OPR-R331-FA-23 Togiak Bay Togiak Bay and Approaches NOAA Ship Fairweather (S220) H13783 2 2NM NE of Black Rock to Anchor Point Alaska United States 40000 2023 CDR Meghan McGovern, NOAA Navigable Area 2023-04-05 2023-05-24 2023-06-02 Multibeam Echo Sounder Multibeam Echo Sounder Bakscatter 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 4N, 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 2 NM NE of Black Rock to Anchor Point, Alaska 58.954166 160.500726 58.72655 160.043175 H13783 sheet limits (in blue) overlaid onto Chart US4AK87M file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/A.1%20survey%20coverage%20sheet%20limits.PNG Data were acquired to the survey limits in accordance with the requirements in the Project Instructions and the 2022 NOS Hydrographic Surveys Specifications and Deliverables (HSSD). Coverage acquired in H13783 is shown in Figure 1. Togiak Bay is well known for its striking landscapes and unique variety of wildlife and fish. The Togiak National Wildlife Refuge’s rivers are home to all five species of Pacific Salmon, Rainbow Trout, Arctic Grayling, Dolly Varden, and Arctic Char. The rivers contribute a large part of Togiak’s fisheries production of nearly 3 million salmon annually and as the primary subsistence resource for local villages including Togiak and Twin Hills. Archaeological evidence indicates the occupation of this area by Alaska Native Peoples for over 4,000 years. This hydrographic survey project will be a continuation of NOAA’s mapping campaign in Bristol Bay, with sister projects surveying from the Nushagak Peninsula area to Kvichak Bay and Southern Cape Newenham. Portions of Togiak Bay were last surveyed in the early 1990s with offshore areas having never been surveyed. Higher priority areas have been identified for updated bathymetry by the Alaska Marine Pilots and the West Alaska Lightering Group. This project will provide modern bathymetric data in an area of high hydrographic risk, improve maritime safety, and support the Seabed 2030 global mapping initiative. The entire survey is adequate to supersede previous data. Data acquired in H13783 meet multibeam echo sounder (MBES) coverage requirements for set line spacing, as required by the HSSD. This includes NOAA allowable uncertainty (see Section B.2.10) and density requirements (see Section B.2.11). This does not include crosslines as less than 8% were acquired (see section B.2.1). All waters in survey area Set Line Spacing MBES at 200m The entirety of H13783 was acquired with set line spacing, meeting the requirements listed above and in the HSSD (see section 5.2.2.4). H13783 survey coverage overlaid onto Chart US4AK87M file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/A.4%20survey%20coverage%20overlay.PNG 2805 0.0 31.39 0.0 0.0 0.0 0.0 0.0 6.13 0.0 2806 0.0 246.67 0.0 0.0 0.0 0.0 0.0 20.64 0.0 2808 0.0 374.39 0.0 0.0 0.0 0.0 0.0 13.06 0.0 0.0 692.46 0.0 0.0 0.0 0.0 0.0 39.83 0.0 0.0 6 0 0 0 26.68 2023-05-24 2023-05-25 2023-05-26 2023-05-27 2023-05-28 2023-05-29 2023-05-30 2023-05-31 2023-06-01 2023-06-02 Refer to the OPR-R331-FA-23 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. 2805 8.6 1.1 2806 8.6 1.1 2808 8.6 1.1 Image of HSL used during survey (2805, 2806, and 2808) file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/launch.jpg MBES Kongsberg Maritime EM 2040 Conductivity, Temperature, and Depth Sensor Sea-Bird Scientific SBE 19plus V2 Positioning and Attitude System Applanix POS MV 320 v5 Sound Speed System Teledyne RESON SVP 71 All launches utilize the Kongsberg EM 2040 MBES, a POS M/V v5 system for position and attitude, SVP 71 surface sound speed sensors, and Sea-Bird SBE 19plus v2 CTDs for conductivity, temperature, and depth casts. Launches 2806 and 2808 are equipped with the Velodyne VLP-16 Lidar for shoreline feature acquisition. Crosslines were collected, processed and compared in accordance with Section 5.2.4.2 of the HSSD. For adequate comparison, 5.75% of crossline to MBES data was acquired. The HSSD specifies 8% for set line spacing. We were not able to acquire 8%. To evaluate crosslines, a surface generated via data strictly from mainscheme lines and a surface generated via data strictly from crosslines were created. From these two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated. Statistics show the mean difference between the depths derived from mainscheme data and crossline data was -0.01 