OPR-O193-RA-13Behm Canal, AKBehm CanalNOAA Ship RAINIERH125192Chickamin River to Sargent BayAlaskaUnited States400002013Richard T. Brennan, CDR/NOAANavigable Area2013-04-012013-05-082013-06-17Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUniversal Transverse Mercator (UTM)UTCPacific Hydrographic BranchNOAAThe area surveyed is referred to as Sheet 2: "Chickamin River to Sargent Bay" within the Project Instructions. The area is in the center of the eastern branch of Behm Canal near Ketchikan, Alaska (Figure 1).55.7525131.05955.5763333333130.7678333331H12519 survey limits.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_Coverage_Overview.pngThe purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products.The entire survey is adequate to supersede previous data.Data acquired on survey H12519 met complete multibeam echosounder (MBES) coverage requirements, including the 5 soundings per node data density requirements outlined in Section 5.2.2.2 of the HSSDM (Figure 3). In order to extract some descriptive statistics of the data density achievements, the density layer of each finalized surface was queried within CARIS and then examined in Excel (Figure 4). Overall, the required data density was achieved in 98.8% of the nodes and 99.8% of the total area.3H12519 data density.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_Density_pic.png4Summary table showing the percentage of nodes satisfying the 5 sounding density requirements, sub-divided by the appropriate depth ranges. Note: The final row has a unit of square meters, and sums the number of different resolution nodes into a common unit of area.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_Density_stats_2.pngIn addition to surveying within the limits prescribed in the Project Instructions, additional data was acquired in a portion of Walker Cove (DN132); which was deemed to be navigationally significant after observing multiple vessels transiting the area (Figure 2).2Additional data collected in Walker Cove submitted with H12519.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_Walker_Addtnl_Data.png5Acquired survey coverage overlaid on Chart 17424.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_A_4_Survey_Coverage.pngComplete multibeam (MBES) coverage was achieved within the limits of hydrography as defined in the Project Instructions with two exceptions: Acoustic Shadowing and Downslope Masking: There were numerous gaps in coverage as a result of acoustic shadowing - lack of coverage on the "back" side of a feature; or downslope masking - lack of coverage resulting from poor geometry associated with rapid drops in the seafloor (Figure 6). All cases were investigated to assure that least depths were found. Holidays: In addition to acoustic shadows, there were several holidays as defined by 3 or more adjacent nodes. These areas were small, with 60% having an area of less than 8 square meters. The largest holiday was 108 square meters in 38 meters of water. All areas were investigated in CARIS Subset Editor to verify that least depths were found. There are numerous gaps in coverage where multibeam data did not meet the sheet limit nor the 4-meter curve. In all cases, these gaps were nearshore and dangerous to approach, and were therefore deemed to be inshore of the NALL. Further, HSD has acknowledged minor gaps along the sheet limits, which the field determines to be non-navigationally significant, need not be acquired (see Supplemental Correspondence - HSD_holidays_on_edge.pdf).6Example of downslope masking in survey H12519. Red line indicates ship track line (nadir beams), yellow swath indicates portion of seafloor ensonified by sonar; gray call-out is the masked portion of the seafloor.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_A_4_downslope_mask.png2013-05-082013-05-102013-05-112013-05-122013-05-142013-05-152013-06-162013-06-1780086040.8S221083.4000008.302801 (RA-4)072.600000002802 (RA-5)058.600000002803 (RA-3)017.300000002804 (RA-6)038.20000021.200270.10000029.5010.8Refer 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.2801283.52802283.52803283.52804283.5S22123116.5Data was primarily acquired by RAINIER (S221) for the deep central portion of the survey, with limited nearshore mainscheme data acquired with survey launches (2801, 2802, 2803 and 2804) (Table 4). The vessels acquired multibeam echosounder (MBES) soundings, sound speed profiles, and bottom samples.KongsbergEM710MBESReson7125MBESApplanixPOS-MV V4Attitude SystemSeabirdSBE 19 PlusSound Speed SystemODIM Brooke Ocean (Rolls Royce Group)MVP30Sound Speed SystemODIM Brooke Ocean (Rollys Royce Group)MVP200Sound Speed SystemResonSVP 71Sound Speed SystemResonSVP 70Sound Speed SystemMultibeam crosslines were acquired using the EM710 on S221 as well as the Reson 7125 on Launch 2804. Crosslines totaled 29.4 NM, which comprised 10.8% of mainscheme hydrography. An 8-meter CUBE