OPR-O351-RA-21 Pleasant Island Glacier Bay NOAA Ship Rainier (S221) H13402 4 This Survey shall be conducted after priorities 1-3 Pleasant Island Alaska United States 10000 2021 Olivia A Hauser, CDR/NOAA Navigable Area 2021-03-04 2021-06-24 2021-07-09 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTC Pacific Hydrographic Branch Any revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 UTM 8N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit. CC0-1.0 (NOAA Field Units) CC0-1.0 https://creativecommons.org/publicdomain/zero/1.0/ https://creativecommons.org/publicdomain/zero/1.0/legalcode These data were produced by NOAA and are in the public domain within the United States. NOAA waives any potential copyright and related rights in these data worldwide through the Creative Commons Zero 1.0 Universal Public Domain Dedication (CC0). NOAA The survey area is referred to as H13402, "Pleasant Island" (sheet 4), within the Project Instructions. The area encompasses approximately 27 square nautical miles in the vicinity of Pleasant Island near the entrance to Glacier Bay, Alaska. 58.413275 135.91545100000002 58.338522000000005 135.520342 Data were acquired within the assigned survey limits as required in the Project Instructions and HSSD unless otherwise denoted. H13402 assigned survey area (Chart 17302). SupportFiles\survey area.PNG Glacier Bay in Southeast Alaska was covered by a single ice sheet as recently as the late 1700s. The tidewater glaciers that visitors see today are remnants of the calving and retreat of this glacial ice. In 2019, Glacier Bay National Park received approximately 675,000 visitors traveling by cruise ships, tour boats, charter boats, and private vessels. Most of the glaciers within the bay are thinning and receding due to rapidly warming atmospheric temperatures and ocean water, exposing uncharted areas at the glacier faces. In addition, glacial till has altered the bathymetry in the fjords near the glaciers. While most of Glacier Bay was last surveyed in 2009, the southern portion was last surveyed prior to 2001. Conducting a modern bathymetric survey in this area will provide critical data for the updating of National Ocean Service (NOS) nautical charting products and services to increase maritime safety in Glacier Bay. Survey data from this project is intended to supersede all prior survey data in the common area. The entire survey is adequate to supersede previous data. All water in survey area Complete Coverage (refer to HSSD Section 5.2.2.3) A significant amount of multibeam echosounder coverage was acquired in H13402 to the inshore limit of hydrography, the Navigable Area Limit Line (NALL). The NALL is defined as the most seaward of the following: the surveyed 3.5 meter depth contour, the line defined by the distance seaward from the observed MHW line which is equivalent to 0.8 millimeters at chart scale (the assigned sheet limits closely reflect this) or the inshore limit of safe navigation. Areas where H13402 coverage reached neither 3.5 meters water depth, nor the assigned survey limits, were due to time constraints or encountering unsafe conditions. See the figures below for examples of H13402 MBES coverage. H13402 MBES coverage and assigned survey limits (dashed black line). SupportFiles\survey_coverage_new.PNG Example where H13402 MBES coverage did not extend to the most inshore limits of the assigned survey area (red indicates 3.5 meter water depth). SupportFiles\RED NALL north.PNG 2801 0.0 168.3 0.0 0.0 0.0 0.0 0.0 9.4 0.0 2803 0.0 288.8 0.0 0.0 0.0 0.0 0.0 7.0 0.0 2802 0.0 314.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 771.6 0.0 0.0 0.0 0.0 0.0 16.4 0.0 0.0 0 2 69 0 20.7 2021-06-25 2021-06-26 2021-06-27 2021-06-28 2021-06-29 2021-06-30 2021-07-02 2021-07-03 2021-07-04 2021-07-05 2021-07-06 2021-07-07 2021-07-08 2021-07-09 Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections. 2803 8.8 1.1 2802 8.8 1.1 2801 8.8 1.1 2701 7.62 0.47 1906 5.8 0.53 RAINIER survey launch 2803. SupportFiles\JTD_0385.JPG All data for H13402 were acquired by NOAA Ship RAINIER survey launches 2801, 2802, and 2803. These launches acquired MBES bathymetry, backscatter imagery and sound speed profiles. NOAA Ship RAINIER's jet boat 2701 and skiff 1906 conducted shoreline feature verification. Positioning System Applanix POS MV 320 v5 Conductivity, Temperature, and Depth Sensor Sea-Bird Scientific SBE 19plus MBES Kongsberg Maritime EM 2040 Sound Speed System Teledyne RESON SVP 70 RAINIER launches 2801 and 2803 acquired 16.4 nautical miles (2.1% of mainscheme) of MBES crossline data across all depth ranges, water masses and boat days that were operationally practical in order to evaluate the internal consistency of H13402 sonar data. Crossline