Schauer, Paul V. (ORCID: 0000-0001-5529-4649) 20240426 2026-05-12 tabular digital data Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Schauer, P.V., 2024, Sounding cross section surveys at Alaska bridge crossings (updated: 2026-05-12): U.S. Geological Survey data release, https://doi.org/10.5066/P9G663NX https://doi.org/10.5066/P9G663NX Since 1993 the U.S. Geological Survey (USGS) has worked with the Alaska Department of Transportation and Public Facilities (ADOT&PF) to provide hydraulic assessments of scour for bridges throughout Alaska. As part of this effort, repeat channel cross section surveys, or channel soundings, have been collected at either the upstream or downstream side of bridges on an annual or as needed basis. Streambed and bank elevations are measured using USGS sounding weights and reels, weighted measuring tapes, acoustic Doppler current profilers, multibeam echo sounders and light detection and ranging and are referenced to the datum of as-built plan set to provide context for the streambed elevations in relation to bridge structures. Channel soundings are collected on an annual basis at most sites, however, as need soundings are collected due to flooding or periods of scour at select sites. Repeat channel soundings are used to access stream stability related to seasons, stage, and long-term aggradation or degradation as well as providing greater context for fixed mount streambed elevation monitoring. New measurements are appended to this data release after they have undergone formal QA/QC processing. Please note the updated date in the suggested citation. These data were collected to access stream stability related to seasons, stage, and long-term aggradation or degradation as well as providing greater context for fixed mount streambed elevation monitoring at Alaska bridge crossings. The USGS Open-File Report 2019-1028 (https://doi.org/10.3133/ofr20191028) published repeated cross section surveys measured by the USGS at select bridges in Alaska, 1971-2016. For this data release, all cross section data from the report were formally reviewed, and corrected if necessary. Those data and subsequently collected and reviewed sounding data are provided in this USGS data release. Additionally, this data release will be regularly updated as new cross section surveys are completed and reviewed. A list of USGS publications that have utilized these data is included with data package. 1990 2025 observed In work As needed -173.6719 -130.4297 71.6913 49.9512 USGS Metadata Identifier USGS:662af09cd34ea70bd5f0c1e2 ISO 19115 Topic Category InlandWaters NASA GCMD Earth Science Keyword Thesaurus Terrestrial Hydrosphere Rivers/streams Discharge/flow USGS Thesaurus Hydrology Geomorphology Scour Acoustic Doppler Current Profiling Alexandria Digital Library Feature Type Thesaurus Bridges None Streambed ADCP USGS Geographic Names Information System (GNIS) Alaska No access constraints. No use constraints. It is requested that the suggested citation for this USGS data release be included in any publications that reference or utilize these data. U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 ascweb@usgs.gov Alaska Department of Transportation and Public Facilities Dworsky, K.L. Conaway, J.S. 2019 publication U.S. Geological Survey Open-File Report 2019-1028 online U.S. Geological Survey Dworsky, K.L., Conaway, J.S., 2019, Measurement of long-term channel change through repeated cross-section surveys at bridge crossings in Alaska: U.S. Geological Survey Open-File Report 2019-1028 doi:10.3133/ofr20191028 https://doi.org/10.3133/ofr20191028 Sounding cross sections are worked from field notes and checked against the bridge as-built plans and historic cross sections. Accuracy is only relative to the land surface at the time of the survey, and most of these points are on streambeds that move. The horizontal location along the bridge structures are noted and cross checked against as-built bridge plans. Sounding cross sections collected by ADCP may have slight differences at the edges due to skewed or irregular banks. A best effort is made to end the transect directly under the up or downstream edge of the bridge in these circumstances, however due to obstacles, currents, or the height of the bridge there may be some discrepancy at the edges. Sounding tapes are checked against a steel tape before each field season and after any adjustments. Sounding reels are maintained by the Alaska Science Center Field Offices and sent to the USGS Hydrologic Instrumentation Facility for calibration. Acoustic Doppler Current Profilers are maintained according to the USGS OSW Technical Memorandum 2014.04. Elevations fall within expected ranges and data were proofed for the presence of duplication and omission. Blank cells indicate where a sounding measurement could not be made. Since the streambed can not be measured at these locations, the cross-section is not interpolated between measured points. Horizontal precision is within 0.1 feet. Dworsky, K.L. Conaway, J.S. 2019 publication U.S. Geological Survey Open-File Report 2019-1028 online U.S. Geological Survey Dworsky, K.L., Conaway, J.S., 2019, Measurement of long-term channel change through repeated cross-section surveys at bridge crossings in Alaska: U.S. Geological Survey Open-File Report 2019-1028 doi:10.3133/ofr20191028 https://doi.org/10.3133/ofr20191028 document 2019 publication date OFR 2019-1028 Original publication of repeated cross-section surveys measured by the USGS at select bridges in Alaska, 1971–2016. U.S. Geological Survey 2014 document U.S. Geological Survey, Office of Surface Water Technical