OPR-L397-RA-18Channel Islands National Marine Sanctuary and VicinirtyCaliforniaNOAA Ship RainierH132054West Santa Cruz ChannelCaliforniaUnited States200002018Benjamin K Evans, CDR/NOAANavigable Area2018-08-172018-09-262018-10-27Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUTCPacific 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 referred to as H13205, "West Santa Cruz Channel" (sheet 4) in the Project Instructions. The survey area is approximately 21.15 square nautical miles.34.0947222222120.02388888933.9402777778119.930555556H13205 assigned survey area (Chart 18728).SupportFiles\H13205_survey_area.jpgData were acquired within the assigned survey limits as required in the Project Instructions and HSSD.The Channel Islands National Marine Sanctuary (CINMS) supports both recreational and commercial fishing efforts, and is regularly host to kayakers, surfers, sightseers, whale watchers, researchers, and Channel Islands National Park concessionaires. Additionally the southeast anchorage off Santa Rosa Island affords protection from southeastern weather. Much of the existing depth data of this area dates back to 1930s vintage lead line or single beam surveys, and is not surveyed to modern standards. This poses a serious risk to life, property and the delicate ecosystem within the Channel Islands National Marine Sanctuary. This survey will provide contemporary data to update National Ocean Service (NOS) nautical charting products and generate backscatter data which will be used in habitat mapping and substrate analysis.The entire survey is adequate to supersede previous data.Pydro QC Tools 2 Grid QA was used to analyze H13205 multibeam echosounder (MBES) data density. The submitted H13205 variable-resolution (VR) surface met HSSD density requirements as shown in the histograms below.Pydro derived histogram plot showing HSSD density compliance of H13205 finalized variable-resolution MBES data.SupportFiles\H13205_MB_VR_MLLW_final.QAv5.density.pngAll waters in survey areaComplete Coverage (Refer to HSSD Section 5.2.2.3)All waters in survey areaAcquire backscatter data during all multibeam data acquisition (Refer to HSSD Section 6.2)Complete multibeam echosounder (MBES) coverage was acquired to the inshore limit of hydrography, the Navigable Area Limit Line (NALL). Areas where survey coverage did not reach the 3.5-meter depth contour, nor the assigned sheet limits, were due to the survey vessel reaching the extent of safe navigation as shown in the figures below. These areas are characterized as being near shore, subject to dangerous wave action or other hazards such as rocks or thick kelp. South of Skunk Point there is a gap in data (holiday) in the vicinity of nearshore rocks, which were deemed too hazardous to approach. When the assigned survey area was completed earlier than expected, H13205 coverage was extended to northwest of the assigned survey limits. This additional surveyed area was originally part of lower priority sheets in the vicinity of Santa Cruz Island.Examples of H13205 NALL determination; the gray dashed line indicates assigned sheet limits and the yellow indicates where the 3.5-meter contour was reached.SupportFiles\H13205_Nall.jpgHoliday on top of an area that was too shoal to acquire complete MBES coverage over safely with a launch, the least depth acquired around the rock was 1.6 meters. The final feature file was updated with a rock of unknown depth placed in the center of the holiday.SupportFiles\H13205_holiday.jpgH13205 MBES coverage and assigned survey limits. Note area where survey coverage was extended beyond sheet limits.SupportFiles\H13205_coverage.jpg2801016.330000010.71028020153.36000006.20028030123.60000000028040174.02000002.8200466.730000019.73000018021.152018-09-262018-10-042018-10-052018-10-082018-10-092018-10-182018-10-192018-10-202018-10-262018-10-27Refer 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.28018.81.128028.81.128038.81.128048.81.127017.60.4719075.70.35ApplanixPOS MV 320 v5Positioning and Attitude SystemKongsberg MaritimeEM 2040MBESSea-Bird ScientificSBE 19plusConductivity, Temperature, and Depth SensorTeledyne RESONSVP 70Sound Speed System19.73 nautical miles of multibeam