Data Acquisition and Processing Report2020-02-18As 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 and Specifications 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.NSPS/THSOA Certified Hydrographer, Chief of Party2020-03-17Jonathan L. Dasler, PE, PLS, CHNSPS/THSOA Certified Hydrographer, Charting Manager / Project Manager2020-03-17Jason Creech, CHIHO Cat-A Hydrographer, Lead Hydrographer2020-03-17Callan McGriff, EITIHO Cat-A Hydrographer, Lead Hydrographer2020-03-17Steven Loy3United States19 NM East of Freemason IslandsLouisiana40000H13262ContractorDavid Evans and AssociatesChandeleur Islands, LouisianaOPR-J311-KR-19Chandeleur Islands2020-01-082019-06-282019Multibeam Echo SounderMultibeam Echo Sounder Backscatter &Side Scan Sonar2019-06-19UTCAtlantic Hydrographic BranchAny 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 16N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.Jonathan L. Dasler, PE, PLS, CHmetersNavigable Areafile:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/OPR-J311-KR-19_Assigned_Survey_Areas.PNGOPR-J311-KR-19 Assigned Survey AreasSurvey Limits were surveyed in accordance with the requirements in the Project Instructions and the HSSD.29.78705288.638619444429.66315688.56152David Evans and Associates, Inc. (DEA) conducted a hydrographic survey of the assigned area in the Chandeleur Islands. Survey H13262 was conducted in accordance with the May 21, 2019 Statement of Work and Hydrographic Survey Project Instructions June 19, 2019. The Hydrographic Survey Project Instructions reference the National Ocean Service (NOS) Hydrographic Surveys Specifications and Deliverables Manual (HSSD) (March 2019) as the technical requirements for this project.The entire survey is adequate to supersede previous data.file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_Survey_Coverage.pngH13262 Survey OutlineMultibeam echosounder (MBES) data with time series backscatter was collected concurrently with side scan sonar (SSS) data to obtain complete coverage in all waters in the survey area. This coverage type follows Option B of the Complete Coverage requirement specified in Section 5.2.2 of the 2019 HSSD. Surveyed contacts and features were developed at complete coverage resolution as required by the coverage classification. Complete coverage multibeam was also obtained within the search radii for all feature disapprovals. All charted depths shallower than adjacent surveyed soundings were verified or disproved by conducting bathymetric splits to comply with section 5.2.2.1 in the 2019 HSSD. Survey coverage was obtained within the survey area depicted in the Project Reference File (PRF) OPR-J311-KR-19_PRF_FINAL.000. Figure 2 depicts the survey outline that was obtained for H13262. Complete Coverage Option B (Refer to HSSD Section 5.2.2.3)All waters in survey area S/V Blake00416.630032.6112.78019.4500416.630032.6112.7804.3219.45128.550002019-06-282019-06-292019-06-302019-07-012019-07-062019-07-072019-07-082019-08-012019-08-022019-11-192020-01-072020-01-08The project’s survey purpose for all surveys, which was defined in the Project Instructions, is “The Chandeleur Islands is an active oil and gas exploration area, as well as a popular fishing grounds and includes the Breton National Wildlife Refuge.*1 The Chandeleur Islands were also severely impacted by recent hurricanes like Dennis and Katrina, which resulted in major erosion of the islands. Erosion, sea level rise, and sediment influx from the Mississippi River have endangered the future of these islands.*2 This area also supports a wide variety of vessel traffic and commercial and sport fishing traffic near the Mississippi Entrance Channel and includes a major portion of the safety fairway. Due to the high traffic, this project has been planned as one of a multi-year approach to update charts in this area. Before this project, this area was last surveyed by the Office of Coast Survey in 1922 and 1940. This survey will allow vessel traffic safe passage to offshore Gulf of Mexico. The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products, this project will address numerous approximately charted hazards, reducing the risk to navigation. Survey data from this project is intended to supersede all prior survey data in the common area.” *1 Breton National Wildlife Refuge. Wikipedia. Retrieved 27 February 2019 *2 Moore, Laura J.; Patch, Kiki; List, Jeffery H.; Williams, S. Jeffress (2014). “The potential for sea-level-rise-induced barrier island loss: Insights from the Chandeleur Islands, Louisiana, USA”. Marine Geology. 355: 244-259. doi:10.1016/j.margeo.2014.05.022. ISSN 0025-3227The Federal Aviation Administration Wide Area Augmentation System (FAA WAAS) was enabled to be active if the English Turn station experienced periods of down time. North American Datum 1983Projected UTM 16English Turn, LA (293 kHz)Real-time positioning for side scan sonar operations was provided by differential GPS using corrections received from the US Coast Guard National Differential GPS (NDGPS) coverage network from differential beacons at English Turn, LA (293 kHz). ERS via VDATUMOPR-J311-KR-19_VDatum2_xyNAD83-MLLW_geoid12b.csarThe separation model listed in Table 13 was provided with the Project Instructions and used for sounding correction within the assigned survey area. Realtime navigation for all MBES survey lines were overwritten with