OPR-E349-BH2-12Central Chesapeake BayChesapeake BayNOAA R/V BAY HYDRO IIH123051No special registry instructionsNortheast of Point No PointMarylandUnited States100002013LTJG Bart O. Buesseler, NOAANavigable Area2013-04-292013-04-112013-12-10Multibeam Echo SounderSinglebeam Echo Sounder Side Scan SonarmetersUniversal Transverse Mercator (UTM)UTCPacific Hydrographic BranchThe purpose of this survey is to provide contemporary surveys to update National Ocean Service (NOS) nautical charts. All separates are filed with the hydrographic data. Notes in red were generated during office processing. The processing branch concurs with all information and recommendations in the DR unless otherwise noted. Page numbering may be interrupted or non-sequential. All pertinent records for this survey, including the Descriptive Report, are archived at the National Geophysical Data Center (NGDC) and can be retrieved via http://www.ngdc.noaa.gov/.NOAAThe survey area is located in Central Chesapeake Bay within the sub-locality of Northeast of Point No Point. An overview of the geographic location of survey H12305 is shown in Figure 1. 38.190616666776.273938.12457576.2185666667H12305 survey limits.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_Survey_Limits_Labeled.pngMechanical failures occurred during the peak of the field season, limiting operational capabilities and acquisition of H12305. Due to this delay the survey area was truncated to 9.5 SNM from the originally assigned 19 SNM.The purpose of this survey is to supersede all bathymetry, seafloor features, and bottom characteristics within the assigned survey area as defined by the Project Instructions for updating NOAA Charts 12233 and 12261. This project covers approximately 9.5 SNM of critical survey area as designated in NOAA Hydrographic Survey Priorities.The entire survey is adequate to supersede previous data.Data acquired on survey H12305 met multibeam echo sounder (MBES) coverage requirements, including the five soundings per node data density requirements outlined in Section 5.2.2.2 of the HSSD. In order to extract descriptive statistics of the data density achievements, the density layer of each finalized surface was queried within CARIS and examined in Excel (Figure 3). Overall, the required data density was achieved in 99.3% of the nodes. A vast majority of the nodes that did not meet the density requirement were due to sparse data in the outer beams of the set line spacing MBES/SSS lines as seen in Figure 2.H12305 data density.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_Density_Overview.pngSummary table showing the percentage of nodes satisfying the 5 sounding density requirements, sub-divided by the appropriate depth ranges.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_Density_Stats.pngIn the deeper section of H12305 where water depths made it operationally advantageous to operate exclusively with MBES, coverage was incorrectly acquired as complete coverage MBES rather than object detection MBES as required by the Project Instructions. This area is shown in Figure 7, and has been digitized in the Final Feature File as a M_QUAL area feature with a CATZOC of "A1". Prior survey data from this area was SBES data acquired from 1940 to 1969 (Figure 8). As the Chesapeake Bay's sandy seafloor is known to shift over time, the hydrographer feels the complete coverage data acquired for H12305 is sufficient to supersede charted data. Area acquired with complete coverage MBES, shown in pink. Blue area indicates object detection coverage.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_CompleteCoverageArea.pngSource diagram for Chart 12233.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_Chart12233_SourceDiagram.pngFor depths 18-40 meters (the deeper depths of this survey) a 1m surface is required for object detection. A 1m surface was created during office processing and finalized at 18 - 40 meters. Object detection coverage was nearly achieved with 94.5% of the nodes meeting the density required 5 soundings/node. During office review this 1m surface was deemed adequate for use in the chart update product.General location of H12305 overlaid onto Charts 12231, 12233, 12261, and 12264.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_Survey_Area_Overview.pngH12305 100% Side Scan Mosaic overlaid onto Chart 12233, 1-meter resolution.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_SSS_Mosaic_100_1m.pngH12305 200% Side Scan Mosaic overlaid onto Chart 12233, 1-meter resolution.