OPR-K379-KR-19Corpus Christi, TX & ApproachesCorpus Christi, TX & ApproachesOcean SurveysH13227712 NM Due East Aransas PassTexasUnited States100002019John R. BeanNavigable Area2019-03-062019-05-142019-08-29Multibeam Echo SounderSide Scan SonarMultibeam Echo Sounder BackscattermetersUTCAtlantic Hydrographic BranchThe information presented in this report and the accompanying digital data represents the results of surveys performed by Ocean Surveys, Inc. during the period of May 14, 2019 to August 29, 2019 and can only be considered as indicating the conditions existing at that time. Reuse of this information by client or others beyond the specific scope of work for which it was acquired shall be at the sole risk of the user and without liability to OSI.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 UTM14N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.ContractorThis survey provides hydrographic data for the Gulf of Mexico waters approaching the Texas coast east of Port Aransas. The general locations of the survey limits are presented in Table 1.27.89323796.97597427.7773696.650176Survey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.The following text is copied verbatim from the Project Instructions' Purpose and Location Section: "This project is located in Corpus Christi Bay, including the Corpus Christi Shipping Channel and offshore approaches. The U.S. Army Corps of Engineers maintains the channel which is dredged through the bay to the jetties of Port Aransas. The Corpus Christi Port primarily supports deepdraft vessels for export of petroleum and energy related products. In addition, the port supports seafood, industrial and agricultural industries in the state of Texas. Metals, stone products, glass, chemicals, and gypsum products are produced near Corpus Christi Bay. Six oil refineries and 1,500 wells are located near the bay as well as a large supply of natural gas. The Channel also serves as a conduit for commercial ship traffic between Houston terminuses and the Gulf. This survey will identify hazards and changes in bathymetry, providing contemporary data to update National Ocean Service (NOS) nautical charting products."The entire survey is adequate to supersede previous data.All waters in survey area.Complete Coverage (refer to HSSD Section 5.2.2.3)Per the Project Instructions, towfish height requirements from HSSD Section 6.1.2.3 were modified for this task order to allow a towfish altitude of 6-20% of range scale.Survey H13227 MBES coverage overlaid on a composite of RNCs.Support Files\H13227_Survey-Coverage.jpgR/V Ocean Explorer0225.02000788.93044.130R/V H.F. Stout00.9100000000225.93000788.93044.1304.35000062.862019-05-142019-05-152019-05-162019-05-172019-05-192019-05-202019-05-302019-05-312019-06-012019-06-022019-06-032019-06-042019-06-072019-07-132019-07-142019-08-202019-08-212019-08-222019-08-252019-08-29The LNM for MBES-only development and fill-in lines were included under the heading "MBES Mainscheme" in Table 3. There was no SSS-only mileage for this survey.Refer to the project DAPR for a complete description of data acquisition and processing systems, survey vessels, quality control procedures, and data processing methods.R/V Ocean Explorer182R/V H.F. Stout90.76The R/V Ocean Explorer was used to collect the majority of the survey data in H13227. The smaller R/V H.F. Stout only surveyed in H13227 on one day, collecting 4 lines of investigation and fill-in data. Teledyne RESONSeaBat 7125 SV2MBESEdgeTech4200SSSEdgeTech4125SSSApplanixPOS MV 320 v5Positioning and Attitude SystemAML OceanographicMicro SVP&TSound Speed SystemAML OceanographicMicroX SVSound Speed SystemODIM Brooke OceanMVP30Sound Speed SystemTrimbleNetR9Positioning SystemAll equipment was installed, calibrated, and operated in accordance with the DAPR. If the investigation and fill-in lines are not included in the mainscheme mileage, then the crosslines acquired for this survey totaled 4.61% of mainscheme acquisition. Crosslines were acquired on May 14 and Aug 21, 2019 (DNs 134 and 233) and run approximately northwest-southeast, with mainscheme lines run perpendicular to the crosslines (Figure 2). Agreement between crossline and mainscheme data was very good, with no