Bjerklie, David M. (ORCID: 0000-0002-9890-4125) Sturtevant, Luke P. (ORCID: 0000-0001-8983-8210) McCarthy, Brendan A. (ORCID: 0000-0003-4993-021X) Dudley, Robert W. (ORCID: 0000-0002-0934-0568) Harlan, Merritt E. (ORCID: 0000-0002-4019-4888) Mason, Christopher A. (ORCID: 0000-0001-9001-8244) Best, Heather R. (ORCID: 0000-0003-0764-3060) 20241217 2026-02-26 tabular digital data Estimated Streamflow Using Satellite Data for Selected Rivers in Alaska . Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Bjerklie, D.M., Sturtevant, L.P., McCarthy, B.A., Dudley, R.W., Harlan, M.E., Mason, C.A., and Best, H.R., 2024, Estimated streamflow using satellite data for selected rivers in Alaska (updated 2026-02-26): U.S. Geological Survey data release, https://doi.org/10.5066/P18WWJHU. https://doi.org/10.5066/P18WWJHU This dataset provides estimated Remote Sensing Streamflow (RSQ) data on a reach along the Holitna River for site: 613757157042301, HOLITNA R, RSQ REACH, ABOVE MOUTH NR SLEETMUTE, AK. Reach-specific relations between satellite-derived water-surface elevation data and dynamic surface water extent data were used with a modified form of the Manning's streamflow equation to estimate streamflows. Reach-specific details are provided in a README PDF document included with this data release. Satellite altimetry water-surface elevation (stage) and estimated streamflow (discharge) were used to derive stage-discharge relations for each river reach to support development of methods to estimate streamflow using remote sensing data. River discharge is estimated from June 1 to September 30. 2015-06-21 2021-09-17 observed Complete As needed -157.092 -157.054 61.642 61.624 USGS Metadata Identifier USGS:66b39789d34eebcf8bb33b26 ISO 19115 Topic Category InlandWaters Elevation USGS Thesaurus Remote sensing Streamflow Altimetry measurement Multispectral imaging USGS Geographic Names Information System (GNIS) Alaska Holitna River No access constraints. No use constraints. These data are marked with a Creative Common CC0 1.0 Universal License and are in the public domain. It is requested that this USGS data release be cited for any subsequent publications that reference or utilize these data. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey, England Water Science Center Mailing and Physical

196 Whitten Road

Augusta Maine 04330 USA 207-626-6600 dmbjerkl@usgs.gov Please see Bjerklie et al. 2023 (https://doi.org/10.1117/1.JRS.17.014520) for the framework for assessing the accuracy of discharge estimates. Spatial error estimates are provided as attributes in the data tables included in this data release. Attribute values fall within expected ranges. No data were omitted, no data are missing. Altimetry horizontal accuracy is approximately 250 to 1000 km relative to the reference ground tracks for the mission. Dynamic Surface Water Extent (DSWE) image-to-image registration accuracy of less than or equal to 12-meter Root Mean Square Error with 95 percent confidence. NASA Global Water Measurements (GWM) unknown online database online National Aeronautics and Space Administration (NASA) NASA Global Water Measurements (GWM) web portal, accessed at https://blueice.gsfc.nasa.gov/gwm/river/Index https://blueice.gsfc.nasa.gov/gwm/river/Index digital database file 2008 present image acquisition date GWM Satellite altimetry data compiled from multiple satellite missions on 10-day and 21-day repeat orbits. Used to relate water surface elevation to observed reach-averaged widths and streamflow computations. USGS National Water Information System (NWIS) 2015 online database Reston, VA U.S. Geological Survey U.S. Geological Survey, 2015, USGS Surface-Water Daily Data for the Nation: U.S. Geological Survey National Water Information System database, https://doi.org/10.5066/F7P55KJN https://doi.org/10.5066/F7P55KJN online database 2008 present access date NWIS Daily streamflows used for calibration and validation of streamflow models. U.S. Geological Survey 2024 web application online U.S. Geological Survey U.S. Geological Survey, 2024, Satellite Tool for River Altimetry and eXtent in Alaska (SatTRAX-AK): U.S. Geological Survey, software release https://doi.org/10.5066/P97N8QL4 https://doi.org/10.5066/P97N8QL4 software 2024 publication date SatTRAX-AK A software application (in the Google Earth Engine environment) that computes the surface water extent of large Alaskan rivers from Landsat and Sentinel imagery at locations with river surface altimetry data from the Global Water Measurements dataset. Altenau, E.H. Pavelsky, T.M. Durand, M.T. Yang, X. Frasson, R.P.M. Bendezu, L. 2023 online