analysis was performed using the Compare Grids function within Pydro Explorer on Caris variable-resolution surfaces of H13402 mainscheme only and crossline only data. 99.5+% of grid nodes met allowable uncertainties, see Pydro generated histograms below. H13402 crossline surface overlaid on mainscheme track lines. SupportFiles\XLs.PNG Pydro derived plot showing absolute difference statistics of H13402 mainscheme to crossline data. SupportFiles\H13402_VR_XLs-H13402_VR_MSs_depth_delta.png Pydro derived plot showing percentage pass value of H13402 mainscheme to crossline data. SupportFiles\H13402_VR_XLs-H13402_VR_MSs_fracAllowErr_Freq.png ERS via VDATUM 0.0 0.13 2808,2803,2804 3 .05 Total Propagated Uncertainty (TVU) values for survey H13402 were derived from from a combination of fixed values for equipment and vessel characteristics, as well as from field assigned values for sound speed uncertainties. Tidal uncertainty was provided in the project instructions for the NOAA vertical datum transformation model used for this survey. In addition to the usual a priori estimates of uncertainty via device models for vessel motion and ERTDM/VDATUM/TCARI, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H13402. Real-time uncertainties were provided via EM2040 MBES data and Applanix Delayed Heave RMS. Following post-processing of the real-time vessel motion, recomputed uncertainties of vessel roll, pitch, gyro and navigation were applied in CARIS HIPS and SIPS via a Smoothed Best Estimate of Trajectory (SBET) RMS file generated in Applanix POSPac. Uncertainty values of the submitted finalized grids were calculated in Caris using "Greater of the Two" of uncertainty and standard deviations (scaled to 95%). Grid QA v5 within Pydro QC Tools was used to analyze H13402 TVU compliance. H13402 met HSSD requirements in over 99.5 percent of grid nodes, which is shown in the histogram plot below. Pydro QC Tools 2 Grid QA was used to analyze H13402 multibeam echosounder (MBES) data density. The submitted H13402 variable-resolution (VR) surface met HSSD density requirements shown in the histograms below. Pydro derived plot showing TVU compliance of H13402 finalized variable-resolution MBES data. SupportFiles\H13402_MB_VR_MLLW_Final.QAv6.tvu_qc.png Pydro derived plot showing HSSD density compliance of H13402 finalized variable-resolution MBES data. SupportFiles\H13402_MB_VR_MLLW_Final.QAv6.density.png Sonar system quality control checks were conducted as detailed on quality control section of the DAPR None Exist There were no conditions or deficiencies that affected equipment operational effectiveness. None Exist There were no other factors that affected corrections to soundings. 80 sound speed profiles were acquired for this survey at discrete locations within the survey area at least once every four hours, when significant changes to surface sound speed were observed, or when moving survey operations to a new area. Sound speed data were acquired using Sea-Bird Scientific SBE 19plus profilers. All casts were concatenated into a master file and applied to H13402 MBES data using "nearest distance within time" (4 hours) profile selection method. H13402 sound speed cast locations. SupportFiles\Master_SVP.PNG H13402 sound speed cast comparison graph. SupportFiles\cast_comparison.PNG All equipment and survey methods were used as detailed in the DAPR. Delayed heave data failed to apply to one H13402 MBES line (0015_20210630_213325_2801_300A_181) due to a data gap that exceeded the allowable two second limit. Our current ERS processing work flow overwrites delayed heave data, therefore the absence of heave on this line had no adverse effect. The line shows good agreement with adjacent data. All sounding systems were calibrated as detailed in the DAPR. Raw backscatter data were acquired as .ALL files logged during MBES operations and subsequently processed by RAINIER personnel. The .GSF files created during processing and backscatter mosaic data has been delivered with this report. Backscatter processing procedures are described in the DAPR. Overview of H13402 multibeam acoustic backscatter coverage. SupportFiles\BackScatter.PNG CARIS HIPS and SIPS 11.3.15 QPS FMGT 7.9.4 NOAA Profile Version 2021 H13402_MB_VR_MLLW CARIS VR Surface (CUBE) Variable Resolution -0.53 152.92 NOAA_VR Complete MBES H13402_MB_VR_MLLW_Final CARIS VR Surface (CUBE) Variable Resolution -0.53 152.92 NOAA_VR Complete MBES Submitted H13402 surfaces were generated using NOAA recommended parameters for depth-based (Ranges) Caris variable-resolution bathymetric grids. Pydro QC Tools (v3.4.5) Flier Finder program was used to assist in the search for spurious soundings following initial cleaning. Flier Finder was run iteratively until the nine fliers remaining were deemed to be real features on the seafloor. Pydro QC Tools v3.4.5 Holiday Finder was used with default settings to find holidays in the finalized H13402 VR surface. Holiday Finder detected 12 holidays in the complete coverage surface. Of the detected holidays, 8 are on known features that could not be safely surveyed over top of. The remaining 4 detected holidays were confirmed to be gaps in data coverage, but they do not impact the reliability of the data. The 4 holidays that were data gaps were reviewed in the MBES data and based on the surrounding depths and location, it is assumed that there are no features or shoals of concern. Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying DAPR. Mean Lower Low Water ERS via VDATUM OPR-O351-FA-20_VDatum_100m_NAD83(2011)-MLLW_XGEOID16B.csar OPR-O351-FA-20_VDatum_100m_NAD83(2011)-MHW_XGEOID16B.csar North American Datum 1983 Projected UTM 8 Precise Positioning-Real time Extended (PP-RTX) processing methods were used in Applanix POSPac MMS (v8.5) software for post-processing horizontal correction of submitted H13402 MBES data. The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition. US4AK36M 80000 1992 2021-07-12 2021-07-12 A significant number of H13402 assigned features were addressed, however features inshore of the NALL were not investigated and are labeled as such in the H13402 Final Feature File (FFF). Due to a limited shoreline window, shoreline investigation was limited to areas with the most navigationally significant features. Ancon Rock near Point Gustavus was found to be mis-charted and has been repositioned. In addition, a charted wreck (PA) near Point Gustavus was disproved with MBES coverage. An obstruction PA located on the northern shore of Icy Passage was inshore of the NALL and not investigated. See the H13402 FFF submitted with this report for more information. No Dangers To Navigation (DTON) were identified within the H13402 survey area. Three previously uncharted wrecks were located within the H13402 survey area. Refer to the H13402 Final Feature File for additional information. H13402 MBES coverage of apparent submerged wreck. SupportFiles\potential wreck.PNG 3-D subset view of apparent H13402 wreck. SupportFiles\Wreck2_sideview.png No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits. Three Aids to Navigation (ATON) were investigated (Icy Passage Light 2, Pleasant Island Lighted Bell Buoy 11 and Ancon Rock Buoy 2) and appeared to be serving their intended purpose. Gustavus Lighted Buoy 1, Gustavus Dock West Light and three markers for the approach to the Salmon River near Gustavus were not investigated due to time constraints. Five Maritime Boundary Points (MBP) were assigned, two were investigated at Pleasant Reef, the other three were not investigated. The unaddressed MBPs where on the south side of Pleasant Island where shoreline investigation was not conducted due to time constraints and limited shoreline windows. Three bottom samples were assigned for this survey. Multiple collection attempts where made, but were unsuccessful. A possible explanation for this unsuccessful outcome is the rocky nature of the seafloor at the sample sites. No overhead features exist for this survey. A feature resembling a cable was seen in a 0.5-meter resolution H13402 MBES surface. The feature, located in Icy Passage, is approximately one nautical mile west of the day mark on the north shore of Pleasant Island, see image below. Feature resembling a cable, located within a charted cable area. SupportFiles\CableArea.png No platforms exist for this survey. Ferry routes and/or terminals exist for this survey, but were not investigated. Some interesting seafloor fetures were observed within the H13402 survey area, including sand waves and scours, see images below. Seafloor scours near Gustavus pier. SupportFiles\underwater features.PNG Sand waves near Gustavus pier. SupportFiles\wavesofsand.PNG No present or planned construction or dredging exist within the survey limits. No new surveys or further investigations are recommended for this area. No new ENC scales are recommended for this area. As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports. All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch. The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys Specifications and Deliverables, Field Procedures Manual, Letter Instructions, and all HSD Technical Directives. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies noted in the Descriptive Report. Olivia A Hauser, CDR/NOAA Chief of Party 2021-12-01 Dylan A Koston, LT/NOAA Field Operations Officer 2021-12-01 James B Jacobson Chief Survey Technician 2021-12-01 Bailey A Schrader Sheet Manager 2021-12-01