geographic pattern to the magnitude of discrepancy. A difference surface was generated in CARIS HIPS to compare a surface of only crosslines to a surface of only mainscheme data, and the average difference was found to be less than 0.01m. Figure 3 is a histogram showing the distribution of depth differences for all comparison grid cells considered. An overview of the crossline layout on a 1m surface created from mainscheme MBES data and colored by depth. A composite of RNCs is in the background.Support Files\H13227_XL_overview.jpgThe graph shows a frequency distribution of the depth differences between the H13227 crossline vs mainscheme MBES data. Statistics from the depth difference sample set are displayed above the graph.Support Files\H13227-XL-main-histogram.jpgERS via VDATUM00.098R/V Ocean Explorer12R/V H.F. Stout12The methods used to minimize the uncertainty in the corrections to echo soundings are described in detail in the project DAPR. The Total Vertical Uncertainty Quality Check (TVU QC) "Ratio Method" was used to evaluate IHO uncertainty for the finalized surfaces of Survey H13227. The finalized surfaces were generated using the CARIS "Finalize Base Surface" utility, with the uncertainty source selected as the greater of the two values between the predicted uncertainty and the standard deviation (scaled to 95% CI). The FPM states that "[ratio] values which do not require further examination are from -1 to 0 and the values which do require further examination are from -100 to -1." Results from the TVU QC indicate that 100% of the nodes in both surfaces "H13227_MB_1m_MLLW_Final.csar" and "H13227_MB_2m_MLLW_Final.csar" meet IHO Order 1 uncertainty specifications.One current survey and two prior surveys junction with Survey H13227. Figure 4 displays the location of the junction surveys for Project OPR-K379-KR-19, and the junctions specific to this survey are listed in Table 9. Junction analyses were conducted by generating a difference surface in CARIS HIPS for the pair of surveys to compare the MBES surfaces where they overlap. A histogram of the depth differences was plotted to show the relative agreement of the surveyed depths, and to indicate shoaling or deepening trends by positive or negative differences. The magnitude of differences were compared to the maximum allowable TVU for the water depths in Survey H13226. The HSSD defines junction discrepancies requiring further examination as those greater than the TVU * sqrt(2), which for the water depths in Survey H13227 was 0.74m to 0.92m.Survey junctions for Project OPR-K379-KR-19.Support Files\H13227_Junction_Overview.jpgH11245400002004OceaneeringEPrior Survey H11245 almost completely surrounds Survey H13227, sharing its western, northern, eastern, and more than half of its southern boundaries. The length of shared borders between the two surveys is approximately 72.5km and the width of the overlapping border varies from approximately 100m to over 1km, but 400m to 600m is common. Bathymetry data for Survey H11245 was not available through the NOAA National Centers for Environmental Information (NCEI) website, but it was provided to OSI by the AHB COR with the project files (see Appendix II for correspondence). The data consisted of a smooth sheet with a scale of 40000, which is sparse relative to the MBES data of Survey H13227 and so yielded a small sample of comparison cells. Data from Survey H13227 was slightly deeper than data from H11245. This was consistent with a deepening trend between Survey H13227 and charted soundings that was observed across the majority of the survey area. There was no observable geographic trend in the depth variation between the two surveys. The maximum difference between the two surveys was 0.72m, therefore 100% of the comparison cells were beneath the TVU-based discrepancy threshold for water depths of Survey H13227. A histogram of the depth differences is shown in Figure 5.Surface-to-surface difference histogram comparing Survey H11245 to H13227.Support Files\H13227-difference-H11245-histogram.jpgH11246400002005OceaneeringEPrior Survey H11246, conducted in 2005 by Oceaneering, overlaps the western portion of Survey H13227's southern boundary. The junction area is