database online University of North Carolina at Chapel Hill Altenau, E.H., Pavelsky, T.M., Durand, M.T., Yang, X., Frasson, R.P.M., Bendezu, L., 2023. SWOT River Database (SWORD). Zenodo. https://doi.org/10.5281/zenodo.10013982 [Accessed by SatTRAX-AK to designate reaches and calculate surface water extent] https://doi.org/10.5281/zenodo.10013982 https://www.swordexplorer.com/ digital database file 2008 present access date SWORD Database of river nodes and reaches of SWOT river vector data products with attached hydrologic variables (water-surface elevation, width, slope, etc.). USGS Earth Resources Observation and Science (EROS) Center unknown remote-sensing image online U.S. Geological Survey, Earth Resources Observation and Science (EROS) Center USGS EarthExplorer web portal https://earthexplorer.usgs.gov/ https://doi.org/10.5066/F7445KQK online database 2008 present Image acquisition date Landsat Landsat satellite imagery utilized by the application for surface water calculations. Copernicus Sentinel unknown remote-sensing image online European Space Agency (ESA) - Copernicus programme EAS Copernicus Browser web portal https://dataspace.copernicus.eu/browser https://dataspace.copernicus.eu/browser online database 2008 present Image acquisition date Sentinel Sentinel satellite imagery utilized by the application for surface water calculations. Caelan E. Simeone Robert W. Dudley 2021 software online U.S. Geological Survey https://doi.org/10.5066/P9C6GGVE software 2021 publication date altimDSWE and RSQcomp USGS New England Water Science Center software packages for relating altimetry hieght, dynamic surface water extent, and discharge. Satellite-measured altimetry data records were downloaded from the Global Water Measurements portal (GWM) for Remote Sensing streamflow (RSQ) gage sites on selected river reaches. Altimetry source data are recorded in the "holitna_sleetmute_SatTRAX_INPUT_DATA.csv", "holitna_sleetmute_SatTRAX_RSQ_DATA.csv", and "holitna_sleetmute_RSQ_GAGE_DATA.csv" data tables. See entity and attribute section of this metadata record for more details. GWM Unknown Surface water streamgage locations were selected as proxies to approximate a time series of streamflow discharge of the same order of magnitude and timing from the USGS National Water Information System (NWIS). The selection of NWIS streamgages is usually (but not necessarily) the closest NWIS streamgage to the GWM site location. The NWIS streamgage measurements were downloaded and matched with GWM records based on collection date. These were used to calibrate, validate, and evaluate the remote sensing discharge estimates. NWIS streamgage data are recorded in the "holitna_sleetmute_SatTRAX_RSQ_DATA.csv" and "holitna_sleetmute_RSQ_GAGE_DATA.csv" data tables. See entity and attribute section of this metadata record for more details. NWIS GWM Unknown The USGS SatTRAX-AK software application was used to develop and compile data records from GWM altimetry and estimated water surface extents from Landsat and Sentinel satellite imagery based on collection dates. Please see the associated "holitna_sleetmute_SatTRAX_README.pdf" document for more detailed information about the process and equations used to develop the relation between satellite altimetry water surface elevation data and streamflow discharge. SatTRAX-AK data are recorded in the "holitna_sleetmute_SatTRAX_INPUT_DATA.csv" data table. See entity and attribute section of this metadata record for more details. SatTRAX-AK Landsat Sentinel Unknown The data source files developed from steps 1 and 3 are input into the altimDSWE and RSQcomp software applications to generate a relation between measured river height and reach-averaged water-surface width and to estimate the water surface slope of the river reach. See the "holitna_sleetmute_[Rating Version]_SatTRAX_RATING_TABLE.csv" data table and the "holitna_sleetmute_SatTRAX_README.pdf" for more information on this processing step. GWM altimDSWE and RSQcomp Unknown Calibration data are obtained from USGS NWIS source material and provides input data for calibration of the discharge rating using the altimDSWE and RSQcomp software application. Data for this processing step are recording in the "holitna_sleetmute_SatTRAX_RSQ_DATA.csv" data table. See entity and attribute section of this metadata record for more details. NWIS altimDSWE and RSQcomp Unknown Streamflow discharge was estimated from the altimetry (GWM) and estimated reach average width input data for the river reach at incremental water surface elevations. As a first step, a positive relation is developed between the