OPR-J347-KR-18Mississippi RiverMississippi RiverDavid Evans and AssociatesH131958Mississippi River, Vicinity of Mile 54 to 26LouisianaUnited States50002018Jonathan L. Dasler, PE, PLS, CHNavigable Area2019-08-082018-08-092019-04-30Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUTCAtlantic 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, LWRP. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.ContractorDavid Evans and Associates, Inc. (DEA) conducted a hydrographic survey of the assigned area in the Mississippi River. Survey H13195 was conducted in accordance with the November 19, 2018 Statement of Work and Hydographic Survey Project Instructions dated August 8, 2019. The Hydrographic Survey Project Instructions reference the National Ocean Service (NOS) Hydrographic Surveys Specifications and Deliverables Manual (HSSD) (March, 2018) as the technical requirements for this project.29.611396388989.879435305629.360400111189.5339456111Survey Limits were surveyed in accordance with the requirements in the Project Instructions and the HSSD. OPR-J347-KR-18 Survey AreasSupportFiles\OPR-J347-KR-18_Survey_Outline.pngThe Ports of Southern Mississippi River represent the largest port complex in the world and one of the most heavily trafficked waterways in the United States. Annually, over 500 million tons of cargo is moved on the Lower Mississippi. This project area includes the Port of South Louisiana, the Port of New Orleans, the Port of Greater Baton Rouge, and Plaquemines Port, all ranking in the top 12 ports for annual tonnage in the United States. The Port of South Louisiana, river mile 114.9 to 168.5, is the largest tonnage port in the western hemisphere, handling approximately 262 million tons. The Port of New Orleans, river mile 81.2 to 114.9, handles approximately 90 million tons annually. The Port of Greater Baton Rouge, river mile 168.5 to 253, and Plaquemines Port, river mile 0 to 81.2, handle approximately 73 and 57 million tons annually, respectively.* Critical Charting updates are needed for the Mississippi River, especially for areas outside of the U.S. Army Corps of Engineers (USACE) federally maintained channel areas. These areas outside of the federally maintained channel account for the majority of the navigable river and include ports and terminals essential for commerce and trade. The new bathymetric data in this project area, encompassing 89 SNM, will support high resolution charting products for maritime commerce and update National Ocean Service (NOS) nautical charting products. * U.S. Army Corps of Engineers, Navigation Data Center, Waterborne Commerce Statistics Center, Principal Ports of the United States, www.navigationdatacenter.us/data/datappor.htmThe entire survey is adequate to supersede previous data.The river bottom is continuously changing due to currents, vessel propeller wash, dredging activity, construction and/or other factors present in the river environment. Changes in the river bed were observed during acquisition, primarily due to sediment migration. Section B.2.6 of this report further discusses these issues and impacts to the final deliverable data. In all cases the hydrographer has verified that soundings accurately depicted the river bed at the time of acquisition.All waters in survey areaObject Detection Coverage (HSSD Section 5.2.2.2) Project Instructions called for high resolution charting at 1:5,000 survey scale to support NOAA’s Precision Navigation initiative for the Mississippi River including: Object Detection Coverage for all waters in the survey area to the 2-meter depth contour; Ellipsoid Reference Survey (ERS) using a custom separation model for the Mississippi River; verification of ATONs; assignment of shoreline and nearshore features (including bridges, overhead wires, revetments, assigned existing terminals, and all uncharted features) to be obtained by a vessel based mobile laser scanning technology and imaging system; and delivery of LAS data referenced using ERS methods. Operational challenges included, but were not limited to: conducting surveys in a heavily congested industrial waterway; high river current velocities and transiting debris from high water levels; over 465 miles of shoreline surveys in restricted waters with small launch operations in close proximity to terminals, large barge fleets, wrecks, ruins, submerged piling, and numerous snags; minimal river access for provisioning and refueling; dynamic sediment migration exceeding 0.25 meters per hour in some areas; resolution of chart datum and revisions to the separation model; coordinating mapping efforts with ships at berth; dense fog; on-going dredging operations; and various navigational trials associated with a heavily trafficked industrial waterway. To mitigate these challenges and with the volume of shoreline operations required, survey operations