OPR-B396-NRT5BH2-16Hudson RiverHudson RiverNavigation Response Team 5 and Bay Hydro IIH128721Hudson To TroyNew YorkUnited States50002016LTJG Sarah L ChappelNavigable Area2016-04-132016-06-242016-08-31Multibeam Echo SoundermetersUniversal 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. Any revisions to the Descriptive Report (DR) generated during office processing are shown in bold red italic text. The processing branch maintains the DR as a field unit product, therefore, all information and recommendations within the body of the DR are considered preliminary unless otherwise noted. The final disposition of surveyed features is represented in the OCS nautical chart update products. All pertinent records for this survey, including the DR, are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via http://www.ncei.noaa.gov/. NOAAThe survey area is located in the central portion of the Hudson River between Troy, NY and Hudson, NY. An overview of the geographic location of H12872 is shown in Figure 1. Due to the river running North-South the Northeast and Southeast corners of the survey were used for survey limits opposite of the Northwest and Southeast as stated in Table 1. 42.749941666773.233813888942.233813888973.8426611111H12872 survey limits on Hudson River, overlaid on Chart 12347 and 12348.SupportFiles\H12872_Survey_Limits.pngSurvey was located on a river that ran North East to South West, as reflected on the survey limits Lat. and Long.MLCSurvey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.The intent of this survey is to supersede all bathymetry, seafloor features, and bottom characteristics within the assigned survey area as defined by these instructions for updating of NOAA Chart 12348. This project covers approximately three SNM of critical survey area as designated in NOAA Hydrographic Survey Priorities.The entire survey is adequate to supersede previous data.Data acquired in H12872 meet multibeam echo sounder (MBES) coverage requirements for object detection, including the five soundings per node data density requirements in section 5.2.2.2 of the Hydrographic Surveys Specifications and Deliverables (HSSD). In order to extract descriptive statistics of the data density achievements, the finalized surface is queried with CARIS and examined in Excel (Figure 2). Overall, the required data density was achieved in 99.4% of the nodes.Summary table showing the percentage of nodes satisfying the five sounding density requirements for H12872. SupportFiles\H12872_Density_stats.pngAll waters in survey areaObject Detection Coverage accomplished using either: A) Object detection MBES, or B) 200% SSS coverage with concurrent set line spacing SBES or MBES. Refer to HSSD Section 5.2.2.1Survey coverage was in accordance with the requirements in the Project Instructions and the HSSD with the exception of a couple of holidays present as a result of acoustic shadowing within the limits provided by HSD, and a couple of sheet limit holidays that are covered by the junction survey F00658. All cases were investigated to ensure that the there is no threat of an obstruction.General location of H12872 overlaid on satellite imagery, subset start indicates location of Albany, NY.SupportFiles\H12872_Survey_locality.pngS54010161.50000000S30020240.20000027.400401.70000027.406.800003.022016-06-242016-06-272016-06-282016-06-292016-07-062016-07-072016-07-082016-07-122016-07-132016-07-142016-07-192016-07-202016-07-212016-07-222016-07-252016-07-262016-07-272016-08-31Refer to each vessel 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.S540117.31.8S30029.1440.5All data for survey H12872 was acquired by NOAA R/V Bay Hydro II and NRT Survey Launch 5. The vessels acquired multibeam depth soundings, backscatter data, and sound speed profiles.KongsbergEM 2040MBESApplanixPOS MV5Positioning and Attitude SystemSonTekCastAwayConductivity, Temperature, and Depth SensorKongsbergEM 3002MBESSeabird SBE19+Conductivity, Temperature, and Depth SensorValportMini SVSSound Speed SystemOdomDigibar ProSound Speed SystemMultibeam crosslines were acquired using NRT5. Crosslines were collected, processed, and compared in accordance with Section 5.2.4.3 of the HSSD. Crossline totals were 27.4 LNM and 6.82% of mainscheme coverage; this coverage exceeds the 4.0% requirement for object detection MBES. A 50cm CUBE surface was created using only mainscheme lines and a second 50cm surface was created using only crosslines. Using the two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated at a 50cm resolution. Statistics show the mean difference between the depths derived from the mainscheme and crosslines was 0.09 meters (crosslines being deeper) with a standard deviation