crosslines were acquired by RAINIER launches 2801, 2802, and 2804 across most depth ranges and multiple boat days. The hydrographer deems them adequate for verifying and evaluating the internal consistency of H13205 survey data. Analysis was performed using the Compare Grids function in Pydro Explorer on finalized VR surfaces of H13205 mainscheme only and crossline only data. 99.5% of nodes met allowable uncertainties. For additional results, see plots below.H13205 crossline surface overlaid on mainscheme tracklines.SupportFiles\H13205_crosslines.jpgPydro derived plot showing percentage-pass value of H13205 mainscheme to crossline data.SupportFiles\H13205_MS_VR_MLLW_final-H13205_XL_VR_MLLW_final_fracAllowErr_Freq.pngPydro derived plot showing absolute difference statistics of H13205 mainscheme to crossline data.SupportFiles\H13205_MS_VR_MLLW_final-H13205_XL_VR_MLLW_final_depth_delta.pngERS via VDATUM00.0832801, 2802, 2803, 28043n\a0.05Total Propagated Uncertainty (TPU) values for survey H13205 were derived from a combination of fixed values for equipment and vessel characteristics, as well as from field assigned values for sound speed uncertainties. Tidal uncertainty was provided in the metadata accompanying the NOAA vertical datum transformation model used for this survey. The uncertainty value of NOAA's Vertical Datum (VDatum) transformation model was documented in metadata that accompanied the VDatum model. 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 this survey. Real-time uncertainties from Kongsberg MBES sonars were recorded and applied in post-processing. Applanix TrueHeave (POS) files, which record estimates of heave uncertainty, were applied during post-processing. Finally, the post-processed uncertainties associated with vessel roll, pitch, yaw and position were applied in Caris HIPS using SBET and RMS files generated using POSPac MMS software. Uncertainty values of the submitted finalized grid was calculated in Caris using "Greater of the Two" of uncertainty and standard deviation (scaled to 95%). Grid QA v5 within Pydro QC Tools 2 was used to analyze H13205 TVU compliance, a histogram plot of the results is shown below. Pydro derived plot showing TVU compliance of H13205 finalized multi-resolution MBES data.SupportFiles\H13205_MB_VR_MLLW_final.QAv5.tvu_qc.pngH13205 junctions with two surveys: one contemporary and one conducted by NOAA Ship Rainier in 2017. Comparisons were made using the Compare Grids program within Pydro Explorer.Overview of H13205 junctions.SupportFiles\H13205_junction_overview.jpgH13088200002017NOAA Ship RAINIERSThe junction with 2017 survey H13088 encompassed approximately 0.1 square nautical miles along the southern boundary of H13205. Pydro's Compare Grids results showed that 99.5+% of nodes in the common area met NOAA allowable error standards. Analysis of the difference surface indicated that H13088 is an average of 0.06 meters deeper than H13205 with a standard deviation of 0.17 meters. See below graphs for more information.Overview of survey junction between H13205 and H13088.SupportFiles\H13205_junction_H13088.jpgPydro derived plot showing allowable error between H13205 and H13088.SupportFiles\H13205_MB_VR_MLLW_final-H13088_MB_VR_MLLW_Final_fracAllowErr_Freq.pngPydro derived plot showing H13205 and H13088 comparison statistics.SupportFiles\H13205_MB_VR_MLLW_final-H13088_MB_VR_MLLW_Final_depth_delta.pngH13087200002018NOAA Ship RAINIERWThe junction with 2018 survey H13087 encompassed approximately 0.9 square nautical miles along the western boundary of H13087. Pydro's Compare Grids results showed that 99.5+% of nodes in the common area met NOAA allowable error standards. Analysis of the difference surface indicated that H13205 is an average of 0.01 meters deeper than H13087 with a standard deviation of 0.10 meters. See below graphs for more information.Overview of survey junction between H13205 and H13087.SupportFiles\H13205_junction_H13087.jpgPydro derived plot showing allowable error between H13205 and H13087.SupportFiles\H13205_MB_VR_MLLW_final-H13087_MB_VR_MLLW_Final_fracAllowErr_Freq.pngPydro derived plot showing H13205 and H13087 comparison statistics.SupportFiles\H13205_MB_VR_MLLW_final-H13087_MB_VR_MLLW_Final_depth_delta.