S-J906-NRTST-23 Mobile River Mobile Alabama NOAA NRT-Galveston H13795 1 No Registry Instructions listed in Project Instructions. Mobile River Alabama United States 10000 2023 Dan Jacobs Navigable Area 2023-05-04 2023-05-09 2023-05-15 Multibeam Echo Sounder Side Scan Sonar meters UTC Pacific Hydrographic Branch Any revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 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. 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 Mobile River commencing at the Chickasaw Bridge and North, terminating at the Interstate 65 Bridge (General WK Wilson Jr. Bridge). 30.914406999999997 88.06321183333333 30.73742213888889 87.94288022222223 S-J906-NRTST-23 Mobile River Project Boundary file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Area_Surveyed_Mobile_River.jpg Acquisition to the assigned survey sheet limits were not attained where floating logs, overhanging branches, shoaling, vessel traffic and vessels tied up alongside precluded the teams' safe approach to the edge of the river bank/sheet limits. This leg of the river is a busy barge hub with frequent traffic at the Chickasaw Swing Bridge. Not all assigned features were addressed for these reasons. This project will provide modern bathymetric data for Mobile Bay. The project area was identified as a high priority area for NOAA's National Water Center, and is a statistically significant hot spot within the 2018 hydrographic health model, a risk model that Coast Survey uses for evaluating priorities based upon navigational risks and the necessary quality of data to support modern traffic. Conducting a modern bathymetric survey in this area will identify hazards and changes to the seafloor, update NOAA National Ocean Survey (NOS) charts and products, and provide forecasters at NOAA's National Water Center with bathymetric data for critical hydrodynamic modeling necessary to understand the timing and impact of rapid river stage increases and decreases, the duration of high water, inundation, or drought. Survey data from this project is intended to supersede all prior survey data in the common area. The entire survey is adequate to supersede previous data. The entire survey is adequate to supersede previous data. 0-20 meters Complete coverage, MBES concurrent with SSS. Survey Coverage was specified as Complete Coverage per the project instructions. Complete Coverage was attained employing MBES bathymetry concurrent with 100 percent side scan imagery per HSSD 5.2.2. Additionally, two UCF areas were assigned requiring object detection coverage (200 percent side scan imagery concurrent with 50cm, MBES bathymetry). Acquisition to the assigned survey sheet limits were not attained where floating logs, overhanging branches, shoaling, vessel traffic and vessels tied up alongside precluded the teams' safe approach to the edge of the river bank/sheet limits. This leg of the river is a busy barge hub with frequent traffic at the Chickasaw Swing Bridge. Not all assigned features were addressed for these reasons. Likewise, the two assigned, unverified charted feature (UCF) radii were not fully examined. However, the field believes neither of the two UCF features exist in the middle of the channel where 200 percent side scan data and nearly 100 percent object detection multibeam data was attained. Barges rafted up along the banks of Mobile River near Chickasaw Creek.[Courtesy of Cooper Barge Co] file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/CooperBarge.jpg Missed 100% SS coverage (white space) inside UCF Radii (blue circle). file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Missed_Coverage_UCF_Radii_100pct_SSS.jpg Missed 200% SS coverage (red space) inside UCF Radii (blue circle). file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Missed_Coverage_UCF_Radii_200pct_SSS_Red.jpg Areas were Complete Coverage Side Scan was not attained (red arrows). file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/missed%20sss%20coverage.jpg S-J906-NRTST-23 Coverage Graphic, Mobile River, vicinity of Mobile AL file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Coverage_Graphic_Overview.jpg S3005 0.0 0.0 0.0 0.0 0.0 57.37 0.0 6.99 0.0 S3008 0.0 0.0 0.0 0.0 0.0 44.03 0.0 3.44 0.0 0.0 0.0 0.0 0.0 0.0 101.4 0.0 10.43 0.0 10.2 0 0 0 0 5.58 Survey dates began on 9MAY2023 and concluded on 15MAY2023. Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections. Note that S3005 had not yet completed its 2023 HSRR when this project was conducted. Using S3005's DAPR and HVFs from 2022. 