row version of snowpack water equivalent data 8) nhm_snowpack_timeseries.csv - One HUC12 per row version of snowpack water equivalent data 9) scripts.zip - A reproducible R workflow to create outputs implemented with the drake package This data release compliments the following related data releases. Soil moisture and recharge: Blodgett, D.L., 2019, Twelve digit hydrologic unit soil moisture and recharge from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System: U.S. Geological Survey data release, https://doi.org/10.5066/P9ZZAWK4. Streamflow: Russell, A.M., Over, T.M., and Farmer, W.H., 2018, Statistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9DPSY6G. Precipitation: https://www.sciencebase.gov/catalog/item/52a7bed0e4b0de1a6d2dd0fd

This dataset is part of the National Water Census Water Budget Estimation and Evaluation Project's ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of actual evapotranspiration and snowpack water equivalent storage are added to the already released estimates of soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. For background on generation of these water budget variables, see: Hay, L.E., 2019, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), by HRU Calibrated Version: U.S. Geological Survey data release, https://doi.org/10.5066/P9NM8K8W The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. All code used for conversions are included as an attachment to this data release. Summary of files included: 1) huc12_ids.csv - twelve digit hydrologic unit (HUC12) code identifiers used in all files 2) timesteps.csv - timesteps used in all files. 3) nhm_eta.nc4 - NetCDF version of actual evapotranspiration data 4) nhm_eta_grid.zip - Zipped CSV with one timestep per row version of actual evapotranspiration data 5) nhm_eta_timeseries.zip - Zipped CSV with one HUC12 per row version of actual evapotranspiration data 6) nhm_snowpack.nc4 - NetCDF version of snowpack water equivalent data 7) nhm_snowpack_grid.zip - Zipped CSV with one timestep per row version of snowpack water equivalent data 8) nhm_snowpack_timeseries.zip - Zipped CSV with one HUC12 per row version of snowpack water equivalent data 9) nhm_recharge.nc4 - NetCDF version of recharge data 10) nhm_recharge_grid.zip - Zipped CSV with one timestep per row version of recharge data 11) nhm_recharge_timeseries.zip - Zipped CSV with one HUC12 per row version of recharge data 12) nhm_soil_moist.nc4 - NetCDF version of soil moisture data 13) nhm_soil_moisture_grid.zip - Zipped CSV with one timestep per row version of soil moisture data 14) nhm_soil_moisture_timeseries.zip - Zipped CSV with one HUC12 per row version of soil moisture data 15) scripts.zip - A reproducible R workflow to create outputs implemented with the drake package

This dataset is part of the National Water Census Water Budget Estimation and Evaluation Project's ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of actual evapotranspiration and snowpack water equivalent storage are added to the already released estimates of soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. For background on generation of these water budget variables, see: Hay, L.E., 2019, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), by HRU Calibrated Version: U.S. Geological Survey data release, https://doi.org/10.5066/P9NM8K8W The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. All code used for conversions are included as an attachment to this data release. Summary of files included: 1) huc12_ids.csv - twelve digit hydrologic unit (HUC12) code identifiers used in all files 2) timesteps.csv - timesteps used in all files. 3) nhm_eta.nc4 - NetCDF version of actual evapotranspiration data 4) nhm_eta_grid.zip - Zipped CSV with one timestep per row version of actual evapotranspiration data 5) nhm_eta_timeseries.zip - Zipped CSV with one HUC12 per row version of actual evapotranspiration data 6) nhm_snowpack.nc4 - NetCDF version of snowpack water equivalent data 7) nhm_snowpack_grid.zip - Zipped CSV with one timestep per row version of snowpack water equivalent data 8) nhm_snowpack_timeseries.zip - Zipped CSV with one HUC12 per row version of snowpack water equivalent data 9) nhm_recharge.nc4 - NetCDF version of recharge data 10) nhm_recharge_grid.zip - Zipped CSV with one timestep per row version of recharge data 11) nhm_recharge_timeseries.zip - Zipped CSV with one HUC12 per row version of recharge data 12) nhm_soil_moist.nc4 - NetCDF version of soil moisture data 13) nhm_soil_moisture_grid.zip - Zipped CSV with one timestep per row version of soil moisture data 14) nhm_soil_moisture_timeseries.zip - Zipped CSV with one HUC12 per row version of soil moisture data 15) scripts.zip - A reproducible R workflow to create outputs implemented with the drake package