of 0.09 meters (Figure 4). A CARIS Quality Control (QC) Report was used to compare MBES crossline soundings to depth estimates of the 50cm CUBE surface. The depth differences were calculated between each crossline and the corresponding mainscheme surface depth. The depth differences were then compared to allowable NOAA uncertainty. The output QC Report classified the percentage of pings that met the NOAA orders by beam angle (Figure 5). The QC Report shows greater than 99% of the crosslines analyzed were within NOAA Order 1a for the swath width. For further discussion of NOAA standards, refer to section B 2.2, Uncertainty.Crossline comparison with mainscheme lines (orange bar represents the zero mark).SupportFiles\H12872_Crossline_comparison.pngCARIS QC report for crossline soundings compared to depth estimates.SupportFiles\H12872_Crossline_QC.png0.053850ERS via VDATUMS54010.5N/A0.2S30020.5N/A0.2Total Propagated Uncertainty (TPU) values for H12872 were derived from a combination of fixed values for equipment and vessel characteristics, as well as field assigned values for sound speed uncertainties. In addition to the usual a priori estimates of uncertainty, some real time and post processed uncertainty sources were also incorporated into the depth estimates of the survey. Real-time uncertainties from the Kongsberg MBES sonars were incorporated and applied during post processing. Uncertainties associated with vessel roll, pitch, gyro, and navigation were applied real-time, because H12872 used a real-time kinematic (RTK) positioning service. The recorded delayed heave Applanix files included an estimate of the heave uncertainty and were applied during post-processing. All of the aforementioned uncertainties were applied in CARIS. As stated, H12872 is an ellipsoidally referenced survey (ERS) and the tidal component was accomplished with a separation model. Additional information about RTK and the separation model is located in section C.1 and C.2 of this document. Uncertainty values of the submitted finalized surface 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 not met for the finalized surface, a custom predicted NOAA compliance layer was created. The layer is based on the difference between calculated uncertainty of the nodes and the allowable NOAA uncertainty. To quantify the extent to which accuracy requirements were met, the predicted NOAA compliance layer was queried with CARIS and examined in Excel (Figure 6). Overall, 100% of the nodes met HSSD uncertainty requirements.Summary table shows the percentage of nodes that satisfy the NOAA accuracy level.SupportFiles\H12872_predicted_IHO_compliance.pngOne junction comparison was completed for H12872. A 50cm surface was created from H12872 survey data to match the junction surface provided with the Project Instructions. A depth comparison was performed using the CARIS difference surface and CARIS compute statistics tool.F0065850002015Navigation Response Team 5SF00658 was a response survey conducted in 2015 that surveyed multiple small areas of the Hudson River. Due to the nature of the response survey, H12872 junctions with F00658 multiple times. Approximately 0.26 square nautical miles of overlap coverage was achieved. A difference surface between the 50cm resolution H12872 surface and the 50cm resolution F00658 surface show a strong depth agreement. The difference range is -2.52 to 3.31 meters with a mean of -0.03 meters (F00658 being deeper) and a standard deviation of 0.13 meters (Figure 7). The greatest difference in depths are in the Hudson River's deeper sections where large sand waves are present. Due to the influence of currents and tides, the sand waves migrate and transform over time. These changes are clearly visible in the difference surface (Figures 8 and 9). However, in less dynamic sections, the difference surface shows good agreement between the two surveys.Difference surface statistics between H12872 and F00658 (orange line represents zero mark).SupportFiles\H12872_JNX_F00658.pngDifference surface between H12872 (teal) and junction survey F00658 (violet) overlaid onto Chart 12348. Area shows good agreement on edges, and differences where sand waves are present.SupportFiles\H12872_JNX_B.pngDifference surface between H12872 (teal) and junction survey F00658 (violet) overlaid onto Chart 12348. Area shows large differences likely due to a dynamic mixing zone caused by an island.SupportFiles\H12872_JNX_A.