surface was created using strictly the mainscheme lines, while a second 8-meter CUBE surface was created using only crosslines, from which a difference surface was generated at an 8-meter resolution (Figure 7). Statistics were then derived from the difference surface and are shown in Figure 8. The average difference between the depths derived from mainscheme and crosslines was 0.20 meters (mainscheme being deeper) with a standard deviation of 2.10 meters. For the respective depths, the difference surface was compared to the allowable IHO accuracy standards (Figure 9). In total, 97.5% of the depth differences between H12519 mainscheme and crossline data are within allowable IHO accuracies (Figure 10). The majority of the inconsistencies are on the steep inclines and may simply be an artifact of the gridding algorithm. In addition to performing a crossline comparison using surface differencing, the CARIS QC Report was used to compare the crossline soundings to the depth estimates of the 8-meter resolution surface. The depth differences are calculated between each 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). Up to 40-degrees from nadir, 95% of the beams meet IHO Order 2 accuracy standards; and overall, 80% of all beams satisfies IHO Order 2 accuracy standards. The relatively low percentage of pings in the outer beams meeting IHO standards is largely due to the depth of water, which at times exceeded the limits of the Reson 7125 (which will seldom return a full swath of data in waters exceeding 200 meters depth).7H12519 crosslines.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_XL_pic2.png8Crossline comparison with mainscheme lines.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_1_X2_Crossline_Histogram.png9Depth differences between H12519 mainscheme and crossline data as compared to allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_1_X3_Crossline_IHO_compliance.png10Summary table showing percentage of difference surface nodes between H12519 mainscheme and crossline data that meet allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_1_X4_Crossline_IHO_table.png11CARIS QC Report comparing crossline soundings to depth estimates.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_1_X1_Crossline_QC_Report.png00.0728013.1528023.1528033.1528043.15S2211.05In 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 survey H12519. Real-time uncertainties from both the EM710 and Reson 7125 were recorded and applied in post-processing. Applanix TrueHeave files are recorded on all survey vessels, which includes an estimate of the heave uncertainty, and are applied during post-processing. Finally, the post-processed uncertainties associated with vessel roll, pitch, gyro and navigation are applied in CARIS HIPS via an SBET 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 then examined in Excel (Figure 13). Overall 98.5% by node and 99.8% by area of survey H12519 met the accuracy requirements stated in the HSSDM.12H12519 met IHO accuracy standards for 99.8% of the survey area.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_IHO_pic.png13Summary table showing the percentage of nodes satisfying the indicated IHO accuracy level, sub-divided by the appropriate depth ranges. Note: The final row has a unit of square meters, and sums the number of different resolution nodes into a common unit of area.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_IHO_table.pngThree junction comparisons were completed for H12519 (Figure 14). One of these surveys, H12518, was acquired concurrently with this survey, and the other two surveys (H11369, H11335) were prior surveys from NOAA Ship FAIRWEATHER in 2004. Depth comparisons were performed using the CARIS Difference Surface and CARIS Subset Editor. For comparison with the FAIRWEATHER surveys, 10-meter and 22-meter grids were created, from H12519 survey data, to match the grids provided with the Project Instructions. For gridding at the 10-meter and 22-meter node size, the CUBE parameters were the same as the defined NOAA resolutions with "Capture_Distance_Min" adjusted to be 1/sqrt(2)*(node size), since this is the only parameter which changes among the other standard resolutions.H11369100002004NOAA Ship FAIRWEATHERSOverlap with survey H11369 was 250 meters wide along the 5,000 meter southern boundary of H12519. The overlap changed from 500 meters wide at the eastern edge of the coverage to 50 meters at the western extents of the coverage (Figure 15). Depths in the junction area range from 20 to 375 meters. For comparison purposes, a 10-meter CUBE surface was generated for H12519 to match the resolution of the BAG of the junctioning survey provided with the Project Instructions. A difference surface analysis between CUBE depth surfaces for each survey showed H12519 to be an average of 0.27 meters shoaler than H11369, with a standard deviation of 2.76 meters (Figure 16). For the respective depths, the difference surface was compared to the allowable IHO accuracy standards (Figure 17). In total, 89.5% of the depth differences between H12519 and junctioning survey H11369 are within allowable IHO accuracies (Figure 18). The majority of the inconsistencies are on the steep inclines and may simply be an artifact of the gridding algorithm. Further, in the decade since the FA survey was completed, significant advances have been made in both positioning and gridding algorithms; some of the differences may be due to these improvements in technology.14Overview of junctions with H12519.