were conducted during daylight hours only, AIS and internet vessel tracking systems were utilized, and continuous communications were made to terminal operators and vessel captains by radio and phone. Object detection coverage was obtained over the survey area in depths greater than 2 meters relative to chart datum using 100% multibeam echosounder (MBES) and backscatter unless otherwise discussed in individual sections of this report. This coverage type follows Option A of the Object Detection Coverage requirement specified in Section 5.2.2 of the 2018 HSSD. Historic flooding of the Mississippi River during OPR-J347-KR-18 survey impacted safe operations in high currents and restricted operations. Many features were in locations that restricted a 90-degree pass due to strong currents and proximity to shoreline, fixed structures or barge fleeting. Further, flooding and strong river currents resulted in significant sediment migration during and between survey operations, evident on this survey sheet. Unavoidable coverage gaps are evident in some areas and are primarily due to large barge fleeting areas. Other features that blocked or impeded safe vessel operations resulting in data gaps included: berthed vessels that remained during survey operations; low wires behind structures; mooring lines; in-water facilities and ruins. Significant efforts were expended to maximize coverage to the extent possible in these areas. Section B.2.10 of this report discusses issues restricting this survey coverage in greater detail. Figure 2 depicts the survey outline that was obtained for H13195. H13195 Survey OutlineSupportFiles\H13195_SurveyOutline.pngS/V Blake0411.0556.00000026.600RHIB Sigsbee0255.65000002.3200666.7056.00000028.9204.34000010.272018-08-092018-08-102019-01-162019-01-172019-01-182019-01-192019-01-202019-01-212019-01-222019-01-232019-01-242019-01-262019-01-272019-01-292019-02-222019-04-30The OPR-J347-KR-18 Data Acquisition and Processing Report (DAPR), submitted with this survey, 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.S/V Blake834.5RHIB Sigsbee181.0S/V BlakeSupportFiles\OPR-J347-KR-18_Blake.pngRHIB SigsbeeSupportFiles\OPR-J347-KR-18_Sigsbee.pngTeledyne RESONSeaBat T50-RMBESTeledyne RESONSeaBat T50-PMBESRIEGLVUX-1HALidar SystemApplanixPOS MV 320 v5Positioning and Attitude SystemApplanixPOS LV 620Positioning and Attitude SystemiXblueHydrinsPositioning and Attitude SystemTrimbleSPS851Positioning SystemTrimbleSPS855Positioning SystemIntuicomRTK Bridge-XPositioning SystemAML OceanographicSmartXSound Speed SystemAML OceanographicSmartXSound Speed SystemAML OceanographicBaseXSound Speed SystemSea-Bird ScientificSBE 19plusConductivity, Temperature, and Depth SensorMultibeam 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 1-meter CUBE surface encompassing mainscheme, fill, and investigation data for the entire survey area. The QC Report tabular output and plots for both survey vessels are included in Separate II Checkpoint Summary and Crossline Comparison. For the S/V Blake the output and plot contain data from a dual-head system, beams 1 to 256 are from the starboard head while 257 to 512 are from the port head. Due to significant sediment migration occurring within the survey, crosslines were generally conducted on the same day as mainscheme acquisition in order to reduce the impact of the changing riverbed on crossline agreement. This resulted in a time differential of over eight hours between mainscheme and crossline acquisition and significant change in the riverbed was still apparent. Tests run prior to the 2019 flooding event, which was in full swing during this survey, showed sediment wave movement at a rate of 0.25 meters per hour with even higher rates observed during flooding. Even with these operational adjustments, crossline statistics from the S/V Blake, which operated in deeper water over the main channel, exceed International Hydrographic Organization (IHO) Order 1 specification as reported by the CARIS HIPS QC Report tool. 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 1-meter resolution CUBE surfaces of mainscheme and crossline depths. Results from the crossline to mainscheme difference analysis are depicted in Figures 5 and 6. Figure 6 depicts a difference surface portraying the sediment migration seen throughout the duration of survey. This figure details crosslines conducted at the end of a survey day, approximately seven hours after the first mainscheme line was acquired for the day of acquisition. Change is significant in the sediment wave field with horizontal migration of up to 13 meters occurring between mainscheme and crossline acquisition. The shape of the waves is apparent in both the difference image and multibeam hillshade. Shades of yellow and red indicate shoaling and shades of blue indicate deepening with both following the form of the