altimetry derived water surface height (elevation) (WSE) and the imagery derived water surface widths. The width-height relation is then used to compute an associated with width with every height observed by the satellite. This step is necessary because there are far fewer width observations than heights and smooths scatter between the two variables due to observational inaccuracies. With observed river channel slope (typically measured from a Digital elevation model or from satellite observations), water-surface height and smoothed width estimates, streamflow discharges are estimated using the MOMMA algorithm (modified Manning equation) that is derived from equations 1 and 15 from Bjerkile and others 2018. The discharge estimates are calibrated against available ground-based information (often an active or discontinued streamgage, or limited field measurements in the reach), and then a height-discharge rating is developed from which discharge is computed for future satellite height observations. For additional calculation details, see the associated "holitna_sleetmute_SatTRAX_README.pdf" file with this data release. GWM Bjerkile and others 2018 Unknown LITERATURE CITED: Altenau, E.H., Pavelsky, T.M., Durand, M.T., Yang, X., Frasson, R.P.M., Bendezu, L., 2021. The Surface Water and Ocean Topography (SWOT) Mission River Database (SWORD): a global river network for satellite data products. Water Resources Research 57(7):e2021WR030054. https://doi.org/10.1029/2021WR030054 Bjerkile, D.M., Birkett, C.M., Jones, J.W., Carabajal, C., Rover, J.A., Fulton, J.W., Garambois, P.A. 2018. Satellite remote sensing estimation of river discharge: application to the Yukon River Alaska. Journal of Hydrology 561:1000-1018. https://doi.org/10.1016/j.jhydrol.2018.04.005 Bjerklie, D.M., Durand, M., LeNoir, J.M., Dudley, R.W., Birkett, C.M., Jones, J.W., Harlan, M.E., 2023, Satellite remote sensing of river discharge: a framework for assessing the accuracy of discharge estimates made from satellite remote sensing observations. Journal of Applied Remote Sensing 17(1):014520. https://doi.org/10.1117/1.JRS.17.014520 Jones, J.W., 2019. Improved Automated Detection of Subpixel-Scale Inundation-Revised Dynamic Surface Water Extent (DSWE) Partial Surface Water Tests. Remote Sensing 11(4):374. https://doi.org/10.3390/rs11040374 Unknown U.S. Geological Survey, National Hydrography Dataset (NHD) reach names and numbers, and streamgage station names and numbers refer to specific geographic locations recorded in the NWIS database. Point 0.0001 0.0001 Decimal degrees World Geodetic System of 1984 (WGS84) World Geodetic System of 1984 (WGS84) 6378137 298.257223563 Earth Gravitational Model 2008 (EGM2008) 0.01 meters Attribute values holitna_sleetmute_SatTRAX_INPUT_DATA.csv Comma Separated Value (CSV) file containing surface water extent, elevation, slope, and identifiers of source satellites, retrieved from different sources, used as input for discharge calculations. Author defined river_nm Name of river containing the study reach. Author defined Geographic Names Information System (GNIS) river name. rsq_site_nm Remote Sensing Streamflow (RSQ) site name. Author defined Unique site name description assigned by USGS. rsq_site_no Remote Sensing Streamflow (RSQ) site number. Author defined Unique site identification value assigned by USGS. obs_date Observation date (i.e., date of satellite image acquisition and altimetry water surface elevation measurement) Author defined Observation date (dd-mm-yy) src_img Satellite source imagery used to estimate water surface extent and estimated reach-averaged width data. Author defined Unique naming system of source imagery file. inst_type Satellite instrument type of the source image. Author defined Satellite type. altim_src Satellite altimeter source. Author defined GWM Global Water Measurements Author defined altim_id Altimetry source identifier. Author defined Unique identifier established by altimetry source repository. altim_ver Altimetry data processing version identifier Author defined Versioning system identifier established by altimetry source repository. altim_miss Altimetry satellite mission name. Author defined Satellite mission name established by altimetry source repository. altim_ht_m The satellite-measured water surface height relative to Earth Gravitation Model (EGM) 2008 datum, in meters. Author defined The satellite-measured water surface height. altim_cycle Satellite repeat cycle number. Author defined Repeat cycle value assigned by altimetry source data. altim_tgtHvar Target height variation with respect to satellite reference pass