OPR-F324-FH-23 Approaches to Wilmington, North Carolina Wilmington, North Carolina NOAA Ship Ferdinand Hassler (S250) H13748 3 49 NM Southeast of Carolina Beach Inlet North Carolina United States 40000 2023 Commander William Winner, NOAA Navigable Area 2023-02-02 2023-05-16 2023-09-09 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTC Atlantic 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 18N, 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 located near Wilmington, North Carolina approximately 49 NM Southeast of Carolina Beach Inlet. 33.546 77.418 33.272 77.214 H13748 sheet limits (in blue) overlaid onto Chart US3SC10M. file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/Sheet%20limits%20on%20US3SC10M.JPG Data were acquired to the survey limits in accordance with the requirements in the Project Instructions and the March 2022 NOS Hydrographic Surveys Specifications and Deliverables (HSSD) as shown in Figure 1. The region around Wilmington, North Carolina experiences high vessel traffic transiting the eastern seaboard of the U.S. as well as traffic to and from the port. The Port of Wilmington has been updating its facilities expanding capacity in recent years, including the ability to handle two post-Panamax vessels concurrently, and in 2020, ranked 67 in tonnage of all U.S. ports, handling over 6,000,000 short tonnes of cargo.1,2,3 Numerous historic storms and hurricanes have impacted this region, potentially having changed the seafloor from the last surveys in the 1940s and 1960s. Additionally a portion of this project is in the top 10% of NOAA’s Hydrographic Health need emphasizing a high need for modern bathymetry for this area. This project 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. 1 https://usace.contentdm.oclc.org/digital/collection/p16021coll2/id/7447/rec/26 2 https://www.wect.com/2022/08/11/port-wilmington-receive-18-million-upgrade-increase-processing-rate/ 3 https://ncports.com/port-improvements/completed-upgrades/ The entire survey is adequate to supersede previous data. Data acquired in H13748 meet multibeam echo sounder (MBES) coverage requirements for complete coverage, as required by the HSSD. This includes crosslines (see Section B.2.1), NOAA allowable uncertainty (see Section B.2.2), and density requirements (see Section B.2.3). All waters in the survey area Complete Coverage per HSSD Section 5.2.2.3 The entirety of H13748 was acquired with complete coverage multibeam, meeting the requirements listed above and in the HSSD. See Figure 2 for an overview of coverage. H13748 survey coverage (4 meter surface) overlaid onto Chart US3SC10M. file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/Coverage%204m%20on%20US3SC10M.JPG S250 0.0 906.65 0.0 0.0 0.0 0.0 0.0 40.4 0.0 0.0 906.65 0.0 0.0 0.0 0.0 0.0 40.4 0.0 4.46 1 0 0 0 69.83 2023-05-16 2023-05-17 2023-06-16 2023-06-17 2023-06-18 2023-08-25 2023-08-26 2023-08-27 2023-08-28 2023-09-06 2023-09-07 2023-09-08 2023-09-09 Refer to the OPR-F324-FH-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. S250 37.7 3.85 NOAA Ship Ferdinand R. Hassler file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/Ship.jpeg MBES Kongsberg Maritime EM 2040 MBES Backscatter Kongsberg Maritime EM 2040 Positioning and Attitude System Applanix POS MV 320 v5 Conductivity, Temperature, and Depth Sensor AML Oceanographic MVP200 Sound Speed System Teledyne RESON SVP 70 Crosslines were collected, processed, and compared in accordance with Section 5.2.4.3 of the HSSD. To evaluate crosslines, a 2 meter CUBE surface using strictly mainscheme lines, and a 2 meter CUBE surface using strictly crosslines were created. From these two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated using Pydro’s Compare Surfaces tool at a 2 meter resolution (Figure 4). Statistics show the mean difference between the depths derived from mainscheme and crosslines was 0.02 meters (with mainscheme being shoaler) and 95% of nodes fall within 0.12 meters (Figure 5). For the respective depths, the difference surface was compared to the allowable NOAA uncertainty standards using Compare Surfaces (Figure 6). In total, 99.5+% of the depth differences between H13748 mainscheme and crossline data were within allowable NOAA uncertainties. The largest differences are seen along the outer beams of the crosslines in the deeper areas of the sheet and areas with sand waves. Overview of H13748 crossline differences file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_Crossline_overview.png H13748 crossline and mainscheme difference statistics. file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_2m_MLLW-H13748_MB_2m_XL_Only_depth_delta.png