wave field as sediment waves migrate. Shades of grey indicate areas that meet requirements and are generally outside the sediment wave field where there has been less change. DEA remains confident that data consistency was maintained during acquisition based on swath to swath comparison of two vessel platforms and three sonars operating simultaneously in the same survey area. DEA confirmed that a systematic error, such as positioning or sound speed measurements, was not a factor leading to these large differences based on weekly system comparisons detailed in Separate I Acquisition and Processing Logs of this report. To further document the system performance, an additional crossline report was run on data acquired in the vicinity of Gulfport Channel, near the project’s mobilization grounds and outside of the influence of sediment migration. The output of this report confirms the S/V Blake’s sonar and acquisition and processing procedures are capable of acquiring data that exceeds IHO specification for Order 1 and Special Order as reported by the HIPS QC Report tool. Output from the report is included in Separate II Checkpoint Summary and Crossline Comparison. This issue was not limited to this survey area; sediment migration affected the entire OPR-J347-KR-18 project area. Impacts of sediment migration are further discussed in section B.2.6 of this report.H13195 Crossline Difference Distribution Summary PlotSupportFiles\H13195_1m_XL_Only-H13195_1m_MS_Only_depth_delta.pngH13195 Crossline Difference Surface portraying sediment migrationSupportFiles\H13195_crossline_difference_example.pngERS via VDATUM0.0300.084S/V Blake1.00.5RHIB Sigsbee1.00.5Additional discussion of these parameters is included in the DAPR. Sound speed profiles collected from the RHIB Sigsbee were acquired with AML BaseX or AML SmartX sound speed sensors. The measurement uncertainty for these sensors is listed in the CTD column in Table 8. 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 great 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 Figures 7 through 9. The finalized surfaces include occasional large vertical uncertainties which exceed IHO Order 1 allowances. These high uncertainties were caused by introducing areas of high depth standard deviation associated with steep slopes when finalizing surfaces with the greater of the two option; and incorporating erroneous real-time sonar uncertainty values during TPU computation. On occasion, the real-time uncertainty logged during acquisition included a sounding with an extremely high depth uncertainty which was well outside of realistic values. During processing, an IHO filter was applied to all sounding data, with rejecting soundings exceeding IHO Order 1 thresholds for TVU. These rejected soundings have at times been reaccepted after thorough review by the hydrographer. This issue appears to have been caused by an unresolved software bug in either the sonar top side unit or acquisition system impacting the reported uncertainty, but not the actual depth.Node TVU statistics - 50cm finalizedSupportFiles\H13195_MB_50cm_LWRP_Final.QAv5.tvu_qc.pngNode TVU statistics - 1m finalizedSupportFiles\H13195_MB_1m_LWRP_Final.QAv5.tvu_qc.pngNode TVU statistics - 4m finalizedSupportFiles\H13195_MB_4m_LWRP_Final.QAv5.tvu_qc.pngSurvey H13195 junctions with current surveys H13194 and H13196. No prior surveys were specified as junctions in the Project Instructions. H1319450002018David Evans & Associates, Inc.WAt the time of writing, data from survey H13194 was still being processed. The Descriptive Report for H13194 will include the junction analysis with H13195. H1319650002018David Evans & Associates, Inc.EAt the time of writing, data from survey H13196 was still being processed. The Descriptive Report for H13196 will include the junction analysis with H13195.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.High Frequency artifact in dual-head MBES systemHigh frequency artifacts are visible periodically in the data collected with the dual-head system on the S/V Blake. Despite extensive testing and troubleshooting of mount stability under a range of vessel motion dynamics and speed, applied offsets, and application of patch tests bias, no single source of the artifact could be identified. The high frequency artifact was transient and unrelated to vessel dynamics and loading on sonar mounts at different speeds and induced rolling during testing and is periodically present in both sonars, with a higher magnitude observed on the port sonar. From the findings of the troubleshooting, it is the hydrographer's belief that this is not related to mount instability relative to the IMU of patch test bias values applied and may be related to minor transient timing issues in the dual head system relative to the application of motion data (primarily role). Under this assumption, the