Memorandum 2014.04 Reston, VA U.S. Geological Survey U.S. Geological Survey, 2014. Quality assurance checks of acoustic doppler current profilers. U.S. Geological Survey, Office of Surface Water Technical Memorandum 2014.04 https://water.usgs.gov/admin/memo/SW/sw14.04.html document 2014 publication date USGS OSW Technical Memorandum 2014.04 Policy regarding routine Acoustic Doppler Current Profiler (ADCP) Quality Assurance checks on ADCPs used for making velocity and discharge measurements. Mueller, D.S. Wagner, C.R. Rehmel, M.S. Oberg, K.A. Rainville, F. 2013 document U.S. Geological Survey Techniques and Methods Book 3, Chapter A22, version 2.0 online U.S. Geological Survey Mueller, D.S., Wagner, C.R., Rehmel, M.S., Oberg, K.A., Rainville, F., 2013, Measuring discharge with acoustic Doppler current profilers from a moving boat (ver. 2.0, December 2013): U.S. Geological Survey Techniques and Methods, Book 3, Chapter A22 https://doi.org/10.3133/tm3A22 https://doi.org/10.3133/tm3A22 publication 2013 publication date USGS Technical Memorandum 3-A22 Guidance on the use of ADCPs for measuring streamflow Mueller, D.S. 2020 software U.S. Geological Survey software release 10.5066/P9OZ8QDL online U.S. Geological Survey Mueller, D.S., 2020, QRev, U.S. Geological Survey software release, https://doi.org/10.5066/P9OZ8QDL https://hydroacoustics.usgs.gov/movingboat/QRev.shtml software 2020 publication date QRev Software that computes the discharge from moving boat ADCP measurements. Teledyne-RDI Unknown software WinRiver II ver 2.x online U.S. Geological Survey https://www.teledynemarine.com/ software Unknown publication date WinRiver II Data collection and post processing software (Windows) for discharge data applications. Since 1993, USGS has made repeated channel cross section surveys, or channel soundings, at select bridge crossings throughout Alaska. Survey measurements are collected at either the upstream or downstream side of bridges on an annual or as needed basis. Streambed and bank elevations are measured using USGS sounding weights and reels, weighted measuring tapes, Acoustic Doppler Current Profilers (ADCP), multibeam echo sounders and light detection and ranging and are referenced to the datum of as-built plans to provide context for the streambed elevations in relation to bridge structures. Unknown Sounding Cross Section Method 1: Horizontal measurements from the left bank end of the bridge, as facing downstream, and vertical measurements from the outside edge of the bridge deck are collected along the length of the bridge. Horizontal measurements are made using a Kevlar tagline, engineer measuring tape, or measuring wheel. Vertical measurements are made using a weighted engineer measuring tape (sounding tape) or sounding weights and reels. The elevation of the outside edge of the bridge deck is determined from as-built plans or by differential leveling. Measurements are made at major slope breaks along the banks and at a constant interval across the channel to measure the general shape of the cross section. Additional points in the channel are measured for better resolution at rapid elevation changes or at bridge piers. The as-built streambed elevation is computed at each horizontal measurement location by subtracting the vertical measurement from the elevation of the outside edge of the bridge deck. Unknown Sounding Cross Section Method 2: Bank points are collected using Sounding Cross Section Method 1. Channel points are collected using an Acoustic Doppler Current Profiler (ADCP). ADCP transects are collected from the left edge of water to the right edge of water, referenced as facing downstream, in accordance with USGS Technical Memorandum 3-A22. The ensemble for each the piers is noted during the sounding transect. The water surface is measured in the as-built datum of the bridge at the start and end of the ADCP transect. The ADCP sounding transect is processed using QRev and the manufacturer's ADCP software. The horizontal distance made good and depth is exported from the transect. The as-built streambed elevation, in feet, is computed from the field notes and ADCP data using the as-built bridge geometry and water surface at the time of the ADCP transect. Due to GPS data quality and moving bed conditions sounding cross sections may be adjusted based on observed channel widths and the location of bridge structures. Unknown Sounding Cross Section Method 3: A sounding cross section is pulled from multibeam bathymetry and boat-mounted Light Detection and Ranging (LiDAR). The sounding cross section is pulled from the topography and bathymetry point clouds so the transect starts at the left bank and ends at the right bank (left and right banks referenced as facing downstream). The bathymetry and topography are collected in NAVD 88. The NAVD 88 elevation is converted to the elevation in the as-built datum based on differential leveling from the GNSS base station to the as-built datum. Unknown Quality Assurance and Quality Control (QAQC): is performed for each sounding cross section. An internal review of all aspects of the sounding cross section surveys is performed by ensuring field notes are archived, checking field notes against streambed elevation computations, and that correct as-built elevations are used to compute streambed elevations. The location of noted bridge structure elements is checked against as-built plans for accuracy. Sounding cross sections are plotted against previously reviewed sounding cross sections and bridge geometry to check for errors in horizontal and vertical computations. Internal reviews of the sounding