S-K936-NRT2-20Neches Rivers and ICWWVicinity of Port Arthur, TXNOAA Navigation Response Team 2F008161Sabine and Neches RiversLouisianaTexasUnited States200002020James L. KirkpatrickNatural Disaster Response2020-09-142020-09-012020-09-02Multibeam Echo SounderSide Scan SonarmetersUTCPacific 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 15N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.NOAAPost Hurricane Laura requests came from United States Army Corps of Engineers (USACOE) through regional Navigation Managers. Two separate areas in the vicinity of Port Arthur, Texas were requested and included in survey F00816. 1. A request to investigate an area of debris in the channel in the Neches River in Beaumont at the reported position 30°04'28.93"/094°03'33.53". 2. NRT2 was also assigned to survey the ICWW from Pavell Island to Mile Marker 260. Survey data from this project is intended to supersede all prior survey data in the common area.30.079395555694.067677388930.0576947593.6257685556All assigned survey limits were ensonified to object detection standards.Survey F00816 is in response to a USACE request for emergency hydrographic surveys due to the effects of Hurricane Laura.The entire survey is adequate to supersede previous data.Data quality control was performed on all accompanying data and was found to meet guidelines in 2020 Hydrographic Surveys Specifications and Deliverables. All waters in survey area.Object Detection Coverage (Refer to HSSD Section 5.2.2.2)Survey coverage was in accordance with the requirements listed above and in the HSSD.Neches River Coverage.SupportFiles\Neches_Coverage.PNGICWW Pavell Island to MM260 Coverage.SupportFiles\ICWW_Coverage.PNGS30090000016.74007.3600000016.74007.3604400000.52020-09-012020-09-02Refer 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.S300910.380.6S3009SupportFiles\S3009.jpgAll survey data for F00816 was collected by Navigation Response Team 2 and S3009.AML OceanographicMicroX SVSound Speed SystemApplanixPOS MV 320 v5Positioning and Attitude SystemEdgeTech4125SSSKongsberg MaritimeEM 2040CMBESYSICastAway-CTDConductivity, Temperature, and Depth SensorAll major systems are discussed in detail in the accompanying Data Acquisition and Processing Report.Crosslines were collected, processed and compared in accordance with Section 5.2.4.32 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, and is submitted in the Separates II Digital Data folder. Statistics show the mean difference between the depths derived from mainscheme data and crossline data was 0.032 meters with a standard deviation of 0.046 meters.F00816 Crossline Statistics.SupportFiles\XL_Stats.PNGERS via VDATUM0.012.9S30092.0N/AN/A0.5In addition to the usual a priori estimates of uncertainty provided via device models for vessel motion, VDatum, Poor Mans VDatum (PMVD), and real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey F00816. Following post-processing of the real-time vessel motion, recomputed uncertainties of vessel GPS height and navigation were applied in CARIS HIPS and SIPS via a Smoothed Best Estimate of Trajectory (SBET) RMS file generated in Applanix POSPac.Poor Man's VDatum (PMVD) was not utilized for this survey. No junction surveys assigned for F00816.Sonar 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.At least every 4 hours.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.200% SSS with concurrent MBES was used over the entire survey area. In deeper areas 100% MBES was achieved.Data DensityThe MBES surface was analyzed using the HydrOffice QC Tools Grid QA feature and the results are shown below. Density requirements for F00816 were achieved with at least 99.5% of surface nodes containing five or more soundings as required by HSSD Section 5.2.2.3. The few nodes that did not meet density requirements are due to sparse data in the outer beams, especially near steep slopes where acoustic shadowing occurred, and at the edges of the survey limits.F00816 Data Density.SupportFiles\F00816_MB_50cm_MLLW_Final.QAv6.density.pngAll data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.Backscatter was not acquired for this survey.Backscatter was acquired by the field unit. Processing of backscatter data was performed by branch personnel. Caris_Support_Files_2020v3F00816_MB_50cm_MLLW_FinalCARIS Raster Surface (CUBE)0.56.81452.279NOAA_0.5mMBES TracklineF00816_SSSAB_1m_400kHz_1of2SSS Mosaic100N/A100% SSSF00816_SSSAB_1m_400kHz_2of2SSS Mosaic100N/A200% SSSThe NOAA CUBE parameters defined in the HSSD were used for the creation of all CUBE surfaces for F00816. 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 be shoaler or deeper than the reliably measured seabed by greater than the maximum allowable Total Vertical Uncertainty at that depth, the noisy data have been rejected by the hydrographer and the surface recomputed. Flier Finder, part of the QC Tools package within HydrOffice, was used to assist the search for spurious soundings following gross cleaning. Flier Finder was run iteratively until all remaining flagged fliers (82) were deemed to be valid aspects of the steep slopes and dynamic nature of the seafloor.Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying DAPR.Mean Lower Low WaterERS via VDATUMS-K936_VDatumLimits_100m_NAD83-MLLW_geoid12b.csarNorth American Datum 1983Projected UTM 15RTXThe Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition.A comparison was performed between survey F00816 and raster charts 11331 and 11343 as well as ENC US5TX73M and US5TX61M using CARIS HIPS and SIPS sounding and contour layers derived from the F00816_MB_50cm_MLLW_Final surface. The contours and soundings were overlaid on the charts to assess differences between the surveyed soundings and charted depths. All data from F00816 should supersede charted data. In general, survey soundings agree with the majority of charted depths.US5TX61M40000252020-05-212020-08-25US5TX73M40000402020-04-162020-11-12No shoals or potentially hazardous features exist for this survey.Charted features exist for this survey, but were not investigated.No uncharted features exist for this survey.All channels investigated were without shoaling as compared to the tabulated and controlling depths of the largest scale ENC's.ATON's were examined visually during transit to the survey areas. No missing or damaged aids were discovered.No Maritime Boundary Points were assigned for this survey.No bottom samples were required for this survey.Overhead features exist for this survey, but were not investigated. Transmission power lines near mile marker 260 of the ICWW were down in the channel at the time of the survey. Recommend verifying new clearance heights.Submarine features exist for this survey, but were not investigated.No platforms exist for this survey.No ferry routes or terminals exist for this survey.No abnormal seafloor 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 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.James L. KirkpatrickChief of Party2020-12-16