OPR-T382-RA-23 American Samoa and PRIA American Samoa and PRIA NOAA Ship Rainier (S221) H13735 6 Tutuila American Samoa United States 40000 2023 Héctor L. Casanova, CAPT/NOAA Basic Hydrographic Survey 2023-01-27 2023-03-23 2023-09-05 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(PA11) UTM Zone 2S, 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 H13735, "Tutuila" (Sheet 6) within the Project Instructions. The surveyed area encompasses approximately 3414 square nautical miles and is located among the largest and most populous island of American Samoa. 13.798786999999999 171.24521299999998 14.992206 170.11074 H13735 assigned survey area and survey outline (Chart US1EEZ3M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_AssignedSurveyArea.JPG H13735 assigned priority area PIFSC bottomfish survey domain (Chart US1EEZ3M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_Priority%20Areas.JPG Data were acquired within the assigned survey limits as required in the Project Instructions and HSSD unless otherwise denoted. In addition to regular survey limits, the Project Reference File included an assigned priority area, Pacific Islands Fisheries Science Center (PIFSC) bottomfish survey domain. Data was acquired within this prioritized area specified BRKLINE in accordance with the HSSD. The ecosystem surrounding American Samoa and the U.S. Pacific Remote Island Area (PRIA) are experiencing stress imposed by climate change and other environmental factors. For this project, NOAA Ship RAINIER operated around American Samoa and PRIA to conduct an extensive hydrographic survey to map bathymetry and habitat around the islands, pinnacles, and reefs in support of nautical charting and habitat mapping. With the collaboration and partnership of the National Centers for Coastal and Ocean Science (NCCOS), the National Coral Reef Monitoring Program (NCRMP), and the National Marine Fisheries Service (NMFS), this project also studied the health of coral reef systems, ocean chemistry, and fisheries habitat. This team has developed a strategy to map the waters from nearshore to depths greater than 1000 meters. Within the project area, the ship's crew collected bathymetric data to update charts and acquire backscatter data to characterized habitat, while visiting scientists from NCRMP performed coral reef assessment dives and other oceanographic observations. Data collected during this mission are pivotal to long-term biological and oceanographic monitoring of coral reef ecosystems in American Samoa and PRIA. This project will add to information collected during previous monitoring and mapping surveys. Oceanographic and ecological time series data will allow scientists to evaluate potential changes in environmental conditions and coral reef health. This will enable federal and state resource managers to more effectively conserve coral reef ecosystems of American Samoa and PRIA, and manage ecosystem services. Data collected during this project also supports monitoring components of the NCRMP Coral Reef Ecosystem Integrated Observing System. A modern bathymetric survey in this area will identify hazards and changes to the seafloor, provide critical data for updating National Ocean Service (NOS) nautical charting products, and improve maritime safety. It will also address data gaps to support the Seabed 2030 global mapping initiative. 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. Pydro QC Tools (v3.10.10) Grid QA (v6) was used to analyze H13735 multibeam echosounder (MBES) data density. The submitted H13735 finalized variable-resolution (VR) surface met density requirements for this project. As shown in the histogram below, Grid QA results determined that only 89 percent of H13735 nodes met full coverage resolution requirements as explained below. For project OPR-T382-RA-23, Resolution Requirements graphs produced by Pydro's Grid QA tool have been showing relatively low percentages of grid nodes meeting full coverage resolution requirements. The likely cause of this issue is RAINIER's use of 64m grids in depths greater than 1000m to maintain a reasonable data density. Since the Grid QA tool was written to match the HSSD specifications with a maximum 32m grid in all water depths greater than 640m, the RAINIER grids using 64m increase in resolution will always fail the resolution requirements check in areas exceeding 1000m. This will decrease the percentage of grid nodes meeting coverage resolution requirements. For surveys with a large percentage of area greater than 1000m in depth, this reduction can be significant. As shown with H13735, the majority of the survey data collected was at depths of 1000m up to 4560m. Pydro Grid QA derived histogram plot showing HSSD resolution requirements of H13735 finalized variable-resolution MBES data. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_FINAL.GQv6.pct_res.full_cov.png All waters in survey area. Complete Coverage (Refer to HSSD Section 5.2.2.3) The majority of the extent of the assigned sheet limits was surveyed for H13735. The north west edge of the H13735 sheet limits intruded into the territory of Samoa and was not surveyed, resulting in the very straight line of un-surveyed area within the original H13735 sheet limits, as seen in the below figure. This project's requirement to coordinate hydrographic operations with nearshore diving priorities, in addition to the limited number of project days allocated to H13735, imposed limitations on the amount of MBES data acquired. Due to these limitations, a portion of shallow water in the southern offshore region of sheet H13735 was not surveyed. H13735 multibeam echosounder coverage was acquired to the inshore limit of hydrography, the Navigable Area Limit Line (NALL), within the sheet limits. The NALL is defined as the most seaward of the following: the surveyed 10m depth contour, the line defined by the distance seaward from the observed MHW line (the assigned sheet limits closely reflect this), or the inshore limit of safe navigation. H13735 MBES coverage and assigned survey limits for Tutuila Island (Charts US1EE3M and US4SP30M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_SurveyCov.JPG S221 0.0 3397.1 0.0 0.0 0.0 0.0 0.0 146.2 0.0 2802 0.0 461.7 0.0 0.0 0.0 0.0 0.0 0.5 0.0 2801 0.0 36.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3895.5 0.0 0.0 0.0 0.0 0.0 146.7 0.0 3.63 0 0 2 0 3413.8 2023-03-23 2023-03-29 2023-03-30 2023-04-08 2023-04-09 2023-04-10 2023-04-11 2023-04-12 2023-04-13 2023-04-14 2023-04-16 2023-04-17 2023-04-18 2023-04-19 2023-04-20 2023-04-21 2023-04-26 2023-04-27 2024-04-28 2023-06-30 2023-07-01 2023-07-02 2023-07-03 2023-07-04 2023-07-05 2023-07-06 2023-07-07 2023-07-08 2023-07-09 2023-07-10 2023-07-11 2023-07-12 2023-07-18 2023-07-27 2023-07-28 2023-08-03 2023-08-04 2023-08-05 2023-08-06 2023-08-09 2023-08-10 2023-08-21 2023-08-22 2023-08-28 2023-09-05 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. S221 70.4 4.7 2801 8.8 1.1 2802 8.8 1.1 NOAA Ship RAINIER. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/S221.jpeg NOAA Ship RAINIER survey launch 2801. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/2801_(RA4).jpg NOAA Ship RAINIER survey launch 2802. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/2802_(RA5).jpg All data for H13735 were acquired by NOAA Ship RAINIER and survey launch 2801 and survey launch 2802. All vessels acquired bathymetric data including depth soundings, backscatter imagery, and sound speed profiles. Survey launches 2801 and 2802 verified shoreline features. MBES Kongsberg Maritime EM 304-MK2 MBES Kongsberg Maritime EM 2040 Positioning and Attitude System Applanix POS MV 320 v5 Sound Speed System Lockheed Martin Sippican Deep Blue XBT Conductivity, Temperature, and Depth Sensor AML Oceanographic MVP200 Conductivity, Temperature, and Depth Sensor Sea-Bird Scientific SBE 19plus Sound Speed System Teledyne RESON SVP 70 NOAA Ship RAINIER, survey launch 2801, and survey launch 2802 acquired 146.7 nautical miles of multibeam crosslines, approximately 3.63 percent, across a range of depths in the mainscheme data. The crosslines were collected in order to evaluate the internal consistency of H13735 sonar data. The Compare Grids function within Pydro Explorer was used to analyze the finalized VR surfaces of H13735 maincheme only and crossline only data. Pydro determined that 99.5 percent of nodes met allowable uncertainties. For additional results, see plots below. H13735 crossline surface overlaid mainscheme tracklines (Charts US1EEZ3M and US4SP30M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_XLs.JPG Pydro derived plot showing absolute difference statistics of H13735 mainscheme to crossline data. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_XL-H13735_MB_VR_MLLW_MS_depth_delta.png Pydro derived plot showing percentage-pass value of H13735 mainscheme to crossline data. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_XL-H13735_MB_VR_MLLW_MS_fracAllowErr_Freq.png ERS via VDATUM 0.0 0.11 S221 1.00 4.00 0.05 2801 3.00 0.05 2802 3.00 0.05 Total Propagated Uncertainty (TPU) values for survey H13735 were derived 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 metadata for the NOAA vertical datum transformation model used for this survey. 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, and vessel motion data from Applanix POS MV were applied during acquisition and initially in post-processing. POSPac SBET and RMS files were subsequently applied in CARIS HIPS to supersede POS MV uncertainties associated with GPS height ans position. Uncertainty values of the submitted finalized grids were calculated in Caris using "Uncertainity" when creating the finalized surface. Grid QA (v6) within Pydro QC tools was used to analyze H13735 TVU compliance. H13735 met HSSD requirements in 99.5 percent of grid nodes as shown in the histogram plot below. Pydro QC Tools 3 Grid QA was used to analyze H13735 multibeam echosounder (MBES) data density. The submitted H13735 variable-resolution (VR) surface met HSSD density requirements shown in the histograms below. Pydro derived plot showing TVU compliance of H13735 finalized variable-resolution MBES data. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_FINAL.GQv6.tvu_qc.png Pydro derived histogram plot showing HSSD density compliance of H13735 finalized variable-resolution MBES data. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_FINAL.GQv6.density.png There are two surveys that junction with H13735. The surveys, H13734 and H13736, were conducted while on OPR-T382-RA-23. H13734 junctions at the southern shore of Tutuila Island on the nearshore H13735 sheet limits. H13736 junctions on the eastern border of the offshore H13735 sheet limits. See figure below that depicts the location of the junction surveys relative to H13735. Refer to H13736 Tau Island Descriptive Report for additional junction details. Information from junction analysis with H13734 can be found below. Overview of H13735, H13736, and H13734 junctions (Charts US1EEZ3M and US4SP30M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_Junctions_Far.JPG Overview of H13735 and H13734 junction (Chart US4SP30M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_Junction_Close.JPG H13734 5000 2023 RAINIER S The junction with survey H13734 borders approximately 4.9 nautical miles along H13735's sheets edge at the entrance of Pago Pago Harbor on the southern nearshore sheet limits of H13735. The Compare Grids function of Pydro Explorer derived a difference surface from H13735 variable-resolution surface and H13734 variable-resolution surface. Pydro Compare Grids showed that 96 percent of nodes in the overlapping area met NOAA allowable standards. Analysis of the difference surface indicated that there is a 0.15 meter average difference between the two surveys. The difference between the surveys is believed to be a result of the very dynamic bottom where the two surveys junction, containing rocks, steep slopes, and corals. For additional results, see figures below. H13735 and H13734 fraction of allowable error junction surface (Chart US4SP30M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_deltaDepth_PagoPagoJunction.JPG Pydro derived plot showing absolute difference statistics of the junction between H13735 and H13734 variable-resolution surface. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_FINAL-H13734_MB_VR_MLLW_FINAL_depth_delta.png Pydro derived plot showing percentage-pass volume of the junction between H13735 and H13734 variable-resolution surface. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_MB_VR_MLLW_FINAL-H13734_MB_VR_MLLW_FINAL_fracAllowErr_Freq.png H13736 40000 2023 RAINIER E Refer to H13736 Tau Descriptive Report for additional junction details. Sonar system quality control checks were conducted as detailed in the 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. At least once every 4 hours or as needed. A total of 192 sound speed profiles were acquired for this survey at discrete locations within the assigned area or just outside the area at least once every four hours, when significant changes to surface sound speed were observed, or when shifting operations into a new area. Sound speed profiles were obtained using AML Oceanographic MVP200 and Lockheed Martin Sippican XBTs on the ship. While on both survey launch 2801 and 2802, sound speed profiles were obtained using the Sea-Bird 19plus SEACAT Profilers. All sound speed profiles were concentrated into a master file and applied to H13735 MBES data using the "nearest in distance within time" (4 hours) profile selection method. One line in H13735 (Line 28, DN192, sonar EM304) had sound speed applied using the "nearest in distance" selection, due to no cast being taken within 4 hours of the line being surveyed. This line was in the southern offshore portion of the sheet and was due to limited time in the southern offshore area in order to conduct diver operations. H13735 sound speed cast locations. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_CastLocations.JPG All equipment and survey methods were used as detailed in the DAPR. 