OPR-R320-FA-19Vicinity of Cape NewenhamBristol BayNOAA Ship Fairweather (S220)H132458Approach to Nanvak BayAlaskaUnited States400002019CDR Marc Moser, NOAANavigable Area2019-04-302019-07-102019-07-13Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUTCPacific Hydrographic BranchThe purpose of this survey is to provide contemporary surveys to update National Ocean Service (NOS) nautical charts. All separates are filed with the hydrographic data. Any revisions to the Descriptive Report (DR) generated during office processing are shown in bold red italic text. The processing branch maintains the DR as a field unit product, therefore, all information and recommendations within the body of the DR are considered preliminary unless otherwise noted. The final disposition of surveyed features is represented in the OCS nautical chart update products. All pertinent records for this survey, including the DR, are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via http://www.ncei.noaa.gov/. NOAAThe survey area is located the vicinity of Bristol Bay, Alaska, within the sublocality of the approach to Nanvak Bay.58.637043162.07090658.555563161.763315H13245 sheet limits (in blue) overlaid onto chart 16305SupportFiles\Sheet_Limits.pngData were acquired to the survey limits in accordance with the requirements in the Project Instructions and the March 2019 NOS Hydrographic Surveys Specifications and Deliverables (HSSD) as shown in Figure 1. In all areas where the 3.5 meter depth contour or the sheet limits were not met, the Navigable Area Limit Line (NALL) was defined as the inshore limit of bathymetry due to the risks of maneuvering the survey vessel in proximity to the steep shoreline. The purpose of this hydrographic survey is to update National Ocean Service nautical charting products and support commerce to the northern Bristol Bay region. Capes Newenham and Peirce, Alaska are the southwestern corner of the Togiak National Wildlife Refuge and provide habitat to numerous birds and sea mammals. Ship and barge traffic delivering industrial, consumer, and energy products to the communities of northern Bristol Bay, or continuing north to the Etolin Strait must transit around these capes. Marine commerce is critical for the survival of these western Alaskan communities as they are detached from the rest of the state road system. Legacy hydrographic data in this sheet area is extremely sparse and was acquired prior to the 1920s. Updating the nautical charts and accurately charting reported shoals by modern hydrographic means is critical for the future safety of regional commerce, local tanker lightering, emergency response, and the protection of the local wildlife. Survey data from the project is intended to supersede all prior survey data in the common area.The entire survey is adequate to supersede previous data.Data acquired in H13245 meet multibeam echo sounder (MBES) coverage requirements for set line spacing, as required by the HSSD. This includes crosslines (see Section B.2.1), NOAA allowable uncertainty (see Section B.2.9), and density requirements (see Section B.2.10).All waters in survey areaSet Line Spacing MBES at 400 meters.The entirety of H13245 was acquired with with set line spacing MBES at 400 meters, meeting the requirements listed above and in the HSSD. See Figure 2 for an overview of coverage.H13245 survey coverage overlaid onto Chart 16305SupportFiles\H13245_coverage_overview.pngFA 2805039.820000000FA 2807090.740000011.3300130.560000011.3308.7500026.92019-07-092019-07-112019-07-12Refer to the OPR-R320-FA-19 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.FA 28078.61.1FA 28058.61.1Kongsberg MaritimeEM 2040MBESSea-Bird ScientificSBE 19plus V2Conductivity, Temperature, and Depth SensorTeledyne RESONSVP 71Sound Speed SystemApplanixPOS MV 320 v5Positioning and Attitude SystemCrosslines were collected, processed and compared in accordance with Section 5.2.4.2 of the HSSD. 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 (Figure 3), and is submitted in the Separates II Digital Data folder. As shown in Figure 4, statistics show the mean difference between depths derived from mainscheme data and crossline data was 0.01 meters with mainscheme being deeper and 95% of nodes falling within +/- 0.17 meters (Figure 4). For the respective depths, the difference surface was compared to the allowable NOAA uncertainty standards. In total greater than 95.5% of the depth differences between H13245 mainscheme and crossline data were within allowable NOAA uncertainties.Overview of H13245 CrosslinesSupportFiles\H13245 Crossline Overview.pngH13245 Crossline and Mainscheme Difference StatisticsSupportFiles\H13245 Crossline Difference.pngERS via ERTDM0.14028052N/A0.528072N/A0.5In addition to the usual a priori estimates of uncertainty provided via device models for vessel motion and ERTDM, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H13245. 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. H13245 junctions with two adjacent surveys from this project, H13238 and H13239, as shown in Figure 5. Data overlap between H13245 and each adjacent survey was achieved. These areas of overlap between surveys were reviewed in CARIS HIPS and SIPS by surface differencing (at equal resolutions) to assess surface agreement. The multibeam data were also examined in CARIS Subset Editor for consistency and agreement. The junctions with H13245 are generally within the NOAA allowable uncertainty in their areas of overlap. For all junctions with H13245, a negative difference indicates H13245 was shoaler and a positive difference indicates H13245 was deeper.Overview of H13245 junction surveysSupportFiles\H13245_junction_overview.pngH13238400002019NOAA Ship FAIRWEATHERWSurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between the surface from H13245 and the surface from H13238 (Figure 6). The statistical analysis of the difference surface shows a mean of 0.04 meters with 95% of the nodes having a maximum deviation of +/- 0.24 meters, as seen in Figure 7. It was found that 99.5+% of nodes are within NOAA allowable uncertainty.Difference surface between H13245 (purple) and junctioning survey H13238 (pink)SupportFiles\H13245_H13238_junction_diff.pngDifference surface statistics between H13245 and H13238 (4 meter surface)SupportFiles\H13245_MB_4m_MLLW_H13238_MB_4m_MLLW_depth_delta.pngH13239400002019NOAA Ship FAIRWEATHERSSurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between the surface from H13245 and the surface from H13239 (figure 8). The statistical analysis of the difference surface shows a mean of -0.02 meters with 95% of the nodes having a maximum deviation of +/- 0.20 meters, as seen in Figure 9. It was found that 99.5+% of nodes are within NOAA allowable uncertainty.Difference surface between H13245 (purple) and junctioning survey H13239 (light blue)SupportFiles\H13245_H13239_junction_diff.pngDifference surface statistics between H13245 and H13239 (4 meter surface)SupportFiles\H13245_MB_4m_MLLW_H13239_MB_4m_MLLW_depth_delta.