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.Cellular network dropoutsThe RTK corrections were acquired with the use of an NTRIP caster (Networked Transport of RTCM via Internet Protocol) which required continuous, stable Internet connection to receive the RTK corrections. The survey teams had a 4G LTE wireless hotspot, but there were specific occasions during survey operations that wireless Internet connectivity was limited, which inhibited RTK corrections to be imported. The dropouts resulted in survey line depths that were significantly different from surrounding data (Figure 10). If the dropout was recognized during acquisition, acquisition on the line ended and the data was reacquired once the signal returned. When the anomaly was identified during processing, data was rejected and a new line was later acquired to ensure object detection MBES coverage was achieved. Three images of sections of the same line (A, B, and C) with data colored by lines. The gold data shows when RTK connections were compromised and "drifted" from the true bottom.SupportFiles\RTK_drift_1.pngNone ExistThere were no other factors that affected corrections to soundings.Surface sound speed was collected real-time and integrated into the bathymetric data for both the Kongsberg EM2040 on Bay Hydro II and the Kongsberg EM3002 on NRT5.Sound speed casts were acquired via CTD with a SonTek CastAway on Bay Hydro II and a Sea-Bird SBE19+ on NRT5. Casts were collected at the beginning, during, and end of the survey day to ensure accurate representation for the survey area. Cast frequency was increased if survey area was large or sectioned. These methods resulted in a cast every three to four hours as outlined in the HSSD. The distribution of sound speed casts are shown below (Figure 11). Casts were applied using the "nearest in distance with time" within three hours. The hydrographer found this method to more accurately represent the sound speed within the survey limits of H12872.Sound speed profiles (orange) acquired for H12782 (teal) overlaid onto Chart 12348.SupportFiles\H12872_sound speed cast.pngAll equipment and survey methods were used as detailed in the DAPR, with the addition of RTK corrections for positional data. All data reduction procedures conform to those detailed in the DAPR. The primary antenna to reference point was remeasured because of a large offset between Bay Hydro II and NRT5 when ERS offsets were applied. The offset discrepancy was not identified until June 30, 2016, DN182, three days after data acquisition commenced. To correct for the changes made to the primary antenna height, the field unit adjusted the daily waterline height for day numbers 179, 180, and 181. The adjustment is located in the HVF associated with this project. GPS Antenna lever arm to reference point.2016-06-30Field unit measurements showed an incorrect offset from previous years.Offset values that changed on 6-30-2016. Bay Hydro II measured a 11 cm discrepancy in the vertical distance between the Navigation Antenna phase center and the Transducer face. The transducer face is Bay Hydro II's reference point. The Hudson River project was an Ellipsoidal Referenced Survey (ERS). The values were changed in the DAPR on 6-30-2016.SupportFiles\H12872_DAPR_Change_1.pngRaw Backscatter was logged in the .all file and has been sent to the Processing Branch. Backscatter was not processed by the field unit.NOAA Profile V_5_4H12872_MB_50cm_HRDCUBE0.50-0.3817.74NOAA_0.5mObject DetectionH12872_MB_50cm_HRD_FinalCUBE0.50-0.3817.74NOAA_0.5mObject DetectionThe surfaces were reviewed where noisy data, or 'fliers'', were 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 maximum allowable vertical uncertainty at that depth, the noise was rejected and the surface recomputed. Bay Hydro II POS MV5There were three instances during survey operations that Bay Hydro II experienced discrepancies in the POS accuracy, which halted data acquisition. The anomaly was related to an aging cable connecting the IMU and the POS topside unit. The image below, taken when the vessel was not moving, shows the significant drift in altitude, as well as incorrect speed and heading readings (Figure 13). The immediate remediation was to discontinue logging the POS file, reboot the system, then continue to survey on a new POS file. This temporary work-around reduced efficiency but allowed for continued survey operations. Problems with POS file data gaps on Bay Hydro II limited the field unit's ability to post process SBETs. Issues appeared to be related to how Bay Hydro II logged POS files via Ethernet logging, but the degraded cable may have influenced the issues. For the first five days of H12872 acquisition, Bay Hydro II logged Ethernet only POS files directly to the network. This was when the POS issue related to post processing in POSPac occurred. Once Bay Hydro II transitioned to logging the POS file locally, on a USB, post processing in POSPac was resolved. NRT5 did