This data release supports the study by Sexstone and others (2019) and contains simulation output from a hydrological modeling experiment using a specific calibration of the conterminous United States (CONUS) application of the Precipitation-Runoff Modeling System (PRMS) (Hay, 2019) as implemented in the National Hydrologic Model (NHM) infrastructure (Regan and others, 2018). The by hydrologic response unit (byHRU) calibrated, baseline version of the NHM-PRMS (Hay, 2019) was used to evaluate the sensitivity of simulated runoff to the representation of snow depletion curves (SDCs) within the NHM-PRMS across the CONUS. The model experiment consisted of seven NHM-PRMS model simulations using the calibrated NHM-PRMS model parameters from Hay (2019). For each of the model simulations, the calibrated SDCs (Hay, 2019) were replaced with a single derived SDC derived based on a lognormal probability distribution function and assigned snow water equivalent coefficient of variation (CV) value. The seven CV values ranged from 0.1 to 2.0. Each of the simulations were completed at a daily time-step over a 14-year period (water years 2003 – 2016). Detailed methods and results are provided in Sexstone and others (2019). The SDC parameters used in this model experiment are provided by this data release. Furthermore, the attached NHM-PRMS variable table lists the selected output variables included in this data release. The individual *.csv files follow a naming convention of nhru_variable name_CVX.X.csv. The variable names included are defined further in NHM-PRMS variable table. The “CVX.X” denotes the CV value that was used to derive the SDC for the model simulation. The structure of each output file includes a header line which labels the columns by the HRU identification number with each row providing daily outputs. An inventory of the files provided within this data release can be found below. This research used resources provided by the Core Science Analytics, Synthesis, & Libraries (CSASL) Advanced Research Computing (ARC) group at the U.S. Geological Survey. Inventory of data release: NHM-PRMS_SDC_study.xml (1 .xml file): FGDC-compliant metadata file for the data release files. SDC_params.csv (1 .csv file): Table of the seven snow depletion curve parameterizations used in the modeling study. NHM-PRMS_variable_table.docx (1 .docx file): Table describing the selected NHM-PRMS output variables provided in this data release. nhru_gwres_flow_CVX.X.csv (7 .csv files): NHM-PRMS groundwater discharge output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_actet_CVX.X.csv (7 .csv files): NHM-PRMS actual evapotranspiration output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_outflow_CVX.X.csv (7 .csv files): NHM-PRMS total flow output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_ppt_CVX.X.csv (7 .csv files): NHM-PRMS precipitation output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_pkwater_equiv_CVX.X.csv (7 .csv files): NHM-PRMS snow water equivalent output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_potet_CVX.X.csv (7 .csv files): NHM-PRMS potential evapotranspiration output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was

This data release supports the study by Sexstone and others (2019) and contains simulation output from a hydrological modeling experiment using a specific calibration of the conterminous United States (CONUS) application of the Precipitation-Runoff Modeling System (PRMS) (Hay, 2019) as implemented in the National Hydrologic Model (NHM) infrastructure (Regan and others, 2018). The by hydrologic response unit (byHRU) calibrated, baseline version of the NHM-PRMS (Hay, 2019) was used to evaluate the sensitivity of simulated runoff to the representation of snow depletion curves (SDCs) within the NHM-PRMS across the CONUS. The model experiment consisted of seven NHM-PRMS model simulations using the calibrated NHM-PRMS model parameters from Hay (2019). For each of the model simulations, the calibrated SDCs (Hay, 2019) were replaced with a single derived SDC derived based on a lognormal probability distribution function and assigned snow water equivalent coefficient of variation (CV) value. The seven CV values ranged from 0.1 to 2.0. Each of the simulations were completed at a daily time-step over a 14-year period (water years 2003 – 2016). Detailed methods and results are provided in Sexstone and others (2019). The SDC parameters used in this model experiment are provided by this data release. Furthermore, the attached NHM-PRMS variable table lists the selected output variables included in this data release. The individual *.csv files follow a naming convention of nhru_variable name_CVX.X.csv. The variable names included are defined further in NHM-PRMS variable table. The “CVX.X” denotes the CV value that was used to derive the SDC for the model simulation. The structure of each output file includes a header line which labels the columns by the HRU identification number with each row providing daily outputs. An inventory of the files provided within this data release can be found below. This research used resources provided by the Core Science Analytics, Synthesis, & Libraries (CSASL) Advanced Research Computing (ARC) group at the U.S. Geological Survey. Inventory of data release: NHM-PRMS_SDC_study.xml (1 .xml file): FGDC-compliant metadata file for the data release files. SDC_params.csv (1 .csv file): Table of the seven snow depletion curve parameterizations used in the modeling study. NHM-PRMS_variable_table.docx (1 .docx file): Table describing the selected NHM-PRMS output variables provided in this data release. nhru_gwres_flow_CVX.X.csv (7 .csv files): NHM-PRMS groundwater discharge output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_actet_CVX.X.csv (7 .csv files): NHM-PRMS actual evapotranspiration output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_outflow_CVX.X.csv (7 .csv files): NHM-PRMS total flow output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_ppt_CVX.X.csv (7 .csv files): NHM-PRMS precipitation output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_pkwater_equiv_CVX.X.csv (7 .csv files): NHM-PRMS snow water equivalent output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_potet_CVX.X.csv (7 .csv files): NHM-PRMS potential evapotranspiration output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was