post-processed navigation solutions in SBET format. Post-processed solutions were generated using Applanix POSPac MMS using the Trimble CenterPoint RTX option which relies on precise satellite orbit and timing information to create centimeter level positioning and elevation without the use of traditional local base stations. Information on survey control is detailed in the DAPR.Mean Lower Low WaterA summary of the horizontal and vertical control for survey H13262 follows.There are four assigned submerged pipelines in the survey extents for H13262. These features were carefully reviewed for any portion of pipeline that was exposed or posed a risk to navigation. No extents of the assigned pipelines in survey H13262 were observed in SSS or MBES data. The pipelines are included in the FFF with a description of ‘Retain’ due to the inability of the field unit to determine if pipelines are buried.No ferry routes or terminals exist for this survey.No present or planned construction or dredging exist within the survey limits.No overhead features exist for this survey.No new insets are recommended for this area.No new surveys or further investigations are recommended for this area.One bottom sample was acquired on August 1, 2019 (DN213). The bottom sampling plan followed suggested sample locations included in the Project Reference File (PRF) provided. Minor adjustments were made to the recommended sampling location in order to sample the varying bottom types observed in the side scan data. This modification was approved by the Contracting Officer’s Representative (COR). Correspondence is included in Appendix II Supplemental Survey Records & Correspondence of this report.No Maritime Boundary Points were assigned for this survey.No Aids to Navigation (ATONs) exist for this survey. No platforms exist for this survey.No abnormal seafloor and/or environmental conditions exist for this survey.No uncharted features were submitted for this survey. No Dangers to Navigation (DtoNs) were submitted for this survey. This survey contains one assigned charted wreck labeled Position Approximate (PA). The charted wreck (PA) with depth unknown was disproved inside an assigned disproval radius with 100% MBES coverage. The charted wreck has been included in the FFF with a description of 'Delete'.The chart comparison was performed by comparing H13262 survey depths to a digital surface generated from electronic navigational charts (ENCs) covering the survey area. A 50-meter product surface was generated from a triangular irregular network (TIN) created from the ENC’s soundings, depth contours, and depth features. The 50-meter HIPS product surface of the entire survey area was generated from the 2-meter CUBE surface. The chart comparison was conducted by creating and reviewing a difference surface using the ENC surface and survey surface as inputs. The chart comparison also included a review of all assigned charted features within the survey area. The results of the comparison are detailed below. The relevant charts used during the comparison were reviewed to check that all US Coast Guard (USCG) Local Notice to Mariners (LNMs) issued during survey acquisition, and impacting the survey area, were applied and addressed by this survey.There are no precautionary areas, traffic separation schemes, or pilot boarding areas within the survey limits. The Mississippi River-Gulf Outlet Channel to Mobile Ship Channel Safety Fairway (33 CFR 166.200) crosses the survey area. No new obstructions or dangers were located within the safety fairway in the survey area. The hydrographer recommends encoding the name of this and other safety fairways in the ENCs. Safety fairway names are included in the Code of Federal Regulations.US3GC04M2500002019-11-19632019-08-01Multibeam backscatter was logged in Hypack 7k format and included with the H13262 digital deliverables. Data were processed periodically in CARIS HIPS to evaluate backscatter quality, but the processed data is not included with the deliverables. For data management purposes, the names of multibeam crosslines have been appended with the suffix XL. This change was made to HIPS files only. The original file names of raw data files (Hypack HSX and 7k) have been retained.All sounding systems were calibrated as detailed in the DAPR.Data reduction procedures for survey H13262 are detailed in the DAPR. Summary multibeam and side scan sonar processing logs are included in Separate I of this report.Designated Soundings There are no soundings designated in bathymetric data to facilitate feature management for inclusion in the H13262 Final Feature File (FFF) or to override the gridded surface model.CARIS HDCS Navigation Sources During processing of HDCS lines, navigation information was imported from SBET.out files while importing motion and associated RMS values. This navigation source, Applanix.SBET, is automatically applied at merge when it exists. However, when a CARIS project file is rebuilt, CARIS will report that the navigation source is the HDCSNav. This is a display issue only and does not change the navigation source. Additionally, when a line is renamed, such as with the suffix _XL, the HDCSNav source disappears from the metadata display. Again, this appears to be a display issue only and does not change any navigation sources. All HDCS lines were processed using the SBET.out files and the navigation