not encounter issues with POS data during post processing. Because of these findings, the field party used RTK positioning data for this project, and the available post processed data (SBETs) as a QC tool. Screen grab of POS data when anomaly occurred. Red boxes outline the incorrect values.SupportFiles\POS drift.png RTK was used for vertical control and the real time solution was written directly to the POSPac file. In CARIS, a GPS tide was applied in reference to the ellipsoid. A VDatum separation model was applied to reduce the data to HRD.Mean Lower Low WaterERS via VDATUMOPR-B396-NRT5BH2-16_HDR (1).csarThe separation file was provided to the field party from the project manager. This survey is referenced to the Hudson River Datum, as stated on RNC 12248. The Hudson River has large fluctuations in water levels due to hydrological, meteorological, and other non-tidal influences that make tidal datums less representative of the average lower water conditions. A fixed low water reference plan, Hudson River Datum (HRD), adopts the chart datum for certain portions of the Hudson River to approximate mean low water when river levels are lowest. The full Hudson River Datum report is included under Appendix 2 of this document.North American Datum of 1983 (NAD83)UTM 18NHorizontal control used Real Time Kinematic (RTK) corrections using CORS stations maintained New York Department of Transportation's (NYDOT) as part of the New York State Spatial Reference Network (NYSNet). Horizontal network datum for NYSNet correctors is NAD83 (CORS96). Additional information regarding the NYSnet system can be found at http://cors.dot.ny.gov/spiderweb/frmIndex.aspx. In order to use the NYSnet correctors, a stable Internet connection and computer software are needed to receive the CORS corrections. The field unit used NTRIP (Network Transport of RTCM data over IP) which is a protocol for transmitting RTK correction data from the base station to the rover (in our case survey vessel) using the Internet. Both NRT5 and Bay Hydro II were equipped with a Sierra Wireless cellular Internet Wi-Fi modem that provides steady, always-on Internet connectivity to its computers. Lefebure (NTRIP) software configured on an acquisition laptop to receive the correction data was transmitted to the POS MV5 via serial cable. During survey acquisition, the Lefebure (NTRIP) window shows the status of the incoming data stream. This was monitored to ensure continuous reception of RTK. In addition, confirmation was attained when vertical and horizontal accuracies of the POS MV5 were less than 5cm.Hudson Falls, NY (324 kHz)Chart comparisons were conducted for RNC Chart 12348, 12347 and ENC US5NY44M, US5NY43M. A sounding section in feet was created at a 1:5000mm chart scale from H12872 50cm resolution surface for comparison with Chart 12348, 12347 and US5NY44M. The soundings were visually inspected to identify any discrepancies. Overall, comparisons between H12872, Chart 12348 and U5NY44M showed good agreement with no gross discrepancies. The following sections highlight any significant differences identified between chart soundings and H12872 data. 12348222340000342010-062016-09-132016-08-27There are three areas where charted soundings differed from H12872 soundings. 1.) The west side of Coxsackie Island does not have a maintained channel. Survey soundings show a significant depth difference (Figure 14) as well as a narrowing of the navigable water way. 2.) The north and south entrance points to the east side of Stockport Middle Ground have significant shoaling (Figure 15). This section of the Hudson River has very little vessel traffic and does not pose a danger to navigation. 3.) The south end of Houghtaling Island has significant shoaling west of the aid to navigation (Figure 16). H12872 depths are 6-8ft shoaler than charted soundings on Chart 12348. Again, this section of the Hudson River has limited vessel traffic and does not pose a danger to navigation.H12872 soundings (blue), compared with soundings from Chart 12348 (black). Yellow overlay depicts H12872 survey coverage. SupportFiles\H12872_Chart_comp_coxsackie.pngH12872 soundings (blue), compared with soundings from Chart 12348 (black). Yellow overlay depicts H12872 survey coverage. SupportFiles\H12872_Chart_comp_stockport_1.pngH12872 soundings (blue), compared with soundings from Chart 12348 (black). Yellow overlay depicts H12872 survey coverage.SupportFiles\H12872_Chart_comp_houghtaling_1.png12347222440000312010-062016-09-202016-09-24There is one area where charted soundings differed from H12872 soundings. The west of the Middle Ground Flats on the northern end, there is significant shoaling and channel migration compared to