approximately 14.7km in length and generally 200m to 400m in width, though a few lines reach up to 700m into the junction survey. Data from Survey H13227 was approximately 0.15m deeper than data from H11246, consistent with the deepening trend between Survey H13227 and charted soundings. Most of the depths matched well, with 99.77% of the data showing depth differences of less than the TVU-based discrepancy threshold. However, approximately 0.2% of the data points measured Survey H11246 as greater than 1m shoaler than Survey H13227, with a maximum difference of 17.4m. These data points were presumed to be fliers in the H11246 data, as they appear scattered without charted features or obstructions nearby. There was no significant geographic pattern observed in the depth differences between the surveys. A histogram of depth differences is shown in Figure 6. Surface-to-surface difference histogram comparing Survey H11246 to H13227.Support Files\H13227-difference-H11246-histogram.jpgH1322250002019Ocean Surveys, Inc.WThe assigned survey limits of contemporary Survey H13222 did not junction with Survey H13227, but the coverage areas extended beyond the assigned limits enough to create a small junction area of approximately 0.11 sq km. Survey H13222 has complete MBES data in this region, therefore the junction area is relatively dense with data. The junctioning data in Survey H13227 was collected on 5/17/2019 and in Survey H13222 on 7/11/2019 (DNs 137 and 192), nearly two months apart. The depth differences between the two surveys were small, with an average difference of just 0.01m. The area of greatest difference is over what appears to be a fresh drag mark in Survey H13222 that was not present during collection of Survey H13227 data. A histogram of the depth differences is shown in Figure 7.Surface-to-surface difference histogram comparing Survey H13222 to H13227.Support Files\H13227-difference-H13222-histogram.jpgSonar system quality control checks were conducted as detailed in the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.SSS RefractionDynamic sound speed changes affected the SSS imagery at times, causing refraction in the outer ranges of the SSS swath (Figure 8). To ensure coverage with high quality SSS data, lines with excessive refraction were rejected. If clear SSS imagery from adjacent lines was insufficient to cover the area of refraction, portions of the line were re-run.SSS imagery showing refraction in both port and starboard channels.Support Files\H13227-FAS-SSS-Refraction.jpgFish in SSS Imagery and MBES DataAn abundance of fish and marine sea life were seen in the SSS and MBES data, either as lone swimmers or in schools (Figures 9 and 10). In cases where large shadows in the SSS imagery or gaps in the MBES data were created by schools of fish or dolphins, additional coverage was obtained to ensure no significant features were located in these fish and dolphin shadows. SSS image showing a school of fish in the starboard channel and the acoustic shadow it casts in the data.Support Files\H13227-FAS-Fish.jpgAn example of dolphins appearing in the water column of the MBES and the SSS, and the acoustic shadows cast in each dataset. Rejected soundings are colored yellow.Support Files\H13227-FAS-Dolphins.jpgMBES "Blowouts"The Reson 7125 systems experienced occasional bursts of motion-induced noise or “blowouts,” typically affecting between one and four sequential profiles. The noise bursts were infrequent and were encountered when sea state worsened. Accepted data affected by blowouts did not show any coverage holidays in the final MBES surface. This figure shows how cavitation noise at the MBES transducer head is presented in the converted data. Rejected soundings are colored yellow.