3008 10.0 0.5 3005 10.0 0.5 NRT Vessel file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/NRT4_Vessel.JPG NRT Vessels are 30 foot, aluminum hulled fire boats modified for NOAA hydrographic survey operations. S3005 and S3008 are powered by dual 225 horsepower Honda outboard engines. A Kohler 7.5 EKD generator supplies AC power for two workstations, 5 monitors, one POS system, one multibeam echosounder system, and one side scan sonar system. MBES Kongsberg Maritime EM 2040C SSS EdgeTech 4125 MBES used aboard S3008 and S3005 file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Kongsberg_EM2040C.png SSS used aboard S3008 and S3005 file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Edgetech_4125_2.jpg Castaway Sound Speed Sensor used aboard S3008 and S3005 file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/SonTek_CastAway.jpeg Please reference NRT-Stennis (S3005) and (S3008) DAPRs, accompanying this project for a complete listing of equipment and specifications. Note that S3005 had not received its annual HSRR during the time of this survey and its DAPR and HVFs from 2022 were used. A crossline percentage of 10.43 LNM met the minimum percentage requirements as specified in the HSSD, Section 5.2.4.2. Uncertainty standards between a 1m Mainscheme grid versus a 1m Crossline grid passed NOAA IHO TVU requirements. See graphic below. Crosslines versus Mainscheme Lines, 99 percent pass file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/H13795_MB_MS_1m_MLLW-H13795_MB_XL_1m_MLLW_fracAllowErr_Freq.png ERS via VDATUM 0.1 0.1 ERS via VDATUM 0.07 0.07 S3008 4 0 0 0.2 S3005 4 0 0 0.2 Per HSSD, Section 5.2.3.3 the above sound speed uncertainty values were implemented and lie within conservative range estimates. Per project instructions, an additional Vdatum model with uncertainty of 0.07m was used in the creation of the 1 meter surface referenced to NAVD88. This non-standard surface will facilitate flood inundation modeling for the river systems north of Mobile Bay. However, the project is being submitted with a MLLW Vdatum model with an uncertainty of 0.10m. All submitted grids passed NOAA's Uncertainty and Density Standards by over 95 percent. Please reference the SupportFiles folder for all histogram outputs. NOAA 1meter Grid Uncertainty 99.5 plus percent pass file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/H13795_MB_50cm_MLLW.GQv6.tvu_qc.png No Junctions were prescribed per Project Instructions. Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. Vessel Hull Design is Noisy the Hull Mounted MBES Bubble sweep artifacts did contribute to noisy MBES data on the outer beams of S3008 and S3005. Hull design modifications are being investigated by NRB/HSTB to mitigate the issue. Over 25 thousand fliers were rejected in the 1cm grid. Despite performing nine rounds of Flier Finder cleaning, 1600 fliers still remain. The Noisy Edges (6) fliers occur at abrupt depth changes such as on the edges of sand waves and cannot be eliminated without creating additional fliers. A memo to PHB Chief regarding the issue can be found in the Project Correspondence folder. Noisy Edges (6) continue to regenerate after careful editing edges of sand waves file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/noisy_edges.jpg Typical TPU breakdown, Noisy Edge Fliers (6) adjacent to Sand Waves file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/TPU_at_Edge_Fliers.jpg River Tubidity and Current Owing to heavy suspended sediment loads and fast moving water (>4 kts) bathymetry suffered near running tug boats and river bends. Migrating sand waves were noted near 12 Mile Island and fliers abounded in that area as well as the Chickasaw Creek region. Migrating sand waves example 1 file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/migrating_riverbed_DN130_versus_DN132_B.jpg Migrating sand waves example 2 file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/migrating_riverbed_DN130_versus_DN132_C.jpg Sound Speed Cast Frequency: Sound speed cast frequency for F00869 was not less than one cast per every four hours of survey. Cast frequency met or exceeded 1 cast per every 4 hours of survey. All equipment and survey methods were used as detailed in the vessel DAPRs. All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Backscatter data was processed using FMGT and Caris softwares - a departure from standard