further away the sensor is from the ship reference point, the great the magnitude of the error. In this case, while the artifact negatively affects the aesthetic of the final surface deliverable, it is well within IHO specifications for this survey. Figures 10 and 11, display the artifact for the dual-head operations.Example of high frequency artifact shown in surface and along track subset. Subsets of differing magnitudes between separate sonar heads of dual-head system shown on port side of swath (starboard beams shown in red, port beams in green)SupportFiles\OPR-J347-KR-18_artifact_port_sonar.pngExample of high frequency artifact shown in surface and along track subset. Subsets of differing magnitudes between separate sonar heads of dual-head system shown on starboard side of swath (starboard beams shown in red, port beams in green)SupportFiles\OPR-J347-KR-18_artifact_stbd_sonar.pngBottom tracking in shallow waterDuring survey acquisition, it was apparent that the combination of shallow water and the river bottom type (an assumption of soft silty mud) made it difficult to get a clean bottom track return from the MBES system. This most frequently was displayed in shallow, flat areas out of the main channel current. To try to mitigate the effects, sonar settings were changed by the hydrographer during acquisition, including changing power, gain, time variable gain (TVG) settings, and pulse length. In the end no clear solution fixed the issue and the hydrographer continuously tuned the sonar for what received the best return at the time. This is likely a limitation of the instrument and the physics of acoustics in the depths being surveyed. The HDCS dataset was well cleaned to mitigate the effects to the final surfaces. However, artifacts within IHO specifications, will be apparent in the final delivered surface as shown in Figure 12.Example of erroneous bottom tracking of flat shoal areas in HDCS data and resultant surface artifact (gray soundings rejected manually by hydrographer to limit effects to the surface)SupportFiles\H13195_BottomTrackArtifact.pngDelayed HeaveDelayed heave was applied to data collected by the S/V Blake using the POS M/V .000 file logged during acquisition. This file is loaded using the CARIS Import Auxillary Data tool. Delayed heave is chosen during the SVC and Merge processing steps. Delayed heave was applied to data collected by the RHIB Sigsbee using the IXSEA Output_E.log file logged during acquisition. This file is formatted similarly to the POS M/V .000 file for delayed heave, but does not contain any position, motion, or associated RMS values. The Output_E.log file was loaded using the CARIS Import Auxillary Data tool and applied during the SVC and Merge processing steps.Sediment MigrationSediment migration on the river bottom was evident throughout the course of this survey. Crosslines and fill lines that were run hours after mainscheme acquisition still exceeded the allowable vertical uncertainty in some areas. Following guidance from HSD OPS and the Atlantic Hydrographic Branch, the hydrographer allowed the CUBE algorithm to estimate a gridded depth in these areas without manual cleaning of the sounding data. The submitted surface has numerous artifacts resulting from these areas of disagreement. When reviewed, soundings deemed as fliers were still rejected. It is the hydrographer's belief that the submitted depths were accurate at the time of the survey. Some areas of the greatest disagreement have been noted in the H13195_Notes_for_Reviewer.hob file with the SNDWAV area feature class, submitted in Appendix II Supplemental Survey Records of this report. This is not an exhaustive list of areas but should detail those that show the major surface artifacts resulting from sediment migration. While in an area of significant sediment migration, a field test was conducted to attempt to quantify the amount of change the river bottom experienced at that time of survey. The same line was run upstream at similar speeds with time elapsing between subsequent passes. A subset of the results is shown in Figures 13 and 14. A high vertical exaggeration is used in Figure 14 to highlight the magnitude of the sediment migration. The hydrographer's best estimate is that the smaller waves on top are migrating at nearly 1 meter/hour while the larger waves, nearly two meters high, are migrating at 5 meters/day.Example of artifacts caused by sediment migration during H13195 operationsSupportFiles\H13195_Sediment_Migration.pngAlong-track subset view of field test portraying river bottom changes due to sediment migrationSupportFiles\OPR-J347-KR-18_Sediment_Migration.pngApproximately 4 hour intervalsAn AML Oceanographic Moving Vessel Profiler (MVP) and an AML SmartX or BaseX were the primary instruments used to acquire sound speed readings during multibeam operations for