meters and 95% of nodes falling within +/- 0.16 meters. For the respective depths, the difference surface was compared to the allowable NOAA uncertainty standards. In total, 100.00% of the depth differences between H13783 mainscheme and crossline data were within allowable NOAA uncertainties. Overview of H13783 crosslines file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/H13783%20Crossline%20Difference.png Difference surface statistics between H13783 MS and H13783 XL (VR surface) file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/B.2%20H13783_MB_VR_MLLW_MS_Final-H13783_MB_VR_MLLW_XL_Final_depth_delta.png ERS via ERTDM 0.17 2805 2 0.5 2806 2 0.5 2808 2 0.5 In addition to the usual a priori estimates of uncertainty, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of this survey. Real-time uncertainties for position, navigation, attitude, and vessel motion data from Applanix POS MV were applied during acquisition and initially in post-processing. We later applied POSPac SBET and RMS files in CARIS HIPS to supercede POS MV uncertainties associated with GPS height and position. No junctions exist for this survey Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. MBES subbottom return near nadir A subbottom return was observed in the near-nadir region of HSL MBES data. This return was present in the majority of lines collected with HSL 2805, 2806, and 2808 and does not appear to effect the surface. Subset Editor was used to reject this data. It could be that a subbottom was observed due to a combination of high frequency (400kHz) and the mud nature of the seafloor resulting in pings extending past the surface. Example of subbottom return in near-nadir region of HSL MBES data as seen in Subset Editor. file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/D.2.8%20sub%20bottom%20image%201.PNG Example of subbottom return in near-nadir region of HSL MBES data as seen in Subset Editor. file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/D.2.8%20sub%20bottom%20image%202.PNG None Exist There were no other factors that affected corrections to soundings. Minimum of one every four hours Casts were conducted at a minimum of one every four hours during launch acquisition. Casts were conducted more frequently in areas where the influx of freshwater had an effect on the speed of sound in the water column and when there was a change in surface sound speed greater than two meters per second. All sound speed methods were used as detailed in the DAPR. Cast locations for H13783 file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/B.2%20cast%20locations.PNG All equipment and survey methods were used as detailed in the DAPR. Holidays H13783 data were reviewed in CARIS HIPS and SIPS for holidays in accordance with Section 5.2.2.3 of the HSSD. Twenty seven holidays which meet the definition described in the HSSD for set line spacing were identified via HydrOffice QC Tools Holiday Finder tool. This tool automatically scans the surface for holidays as defined in the HSSD and was run in conjunction with a visual inspection of the surface by the hydrographer. After careful inspection in CARIS using subset editor, 24 of these holidays were identified at the instersection of crosslines set lines and were deemed to be fully covered. Three were identified to be caused by "blow outs" when a boat hit the trough of a wave hard causing bubbles to interrupt the sonar and lose bottom. All holidays are represented in Figure 9 below. H13783 Holidays plotted over survey coverage with charts US4AK87M file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/H13783_Holidays.png NOAA Allowable Uncertainty The surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Overall, 99.5% of nodes within the surface meet NOAA Allowable Uncertainty specifications for H13783. H13783 allowable uncertainty statistics file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/H13783_MB_4m_MLLW_Final.GQv6.tvu_qc.png Density The surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Density requirements for H13783 were achieved with at least 99.5% of surface nodes containing five or more soundings as required by HSSD Section 5.2.2.3. H13783 data density statistics file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/B.2%20H13783_MB_VR_MLLW_Final.QAv6.density.png All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Raw backscatter data were stored in the .all file for