\Support Files\H13227-FAS-MB-Blowout.jpgOn board the R/V Ocean Explorer, sound speed profile data were acquired with the AML MVP30 approximately every 15 minutes. On board the R/V H.F. Stout sound speed profiles were acquired with the AML Base X at intervals of approximately 1-2 hours.All MBES lines were sound speed corrected using CARIS HIPS' "Nearest in Distance Within Time" method. The time interval used was 2 hours for the R/V H.F. Stout and 1 hour for the R/V Ocean Explorer. OSI submitted H13227 sound speed data in NetCDF format to the National Centers for Environmental Information (NCEI) on Jan 6, 2020 via the S2N tool. NCEI assigned Accession Number 0208349 to the R/V Ocean Explorer data and Accession Number 0208350 to the R/V H.F. Stout data. Correspondence regarding the NCEI data submission is included in Appendix II.Survey H13227 was conducted to achieve Complete Coverage, using 100% SSS coverage with concurrent MBES for the majority of the area (Option B; HSSD Section 5.2.2.3), and Complete Coverage Multibeam for the eastern end of the survey where the water was deepest (Option A; HSSD Section 5.2.2.3). All potentially significant features located by mainscheme SSS or MBES were also developed with MBES data to meet the Complete Coverage Multibeam requirements. For single-resolution surfaces, HSSD Section 5.2.2.3 specifies a grid resolution of 1m for depths less than 20m and a grid resolution of 2m for depths between 18 and 40m. Water depths in Survey H13227 ranged from 12.57m to 32.23m, therefore two separate single-resolution grids were submitted to meet the resolution requirements: a 1m grid for depth shoaler than 20m and a 2m grid for depths greater than 18m. The survey area covering depths between 18m and 20m is represented in both grids. The CARIS HIPS and SIPS "Compute Statistics" tool was used to verify that the grid nodes met the density coverage requirements, defined in the HSSD as having at least 95% of the nodes populated with at least 5 soundings. Both surfaces meet this requirement, with 99.44% of nodes in the 1m resolution surface and 99.68% of nodes in the 2m resolution surface having 5 or more soundings. The survey methods used to meet coverage requirements did not deviate from those described in the DAPR. All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.All equipment and survey methods were used as detailed in the DAPR.NOAA Profile Version 2019H13227_MB_1m_MLLW_Final.csarCARIS Raster Surface (CUBE)112.57620NOAA_1mComplete MBESH13227_MB_1m_MLLW.csarCARIS Raster Surface (CUBE)1NOAA_1mComplete MBESH13227_MB_2m_MLLW_Final.csarCARIS Raster Surface (CUBE)21832.352NOAA_2mComplete MBESH13227_MB_2m_MLLW.csarCARIS Raster Surface (CUBE)2NOAA_2mComplete MBESH13227_SSSAB_1m_600kHz_1of1.tifSSS Mosaic1N/A100% SSSIn addition to the surfaces in Table 10, a set of 0.25m SSS mosaic images were submitted in Enhanced Compressed Wavelet (ECW) format to assist with the survey review.AHB: After removal of deep fliers identified in the field submitted data, the maximum depth of the H13227_MB_2m_MLLW_Final.csar is 31.370 m.Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterERS via VDATUMbuff_xyNAD83-MLLW_geoid12b.csarNorth American Datum 1983Projected UTM 14Smart BaseCorpus Christi R2TXCCPort LavacaTXPVBeevilleTXBEKingsvilleTX2006KVTXLaguna VistaTXLNClute CoopDWI1AliceTXAIVictoriaTXVARaymondvilleTXRVOSI Port AransasOSPAThe primary CORS stations used for Project OPR-379-KR-19 are listed in Table 12. Additional stations used on 8 or fewer survey days include TXFE, DEV1, TXBC, TXED, LCSM, TXKC, ANG5, COH2, TXAG, and TXBV. See the HVCR for details.Chart comparisons were conducted visually using a difference surface generated by subtracting ENC soundings from a finalized CUBE depth surface of survey MBES data. The difference surface in Figure 12 represents regions of deepening with negative depth differences (cool colors), and grey indicates areas of no significant change. Shoaling would be indicated by positive depth difference (warm colors), however, no shoaling was observed in Survey H13227. The CUBE depth surface of survey data used for this difference surface had a resolution of 10m. ENC soundings were taken from the latest editions of the charts available on the NOAA OCS website. There are 3 ENCs assigned in the Project Instructions that cover portions of Survey H13227, and their soundings were combined into a single sounding set using data from only the largest-scale chart that provided coverage at any given point. The ENCs used for final comparisons were submitted with the survey deliverables. Local NTMs and NTMs from March 6, 2019 to August 30, 2019 were reviewed in conjunction with the chart comparison, but no notices