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.None ExistThere were no other factors that affected corrections to soundings.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.All equipment and survey methods were used as detailed in the DAPR.NOAA Allowable UncertaintyThe surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Overall greater than 99.5% of nodes within the surface meet NOAA Allowable Uncertainty specifications for H13245.H13245 Allowable uncertainty statisticsSupportFiles\H13245_MB_4m_MLLW_final.QAv5.tvu_qc.pngDensityThe surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Density requirements for H13245 were achieved with at least 99.5% of surface nodes containing five or more soundings as required by HSSD Section 5.2.2.3.H13245 Data density statisticsSupportFiles\H13245_MB_4m_MLLW_final.QAv5.density.pngTo compensate for the relatively high uncertainty of the data in the outer beams of the tracklines which led to excessive fliers, all data outside of 60 degrees from nadir were filtered following conversion via the Swath HIPS Data Filter.For clarification: Excessive fliers in the outer beam data is due to the geometry and acoustics of the outer beams, not uncertainty.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 7.8.10. See Figure 12 for a greyscale representation of the complete mosaic. A relative backscatter calibration was performed by HSTB via a patch test in order to bring the survey systems on each of the launches into alignment. See Figure 13 for a table of the calibration values entered into the Processing Settings within FMGT. Approximate inter-calibration corrections for offsets between sonar systems were applied to the mosaic.Backscatter Mosaic for H13245SupportFiles\H13245 Backscatter Mosaic.pngBackscatter Calibration ValuesSupportFiles\H13245_backscatter_calibration_values.pngTeledyne CARISHIPS and SIPS11.1.3QPSFledermaus FMGT7.8.10NOAA Profile Version 2019H13245_MB_4m_MLLWCARIS Raster Surface (CUBE)40.634.9NOAA_4mMBES Set Line SpacingH13245_MB_4m_MLLW_FinalCARIS Raster Surface (CUBE)40.634.9NOAA_4mMBES Set Line SpacingThe NOAA CUBE parameters defined in the HSSD were used for the creation of all CUBE surfaces for H13245. 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 all remaining flagged fliers were deemed to be valid aspects of the surface.Data LogsData acquisition and processing notes are included in the acquisition and processing logs, and additional processing such as final separation model reduction and sound speed application are noted in the H13245 Data Log spreadsheet. All data logs are submitted digitally in the Separates I folder. Per Section 5.1.2.3 of the Field Procedures Manual (2014 ed), no Horizontal and Vertical Control Report has been generated for H13245.Mean Lower Low WaterERS via ERTDMR320FA2019_ERTDM_NAD83-MLLW.csarERS methods were used as the final means of reducing H13245 to MLLW for submission.North American Datum 1983Projected UTM 3RTXVessel 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.The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition. During real-time acquisition, 2805 and 2807 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 H13245 as no DGPS stations were available for realtime horizontal control.A comparison was performed between survey H13245 and ENC US4AK86M using CARIS HIPS and SIPS. All data from H13245 should supersede charted data. In general, surveyed soundings do not agree with the charted depth. A full discussion of the comparisons follows in section D.1.1.US4AK86M4000052017-12-272017-12-27falseThe ENC contained one 13.5 meter sounding in the northwest corner of H13245. The survey disproved this sounding, finding the depth to be approximately 30.5 meters. No Maritime Boundary Points were assigned for this survey.No charted features exist for this survey.No uncharted features exist for this survey.No shoals or potentially hazardous features exist for this survey.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.Five bottom samples were acquired in accordance with the Project Instructions for survey H13245. One bottom sample location was adjusted from project instructions to better encompass the full range of variation in the backscatter mosaic.Due to the risk of utilizing the image grab sampler from the launches in the observed sea states while on project, the smaller, non-image recording bottom sampler was used for all samples. All five bottom samples were entered in the H13245 Final Feature File. See Figure 14 for a graphical overview of sample locations. H13245 Bottom sample locationsSupportFiles\Bottom_Sample_Overview.pngFairweather personnel conducted limited shoreline verification and reconnaissance, at times near predicted negative or low tides within the survey limits. Inaccessible features inshore of the NALL were attributed in the Final Feature File with the description of “Not Addressed” and remarks of “Retain as charted, not investigated due to being inshore of NALL” as per HSSD Section 7.3.1. Annotations, information, and diagrams collected on Detached Position (DP) forms and boat sheets during field operations were scanned and included in the Separates I Detached Positions folder. Shoreline verification procedures for H13245 conform to those detailed in the DAPR. No Aids to navigation (ATONs) exist for this survey.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 and/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 insets 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.CAPT Marc Moser, NOAAChief of Party2019-09-05LT Steve Moulton, NOAAField Operations Officer2019-09-03Sam CandioChief Survey Technician2019-09-03LTJG Jeffrey Calderon, NOAASheet Manager2019-09-03