the S/V Blake and the RHIB Sigsbee, respectively. Due to the consistent sound speed profile encountered in this reach of the river, sound speed profiles were measured at approximately one to two-hour intervals during survey operations. Sound speed readings were applied in CARIS at an approximate interval of four hours based on consistent profiles observed throughout the day of survey. During H13195 survey operations, sound speed was observed to be well mixed with very little temporal or spatial variation. Additional discussion of sound speed methods can be found in the DAPR. All sound speed measurements were made within 250 meters of the planned survey boundary. In general, a sound speed measurement was made immediately preceding bathymetric operations, per HSSD. Occasionally a sound velocity profile was taken before survey operations and then rejected during data QC or taken shortly after the start of acquisition. Figure 15 details all instances when there was a deviation from the HSSD for H13195. Sound speed measurement exceeding start of operations specificationSupportFiles\H13195_SV_Casts.pngSurvey speeds were typically maintained to meet or exceed along-track density requirements. However, due to conditions present, including swift current and vessel traffic, occasional along-track low-density areas are present in the final data. These typically are narrow swaths centered along nadir and do not impact meeting density requirements for 95% of all nodes. Mobile lidar coverage was obtained on the full extents of both river banks spanning the survey area with one exception. A 1-mile gap in coverage exists on the West bank between river miles 33 and 34 where the vessel veered away from the shoreline to capture a mid-channel buoy. The section was later investigated by the RHIB Sigsbee. No assigned features were present, and no uncharted features were observed within the gap in data.DensityThe 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 Figures 16 through 18. Node density statistics - 50cm finalizedSupportFiles\H13195_MB_50cm_LWRP_Final.QAv5.density.pngNode density statistics - 1m finalizedSupportFiles\H13195_MB_1m_LWRP_Final.QAv5.density.pngNode density statistics - 4m finalizedSupportFiles\H13195_MB_4m_LWRP_Final.QAv5.density.pngData gaps in bathymetric coverage Occasional data gaps in the final Object Detection surfaces exist due to operational restrictions at time of survey. These data gaps were further analyzed after acquisition and determined to be unattainable due to safety or other factors impacting vessel operations. Significant effort was expended during survey operations to maximize object detection coverage in these areas. Some of the sources for these data gaps include: - Holidays or 2-meter coverage gaps behind pier structures where field unit was physically unable to operate, or safety concerns limited their ability. - Holidays beyond the 2-meter curve (NALL) which were not further investigated due to safety concerns in shallow water. - Holidays or 2-meter coverage gaps underneath barge fleets or anchored/moored vessels. These were revisited at least one other time in subsequent days. Typically, the field hydrographer would acquire data along the achievable extents of the gap, and document the existence of the barge fleet or vessel with targets and/or photos. AIS or internet-based vessel tracking tools were used to alert the field unit when vessels were underway. - Holidays created beneath baring structures that met the area requirements were rejected in the survey data for final delivery. Holidays that exist in the final surfaces have been noted in the H13195_Notes_for_Reviewer.hob with the cvrage area feature class, submitted in Appendix II, and attributed with remarks stating the contributing factor leading to the data gap. Areas were the 2-meter curve was not met are included in the H13195_Notes_for_Reviewer.hob with SLCONS feature class and attributed with remarks stating the contributing factor for this deficiency.All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.Multibeam backscatter was logged in Hypack 7k format and included with the H13195 digital deliverables. Data were processed periodically in CARIS HIPS to evaluate backscatter quality, but the processed data is not included with the deliverables. For dual-head MBES data on S/V Blake, individual 7k files were logged for each sonar head in order to better facilitate additional changes required between systems. 