mean level, in meters. A value of 999.99 indicates that height variation data are not available. Author defined Target height variation with respect to satellite reference pass mean level, in meters. altim_error Estimated error of target height variation with respect to reference mean level, in meters. A value of 999.99 indicates that estimated error data are not available. Author defined Estimated error of target height variation with respect to reference mean level, in meters. altim_backScatCoef Altimetry backscatter coefficient (unitless). Author defined Altimetry backscatter coefficient (unitless). sword_ver Surface Water and Ocean Topography (SWOT) satellite mission SWOT River Database (SWORD) version. Surface Water and Ocean Topography (SWOT) satellite mission Versioning system establish by source repository. sword_id Identifier of the river reach in the SWORD database, used by SatTRAX-AK for surface water extent calculation. Surface Water and Ocean Topography (SWOT) satellite mission Unique identification system established by source repository. sword_width_m Estimated reach-averaged width for river surface from the SWORD database, in meters. Author defined Estimated reach-averaged width for river surface from the SWORD database, in meters. sword_wse_m Estimated reach-averaged water surface elevation from the SWORD database, in meters. Author defined Estimated reach-averaged water surface elevation from the SWORD database, in meters.. sword_slope_m_m Estimated reach-averaged slope from the SWORD database, in meters per meter. Author defined Estimated reach-averaged slope from the SWORD database, in meters per meter. swordLength_km Length of the river reach from the SWORD database, in kilometers. Author defined Length of the river reach from the SWORD database, in kilometers. swot_ver Surface Water and Ocean Topography version. Blank cells indicate that there are no data. Author defined Version system identifier established by SWOT mission. swot_width_m Estimated river width from the SWOT database, in meters. Blank cells indicate that there are no data. Author defined Estimated river width from the SWOT database, in meters. swot_wse_m Estimated water surface elevation from the SWOT database, in meters. Blank cells indicate that there are no data. Author defined Estimated water surface elevation from the SWOT database, in meters. swot_slope_m_m Estimated reach-averaged slope from the SWOT database, in meters per meter. Blank cells indicate that there are no data. Author defined Estimated reach-averaged slope from the SWOT database, in meters per meter. reach_slope_m_m Calculated slope of river reach using Alaska IFSAR digital elevation model, in meters per meter. Author defined Calculated slope of river reach using Alaska IFSAR digital elevation model, in meters per meter. sattrax_ver USGS SatTRAX software application version used to develop this record. Author defined Version system identifier established by USGS. run_date The date SatTRAX was run to develop this record. Date in format of MM/DD/YYYY where M=Month, D=Day, and Y=Year. Author defined The date SatTRAX was run to develop this record. param_cloudCover The SatTRAX parameter value for cloud cover used to develop this record, percentage. Author defined The SatTRAX parameter value for cloud cover, percentage. param_startYear The SatTRAX parameter for Start Year used to develop this record. Blank cells indicate that there are no data. Author defined The SatTRAX parameter for Start Year. param_endYear The SatTRAX parameter for End Year used to develop this record. Blank cells indicate that there are no data. Author defined The SatTRAX parameter for End Year. param_startMonth The SatTRAX parameter for Start Month used to develop this record. Blank cells indicate that there are no data. Author defined The SatTRAX parameter for Start Month. param_endMonth The SatTRAX parameter for End Month used to develop this record. Blank cells indicate that there are no data. Author defined The SatTRAX parameter for End Month. param_reachBuffer The SatTRAX parameter reach buffer multiplier used to develop this record. Blank cells indicate that there are no data. Author defined The SatTRAX parameter reach buffer multiplier. param_channelized The SatTRAX parameter for channelization option used to develop this record. Blank cells indicate that there are no data. Author defined The SatTRAX parameter for channelization option. 