This data release contains inputs and outputs for hydrologic simulations of the conterminous United States (CONUS) using the National Hydrologic Model (NHM) application of the Precipitation Runoff Modeling System (PRMS) in ASCII and binary format and explanatory graphics in pdf format. These simulations were developed to provide estimates of water availability for historical conditions for the period October 1, 1980 to September 30, 2016 for five different calibration configurations; the first three years of the simulation should be considered the initialization period and should not be used for subsequent analysis. The five versions of model parameters and associated model output included in this data release are described in table 1 and in the Supplemental Information section of this metadata record. Table 2 provides information about the baseline datasets used for model calibration for each of the five parameter configurations. Figure 1 shows a schematic of the multi-step calibration procedure used to develop the model parameters. Table 3 describes the 36 model output variables that are included in the five attached folders. Five .tar folders are named according to the simulation configuration in table 1 and include the 36-model output variable files. Table 4 provides information about the 8,274 streamgage locations that are included in the NHM-PRMS. The NHM-PRMS parameter and control files for each of the five simulations are located on the child pages associated with this data release. The PRMS climate forcing input files for the simulations are in the DAYMET_CBH.zip folder. Summary files by streamgage of measured and simulated streamflow for the byHRU, byHRU_musk, and byHRU_musk_obs simulations are in the Streamgage_location_simulations_5999.zip folder. Any time series data in the model output files prior to the October 1, 1983 start date should be considered part of the model initialization period and should not be used. Please refer to the Supplemental Information element of this metadata record for more information about the model calibration, inputs, outputs, and summaries included in this data release.

This data release contains inputs and outputs for hydrologic simulations of the conterminous United States (CONUS) using the National Hydrologic Model (NHM) application of the Precipitation Runoff Modeling System (PRMS) in ASCII and binary format and explanatory graphics in pdf format. These simulations were developed to provide estimates of water availability for historical conditions for the period October 1, 1980 to September 30, 2016 for five different calibration configurations; the first three years of the simulation should be considered the initialization period and should not be used for subsequent analysis. The five versions of model parameters and associated model output included in this data release are described in table 1 and in the Supplemental Information section of this metadata record. Table 2 provides information about the baseline datasets used for model calibration for each of the five parameter configurations. Figure 1 shows a schematic of the multi-step calibration procedure used to develop the model parameters. Table 3 describes the 36 model output variables that are included in the five attached folders. Five .tar folders are named according to the simulation configuration in table 1 and include the 36-model output variable files. Table 4 provides information about the 8,274 streamgage locations that are included in the NHM-PRMS. The NHM-PRMS parameter and control files for each of the five simulations are located on the child pages associated with this data release. The PRMS climate forcing input files for the simulations are in the DAYMET_CBH.zip folder. Summary files by streamgage of measured and simulated streamflow for the byHRU, byHRU_musk, and byHRU_musk_obs simulations are in the Streamgage_location_simulations_5999.zip folder. Any time series data in the model output files prior to the October 1, 1983 start date should be considered part of the model initialization period and should not be used. Please refer to the Supplemental Information element of this metadata record for more information about the model calibration, inputs, outputs, and summaries included in this data release.

This data release contains 16 variables from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS) version 1.1 modeling application forced with CONUS404-BA (Markstrom and others, 2024) from January 1980 through September 2021 that are summarized to a monthly time step and a twelve-digit hydrologic unit code for the spatial extent of the conterminous United States. The following fluxes and storages are included: total monthly precipitation, evapotranspiration, lateral flow, surface runoff, interflow, recharge, groundwater flow, and the average monthly snow water equivalent, interflow storage, groundwater storage, total storage, and soil moisture. These data can be found in the “huc12_monthly_nhmprms_conus404ba_1980_2021.nc” file. Additionally, two supplementary files are also included in this data release. The first file (“weights_hru_to_huc12_nhmprms_conus404ba.csv”) contains the spatial weights or fraction that is used to “weight” the modeling output in the area-weighting process. The second file (“summed_weights_per_huc12_nhmprms_conus404ba.csv”) contains the total fractional area within each twelve-digit hydrologic unit code that is covered by the modeling output and is important for filtering results in the data file (where a fractional coverage may be less than one).