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.Backscatter processing to be performed at the Branch deviates from the current OCS Backscatter Processing SOP dated 02/21/2020. Specifically, for the dual-head sonar configuration used in this survey, the processed depth files in the HDCS survey lines contain combined bathymetric data from both sonar heads. However, due to software limitations, the resulting GSF format data files and backscatter mosaic are based on time series data in .7k files (snippets data) from one individual sonar head, paired with the dual-head sounding data. This is represented in the backscatter mosaic with the vessel name BlakeDHS or BlakeDHP, indicating one set of .7k files from the starboard or port head, respective of the dual-head system was paired with the combined-head HDCS. The naming convention for the MBAB mosaic is H13195_MBAB_2m_BlakeDHS_350kHz_1of2.tiff (DHS for the starboard head of a dual head configuration). This product is the best available from the files associated with this particular dual-head sonar configuration and combined-head acquisition process.CARISHIPS/SIPS10.4.5NOAA Profile Version 5.7A detailed listing of all data processing software, including software used to process the mobile lidar data, is included in the DAPR.H13195_MB_50cm_LWRPCARIS Raster Surface (CUBE)0.5-0.79855.808NOAA_0.5mObject DetectionH13195_MB_1m_LWRPCARIS Raster Surface (CUBE)1-0.75955.719NOAA_1mObject DetectionH13195_MB_4m_LWRPCARIS Raster Surface (CUBE)4-0.68355.636NOAA_4mObject DetectionH13195_MB_50cm_LWRP_FinalCARIS Raster Surface (CUBE)0.5-0.79820.000NOAA_0.5mObject DetectionH13195_MB_1m_LWRP_FinalCARIS Raster Surface (CUBE)118.00040.000NOAA_1mObject DetectionH13195_MB_4m_LWRP_FinalCARIS Raster Surface (CUBE)436.00055.636NOAA_4mObject DetectionBathymetric grids were created relative to LWRP in CUBE format using Object Detection resolution requirements as described in the HSSD.Grids were originally submitted by the field unit as 50 cm, 1 m and 4 m finalized single resolution grids and were accepted by the Branch as meeting specifications during the H13195 RSA. After additional review during the SAR, it was found some grids required additional re-computation and re-finalization due to minor revisions of the sounding data and FFF. It was agreed amongst both PHB and AHB to modify the final grid products from single resolution to variable resolution (VR) grids following the NOAA object detection depth based (ranges) estimation method parameters. The effect was improved grid management reducing the number of total number grids from eight (8) to three (3). Given final products are now submitted as VR, no final combined surface is included with this submission.Designated SoundingsA total of 92 soundings in H13195 were designated in bathymetric data: 79 features to facilitate feature management for inclusion in the H13195 Final Feature File (FFF), and 13 to override the gridded surface model. CARIS HDCS Navigation SourcesDuring processing of S/V Blake HDCS lines, navigation information was imported from POS M/V .000 files while importing delayed heave, motion and associated RMS values. This navigation source, Applanix.ApplanixGroup1, 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. This is not an issue for data collected by the RHIB Sigsbee, which relies on HDCS navigation, and does not apply logged navigation, motion and RMS. 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.Mobile Laser Scanner DataA vessel based Mobile Mapping System (MMS) was used to acquire lidar and imagery data along the survey area’s shoreline in order to facilitate the survey, management, and reporting of shoreline and nearshore features. Processed LAS data from the laser scanner are included with the survey deliverables in the Processed directory. Imagery data collected by the MMS were used for feature interpretation during processing. Photos of individual features were extracted from the imagery data or taken during hydrographic survey operations and included with the images attribute in the FFF.A complete description of the horizontal and vertical control for survey H13195 can be found in the OPR-J347-KR-18 Horizontal and Vertical Control Report (HVCR), to be submitted with the final survey for this project. A summary of horizontal and vertical control for this survey follows.LW Reference Plane 2007ERS via VDATUMNAD83-LWRP2007_RM13.4_MLLW2012-2016_Geoid12B.csarWhile ERS via VDATUM is listed in Table 12, it was one of the limited options available in the XML DR schema’s enumerated values. The separation model covering the H13195 survey area was constructed by the HSD Operations Branch specifically for this survey project using NAVD88 (GEOID 2012B) to Mississippi River Low Water Reference Plane of 2007 (LWRP 2007) values published by USACE. Refer to the HVCR submitted under separate cover for additional information.North American Datum 1983Projected UTM 16During acquisition, RTK correctors were obtained from Louisiana State University’s (LSU) Center for Geoinformatics (C4G) service via a dedicated cellular modem. These correctors provided RTK level of accuracy for horizontal and vertical positions for all survey data. If a loss of service was experienced