H13748 crossline and mainscheme NOAA allowable uncertainty statistics file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_2m_MLLW-H13748_MB_2m_XL_Only_fracAllowErr_Freq.png ERS via VDATUM 0.126 S250 N/A 2 N/A 0.5 In addition to the usual a priori estimates of uncertainty provided via device models for vessel motion and VDATUM, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H13748. Real-time uncertainties were provided via EM 2040 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. H13748 junctions with one survey from prior projects, H12934, as shown in Figure 7. Data overlap between H13748 and H12934 was achieved. To evaluate junction agreement, a BAG surface from the junction survey was compared to a CSAR surface from H13748 with the same resolution. The multibeam data were also examined in CARIS Subset Editor for consistency and agreement. The junctions with H13748 are generally within the NOAA allowable uncertainty in their areas of overlap. A negative difference indicates H13748 was shoaler, and a positive difference indicates H13748 was deeper. Overview of H13748 junction surveys. file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/Overview%20of%20H13748%20junction%20surveys.png H12934 40000 2016 NOAA Ship Ferdinand R. Hassler SW Surface differencing using the Pydro Compare Surfaces tool was used to assess junction agreement between the 4 meter combined surface from H13748 and the 4 meter combined surface from H12934. A detailed graphical overview can be seen in Figure 8. The statistical analysis of the difference surface shows a mean of 0.11 meters with 95% of all nodes having a maximum deviation of +/- 0.24 meters, as seen in Figure 9. It was found that 100% of nodes are within NOAA allowable uncertainty (Figure 10). Difference surface between H13748 (Gray) and junctioning survey H12934 (Pink) file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_junc_diff.png Difference surface statistics between H13748 and H12934 (4 meter surface) file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_4m_MLLW-H12934_MB_4m_MLLW_combined_depth_delta.png NOAA Allowable Uncertainty statistics between H13748 and H12934 (4 meter surface) file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_4m_MLLW-H12934_MB_4m_MLLW_combined_fracAllowErr_Freq.png 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. Attitude Newtork Issue Data correction errors like those seen in Figure 11 were found throughout the survey. This error was determined to be caused by a networking issue between the POS MV and the Kongsberg EM2040 and, where the issue occurs, only affects a single ping. The errors caused by this issue and are very small and generally did not affect the gridded surface. Any erroneous soundings caused by this issue were rejected and the surface recomputed. Example attitude networking issue on H13748 file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/SV.png Casts were conducted at a minimum of one every 4 hours during acquisition. Casts were conducted more frequently in areas where there was a change in surface sound speed greater than two meters per second. MVP casts on S250 were guided by observation of the surface sound speed in SIS and targeted to deeper areas. All sound speed methods were used as detailed in the DAPR. All equipment and survey methods were used as detailed in the DAPR. NOAA Allowable Uncertainty The surfaces were analyzed using the HydrOffice QC Tools V3 Grid QA feature to determine compliance with specifications. Overall, 99.5+% of nodes within the 2m final surface and 99.5+% of nodes within the 4m final surface meet NOAA Allowable Uncertainty specifications for H13748 (Figure 12 and 13). H13748 NOAA Allowable uncertainty statistics, 2m finalized surface file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_2m_MLLW_Final.GQv6.tvu_qc.png H13748 NOAA Allowable uncertainty statistics, 4m finalized surface file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_4m_MLLW_Final.GQv6.tvu_qc.png Density The surfaces were analyzed using the HydrOffice QC Tools V3 Grid QA feature to determine compliance with specifications. Density requirements for H13748 were achieved with at least 99.5+% of surface nodes in the 2m finalized surface, and 99.5+% of surface nodes in the 4m finalized surface containing five or more soundings as required by HSSD Section 5.2.2.3 (Figures 14 and 15). Zooming in on the 2m surfaces reveals apparent along track data density issues as seen in Figure 16. While unconfirmed, this is likely due to the dual swath setting of the EM2040 being turned off in SIS or the vessel moving too fast for the SIS selected