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 acquired as .ALL or .KMALL files logged during MBES operations and subsequently processed by RAINIER personnel. The .GSF files created during processing and backscatter mosaics per vessel and per frequency are delivered with this report. Backscatter processing procedures are described in the DAPR. Overview mosaic of H13735 multibeam acoustic backscatter coverage (Chart US1EEZ3M). file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_Backscatter.PNG CARIS HIPS and SIPS 11.4.6 CARIS BASE Editor 5.5.16 QPS Fledermaus 7.10.2 NOAA Profile Version 2023v1 H13735_MB_VR_MLLW CARIS VR Surface (CUBE) Variable Resolution 2.0 4558.6 NOAA_VR Complete MBES H13735_MB_VR_MLLW_FINAL CARIS VR Surface (CUBE) Variable Resolution 2.0 4558.6 NOAA_VR Complete MBES Submitted H13735 surfaces were generated using NOAA recommended parameters for density-based (Ranges) Caris variable-resolution bathymetric grids. Per correspondence with the Project Manager, the submitted surfaces were generated with an updated Range/Resolution file, NOAA_DepthRanges_CompleteCoverage_2023_RA, that includes 64 meter grids for depths exceeding 1000 meters. See Supplemental Records for more information. Pydro QC Tools (v3.10.10) Flier Finder, with default settings was used to identify sounding "fliers" in the Finalized H13735 VR surface. Obvious noise was rejected by the hydrographer in Caris Subset Editor. After data cleaning, the Flier Finder tool was run again and found 2821 potential fliers in the Complete Coverage surface. These were investigated and determined to be a result of the significant slope in the terrain and limited data density on both the steep slopes and offshore coverage where depths exceeded 1000m. Therefore, these fliers have been found to be false positives. The image below depicts an example of fliers that have been determined to be false. Pydro QC Tools (v3.10.10) Holiday Finder was used with default settings to find holidays in the finalized H13735 VR surface. Holiday Finder detected 87 certain holidays and 37 possible holidays in the Complete Coverage Surface. All of the holidays are all located in dynamic shoal areas, susceptible for acoustic shadows, and areas outside 3000 meters depth and are primarily a result of low data density at those depths. The holidays were reviewed and do not impact the quality or reliability of the data. See figures below for more information. Example of fliers determined to be false. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_Flier.JPG Example of holiday detected by QC Tools Holiday Finder. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_Holiday.JPG Excessivley large dataset During data acquisition for H13735, the HIPS file with processed data failed and was unrepairable due to the file size being so large. This failure was observed two times over the course of the field season and required two instances where restarting data processing was necessary. RAINIER's solution was to create two separate HIPS files, one with only data from the Kongsberg EM304 sonar and the other with data from all of the platform's Kongsberg EM2040 data. Utilizing two HIPS files for data processing was communicated to and approved by the project manager for this sheet. See email correspondence. Possible division of the H13735 sheet may have prevented the restarts experienced in the data processing. 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-T382-RA-23_American_Samoa_ERTDM_NAD83(PA11)-MHW_11cm1sigma.csar OPR-T382-RA-23_American_Samoa_ERTDM_NAD83(PA11)-MLLW_11cm1sigma.csar North American Datum 1983 (PA11) Projected UTM 2 Precise Positioning-Real Time Extended (PP-RTX) processing methods were used in Applanix POSPac MMS (v8.9) software during post-processing horizontal correction of submitted H13735 MBES data. US1EEZ3M 3500000 2 2020-08-28 2020-08-28 US4SP30M 60000 10 2023-05-19 2023-05-19 No shoals or potentially hazardous features exist for this survey. Refer to the Final Features File. Refer to the Final Features File. No channels exist within the survey limits. While RAINIER was departing Tutuila, the G"1" channel buoy into Pago Pago Harbor was observed off station and was washed up on shore. See figure below. The out of position buoy was reported. Upon clarification with the Coast Guard, it was confirmed that the channel buoy was placed back on station. See email correspondence. We are unsure of the exact position of the replaced channel buoy and recommend further investigation of its position. G"1" buoy washed up on the rocks nearshore on the southern shore of Tutuila within H13735. It was later re-installed on its rightful position. file:///M:/OPRT382RA23/Surveys/H13735/01_HDR/Reports/Descriptive_Report/H13735_DR/SupportFiles/H13735_WashedUpG1.jpg No Maritime Boundary Points were assigned for this survey. No bottom samples were required for this survey. No overhead features exist for this survey. Refer to the Final Feature File. 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. Due to time constraints and dive operations priority, the seamount located near the southern edge of the H13735 sheet limits was not fully investigated. It is the recommendation of this survey party that this area receive particular attention when conducting future survey operations. Lidar operations inshore of the NALL around Tutuila is recommended for enhanced nearshore coverage. 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. Héctor L. Casanova CAPT/NOAA Chief of Party 2024-03-11 Garrison L. Grant LT/NOAA Field Operations Officer 2024-03-11 James B. Jacobson Chief Survey Technician 2024-03-11 Franco R. Pilone Sheet Manager 2024-03-11