1 Channelization option used for SatTRAX application. Author defined holitna_sleetmute_SatTRAX_RSQ_DATA.csv Comma Separated Value (CSV) file containing satellite-measured altimetry, width, and streamflow data from Global Water Measurements satellite crossing sites and nearest NWIS streamgage merged by observation date. Used to estimate, calibrate, and validate remotely sensed streamflows (RSQ). Author defined altim_src Satellite altimeter source. Author defined GWM Global Water Measurements Author defined altim_id The unique identifier from the altimetry source data. Author defined Unique identifier assigned by altimetry source data. altim_ver Version system of the altimetry source data. Author defined Unique version identifier of the altimetry source data. altim_miss The name of the satellite mission that the altimetry data records were collected from. Author defined JASN2 Joint Altimetry Satellite Oceanography Network (JASON) mission 2. Author defined JASN3 Joint Altimetry Satellite Oceanography Network (JASON) mission 3. Author defined SENT6 Sentinel 6 mission. Author defined altim_cycle Satellite repeat cycle number. Author defined Repeat cycle value assigned by altimetry source data. altim_ht_m The satellite-measured water surface height relative to Earth Gravitation Model (EGM) 2008 datum, in meters. Author defined The satellite-measured water surface height,in meters. obs_date Observation date (i.e., date of satellite image acquisition and altimetry water surface elevation measurement) Author defined Observation date (MM/DD/YYYY) CalVal_Q_cfs NWIS streamgage measurement to compare discharge, in cubic feet per second. Output from NWIS. A null value (blank cell) indicates that no NWIS data are available. Author defined NWIS streamgage measurement to compare discharge, in cubic feet per second. CalVal_GH_ft NWIS streamgage height measurement, in feet. Output from NWIS. A null value (blank cell) indicates that no NWIS data are available. Author defined NWIS streamgage height measurement, in feet. CalVal_Q_cms NWIS streamgage measurement to compare discharge, in cubic meters per second. Output from NWIS. A null value (blank cell) indicates that no NWIS data are available. Author defined NWIS streamgage measurement to compare discharge, in cubic meters per second. CalVal_GH_m NWIS streamgage height measurement, in meters. Output from NWIS. A null value (blank cell) indicates that no NWIS data are available. Author defined NWIS streamgage height measurement, in meters. Q_cal Whether the NWIS streamgage discharge measurement was used for calibration. A null value (blank cell) indicates that no NWIS data are available. Author defined TRUE NWIS streamgage discharge measurement was used for calibration. Author defined FALSE NWIS streamgage discharge measurement was not used for calibration. Author defined Q_val Whether the NWIS streamgage discharge measurement was used for validation. A null value (blank cell) indicates that no NWIS data are available. Author defined FALSE NWIS streamgage discharge measurement was not used for validation. Author defined TRUE NWIS streamgage discharge measurement was used for validation. Author defined reach_slope_m_m Ground measured slope of the water surface in the study reach used for calibration, in meters per meter. A null value (blank cell) indicates that no slope data are available. Author defined Ground measured slope of the water surface in the study reach used for calibration, in meters per meter. obs_slope Whether the ground measured slope was used for calibration. Author defined FALSE Satellite observed slope was not used for evaluation. Author defined TRUE Satellite observed slope was used for evaluation. Author defined obs_width Whether the study reach-averaged width was observed using HLS DSWE data or computed from an empirical altimetry-width relation. Author defined FALSE Satellite observed width is not used for evaluation. Author defined TRUE Satellite observed width is used for evaluation. Author defined width_m RSQ estimated reach averaged water surface width, in meters. A null value (blank cell) indicates that no width estimate is available. Author defined RSQ estimated reach averaged water surface width, in meters. Y_m_momma RSQ estimated reach averaged water depth, in meters. Computed with the Modified Optimized Manning Method Algorithm (MOMMA). A null value (blank) indicates that no estimate is available. Author defined RSQ estimated reach averaged water depth, in meters. A_m2_momma RSQ estimated reach averaged cross-sectional streamflow area, in square meters. Computed with the Modified Optimized Manning Method Algorithm (MOMMA). A null value (blank) indicates that no estimate is available. Author defined RSQ estimated reach averaged cross-sectional streamflow area, in square