ping rate. While seen in the surface, no holidays meeting the definition in the 2022 HSSD are present that were not covered by the 4m surface as explained in the Holiday discussion below (B.2.11). As indicated above, the density statistics meet the requirements of the HSSD for all surfaces. H13748 Data density statistics, 2m finalized surface file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_2m_MLLW_Final.GQv6.density.png H13748 Data density statistics, 4m finalized surface file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_MB_4m_MLLW_Final.GQv6.density.png Apparent along track data density issue on H13748 file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/Along%20track%20density.png Holidays H13748 data were reviewed in CARIS HIPS and SIPS, with aid from Pydro's Flier Finder tool, for holidays in accordance with Section 5.2.2.3 of the HSSD. Flier finder automatically scans finalized surfaces for holidays as defined in the HSSD and was run in conjunction with a visual inspection of all surfaces by the hydrographer. Due to the dynamic nature of the bathymetry, the finalized surfaces show many data gaps due to the sand waves passing through the overlap between the 2 and 4m surfaces. The holidays found using Holiday Finder in the 2m surface are covered by the 4m surface and vis versa. This leads to confidence that these flagged holidays are false and no dangers to navigation exist. Additionally, Holiday Finder flagged several single node holidays which are false positives according to the HSSD. These holidays are not flagged when assessing the base surfaces also provided with this survey submission. All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Raw backscatter data are stored in the .all files for Kongsberg systems. All backscatter were processed to GSF files and a floating point mosaic was created by the field unit via QPS Fledermaus FMGT 7.9.0 . See Figure 17 for a greyscale representation of the complete mosaic. H13748 Backscatter Mosaic file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_Backscatter.png CARIS HIPS and SIPS 11.4.25 NOAA Pydro 22.1 Applanix POSPac 8.9 QPS Fledermaus 7.7.6.628 NOAA Profile Version 2023 H13748_MB_2m_MLLW.csar CARIS Raster Surface (CUBE) 2 NOAA_2m Complete MBES H13748_MB_2m_MLLW_Final.csar CARIS Raster Surface (CUBE) 2 18.0 40.0 NOAA_2m Complete MBES H13748_MB_4m_MLLW.csar CARIS Raster Surface (CUBE) 4 NOAA_4m Complete MBES H13748_MB_4m_MLLW_Final.csar CARIS Raster Surface (CUBE) 4 36.0 80.0 NOAA_4m Complete MBES H13748_MBAB_2m_S250_300kHz_1of1.tiff MB Backscatter Mosaic 2 N/A Complete MBES The NOAA CUBE parameters defined in the HSSD were used for the creation of all CUBE surfaces in H13748. The surfaces have been reviewed for noisy data, or "fliers," causing the surface to be shoaler or deeper than the true sea floor. Where these spurious soundings cause the gridded surface to be shoaler or deeper than 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 all remaining flagged fliers were deemed to be valid aspects of the surface. Many fliers were flagged on the final surfaces by Flier Finder after surface cleaning. All of these are flagged as isolated nodes due to the dynamic sea floor where sand waves exist and the depths pass between the 2 and 4 meter surface depths. The hydrographer determined these to be false flags and ceased further edge cleaning in these areas. Data Logs Data acquisition and processing notes are captured in field acquisition logs. Additional processing such as final tide, positioning, and sound speed application are noted a data log spreadsheet. Processed vs. raw line count comparisons are also completed in the data log. The hydrographer reviewed these documents to ensure proper correctors were applied to each line and all data issues are captured in this report. Per Section 5.2.2.1.3 of the 2021 Field Procedures Manual no Horizontal and Vertical Control Report has been generated for H13748. Mean Lower Low Water ERS via VDATUM OPR-F324-FH-23_NAD83_2011_VDATUM_MLLW.csar ERS methods were used as the final means of reducing H13748 to MLLW for submission. North American Datum 1983 Projected UTM 18 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, S250 received correctors from the Wide Area Augmentation System (WAAS) for increased accuracies similar to USCG DGPS stations. WAAS and SBETs were the sole methods of positioning for H13748 as no DGPS stations were available for realtime horizontal control. DN 169 GPS Week Issue Acquisition of POSMV data associated with MBES lines 0120 and 0121 on DN169 began prior to UTC midnight on Saturday DN168 (JUN 17). This caused a GPS week mis-match