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_SSS_Mosaic_200_1m.pngS5401066.29000225.37029.140066.29000225.37029.14010.0610009.542013-04-112013-05-162013-06-202013-06-242013-06-252013-07-312013-08-052013-08-262013-08-272013-09-052013-10-212013-10-222013-11-062013-12-022013-12-042013-12-09Refer 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.S540117.31.8BAY HYDRO II collected all multibeam, side scan sonar, single beam, sound speed, and attitude data for Survey H12305.ODOMEchotrac CV-200SBESKongsbergEM2040MBESRESONSeaBat 7125MBESEdgeTech4200SSSApplanixPOS M/V V4Positioning and Attitude SystemSea-BirdSBE 19+Conductivity, Temperature, and Depth SensorODOMDigi-Bar ProSound Speed SystemValeportMiniSVSSound Speed SystemVessel configurations, equipment operations and data acquisition and processing were consistent with specifications described in the DAPR.Crosslines were collected, processed, and compared in accordance with Section 5.2.4.3 of the HSSD. BAY HYDRO II collected a total of 29.14 LNM of crosslines between the ODOM CV-200 SBES (6 lines, 14.93 LNM), Reson 7125 MBES (2 lines, 1.64 LNM), and the Kongsberg EM2040 MBES (5 lines, 12.56 LNM) as seen in Figure 9. Calculating the crossline distance by coverage type, BAY HYDRO II achieved 9.2% crossline coverage for set line spacing MBES, and 12.8% crossline coverage for complete coverage MBES.This exceeded the requirements of 8% for set line spacing MBES and 4% for complete coverage MBES. To evaluate the crosslines a 2-meter CUBE surface was created using strictly mainscheme lines, and a second 2-meter CUBE surface was created using only crosslines. From these two surfaces a difference surface was generated at a 2-meter resolution. Statistics were then derived from the difference surface and shown in Figure 10. The average difference between the depths derived from mainscheme and crosslines was 0.03 meters (crosslines being shoaler) with a standard deviation of 0.11 meters. In addition to performing a crossline comparison using surface differencing, the CARIS Quality Control (QC) Report was used to compare the MBES crossline soundings to the depth estimates of the 2-meter CUBE surface. The depth differences are calculated between each MBES crossline ping and mainscheme surface; and that depth difference is then compared to allowable IHO uncertainties. The output QC Report classifies the percentage of pings meeting IHO orders by beam angle. This table was copied and examined in Excel (Figure 11). Over 95% of the crosslines analyzed were within IHO Order 1a for the entire swath width. For further discussion of IHO standards, refer to Section B.2.2, Uncertainty.H12305 crosslines, SBES lines highlighted in blue as they are difficult to see in the surface. file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_XL_Overview.pngCrossline comparison with mainscheme lines.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_XL_Stats.pngCARIS QC Report comparing the crossline soundings to depth estimates.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_IHOness_byBeam.pngS54014.0 N/A0.5 In addition to the a priori estimates of sound speed uncertainty, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H12305. Real-time uncertainties from the EM2040 were recorded and applied in CARIS. The Tidal Constituent and Residual Interpolation (TCARI) grid used to apply tidal correctors also calculates real time uncertainty measurements associated with water level interpolation. These real time uncertainty values are then applied in CARIS. Applanix TrueHeave files were recorded which includes an estimate of the heave uncertainty, these were applied in CARIS. Finally, the post-processed uncertainties associated with vessel roll, pitch, gyro and navigation were applied where available in CARIS via an SBET and RMS file generated in POSPac. Uncertainty values of submitted finalized grids were calculated in CARIS using the "Greater of the Two" of uncertainty and standard deviation (scaled to 95%). To visualize the locations in which accuracy requirements were met for each finalized surface, a custom predicted IHO-compliance layer was created, based on the difference between calculated uncertainty of the nodes and the allowable IHO uncertainty (Figure 12). To quantify the extent to which accuracy requirements were met, the preceding predicted IHO compliance layers were queried within CARIS and examined in Excel (Figure 13). Overall 100.0% by node of survey H12305 met the accuracy requirements stated in Section 5.1.3 of the HSSD.H12305 met IHO accuracy standards for 100.0% of the survey area.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_IHOness_Overview.pngSummary table showing the percentage of nodes satisfying the indicated IHO accuracy level, sub-divided by the appropriate depth ranges.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_IHOness_Stats.pngFour surveys junction with H12305 as seen in Figure 14. Junctions were analyzed by creating a difference surface of the 4-meter resolution combined surfaces of each survey. These difference surfaces were evaluated using the CARIS Compute Statistics tool.Overview of surveys that junction with H12305.