backscatter processing using only CARIS. The new SOP is included in the supplemental folder of the Descriptive Report. CARIS HIPS and SIPS 11.4.25 Applanix POSPac 8.9 CARIS HIPS and SIPS 11.4.25 NOAA Profile Version 2023. NOAA Profile Version 2023 was utilized by the Caris Object Catalogue, Caris HIPS and SIPS, version 11.4.25 H13795_MB_1m_MLLW CARIS Raster Surface (CUBE) 1 0.49 20.3 NOAA_1m Complete MBES H13795_MB_1m_MLLW_Final CARIS Raster Surface (CUBE) 1 0.49 20.3 NOAA_1m Complete MBES H13795_MB_1m_NAVD88 CARIS Raster Surface (CUBE) 1 0.49 20.3 NOAA_1m Complete MBES H13795_SSAB_1m_400kHz_1of2 SSS Mosaic 1 0.0 20.0 NOAA_1m 100% SSS H13795_SSAB_1m_400kHz_2of2 SSS Mosaic 1 0.0 20.0 NOAA_1m 200% SSS H13795_MB_50cm_MLLW CARIS Raster Surface (CUBE) 0.5 0.49 20.3 NOAA_0.5m Object Detection H13795_MB_50cm_MLLW_Final CARIS Raster Surface (CUBE) 0.5 0.49 20.3 NOAA_0.5m Object Detection H13795_MB_1m_NADV88_Final CARIS Raster Surface (CUBE) 1 0.49 20.3 NOAA_1m Complete MBES The project is a Complete Coverage survey consisting of 100 percent side coverage accompanied with skunk-stripped, 1m multibeam. However, a 200 percent side scan layer and a half-meter, object detection, multibeam surface is also being submitted for the south end of the sheet to address two UCF radii. Although the radii were not completely esonified due to vessels moored alongside, the field believes neither UCF exist in the main channel where half-meter MBES object detection MBES also occurred. Per project instructions, an additional Vdatum model with uncertainty of 0.07m was used in the creation of the 1 meter surface referenced to NAVD88. This non-standard surface will facilitate flood inundation modeling for the river systems north of Mobile Bay. However, the project is being submitted in the MLLW Vdatum with an uncertainty of 0.10m. Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR. Mean Lower Low Water ERS via VDATUM S-J906-NRTST-23_NAD83(2011)-NAVD88(GEOID18)_1sigma7cm S-J906-NRTST-23-TensawRiver_2023-06-26_NAD83-MLLW_PtCloud_1sigma10cm Per project instructions, an additional Vdatum model with uncertainty of 0.07m was used in the creation of the 1 meter surface referenced to NAVD88. This non-standard surface will facilitate flood inundation modeling for the river systems north of Mobile Bay. However, the project is being submitted with a MLLW Vdatum model with an uncertainty of 0.10m. Please reference the memo "Vdatum_Instructions_Jack_Riley" in the Project Correspondence folder of this project for ERTDM modeling discussions. North American Datum 1983 Projected UTM 16 RTX The horizontal datum for this project is North American Datum of 1983 (NAD 83). The projection used for this project is Universal Transverse Mercator (UTM) Zone 16N. Horizontal and vertical positioning were achieved in accordance with practices outlined in the DAPR. Processing and products for Survey H13795 were conducted and completed in NAD 83 per HSSD specification. Refer to the DAPR for a complete description of horizontal control procedures. RTX Precise Positioning-Real Time Extended (PP-RTX) processing methods were used in Applanix POSPac MMS software to produce Smoothed Best Estimate of Trajectory (SBET) files and their associated uncertainty for post-processing horizontal correction. Trimble CenterPoint RTX is the preferred method for the positioning for then Gulf of Mexico where horizontal accuracies of 2cm or less may be achieved without the use of reference stations. CenterPoint RTX service was accessed via an internet connection within one hour after field operations had concluded. Applanix POSPac MMS 8.8 software was used to access Trimble RTX servers to produce a Smoothed Best Estimate of Trajectory (SBET) file implementing the Applanix proprietary "SmartBase" algorithm. The SBET file consisted of GPS position and attitude data corrected and integrated with inertial measurements and correctors which were then exported to the reference ellipsoid. These SBET navigation and attitude files were applied to all lines in CARIS and supersede initial positioning and attitude data. The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition. A chart comparison was performed for all 5 ENCs spatially coinciding to the survey area. Note that the northern third of the survey area has no associated ENCs. Six (6) soundings were flagged as DTON candidates using the "CA Tools" utility in Pydro 22. The Hydrographers did not deem any of the deeper chart soundings