source is Applanix.SBET for this survey. Additional processing information is detailed in the DAPR.NOAA_2m2Complete MBES20.93028.970H13262_MB_2m_MLLWCARIS Raster Surface (CUBE)NOAA_2m2Finalized Complete MBES20.93028.970H13262_MB_2m_MLLW_FinalCARIS Raster Surface (CUBE)N/A1100% SSS0.0000.000H13262_SSSAB_1m_600kHz_1of1SSS MosaicBathymetric grids were created relative to Mean Lower Low Water (MLLW) in CUBE format using Complete Coverage resolution requirements as specified in the HSSD. A detailed listing of all data processing software is included in the OPR-J311-KR-19 DAPR.NOAA Profile Version 5.7CARISHIPS/SIPS10.4.5Chesapeake Technology, Inc.SonarWiz7.04.01Teledyne RESONMBESSeaBat 7101EdgeTechSSS4200ApplanixPositioning and Attitude SystemPOS MV 320 v5AML OceanographicSound Speed SystemMVP30-350AML OceanographicSound Speed SystemBaseX2AML OceanographicSound Speed SystemMicro SV-XchangeTrimblePositioning SystemSPS851TrimblePositioning SystemRTXfile:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/OPR-J311-KR-19_Blake.pngS/V BlakeS/V Blake824.5The OPR-J311-KR-19 Data Acquisition and Processing Report (DAPR), previously submitted with survey H13260, details equipment and vessel information as well as data acquisition and processing procedures. There were no vessel or equipment configurations used during data acquisition that deviated from those described in the DAPR.file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_Junctions_graphic.pngSurvey junctions with registry number H13262file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW-H13260_MB_1m_MLLW_depth_delta.pngDistribution summary plot of survey H13262 2-meter vs H13260 1-meter2019David Evans & Associates, Inc.N40000H13260The mean difference between H13262 and H13260 survey depths is 1 centimeter (H13262 deeper than H13260), shown in Figure 7. file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW-H13261_MB_2m_MLLW_depth_delta.pngDistribution summary plot of survey H13262 2-meter vs H13261 2-meter2019David Evans & Associates, Inc.NE40000H13261The mean difference between H13262 and H13261 survey depths is 2 centimeters (H13262 shoaler than H13261), shown in Figure 8. file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW-H13263_MB_2m_MLLW_depth_delta.pngDistribution summary plot of survey H13262 2-meter vs H13263 2-meter2019David Evans & Associates, Inc.E40000H13263The mean difference between H13262 and H13263 survey depths is 0 centimeters, shown in Figure 9. file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW-H13134_MB_1m_MLLW_Combined_depth_delta.pngDistribution summary plot of survey H13262 2-meter vs H13134 1-meter2018LeidosS40000H13134The mean difference between H13262 and H13134 survey depths is 30 centimeters (H13262 deeper than H13134), shown in Figure 10. Major differences are representative of surveys impacted by subsidence over a one year period and the use of varying tidal application methods. According to the Descriptive Report for the prior survey, H13134 used ERS with Poor Mans VDATUM for Vertical Control methods where survey H13262 used ERS methods relying on the published VDATUM model for the area. Using prior data available on the National Centers for Environmental Information (NCEI) website, the separation model used for survey H13134 was recreated and compared to the separation model used for survey H13262. The prior model was reconstructed by computing a difference surface between the combined MLLW and ellipsoid bathymetry grids available for survey H13134. The hydrographer found a 14-centimeter difference between the two models at the survey junction.file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW-H13135_MB_2m_MLLW_Combined_depth_delta.pngDistribution summary plot of survey H13262 2-meter vs H13135 2-meter2018LeidosS40000H13135The mean difference between H13262 and H13135 survey depths is 26 centimeters (H13262 deeper than H13135), shown in Figure 11. Major differences are representative of surveys impacted by subsidence over a one year period and the use of varying tidal application methods. According to the Descriptive Report for the prior survey, H13135 used ERS with Poor Mans VDATUM for Vertical Control methods where survey H13262 used ERS methods relying on the published VDATUM model for the area. Using prior data available on the National Centers for Environmental Information (NCEI) website, the separation model used for survey H13135 was recreated and compared to the separation model used for survey H13262. The prior model was reconstructed by computing a difference surface between the combined MLLW and ellipsoid bathymetry grids available for survey H13135. The hydrographer found a 13-centimeter difference between the two models at the survey junction. Survey H13262 junctions with current surveys H13260, H13261, and H13263. Prior surveys H13134 and H13135 were specified as junctions in the Project Instructions for survey H13262. Figure 6 depicts H13262 and the junctioning surveys. Densityfile:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW_Final.QAv5.density.pngNode density statistics - 2m finalizedThe sounding density requirement of 95% of all nodes, populated with at least five soundings per node, was verified by analyzing the density layer of each finalized surface. Individual surface results are stated in Figure 12.None ExistThere were no other factors that affected corrections