meters. n_momma RSQ estimated Manning streamflow resistance coefficient. Computed with the Modified Optimized Manning Method Algorithm (MOMMA). A null value (blank) indicates that no estimate is available. Author defined RSQ estimated Manning streamflow resistance coefficient. v_mps_momma RSQ estimated reach averaged velocity of streamflow, in meters per second. Computed with the Modified Optimized Manning Method Algorithm (MOMMA). A null value (blank) indicates that no estimate is available. Author defined RSQ estimated reach averaged velocity of streamflow, in meters per second. froude_momma RSQ estimated reach averaged Froude number of the streamflow. Computed with the Modified Optimized Manning Method Algorithm (MOMMA). A null value (blank) indicates that no estimate is available. Author defined RSQ estimated reach averaged Froude number of the streamflow. Q_cms_momma RSQ estimated streamflow (discharge) in the reach, in cubic meters per second. Computed with the Modified Optimized Manning Method Algorithm (MOMMA). A null value (blank) indicates that no estimate is available. Author defined RSQ estimated streamflow (discharge) in the reach, in cubic meters per second. rating_ver Version number of the stage-discharge rating. Author defined Versioning system value assigned by USGS. holitna_sleetmute_[Rating Version]_SatTRAX_RATING_TABLE.csv Comma Separated Value (CSV) file containing altimetry water-surface elevations paired with remotely sensed streamflow (RSQ) estimates developed from associated data table "holitna_sleetmute_SatTRAX_RSQ_DATA.csv". The CSV contains a comment header section (denoted by "#") with details of the ratings provided in the table. Author defined header rows Nine rows with details of the ratings provided in the table. Author defined # Rating Version: Version of rating equations. # Rating Effective Date: Date that the rating was established (mm/dd/yyyy). # Rating Termination Date: Date that the rating was deprecated (mm/dd/yyyy). "N/A" indicated thatathe rating is still current. # Width-Height Relation Equation: Width to height relation equation described in associated read me file as equation 1. # Calval USGS Gage ID: USGS surface water streamgage ID used for calibration/validation. "N/A" indicates that there is no nearby gage location used for calibration/validation. # SWORD Reach ID: The SWOT River Database river reach center line ID number associated with the given site. # Altimetry Source: The source of altimetry data used to establish rating data. # Altimetry Identifier: The unique identifier of the altimeter source data. # Altimetry Version: The version of the altimeter source data. wse_m The satellite-measured water surface height relative to Earth Gravitation Model (EGM) 2008 datum, in meters. Author defined The satellite-measured water surface height, in meters. flow_cms Remotely sensed estimated streamflow (RSQ), in cubic meters per second. Author defined Remotely sensed estimated streamflow (RSQ), in cubic meters per second. flow_cfs Remotely sensed estimated streamflow (RSQ), in cubic feet per second. Author defined Remotely sensed estimated streamflow (RSQ), in cubic feet per second. holitna_sleetmute_RSQ_GAGE_DATA.csv Comma Separated Value (CSV) file containing compiled gage and Remote Sensing Streamflow (RSQ) data for all available sites. The CSV contains a comment header section (denoted by "#") with a disclaimer statement and column header definitions. Author defined obs_datetime Date and time of satellite observation. Date time value formatted MM/DD/YYYY hh:mm where M=Month, D=Day, Y=Year, h=24-hour time, m=minutes Author defined Date and time of satellite observation. tzone_code Time zone corresponding to date and time. Author defined UTC Coordinated Universal Time Author defined altim_src Satellite altimeter source. Author defined GWM Global Water Measurements Author defined altim_id The unique identifier from the altimetry source data. Author defined Unique identification system of the altimetry source. altim_ver Version system of the altimetry source data. Author defined Unique version identifier of the altimetry source data. altim_miss The name of the satellite mission that the altimetry data records were collected from. Author defined JASN2 Joint Altimetry Satellite Oceanography Network (JASON) mission 2. Author defined JASN3 Joint Altimetry Satellite Oceanography Network (JASON) mission 3. Author defined SENT6 Sentinel 6 mission. Author defined swot_collection Version of Surface Water and Ocean Topography (SWOT) mission used for observation, if applicable. Blank cells indicate that no SWOT record is