cross sections are logged and archived with field notes and raw project data. A second review of data is performed before publication ensuring that all cross sections have been reviewed and that data tables and plots are complete. Unknown Bridge crossing location descriptions and road mile points are from the latest ADOT Bridge and Tunnel Inventory Report Point 0.001 0.001 Decimal degrees World Geodetic System of 1984 (WGS84) World Geodetic System of 1984 (WGS84) 6378137 298.257223563 North American Vertical Datum of 1988 0.1 feet Attribute values Land survey datum 0.1 feet Attribute values [FOLDER] streambedElevation_AKbridgeCrossing_data Folder with tables of channel elevations from sounding cross section surveys at 30 Alaska bridge crossings. Each table provides cross sections from a single bridge crossing at multiple dates, presented in a Comma Separated Value (CSV) formatted table. Filenaming convention: streambedElevation_AKbridgeCrossing_[NNNN].csv; where: [NNNN] is a unique four-digit Alaska bridge inventory number from the Alaska Department of Transportation and Public Facilities (ADOT&PF). For visual reference, images showing sounding cross section surveys plotted with the bridge geometry are included with this data package, in the folder "streambedElevation_AKbridgeCrossing_plots". Author defined Survey Identifier (consecutively numbered) of each cross section survey at each bridge. Author defined Identifier (consecutively numbered) of each cross section survey at each bridge. Bridge Identifier of elevations determined from as-built plans to plot the bridge as reference against sounding cross sections. Author defined Asbuilt Identifier for a sounding cross section determined from as-built plans as a reference sounding cross section. Author defined Date Date that the sounding cross section was collected, in MM/DD/YYYY format. No dates are provided for 'Bridge' and 'Asbuilt' records, indicated by blank cells. Author defined Date that the sounding cross section was collected, in MM/DD/YYYY format. Side Upstream or downstream side of the bridge that the sounding cross section was collected. No 'Side' is provided for 'Bridge' and 'Asbuilt' records, indicated by blank cells. Author defined US Sounding cross section made along the upstream side of the bridge. Author defined DS Sounding cross section made along the downstream side of the bridge. Author defined Station Distance from the left bank end of the bridge as facing downstream, in feet (measurement resolution 0.1 ft). Negative numbers are shoreward of the left bank end of the bridge. Author defined Distance from the left bank end of the bridge as facing downstream, in feet. Elevation Elevation of streambed relative to the as-built datum, in feet (measurement resolution 0.1 ft). Blank cells indicate that no elevation is provided. The as-built datum is provided in the table "streambedElevation_AKbridgeCrossing_referenceDatum.csv" included with this data package. Author defined Elevation of streambed relative to the as-built datum, in feet. EOW Designation that the survey point was collected at the left or right edge of water (LEW and REW respectively) as looking downstream. Multiple water surfaces are present where bars or islands separate channels. Blank cells indicate elevations not from the edge of water. Author defined LEW Left edge of water as looking downstream. Author defined REW Right edge of water as looking downstream. Author defined streambedElevation_AKbridgeCrossing_referenceDatum.csv Table with location and reference information for all bridges in this data package. Presented in a Comma Separated Value (CSV) formatted table. Author defined BN A unique four-digit Alaska bridge inventory number from the Alaska Department of Transportation and Public Facilities (ADOT&PF). Author defined Alaska bridge inventory number Lat Latitude of bridge. Author defined 57.776038 67.437566 Decimal degrees (WGS84) Long Longitude of bridge. Author defined -164.746912 -135.932517 Decimal degrees (WGS84) Crossing Description of the crossing and road mile point as described in the latest Alaska Department of Transportation and Public Facilities Bridge and Tunnel Inventory Report. Author defined Description of the crossing and road mile point. Datum_Reference As-built datum reference point. Author defined Location on the bridge with a known as-built datum elevation. Elevation As-built datum elevation, in feet. Datum is arbitrary. Author defined Elevation of the as-built datum reference point, in feet. [FOLDER] streambedElevation_AKbridgeCrossing_plots For visual reference, a folder with PDF files showing: sounding cross section surveys plotted against the bridge geometry and a reference sounding cross section determined from as-built plans. Filenaming convention: streambedElevation_AKbridgeCrossing_plots_[NNNN].pdf; where: [NNNN] is a unique four-digit Alaska bridge inventory number from the Alaska Department of Transportation and Public Facilities (ADOT&PF). Author defined U.S. Geological Survey USGS ScienceBase Mailing and Physical

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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). Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data for other purposes or on all computer systems, nor shall the act of distribution constitute any such warranty. 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; supplemental bridge geometry in PDF format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/P9G663NX None 20260512 U.S. Geological Survey, Alaska Science Center Mailing and Physical

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