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_junctions_overview.PNGH12239100002010David Evans & Associates, Inc.SH12239 junctions with approximately 9,600 meters along the southwestern edge of H12305 (Figure 15). The junction averages 150 meters of north/south overlap. The difference surface between the 4-meter resolution H12305 grid and 4-meter resolution H12239 grid shows strong agreement between the two surveys. The difference range is -0.64 and 0.31 meters with a mean difference of -0.09 meters and a standard deviation of 0.10 meters (Figure 16). Difference surface between H12305 (orange) and junction survey H12239 (teal).file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12239_overview.PNGDifference surface statistics between H12305 and H12239 CUBE depth layers (4-meter grid size). H12305 is an average of 0.09 meters shoaler.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12239_4m_stats.PNGH12240100002010David Evans & Associates, Inc.SWH12240 junctions with approximately 950 meters along the southwestern edge of H12305 (Figure 17). The junction averages 150 meters of north/south overlap. The difference surface between the 4-meter resolution H12305 grid and 4-meter resolution H12240 grid shows strong agreement between the two surveys. The difference range is -0.39 and 0.21 meters with a mean difference of -0.05 meters and a standard deviation of 0.07 meters (Figure 18). Difference surface between H12305 (orange) and junction survey H12240 (pink).file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12240_4m_overview.PNGDifference surface statistics between H12305 and H12240 CUBE depth layers (4-meter grid size). H12305 is an average of 0.05 meters shoaler.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12240_4m_stats.pngH12304100002011NOAA R/V BAY HYDRO IINH12304 junctions with approximately 4,400 meters along the northwestern edge of H12305 (Figure 19). The junction averages 100 - 150 meters of north/south overlap. The exception is the area of complete MBES coverage that covers 800 meters of the total 4,400 junction, and overlaps by approximately 200 meters between the two surveys. The difference surface between the 4-meter resolution H12305 grid and 4-meter resolution H12240 grid shows good agreement between the two surveys. The difference range is -0.65 and 1.28 meters with a mean difference of 0.09 meters and a standard deviation of 0.16 meters (Figure 20). Difference surface between H12305 (orange) and junction survey H12304 (violet).file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12304_4m_overview.PNGDifference surface statistics between H12305 and H12304 CUBE depth layers (4-meter grid size). H12305 is an average of 0.09 meters deeper.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12304_4m_stats.pngH12367100002012NOAA R/V BAY HYDRO IINEH12367 junctions with approximately 250 meters along the northeastern edge of H12305 (Figure 21). The junction averages 125 meters of north/south overlap. The difference surface between the 4-meter resolution H12305 grid and 4-meter resolution H12367 grid shows good agreement between the two surveys. The difference range is -0.24 and 0.30 meters with a mean difference of -0.10 meters and a standard deviation of 0.10 meters (Figure 22). Difference surface between H12305 (orange) and junction survey H12367 (light orange).file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12367_4m_overview.PNGDifference surface statistics between H12305 and H12367 CUBE depth layers (4-meter grid size). H12305 is an average of 0.10 meters shoaler.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-H12367_4m_stats.PNGSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.Hypack .hsx File Freeze on DN176On DN176 the file 1017.hsx froze while logging MBES data with the Reson 7125 in Hypack. Hypack itself did not freeze and most of the functions in it continued normally, but it was noticed that the 1017.hsx file was not growing in size. Hypack was restarted and surveying continued the rest of the day without any other issues arising. When file 1017.hsx was converted in CARIS HIPS and SIPS, it was found that the HDCS line did not end correctly. The navigation for the HDCS line continued to the equator instead of ending in the location in the survey area. The 1017.hsx file was opened as a text file to see if an issue could be found. At the very end of the text file, instead of ending with a 'stop' command, the file abruptly cut in the middle of logging data points. After referring to other .hsx files, a 'stop' command line was manually entered into 1017.hsx and then the file was converted in CARIS HIPS and SIPS without any issues. The data has been reviewed alongside the other MBES lines and no issues have been discovered, thus the hydrographer suggests that the data from HDCS line 1017.hsx should supersede all previous hydrographic data. Noise from biological sourcesOn DN239, a large amount of biological noise in the form of schools of small fish were present and represented itself in the processed MBES data. To the greatest extent possible, this biological noise was cleaned from the MBES lines. Some of the biological noise was very close to the seafloor, making it difficult to