Kongsberg systems. All backscatter were processed to GSF files and a floating point mosaic was created by the field unit via Fledermaus FMGT 7.10.2. See Figure below for a greyscale representation of the complete mosaic. A single backscatter mosaic was created at 2m resolution based on the specifications for a 400kHz system. All equipment and survey methods were used as detailed in the DAPR. Upon processing an artifact appeared across the mosaic. Evidence of this is not present in the log or in the GSF files. The cause is unknown and it does not appear to effect the data from the backscatter mosaic. Combined backscatter mosaic for H13783 file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/B.4%20backscatter.PNG Detail of backscatter mosaic artifiact for H13783 file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/B.4%20backscatter%20artifact.PNG CARIS HIPS and SIPS 11.4 QPS Fledermaus 7.10.2 NOAA Profile Version 2023 H13783_MB_4m_MLLW CARIS Raster Surface (CUBE) 4 4.8 32.8 NOAA_4m MBES Set Line Spacing H13783_MB_4m_MLLW_Final CARIS Raster Surface (CUBE) 4 4.8 32.8 NOAA_4m MBES Set Line Spacing The NOAA CUBE parameters defined in the HSSD were used for the creation of all CUBE surfaces for H13783. The surfaces have been reviewed where noisy data, or "fliers" are incorporated into the gridded solutions causing the surface to be shoaler or deeper than the true sea floor. Where these spurious soundings cause the gridded surface to vary from the reliably measured seabed by greater than the maximum allowable Total Vertical Uncertainty at that depth, the noisy data have been rejected by the hydrographer and the surface recomputed. Flier Finder, part of the QC Tools package within HydrOffice, was used to assist the search for spurious soundings following gross cleaning. Flier Finder was run iteratively until there were 160 areas flagged as fliers deemed as valid aspects of the surface. A large number of edge fliers are to be expected given the nature of the set line spacing. Remaining 160 areas flagged as fliers deemed as valid aspects of the surface file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/H13783_Fliers.png Per Section 5.2.2.1.3 of the 2022 Field Procedures Manual no Horizontal and Vertical Control Report has been generated for H13783. Mean Lower Low Water ERS via ERTDM OPR-R331-FA-23_AK_ERTDM_2023_NAD83-MLLW ERS methods were used as the final means of reducing H13783 to MLLW for submission. North American Datum 1983 Projected UTM 4 RTX Vessel kinematic data were post-processed using Applanix POSPac processing software and RTX positioning methods described in the DAPR. Smoothed Best Estimate of Trajectory (SBET) and associated error (RMS) data were applied to all MBES data in CARIS HIPS and SIPS. During real-time acquisition, all platforms received correctors from the Wide Area Augmentation System (WAAS) for increased accuracies. Chart comparison between ENC and soundings from collected data. The soundings from H13783 are generally in agreement ENC US4AK87M. Survey coverage with soundings (in red) overlaid onto ENC US4AK87M file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/D.1%20chart%20comparison.PNG US4AK87M 100000 5 2022-09-15 2023-01-24 No shoals or potentially hazardous features exist for this survey. No charted features exist for this survey. No uncharted features exist for this survey. No channels exist within the survey limits. No Aids to navigation (ATONs) exist for this survey. No Maritime Boundary Points were assigned for this survey. Six bottom samples were acquired in accordance with the Project Instructions for survey H13783. All bottom samples were entered in the H13783 Final Feature File. See Figure for a graphical overview of sample locations. H13783 Bottom Samples overlaid onto Chart US4AK87M (ArcGIS) file:///M:/OPRR331FA23/Surveys/H13783/01_HDR/Working/DR/Original/DR%20images/D.2.1%20bottom%20samples%20Arcgis.PNG No overhead features exist for this survey. No submarine features exist for this survey. No platforms exist for this survey. No ferry routes or terminals exist for this survey. No abnormal seafloor or environmental conditions exist for this survey. 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. CDR Meghan McGovern Commanding Officer 2023-11-07 LT Taylor Krabiel Operations Officer 2023-11-07 HST Finnegan Sougioultzoglou Sheet Manager 2023-07-28 HST Michael Lauzon Sheet Manager 2023-11-07