available. Author defined Unique version identifier assigned by SWOT mission source data. sword_version SWOT River Database (SWORD) version used to define reach. Author defined Unique version identifier assigned by SWOT River Database (SWORD). sword_reach_id Unique reach center line code identifier from the SWORD database. Author defined Unique reach center line identifier from the SWORD database. rsq_site_nm Remote Sensing Streamflow (RSQ) USGS gage site name. Author defined Unique site name assigned by USGS. rsq_site_no Unique USGS Site number for Remote Sensing Streamflow (RSQ) Gage. Author defined Unique site identification value assigned by USGS. rsq_gage_latitude Latitudinal coordinates in decimal degrees of the river reach in EPGS 4326. Author defined Latitude in decimal degrees (WGS84). rsq_gage_longitude Longitudinal coordinates in decimal degrees of the river reach in EPGS 4326. Author defined Longitude in decimal degrees (WGS84). calval_usgs_gage_id USGS Gage Station identification number, if applicable. These gages are used for calibration and validation of RSQ data. Blank cells indicate that there is no ground gage used for calibration or validation. Author defined Unique USGS surface water ground gage station identifier. rsq_obs_height_m Satellite observed water surface elevation, in meters relative to Earth Gravitational Model 2008 (EGM2008) geoid. Blank cells indicate that there is no data available. Author defined Satellite observed water surface elevation, in meters. rsq_obs_height_u_m Satellite observed water surface elevation uncertainty, in meters. A value of 999.99 indicates that elevation uncertainty data are not available. Author defined Satellite observed water surface elevation uncertainty, in meters. rsq_est_width_m Estimated reach-averaged river width, in meters. Blank cells indicate that there is no data available. Author defined Estimated reach-averaged river width, in meters. rsq_est_discharge_m3s Estimated river discharge, in cubic meters per second. Blank cells indicate that there is no data available. Author defined Estimated river discharge, in cubic meters per second. rsq_obs_width_m Satellite observed reach-averaged river width, in meters. Blank cells indicate that there is no data available. Author defined Satellite observed reach-averaged river width, in meters. rsq_obs_width_u_m Satellite observed reach-averaged river width uncertainty, in meters. Blank cells indicate that there is no data available. Author defined Satellite observed reach-averaged river width uncertainty, in meters. date_retrieved Date of altimetry data download. Formatted as YYYYMMDD where Y=Year, M=Month, D=Day. Author defined Date of altimetry data download. rsq_rating_id Version of rating table used to derive rsq_est_width_m and rsq_est_discharge_m3s. Formatted to be version number, abbreviated month, and year. Author defined Version identifier assigned by USGS. ice_flag Boolean for ice observed by satellite. 0 = No ice observed, 1=Ice observed. Author defined 0 No ice observed by satellite. Author defined 1 Ice cover observed by satellite. Author defined rating_bounds_flag Boolean flag for rsq_obs_height_m observation being outside the bounds of the rating table. 0 = Inside rating table bounds, 1=Outside rating table bounds. Author defined 0 Altimetry height value within the bounds of equation. Author defined 1 Altimetry height value outside of the bounds of equation. Author defined holitna_sleetmute_SatTRAX_README.pdf Document with details of the streamflow calculations and parameters used for the specific river reach discharge estimate. Presented in a PDF formatted document. Author defined U.S. Geological Survey USGS ScienceBase Team Mailing and Physical

Denver Federal Center, Building 810, Mail Stop 302

Denver Colorado 80225 USA 1-888-275-8747 sciencebase@usgs.gov The U.S. Geological Survey, Alaska Science Center is the authoritative source of these data, distributed by ScienceBase (a USGS Trusted Digital Repository). This database, identified as "Estimated Streamflow using Satellite Data for Selected Rivers in Alaska", has been approved for release by the U.S. Geological Survey (USGS). Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the database is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. CSV Tabular data in CSV format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/P18WWJHU None 20260226 U.S. Geological Survey, Alaska Science Center Mailing and Physical

4210 University Drive

Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov FGDC Content Standard for Digital Geospatial Metadata (CSDGM) FGDC-STD-001-1998