determine the location of the true seafloor. The hydrographer cleaned these areas to the best of their ability to best represent the true seafloor. This noise was also present in the 200% SSS imagery for DN239, however it did not significantly impact the data quality. This was verified by examining overlapping 100% SSS imagery from DN176. The hydrographer feels that the object detection criteria were therefore still met, thus this cleaned MBES data and SSS imagery is adequate to supersede previous data.Sound Speed Refraction ErrorErrors resulting from refraction due to sound speed profiles were seen in the Kongsberg EM2040 data on DN238 in the northeastern section of the survey sheet. Although the sound speed cast was recent (casts acquired at 15:02 and 16:53) and within relatively close proximity, the artifact was still seen. Upon further analysis it was determined that the cast nearest in time (16:53) only reached a depth of approximately 50% of the total depth for the survey area. As the difference in sound speed was only in the order of 1 m/s, the 16:53 cast was removed from the concatenated file and not used for processing. The refraction error was not visible in the submitted data.Surface sound speed was collected in real time and integrated into the RESON 7125 and Kongsberg EM2040 bathymetric data. Sound speed casts for MBES survey were acquired via CTD profiles. Casts were conduced at the start of the day, the midpoint of the day, and at the end of the day. This generally resulted in a cast interval of 3 hours. Additional casts were conducted if the interval was nearing 4 hours as required by the HSSD, or when sound speed variations of greater than 1 m/s were observed. Sound speed casts for SBES survey were acquired via CTD profiles. Casts were conduced weekly. For both multibeam and vertical beam data, the Nearest in Time option was used to apply profiles in CARIS. The Nearest In Time method has been found to most accurately reflect the sound speed changes in the Chesapeake Bay due to tidal influences. Distribution of sound velocity casts is shown in Figure 23. Sound speed profiles acquired for H12305, shown in red.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_SoundSpeedCasts.pngAll equipment and survey methods were used as detailed in the DAPR.Holiday AssessmentSeveral holidays appear in the Kongsberg EM2040 data where biological materials in the water column are thought to have interfered in the sonar (see Section B.2.6, Noise from biological sources). These holidays are located on the set line spaced data only. SSS imagery was investigated over these areas to make sure no objects were missed. As there were no objects to investigate, and the seafloor was mostly flat in these areas, they were not reacquired. Figures 24 and 25 show examples of these holidays. There were three MBES holidays with the set line spacing data due to a dropout in the MBES system. The largest, located around 38-09-34 N 076-14-42 W, is approximately 3 meters in length (Figure 26). 200% SSS coverage was checked over these areas and no features were identified. There was one true MBES holiday was located near 38-10.38N 076-14.22W (Figure 27). This holiday was created due to a lack of TrueHeave data as the result of a system crash. This area was roughly 20 meters by 100 meters and covered with 100% SSS. SSS coverage was investigated and no features were identified. Several SSS holidays exist at the sheet limits where full 200% coverage was not achieved. The largest is a 15 meter by 1,080 meter strip along the northeast corner of the survey. All of these areas have 100% coverage, and this coverage was investigated for possible features. No features were identified in these areas. All holidays with the exception of biological noise holidays are identified and digitized in the "H12305_Holidays.000" file accompanying this submission.Holidays in the set line spaced data. file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_setline_holidays.PNGSubset of a holiday caused by the editing of MBES data to clean out biological data within set line spaced data. file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_holidays_subset.PNGA holiday caused by a multibeam drop out.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_dropout_holiday.PNGA holiday caused by lack of TrueHeave data.