during acquisition it was noted by the field watch stander, and those data were further analyzed to be resurveyed. No prolonged outages were experienced during survey acquisition of H13195. Verification of the C4G Network correctors were conducted by the field unit at various monuments established by USACE along the shoreline of the OPR-J347-KR-18 project area. Methods, analysis and results of these monument check-ins are further documented in the project wide HVCR. Water Level FloatsWater level floats were conducted by the field unit at the location of each USACE or NOAA gauge within the OPR-J347-KR-18 project area. Methods, analysis and results of these floats are further documented in the project wide HVCR. In general, these floats helped identify issues between the USACE and NOAA datums and that of the LWRP 2007 separation model utilized during acquisition. These tests resulted in iterations to the model by NOAA, discussed in detail in the HVCR. Separation model change and re-processingAs discussed in section C4 of the DAPR and the project wide HVCR, due to a revision of the separation model used during acquisition, all ERS water levels were reprocessed after the revised model was issued. Refer to section B4.c of the DAPR for an outline of the processing steps.The chart comparison was performed by comparing H13195 survey depths to a digital surface generated from electronic navigational charts (ENCs) covering the survey area. A 10-meter product surface was generated from a triangular irregular network (TIN) created from the ENC’s soundings, depth contours, and depth features. An additional 10-meter HIPS product surface of the entire survey area was generated from the 4-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. Sediment migration and other river environmental conditions contribute to a continually changing river bottom resulting in large differences observed by the field unit daily. 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.US6LA53M1200082018-10-232019-04-04falseENC US6LA53M covered the full extents of survey H13195. Large differences exist between the surveyed depths and charted soundings mainly contributed to the continuously changing river environment. Figures 19 through 30 show the magnitude of differences along the comparison area.Depth difference between H13195 and chart US6LA53M, area 1 of 12SupportFiles\H13195_Chart_comp_US6_1.pngDepth difference between H13195 and chart US6LA53M, area 2 of 12SupportFiles\H13195_Chart_comp_US6_2.pngDepth difference between H13195 and chart US6LA53M, area 3 of 12SupportFiles\H13195_Chart_comp_US6_3.pngDepth difference between H13195 and chart US6LA53M, area 4 of 12SupportFiles\H13195_Chart_comp_US6_4.pngDepth difference between H13195 and chart US6LA53M, area 5 of 12SupportFiles\H13195_Chart_comp_US6_5.pngDepth difference between H13195 and chart US6LA53M, area 6 of 12SupportFiles\H13195_Chart_comp_US6_6.pngDepth difference between H13195 and chart US6LA53M, area 7 of 12SupportFiles\H13195_Chart_comp_US6_7.pngDepth difference between H13195 and chart US6LA53M, area 8 of 12SupportFiles\H13195_Chart_comp_US6_8.pngDepth difference between H13195 and chart US6LA53M, area 9 of 12SupportFiles\H13195_Chart_comp_US6_9.pngDepth difference between H13195 and chart US6LA53M, area 10 of 12SupportFiles\H13195_Chart_comp_US6_10.pngDepth difference between H13195 and chart US6LA53M, area 11 of 12SupportFiles\H13195_Chart_comp_US6_11.pngDepth difference between H13195 and chart US6LA53M, area 12 of 12SupportFiles\H13195_Chart_comp_US6_12.pngNo Maritime Boundary Points were assigned for this survey.Numerous charted features exist within the limits of sheet H13195. The FFF submitted with these data contains all information and recommendations acquired during acquisition. Refer to the FFF for additional information.All uncharted features discovered during survey acquisition are addressed in the FFF. Refer to the FFF for additional information.No DtoNs were submitted for this survey. Potential DtoNs are included as new features in the FFF. Because of the significant change that occurred within the project area since the last survey of the Mississippi River, HSD staff advised DEA to limit reporting of Dangers to Navigation to immediate hazards that could cause loss of life or impact waterborne commerce. No charted channels exist within the limits of H13195. The following anchorages are charted within the H13195 survey limits: Magnolia Anchorage, Port Sulphur Anchorage, Point Celeste Anchorage, Davant Anchorage, and Point Michel Anchorage. MBES data acquired within these anchorages were carefully reviewed for features that could pose a risk to anchoring or navigation. New uncharted features were discovered the Port Sulphur, Port Michel and Magnolia anchorages. All surveyed features within designated anchorages are included in the FFF.No