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.2801 Roll Bias AdjustmentAn intermittent, minor roll bias was noted on some H13205 2801 MBES data. Numerous possible equipment and software related issues were investigated, however at the time of this report, a conclusive cause of the offset has yet to be determined. A value of -0.175 degrees roll was added to 2801_EM2040.hvf in order to address this slight bias. All submitted H13205 MBES data meet HSSD specifications. TPU and Crossline Comparison analysis also indicates an improvement in data correlation. Pydro derived QC TVU histograms of pre (left) and post (right) roll corrected H13205 MBES data.SupportFiles\H13205_roll_bias.pngSuboptimal Sound Speed CorrectionDue to water column variations such as thermal layering and salinity differences, a distinct demarcation of water masses was sometimes encountered in the field. At times, this proved problematic in the acquisition and application of optimal sound speed correction data. Despite the best efforts of the hydrographers to conduct sufficient sound speed casts distributed spatially and temporally, in some areas, particularly in the northern part of the survey, sound speed correction was suboptimal. This was evidenced by the appearance of systematic artifacts in the survey grid and the characteristic "smiles" or "frowns" of the data when viewed in subset editor. To address this issue, the Hydrographer rejected the most egregious outer beam soundings obviously in error in an attempt to produce a surface that best represented the sea floor. All examined sound speed related offsets were observed to be within NOAA HSSD standards.Example of area with suboptimal sound speed correction. Inset shows subset view with rejected sounding colored grey. It should be noted that both surface and subset are shown with high vertical exaggeration.SupportFiles\H13205_SoundSpeed_smiles.jpg49 Sound speed profiles were acquired for this survey at discrete locations within the survey area at least once every four hours, when significant changes in surface sound speed were observed, or when operating in a new area. Sound speed profiles were obtained using Sea-Bird 19plus SEACAT Profilers. All casts were concatenated into a master file and applied to MBES data using the "Nearest distance within time" (4 hours) profile selection method with a few exceptions. During processing it was found that occasionally Caris was not selecting the most appropriate cast during sound velocity correction. Due to processed sound speed artifacts the lines below were corrected with the following methods. Vessel 2802 DN299 lines 0039-0043 and XL 0044 were processed by unchecking the "Use Surface Sound Speed" box. Vessel 2802 DN281 lines 0004,0005 and 0007-0012 were processed by force applying cast "2018_281_210532.svp". Vessel 2804 DN278 lines 0001-0007 were processed by force applying cast "2018_278_1542000.svp". H13205 sound speed cast locations. SupportFiles\H13205_sound_speed_locations.jpgAll equipment and survey methods were used as detailed in the DAPR.All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.Raw Backscatter data were acquired as .all files and submitted to NOAA's Pacific Hydrographic Branch. Backscatter data were processed by the field unit and mosaics generated. One mosaic per vessel per frequency has been delivered with this report. All backscatter processing procedures utilized follow those detailed in the DAPR. Software used to process and produce backscatter mosaics were Fledermaus Geocoder Toolbox version 7.8.1.Overview of H13205 backscatter mosaics.SupportFiles\H13205_backscatter.jpgNOAA Profile V_5_7H13205_MB_VR_MLLWCARIS VR Surface (CUBE)Variable Resolution1.693.3NOAA_VRComplete MBESH13205_MB_VR_MLLW_FinalCARIS VR Surface (CUBE)Variable Resolution1.693.3NOAA_VRComplete MBESSubmitted surfaces were generated using the recommended parameters for depth-based (Ranges) Caris variable-resolution bathymetric grids as specified in the 2018 HSSD. Pydro QC Tools 2 Detect Fliers was used with default settings to find fliers in a finalized VR surface. Obvious noise was rejected by the hydrographer in Caris Subset Editor. After