to be actual DTONs based on their close proximity to the river's edge and/or vessel draft maximums of 9 feet. The field recommends updating, repositioning, or deleting those ENC soundings. A comprehensive soundings analysis can be found in the appendices folder. See images, below. Not all designated soundings are associated to features in the final feature file, as some were chosen to capture the shoalest point on the river bottom where migrating sand waves confounded the CUBE algorithm. US4AL11M Chart Comparison to H13795 Soundings file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Chart_Comparison_US4AL11M.png Sounding Comparison Index, All Soundings in Meters file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/ENC_Compare_Survey_Index.jpg Inset 1, US4AL11M sounding (Black) vs H13795 soundings (Blue) file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Inset_01.jpg Inset 2, US5MOBJF sounding (Black) vs H13795 soundings (Blue) file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Inset_02.jpg Inset 3, US5MOBJF sounding (Black) vs H13795 soundings (Blue) file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Inset_03.jpg Inset 4, US5MOBJF sounding (Black) vs H13795 soundings (Blue) file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Inset_04.jpg Inset 5, US5MOBJF sounding (Black) vs H13795 soundings (Blue) file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Inset_05.jpg Inset 6, US5MOBJE sounding (Black) vs H13795 soundings (Blue) file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Inset_06.jpg US5MOBIE 10000 1 2023-09-28 2023-05-31 US5MOBJF 10000 1 2023-09-28 2023-05-31 US5MOBJE 10000 1 2023-09-28 2023-05-31 US5MOBIF 10000 1 2023-09-28 2023-05-31 US4AL11M 80000 70 2023-09-28 2023-09-27 Six (6) soundings were flagged as DTON candidates using the "CA Tools" utility in Pydro 22. The Hydrographers did not deem any of the deeper chart soundings to be actual DTONs based on their close proximity to the river's edge and/or vessel draft maximums of 9 feet. The field recommends updating, repositioning, or deleting those deeper ENC soundings. A comprehensive soundings analysis can be found in the appendices folder. Not all designated soundings are associated to features in the final feature file, as some were chosen to capture the shoalest point on the river bottom where sand waves confounded the CUBE algorithm. Please reference the final feature file. Please reference the final feature file. No Channel survey depths were shallower than tabulated in the ENC. The Chickasaw Creek region of this survey is regularly dredged. Per the investigation requirements, these dredged areas are not included in the final feature file. Navigation aids exist and were assigned to H133795. All navigation aids were present, charted in the correct position and serving their intended purpose. Please reference the Final Feature File. No Maritime Boundary Points were assigned for this survey. No bottom samples were required for this survey. All charted/assigned overhead cables were visually confirmed by the field and no discrepancies existed. Per the investigation requirements, they are not included in the final feature file. Overhead Cables file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Overhead%20Cables.jpg A charted (US5MOBIF)/assigned submarine pipe was investigated. Its scour appears to be within 17m of the charted position. The feature appears to be covered in the riverbed. Submarine feature located within 20m of Charted (US5MOBIF) position file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/Pipeline_within_20m_of_Charted.jpg No platforms exist for this survey. No ferry routes or terminals exist for this survey. Owing to heavy suspended sediment loads and fast moving water (>4 kts) bathymetry suffered near running tug boats and river bends. Migrating sand waves were noted north of 12 Mile Island and fliers abounded in that area as well as the Chickasaw Creek region. Migrating Sand Waves file:///M:/SJ906NRTST23/Surveys/H13795/01_HDR/Working/DR/Field/SupportFiles/SupportFiles/migrating_riverbed_DN130_versus_DN132_C.jpg 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. Please note that this survey has 1611 fliers occurring at sand wave edges. A memo explaining the issue to PHB Chief can be found in the project correspondence folder. The DR also calls out these edge fliers, which continue to re-generate inward after careful deletion. Dan Jacobs Chief of Party 2023-10-18