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_Holiday_HeaveHoliday.pngThe data is adequate for charting despite the holidays.All data reduction procedures conform to those detailed in the DAPR.The Reson 7125 was originally calibrated with a patch test on DN073 for the yearly Hydrographic Systems Readiness Review. A second patch test was performed on the system on DN156 because the transceivers had been removed and then reinstalled on the sonar strut. They were removed so a mounting could be manufactured for the new Kongsberg EM2040 system that was to be installed on BAY HYDRO II later in the field season. Patch Test2013-06-05Reinstallation of multibeam sonar. Raw Backscatter was logged (*.7k file for Reson data and *.all file for Kongsberg data) and was sent to the processing branch for analysis. NOAA Extended Attribute Files V5_3_2H12305_MBES_1mCUBE111.5335.85NOAA_1mMBES TracklineSBES Set Line SpacingH12305_MBES_2mCUBE211.5335.82NOAA_2mMBES TracklineSBES Set Line SpacingH12305_SBES_4mCUBE412.5135.51NOAA_4mMBES TracklineSBES Set Line SpacingH12305_MBES_1m_FinalCUBE111.5320.00NOAA_1mMBES TracklineSBES Set Line SpacingH12305_MBES_2m_FinalCUBE218.0035.82NOAA_2mComplete MBESH12305_SBES_4m_FinalCUBE46.0735.51NOAA_4mMBES TracklineSBES Set Line SpacingH12305_Combined_4m_FinalCUBE411.5335.82NOAA_4mMBES TracklineSBES Set Line SpacingH12305_100%_1mSSS Mosaic1N/A100% SSSH12305_200%_1mSSS Mosaic1N/A200% SSSH12305_ERS_MBES_1mCUBE147.1971.52NOAA_1mMBES TracklineSBES Set Line SpacingH12305_ERS_MBES_2mCUBE247.2271.52NOAA_2mMBES TracklineSBES Set Line SpacingH12305_ERS_SBES_4mCUBE448.1071.21NOAA_4mMBES TracklineSBES Set Line SpacingH12305_ERS_Combined_4mCUBE447.1971.50NOAA_4mMBES TracklineSBES Set Line SpacingThe surfaces have been reviewed where noisy data, or 'fliers' are incorporated into the gridded solution causing the surface to be shoaler than the true seafloor. Where these spurious soundings cause the gridded surface to be shoaler than the reliably measured seabed by greater than the maximum allowable vertical uncertainty at that depth, the noise was rejected and the surface recomputed. The majority of H12305 was concurrent MBES/SSS acquisition, however for the deep channel in the bay complete coverage MBES was used. This area corresponds well to the finalized 2-meter CUBE surface extents of 18 - 40 meters depth. As such this surface is listed as "Complete MBES" in Table 9 above. As a VDatum evaluation was performed as an academic exercise for the survey (see Section B.5.3, VDatum Tidal Reduction Evaluation), surfaces referenced to the ellipsoid have also been included for evaluation by the branch. A 1m surface was created during office processing, finalized at 18-40 meters, and used in the compilation process. See comment in Section A.4.VDatum Tidal Reduction EvaluationAs an academic exercise, data from H12305 was reduced to MLLW using VDatum and gridded to provide a comparison to TCARI reduced data. This was accomplished by using the GPS height determined from the SBET file (see Section C.1, Vertical Control), and an ellipsoid separation model. As both VDatum and TCARI reduce depths to MLLW, one should see no differences between either surface. Any deviations would be the result of an error intrinsic to either the VDatum or TCARI processing work flow. For example, misprojected SBETs, current-induced dynamic draft, incorrect waterline measurements, corrupt TrueHeave files, or poorly-modeled water levels / separation models are all examples of artifacts that can be identified through the difference of the VDatum and TCARI-reduced surfaces. Difference surfaces were created in CARIS to compare the VDatum and TCARI surfaces. Statistics were then derived from the difference surfaces. Figure 28 shows the overall comparison between VDatum and TCARI surfaces of survey H12305. The TCARI surface was found to be shoaler by an average of 0.06 meters, with a standard deviation of 0.06 meters. These values are within the uncertainties of the VDatum model and are in line with the individual values from each sonar. This shows good agreement between the TCARI and VDatum surfaces. Given the good agreement, none of the other artifacts mentioned in the first paragraph of this section are likely present, in any substantial amount, for survey H12305.H12305 difference surface between VDatum and TCARI reduced surfaces, 1-meter resolution.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_VDatum_All_diffSurface_1m.pngSSS Mosaic Creation ProcessAcquired SSS data was converted using a range of CARIS SIPS versions, from 7.1 SP2 to 8.1.4 as continual software improvements were being made during the course of acquisition and processing for H12305. This did not impede contact identification and selection, but resulted in poor quality mosaics due to the varying intensity values assigned at conversion by the different SIPS versions. In order to provide high quality mosaics to NOAA's Chesapeake Bay Office as required by the Project Instructions, all SSS data was reconverted into a new, separate project using CARIS SIPS version 8.1.10. The original project containing all of the selected contacts was maintained, and both the original and re-converted project are included in the data submission. Reconverting all raw SSS data with CARIS SIPS version 8.1.10 produced uniform intensities and a clean, high quality, SSS mosaic. These recomputed SSS mosaics (seen in Figure 5 and Figure 6) are used as the final SSS mosaic deliverable for H12305.Vertical and horizontal control was achieved via established tidal networks and CORS stations. No user installed reference stations