data cleaning, Detect Fliers was run again and found 2 certain fliers; these were investigated and found to be false positives. The results of the Detect Fliers tool are included as a .000 files in the Separates section of this report. Two critical soundings were created for this survey; One was identified as a Danger to Navigation. Additional information about DTONS is included in section D.1 Chart Comparison.Shoreline features were reduced to MLLW using traditional tide methods via TCARI. All MBES bathymetry were acquired relative to the ellipsoid and reduced to MLLW via VDATUM.Mean Lower Low Water Los Angeles, CA9410660Santa Monica, CA9410840 Santa Barbara, CA9411340 Oil Platform Harvest, CA9411406Port San Luis, CA9412110Monterey, CA9413450TCARIH13205_tidesFinal ApprovedL397RA2018.tcFinal2018-10-292019-01-29ERS via VDATUMOPR_L397_RA_18_lgECpoly_xyNAD83-MLLW_geoid12b.csarNorth American Datum 1983Projected UTM 11The Wide Area Augmentation System (WAAS) was used for real-time horizontal control for this survey.SBET Processing MethodPrecise Positioning-Real Time Extended (PP-RTX) processing methods were used in Applanix POSPac MMS 8.2.1 software to produce SBETs for post-processing horizontal correction.A comparison was made between H13205 survey data and Electronic Navigation Chart (ENC) US5CA66M using CUBE finalized VR surfaces, selected soundings and contours created in Caris HIPS. US5CA66M4000042017-08-242017-08-24falseA comparison was made between H13205 derived survey contours and ENC US5CA66M with the following results: The ENC’s depth curves are in general agreement with H13205 derived survey contours with a few notable exceptions. Approximately 400 meters northwest of the Southeast anchorage, H13205 data revealed an uncharted 5 fathom shoal. The offshore 5 fathom shoal east of Skunk Point extends approximately 200 meters farther seaward than charted. Additionally in this same area H13205 data revealed an uncharted 3 fathom shoal. In the northern portion of Santa Cruz Channel the 20-fathom survey contour line is approximately 500 -1500 meters farther west than its charted position. Two Dangers to Navigations (DTON) were identified in the H13205 survey area and submitted to Marine Chart Division’s (MCD) Nautical Data Branch. Refer to H13205_DTON.pdf for location and descriptions.Section of ENC US5CA66M showing uncharted 5 fathom shoal near Southeast anchorage. SupportFiles\Chart_comparison_5 fathom.jpgShoal east of Skunk Point overlaid with 3,5,10, and 20 fathom survey contours derived from H13205. SupportFiles\Chart_comparison_shoals.jpgSection of ENC US5CA66M overlaid with 20-fathom survey contours derived from H13205. Uncharted 3 fathom shoal was submitted as a DTON.SupportFiles\Chart_comparison_20fathom.jpgNo Maritime Boundary Points were assigned for this survey.No charted features exist for this survey.No uncharted features exist for this survey.Shoals and features of navigational significance are discussed in the chart comparison sections above or are included in the H13205 Final Feature File submitted with this report.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.No bottom samples were required for this survey.Limited shoreline verification was conducted in accordance with applicable sections of NOAA HSSD and FPM using the Project Reference File (PRF) and Composite Source File (CSF) provided with the Project Instructions. In the field, all assigned features that were safe to approach, were addressed as required with S-57 attribution and recorded in the H13205_FFF to best represent the features at chart scale. This file also includes new features found in the field as well as recommendations to update, retain or delete assigned features.No Aids to navigation (ATONs) exist for this survey.No overhead features exist for this survey.No submarine features exist for this survey.No platforms exist for this survey.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, 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.Benjamin K. Evans, CDR/NOAACommanding Officer2019-04-09Hadley A. Owen, LT/NOAAField Operations Officer2019-04-09James B. JacobsonChief Survey Technician2019-04-09Audrey E. JerauldSheet Manager2019-04-09