bottom samples were required for this survey.Shoreline investigations were completed using lidar survey techniques. Refer to the DAPR for additional information regarding the acquisition and processing of these data. All new and assigned features have been included in the sheet’s FFF with appropriate comments and recommendations.Aids to Navigation (AtoNs) were investigated using mobile lidar and visual observations. AtoNs that were missing, damaged, or not serving their intended purpose were reported to the USCG via email on June 26, 2019. Due to the large number of AtoNs requiring reporting, email was used for reporting instead of using the USCG Navigation Center’s Online ATON Discrepancy Report as specified in the HSSD. This method was approved by the HSD Project Manager for this hydrographic survey. A copy of the email submittal is included in Appendix II. AtoNs have been included in the sheet’s FFF with appropriate comments and recommendations.No overhead features exist for this survey.All submarine features were investigated entirely using object detection MBES coverage. The OPR-J347-HR-18 Project Instructions required that all revetments within the survey area be investigated and delineated in the FFF if detected in the MBES data. The geometry of charted revetment polygons within the survey area, which were included in the project reference file (PRF) as CRANES area features, have been copied to the FFF as RESARE area features which is the feature type used to depict revetment areas on the ENCs. In most areas, revetments or sections of revetments are visible in the MBES data and surfaces. In areas where the charted revetments are not visible, the hydrographer is unable to determine if the revetment mats are not visible because they are no longer present, or if they have been buried by sediment. In all cases, the revetments provided in the PRF have been included in the FFF with a description of ‘Retain’. Revetment mats visible in the MBES data and extending beyond the limits of the PRF revetment polygons have been included in the FFF as obstruction areas features. The VALSOU of each area obstruction has been populated with the minimum gridded depth within the obstruction area polygon. The HSD Project Manager and AHB personnel provided input on portrayal of revetments in the FFF. Correspondence related to this guidance is included in Appendix II. Two pipeline reports were submitted to the Bureau of Safety and Environmental Enforcement (BSEE) reporting sections of exposed or unburied pipeline visible in the MBES data. These reports, which were submitted on April 8, 2019 and August 21, 2019, are included in Appendix II. The reports included the positions of the start and end points of sections of what appear to be exposed pipelines based on interpretation of multibeam data. It is possible that some of the reported items include submerged outfalls and other linear features with a signature of a pipeline that are not associated with oil and gas infrastructure. Due to the inability to accurately depict the location and orientation of all exposed pipelines with a single line segment, these features have been included in the FFF should further action be required after survey submittal. It is not the hydrographer’s intention that these pipeline features be used as source information for charting without further validation of origin. No platforms exist for this survey.One ferry route exists within the limits of H13195. The ferry and terminals were visually verified during survey operations. The terminal on the east bank is approximately 50 meters north of a charted FERYRT feature. This feature has not been included in the FFF as specified in the feature's Composite Source File (CSF) investigation requirements. Evidence of large and quickly moving sediment waves were visible in the MBES data during acquisition. Refer to section B.2.6 of this report for additional information.No construction or dredging were observed within the survey limits during survey operations.The hydrographer recommends that this area be resurveyed regularly due to the significant change in depths from sediment migration observed over the project timeline.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, with the exception of the deficiencies outlined in this report. 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, and Letter Instructions. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required.Jonathan L. Dasler, PE, PLS, CHNSPS/THSOA Certified Hydrographer, Chief of Party2019-10-10Jason Creech, CHNSPS/THSOA Certified Hydrographer, Charting Manager / Project Manager2019-10-10Callan McGriff, EITIHO Cat-A Hydrographer, Lead Hydrographer2019-10-10David T. Moehl, PLS, CHNSPS/THSOA Certified Hydrographer, Lead Hydrographer2019-10-10Data Acquisition and Processing Report2019-09-19Coast Pilot Report2019-07-11