Chart 12347 (Figure 17 and 18). Because the project instructions inshore limit of the project was the NALL, the field unit did not extend the survey area around the shoaling section of the Middle Ground Flats. This area has limited vessel traffic, and does not pose a danger to navigation. H12872 soundings (blue), compared with soundings from Chart 12347 (black). Yellow overlay depicts H12872 survey coverage.SupportFiles\H12872_Chart_comp_MiddlegroundFlats_2.pngH12872 soundings (blue), compared with soundings from Chart 12347 (black). Yellow overlay depicts H12872 survey coverage.SupportFiles\H12872_Chart_comp_MiddlegroundFlats_1.pngUS5NY44M40000152015-06-152016-07-16falseThe sounding selection comparison has the same results as raster Chart 12348US5NY43M40000142016-07-112016-07-11falseThe sounding selection comparison has the same results as raster Chart 12347No Maritime Boundary Points were assigned for this survey.In total, H12872 had 27 assigned features and 2 had a label containing PA, ED, PD, or Rep. 1) Submerged pile PA was identified in MBES coverage about 40 meters northwest of the original position. Based on MBES data the obstruction is about 0.67 meters tall and is positioned on the channel slope (Figure 19). 2) The wreck PA was not addressed by the survey team due survey vessel safety. The position of the wreck PA is inshore of the NALL and there is no indication of a wreck in the available MBES data (Figure 20).New position of submerged pile PA.SupportFiles\H12872_Charted_Feature_1.pngWreck PA not addressed by survey team due to vessel safety in shallow water.SupportFiles\H12872_Charted_Feature_2.png All survey features are referenced and attributed in the digital data of the submitted Final Feature File.1H12872_DTON_201607072016-07-07Danger to Navigation Reports are included in Appendix II of this report.In reference to Chart 12348, three shoaling areas were reported within the H12872 survey boundary. Two of these shoaling areas were investigated with MBES coverage up to the 12 ft. contour as required in the Project Instructions. The reported shoaling in 1976 near R"144"is not present in H12872 data (Figure 21). The MBES data shows good agreement with the 12ft. contour line on Chart 12348. The reported shoaling in 1999 at the turning basin is clearly identified in H12872 data (Figure 22). The shoaling area on the north side of Stockport Middle Ground Island was not investigated (Figure 14 and Figure 23). It appears that shoaling has expanded to the entrances to the east side of Stockport Middle Ground Island which prohibited the field unit from safely investigating further.Reported shoaling in 1976. H12872 soundings (blue) and coverage (yellow) are overlaid onto Chart 12348.SupportFiles\H12872_shoaling_R144.pngReported shoaling 1999 in turning basin. H12872 soundings (blue) and coverage (yellow) are overlaid onto Chart 12348.SupportFiles\H12872_shoaling_turing_basin.pngReported shoaling in in the north side of Stockport Middle Ground Island. H12872 soundings (blue) and coverage (yellow) are overlaid onto Chart 12348SupportFiles\H12872_shoaling_stockport_middle_grounds.pngThe Hudson River maintained channel was not assigned as part of sheet H12872, however, some channel investigation occurred during acquisition, specifically in the northern section of the survey near Troy, NY. In this section, the channel tabulated depths were shoaler than H12872 data, including the identified obstructions within the maintained channel. Obstructions are present in the channel, but the tabulated depth is shoaler than the observed least depth of the obstructions which eliminated the need for a DTON report (Figure 24). H12872 contained one anchorage area. The Stuyvesant Anchorage area comparison showed similar depths between survey data and the tabulated depths on Chart 12348 (Figure 25).H12872 coverage (red and green) overlaid on Chart 12348. SupportFiles\H12872_Channel_1.pngH12872 coverage (red and green) overlaid on Chart 12348.SupportFiles\H12872_Channel_2.pngNo bottom samples were required for this survey.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.Limited shoreline investigation was conducted by the hydrographer. All assigned features with the hydrographer's recommendations are included in the H12872 Final Feature File. No prior survey comparisons exist for this survey.Aids to navigation (ATONs) exist for this survey, but were not investigated.Overhead features exist for this survey, but were not investigated.Submarine features exist for this survey, but were not investigated.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, 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.LTJG Sarah L ChappelChief of Party2017-01-19