to soundings.An AML Oceanographic Moving Vessel Profiler (MVP) was the primary instrument used to acquire sound speed readings during multibeam operations. Additional discussion of sound speed methods can be found in the DAPR. For H13262 survey operations, casts were distributed both temporally and spatially based on observed changes in the sound speed profiles. Sound speed readings were applied in CARIS using the nearest in distance within a one-hour interval. All sound speed measurements were made within 500 meters of the survey limits. During survey operations on July 6, 2019 (DN187), the MVP required a cable retermination. Sound speed readings were applied in CARIS using the nearest in distance within a two-hour interval based on equipment being offline for the following lines: 2019BL1872102 2019BL1872112 2019BL1872119 2019BL1872128 During survey operations on July 7, 2019 (DN188), the MVP was receiving intermittent data on the up cast due to a failing cable termination. All MVP casts for this day were processed using the down cast rather than the up cast which is the standard procedure discussed in the DAPR. On July 8, 2019 (DN189), the field unit conducted bathymetric splits in the southeast extents of the sheet in accordance to the HSSD (2019) specifications. A single MVP cast was taken in this region due to negligible change in sound speed measurements. As a result, sound speed readings were applied in CARIS using the nearest in distance within a three-hour interval for the following lines: 2019BL1891641 2019BL1891712 2019BL1891721 2019BL1891727 These deviations on DN187, DN188, and DN189 had no discernable impact on data quality as casts were relatively consistent.Approximately 20 minute intervals file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_2m_XL-H13262_2m_MS_depth_delta.pngH13262 Crossline DifferenceMultibeam crosslines were run across the entire survey area to provide a varied spatial and temporal distribution for analysis of internal consistency within the survey data. Crossline analysis was performed using the CARIS Hydrographic Information Processing System (HIPS) Quality Control (QC) Report tool, which compares crossline data to a gridded surface and reports results by beam number. Crosslines were compared to a 2-meter CUBE surface encompassing mainscheme, fill, and investigation data for the entire survey area. The QC Report tabular output and plots are included in Separate II Crossline Comparison. DEA performed an additional crossline analysis using the NOAA Pydro Compare Grids tool to analyze the differences between gridded mainscheme depths and gridded crossline depths. Input grids were 2-meter resolution CUBE surfaces of mainscheme and crossline depths. Results from the crossline to mainscheme difference analysis are depicted in Figure 4, units are represented in meters. Quality control is discussed in detail in Section B of the DAPR. Results from weekly position checks and weekly multibeam bar checks are included in Separate I Acquisition and Processing Logs of this report. Sound speed checks can be found in Separate II Sound Speed Data Summary of this report. Multibeam data were reviewed at multiple levels of data processing including: CARIS HIPS conversion, subset editing, and analysis of anomalies revealed in CUBE surfaces.Survey speeds were maintained to meet or exceed along-track sounding density requirements and side scan sonar ensonification requirements. Multibeam data and side scan mosaics were thoroughly reviewed for holidays and areas of poor-quality coverage due to biomass, vessel wakes, or other factors. Side scan sonar contacts were developed with multibeam sonar to obtain a least depth of the contact using Complete Coverage requirements. Obtained survey depths were compared to existing charts at specified scales to develop bathymetric split line plans for all charted soundings that were shallower than adjacent soundings. Complete coverage multibeam was acquired inside the disproval radii for assigned charted features and over all new features. Additional discussion of coverage methods can be found in the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.file:///Q:/Survey/H13262_J311_KR_19/AHB_H13262/01_SAR/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13262_MB_2m_MLLW_Final.QAv5.tvu_qc.pngNode TVU statistics - 2m finalizedS/V Blake0.5n/a1.00.168ERS via VDATUM0.05Additional discussion of these parameters is included in the DAPR. During surface finalization in HIPS, the "Greater of the two values" option was selected, where the calculated uncertainty from Total Propagated Uncertainty (TPU) is compared to the standard deviation of the soundings influencing the node, and where the greater value is assigned as the final uncertainty of the node. The uncertainty of the finalized surfaces increased for nodes, where the standard deviation of the node was greater than the TPU. To determine if the surface grid nodes met IHO Order 1 specification, a ratio of the final node uncertainty to the allowable uncertainty at that depth was determined. As a percentage, this value represents the amount of error budget utilized by the total vertical uncertainty (TVU) at each node. Values greater than 100% indicate nodes exceeding the allowable IHO uncertainty. The resulting calculated TVU values of all nodes in the submitted finalized surfaces are shown in Figure 5.