were made during this time that concerned Survey H13226. The last NTM reviewed was No. 35, dated August 31, 2019, and the last Local NTM reviewed was notice 35/19, dated August 28, 2019. A depth difference surface overlaid on a composite of RNCs provides an overview of the areas of change between charted depths and H13227 surveyed soundings.Support Files\H13227_Difference_Map.jpgA depth surface with contours shows the 60-foot and 90-foot contours at their charted and surveyed positions.Support Files\H13227_Chart-Comparison.jpgUS3GC01M350000292019-08-082019-08-19US4TX21M80000202018-11-062019-08-19US4TX28M80000192019-06-102019-07-10No shoals or potentially hazardous features exist for this survey. No DTONS were submitted.There were 5 charted features within Survey H13227 assigned in the CSF: 1 wreck, 1 mooring buoy, 2 platforms, and 1 pipeline. An obstruction was surveyed approximately 80m from the charted wreck, and was the only feature in the vicinity. It does not have obvious characteristics of a wreck, though it may be the remnants of it. The feature was included in the FFF as an obstruction, and is recommended to be charted as either a wreck or an obstruction. The charted mooring buoy labeled "PA" was not visible on the surface, nor was there any evidence of its presence in the sonar data. No uncharted features exist for this survey.Almost the entire survey area was either an anchorage area, fairway, or both. There were 2 anchorage areas and 3 fairways in Survey H13227. The fairways cover more than half of the survey area in the east, and the anchorage areas cover the remainder to the west with some overlap with the fairways along the southern edge in the center. Surveyed depths in these areas were found to be slightly deeper than charted, as discussed in the chart comparison above. No ATONs exist for this survey.No Maritime Boundary Points were assigned for this survey.No bottom samples were required for this survey.No overhead features exist for this survey.There was 1 submarine pipeline charted within Survey H13227. The pipeline was not observed to be exposed or elevated. In addition to the ENC and the CSF, pipeline data from the Bureau of Ocean Energy Management (BOEM) were reviewed prior to field operations and during data processing to identify any potential uncharted BOEM pipelines in the survey area. There was 1 BOEM pipelines within Survey H13227, which matched the pipeline represented in the ENC and the CSF. The BOEM pipeline data (last updated on Oct 1, 2019) were obtained as a shape file "ppl_arcs.shp" from the BOEM website (https://www.data.boem.gov/Main/Mapping.aspx) and re-projected as a .DXF file “BOEM_Pipelines_UTM_14N_NAD83_Meters.dxf.” These files are included with the digital deliverables for Survey H13227.There were 2 platforms charted within Survey H13227, 1 of which was found to be present and the other was disproved. In addition to the ENC and the CSF, BOEM platform data were reviewed prior to field operations and during data processing to identify any potential uncharted BOEM platforms in the survey area. There were 2 BOEM platforms within Survey H13227, both of which were near the position of the existing charted platform. The BOEM platform data (last updated on Oct 1, 2019) were obtained as a shape file "platform.shp" from the BOEM website (https://www.data.boem.gov/Main/Mapping.aspx) and re-projected as a .DXF file “BOEM_Platforms_UTM_14N_NAD83_Meters.dxf.” These files are included with the digital deliverables for Survey H13227.No ferry routes or terminals exist for this survey.No abnormal seafloor and/or environmental conditions exist for this survey.No present or planned construction or dredging exist within the survey limits.No new surveys or further investigations are recommended for this area.No new insets are recommended for this area.As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports.All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch.The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys Specifications and Deliverables (2018), Field Procedures Manual (2014), Project 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.John R. BeanChief of Party2020-01-23David T. SomersData Processing Manager2020-01-23