between the POS data and the MBES data for these two lines leading to the inability for Caris HIPS to process heave data, manifesting as a heave artifact in the CUBE surface. To overcome this, POS delayed heave was reapplied to lines 0120 and 0121 manually in Caris HIPS setting the GPS week to JUN 10. Doing this allowed Caris to process the delayed heave for these lines. Afterwards, SBETS were reapplied and the lines re-georeferenced. The surface was recomputed confirming that the heave artifact was resolved. DN 237 File Naming Issue On DN 237, while setting up POS View to collect data, it was unclear if the system was logging data. As a result the POS MV was mistakenly set to record data under two file names (2023_237_S250 and 2023_237_S250_b). Since the POS was logging at the time the second file convention was created, it began to log alternatively between the file names. This resulted in two sets of .000 files. Some of the files in each set were 0KB in size. This caused issues with applying POS .000 files to the data for delayed heave and in SBET generation. To overcome the delayed heave issue, the Hydrographer removed the 0KB files from the raw data storage and removed the _b from all remaining files that contained it in the name, with the exception of the _b.000 file. Since two .000 files were present, the larger of the two (the non-_b.000) was kept, and the smaller one (the _b.000) was set aside. The result was a complete set of raw POS files from 2023_237_S250.000-.009. These files were applied using Pydro/Charlene to all of the line files. All lines except 0131, 0132, and 0133 accepted these files. To get delayed heave added to these three lines, the original _b POS data set was used including the 2023_237_S250_b.000 and the 0KB files. Using this data set, lines 0131, 0132, and 0133 accepted delayed heave. As a result, two sets of raw POS files are submitted in the submission package. Pydro/ Charlene was used to create an SBET using only the raw POS files that were renamed and the 0KB files removed as described above. The SBET made with these files was used for the entirety of DN 237. All of the lines accepted the SBET except LN 0134, which only partially accepted it. The area that was not SBET corrected was recollected as a holiday and the uncorrected data rejected. A comparison was performed between survey H13748 and ENC US3SC10M using CARIS HIPS and SIPS sounding and contour layers derived from the 4 meter combined surface. The contours and soundings were overlaid on the charts to assess differences between the surveyed soundings and charted depths. All data from H13748 should supersede charted data. In general, surveyed soundings agree with the majority of charted depths to within 1m. H13748 Soundings Overlaid on ENC US3SC10M (H13748 soundings in pink, US3SC10M soundings in purple) file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_Soundings%20overview.png US3SC10M 432720 37 2022-07-28 2023-08-17 No shoals or potentially hazardous features exist for this survey. No charted features exist for this survey. No uncharted features exist for this survey. Water column data was collected over a potential feature. This data was reviewed in QPS FM Midwater. No object was identified meeting the feature definition in HSSD. 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. One bottom sample was acquired in accordance with the Project Instructions for survey H13748. The bottom sample was entered in the H13748 Final Feature File. See Figure 19 for a graphical overview of sample location indicated by the pink T. This location was selected by reviewing the acquired bathymetry and backscatter. The remaining assigned bottom samples could not be acquired due to weather. H13748 bottom sample location. file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_Bottom%20Samples.png H13748 bottom sample file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_SBDARE_01.jpg 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. The sheet has large sand waves throughout, especially in the deeper section to the south east. Some are as deep as 3.5 meters. Two sandwave areas are included in the H13748 Final Feature File detailing the location of the largest sandwaves. Sand waves on H13748 file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/H13748_Sandwaves.png Example sand wave cross section on H13748 file:///B:/OPR-F324-FH-23/Surveys/H13748/01_HDR/Reports/Descriptive_Report/images/Sand%20wave%20cross%20section.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. CDR William Winner Commanding Officer 2023-11-03 LT Patrick Debroisse, CMH CAT-A Operations Officer 2023-11-03