were required for H12305. Mean Lower Low WaterTCARISolomons Island, MD857730Lewisetta, VA8635750Bishops Head, MD8571421E349BH22013_Rev.tcFinalE349BH22014_Rev.tcFinal2013-12-112013-12-23TCARI tides were used for all data in H12305. Although E349BH22013_Rev.tc was originally intended for all data, data dropouts caused by silting of the Solomons, MD gauge (857730) impacted the application of TCARI tides to H12305. Preliminary or verified tides were not available after DN294 due to data dropouts. On the recommendation of CO-OPS, a new TCARI grid (E349BH22014_Rev.tc) was used to apply verified tides for DN294 to DN343. This new TCARI grid does not include the Solomons gauge and was created by CO-OPS for BAY HYDRO II's 2014 field season. VDatumH12305_SEP_CORRECT_2m.csarAs referenced in Section B.5.3, VDatum was performed as an academic exercise for this survey. A separation file was provided to the field unit by the Operations Branch Team Lead at Hydrographic Surveys Division. The separation file is included with the data submission in Appendix II of the DR along with the email string between the field unit and HSD. Smoothed best estimate of trajectories (SBETs) were used to calculate ellipsoid heights required for the VDatum process. SBETs were processed using Applanix SmartBase and a QC log can be found in Separates I of the data submission. Tide Note is appended to this reportNorth American Datum of 1983 (NAD83)UTM-18NSmart BaseVessel kinematic data was post processed using Applanix POSPac processing software as described in the DAPR. Smart Base processing was used, which automatically selects local CORS stations and other known base stations to provide best coverage of the survey area. Annapolis, MD (301 kHz)DGPS was used for primary positioning during acquisition. Following PPK processing, DGPS position data was replaced with improved SBET navigation data. Measured Dynamic DraftFor H12305 an Ellipsoidally Referenced Dynamic Draft (ERDDM) measurement technique was used. This technique utilizes post-processed GPS data and extracts ellipsoidally referenced heights in order to determine dynamic draft. This method provides an operational advantage as it requires less time and resources to collect and process. It is, however, more sensitive than the MBES method to environmental impacts such as current. Comparing the 2013 ERDDM dynamic draft curve to the 2012 MBES curve, showed a significant difference (Figure 29). To resolve this uncertainty a new MBES dynamic draft was acquired as part of the 2014 HSRR. As these values were in line with the 2012 values, H12305 has been processed using the 2014 MBES dynamic draft values. Dynamic draft measurements as a function of speed by year (positive values indicate squat).file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/DynamicDraftChart.pngA sounding selection in feet was created at a scale of 1:40000 from the combined 4-meter resolution surface for comparison with raster Charts 12233 and 12261. These soundings were then compared to each of the soundings located on the charts for continuity. A 4-meter resolution surface was interpolated from the soundings on ENC US5VA22M. This surface was differenced from a surface interpolated from the sounding selection made at a 1:40000 meter scale using the 4-meter resolution combined surface from survey H12305. This difference surface was visually inspected to determine discrepancies between ENC US5VA22M and survey H12305. 12233140000382014-012014-08-052014-08-02Chart 12233 overlaps with all of survey H12305 and is generally a few feet deeper than survey H12305 except in a few locations. In the central Eastern section of the survey where the deepest section is located (Figure 30) charted soundings are anywhere from 2 to 7 feet deeper than surveyed soundings (Figure 31). A comparison of soundings from H12305 and Chart 12233 (H12305 soundings in blue, Chart 12233 soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_12233_overview_deeper_section.PNGThe southeast section of H12305 where the most significant differences were observed (H12305 soundings in blue, Chart 12233 soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_12233_soundings.PNGUnder 12233 - Discussion should read "...generally a few feet shoaler..."12261140000302012-122014-08-122014-08-02Chart 12261 overlaps with survey H12305 for approximately 800 meters in the Northern part of the survey (Figure 32). Like with Chart 12233, soundings from Chart 12261 are generally shoaler than soundings from survey H12305 except in the deeper section of the survey (reference Figure 25 above). Survey H12305 is shoaler by approximately 1 to 4 feet in this location (Figure 33). A comparison of soundings from H12305 and Chart 12261 (H12305 soundings in blue, Chart 12261 soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_12261_overview.PNGThe northeast section of H12305 where the most significant differences were observed (H12305 soundings in blue, Chart 12261 soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_12261_soundings_shoaler.PNGUS5VA22M40000242014-06-132014-06-13falseThe difference surface of the interpolated 4-meter resolution grid created at a 1:40000 scale from the sounding selection of surveyed data minus the interpolated 4-meter resolution grid created at a 1:40000 meter scale from ENC US5VA22M is in Figure 34. The range of difference of this surface is between -8.85 and 4.80 meters. The mean of this difference surface is 0.5 meters indicating that on average soundings from H12305 are shoaler than the soundings charted on US5VA22M (Figure 35). Similar to the comparisons with the raster charts above, ENC US5VA22M primarily disagrees with survey H12305 in the deeper Eastern section of the survey. This can be seen in the soundings near 38-08-49 N 076-14-07 W, where a 96 foot sounding from US5VA22M is surrounded by a 57 foot, 62 foot, 87 foot, and 92 foot sounding from H12305 (Figure 36). Both the northern (Figure 37) and the southern (Figure 38) extents of the deeper section of H12305 are generally found to be 1.5 feet shoaler than the corresponding depth from the ENC. Overview of the difference surface between H12305 and US5VA22M. file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-USVA22M_ENC_DiffSurface_Overview.pngDifference surface statistics between H12305 and US5VA22M depth layers (4-meter grid size). H12305 is an average of 0.5 meters shoaler.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-USVA22M_ENC_DiffSurface_Stats.pngThe central eastern section of the difference surface where the most significant differences were observed (H12305 soundings in blue, US5VA22M soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-USVA22M_ENC_DiffSurface_DeepDiff.pngThe southeastern section of the difference surface (H12305 soundings in blue, US5VA22M soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-USVA22M_ENC_DiffSurface_SEcorner.pngThe northeastern section of the difference surface (H12305 soundings in blue, US5VA22M soundings in black). Soundings are in Feet.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305-USVA22M_ENC_DiffSurface_NEcorner.pngOne AWOIS item, a wreck is located at 38-09-55 N 076-13-29 W. The surveyed location of the least depth of this wreck is approximately 20 meters from the location charted on ENC US5VA22M. Since this chart has a scale of 1:40000 the hydrographer did not submit a new feature location to be charted. The wreck is included in the Final Feature File with the description update since the surveyed depth has increased by approximately one half meter. Full coverage multibeam and 200% side scan sonar data were obtained over the wreck (Figure 39 and Figure 40). MBES subset of charted AWOIS wreck located within H12305.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_charted_wreck.PNGProcessed side scan image of of charted AWOIS wreck located within H12305.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_charted_wreck_ss.PNGThe wreck was recommended to be charted at the surveyed position. AWOIS report is appended to this document.No Maritime Boundary Points were assigned for this survey. One charted feature, an AWOIS item, is discussed in the AWOIS section. Three uncharted features were discovered during collection of survey H12305. An example is shown in Figure 41. These features are recorded in the Final Features File accompanying this submission.Uncharted feature discovered within H12305.file:///M:/OPRE349BH212/Surveys/H12305/Report/Original/DRimages/H12305_unchart_obs_1.PNGFour uncharted obstructions were found during data acquisition. All obstructions were recorded in the Final Feature File by the hydrographer. No Danger to Navigation Reports were submitted for this survey.No shoals or potentially hazardous features exist for this survey.No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits.Six bottom samples were collected for sheet H12305 using a benthic grab operated by hand using line over the side of the vessel (Wildco Petite Ponar Grab). While all six of the samples were very similar in composition, four out of the six also contained a fine sand from the bay floor. Acquired bottom samples are addressed, as required, with S-57 attribution and recorded in the Final Features File accompanying this submission.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.Prior survey comparisons exist for this survey, but were not investigated.One buoy and light were investigated by the field unit. They were both on station serving their intended purpose. No overhead features exist for this survey.No submarine features exist for this survey.No ferry routes or terminals exist for this survey.No platforms exist for this survey.No significant features 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 and Specifications Deliverables Manual, Field Procedures Manual, Standing and 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.Bart O. Buesseler, LTJG/NOAAChief of Party2015-03-13