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_JNX_Overview.png15Difference surface between H12519 (orange) and junctioning survey H11369 (lavender).file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_H11369_JNX_pic2.png16Difference surface statistics between H12519 and H11369 CUBE depth layers (10-meter grid size). H12519 is an average of 0.27 meters shoaler.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_H11369_JNX_graph.png17Depth differences between H12519 and junctioning survey H11369 as compared to allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_X1_H11369_Junction_IHO_compliance.png18Summary table showing percentage of difference surface nodes between H12519 and junctioning survey H11369 that meet allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_X1b_H11369_Junction_IHO_table.pngH11335100002004NOAA Ship FAIRWEATHERSEOverlap with survey H11335 was 300 meters wide along the 4,000 meter southeast boundary of H12519. The overlap changed from 400 meters at the northern edge of the coverage to 250 meters at the southern edge of the coverage (Figure 19). Depths in the junction area range from 20 to 500 meters. For comparison purposes, a 22-meter CUBE surface was generated for H12519 to match the resolution of the BAG of the junctioning survey provided with the Project Instructions. A difference surface analysis between CUBE depth surfaces for each survey showed H12519 to be an average of 3.89 meters deeper than H11335, with a standard deviation of 5.95 meters (Figure 20). For the respective depths, the difference surface was compared to the allowable IHO accuracy standards (Figure 21). In total, 81.3% of the depth differences between H12519 and junctioning survey H11335 are within allowable IHO accuracies (Figure 22). The majority of the inconsistencies are on the steep inclines and may simply be an artifact of the gridding algorithm. Further, in the decade since the FA survey was completed, significant advances have been made in both positioning and gridding algorithms; some of the differences may be due to these improvements in technology.19Difference surface between H12519 (orange) and junctioning survey H11335 (lavender).file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_H11335_JNX_pic2.png20Difference surface statistics between H12519 and H11335 CUBE depth layers (22-meter grid size). H12519 is an average of 3.89 meters deeper.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_H11335_JNX_graph.png21Depth differences between H12519 and junctioning survey H11335 as compared to allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_X2_H11335_Junction_IHO_compliance.png22Summary table showing percentage of difference surface nodes between H12519 and junctioning survey H11335 that meet allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_X2b_H11335_Junction_IHO_table.pngH12518400002013NOAA Ship RAINIERNOverlap with survey H12518 was 400 meters wide along the 4,000 meter northern boundary of H12519 (Figure 23). Depths in the junction area range from 20 to 350 meters. A 16-meter CARIS Difference Surface analysis between CUBE depth surfaces for each survey showed H12519 to be an average of 0.04 meters deeper than H12518, with a standard deviation of 2.06 meters (Figure 24). For the respective depths, the difference surface was compared to the allowable IHO accuracy standards (Figure 25). In total, 91.2% of the depth differences between H12519 and junctioning survey H12518 are within allowable IHO accuracies (Figure 26). Inspection of the data in CARIS Subset Editor (Figure 27), shows great agreement between the two surveys, suggesting the majority of the inconsistencies seen in the difference surfaces are just artifacts of the gridding algorithm.23Difference surface between H12519 (orange) and junctioning survey H12518 (lavender).file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_H12518_JNX_pic2.png24Difference surface statistics between H12519 and H12518 CUBE depth layers (16-meter grid size). H12519 is an average of 0.04 meters deeper.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_H12518_JNX_graph.png25Depth differences between H12519 and junctioning survey H12518 as compared to allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_X3_H12518_Junction_IHO_compliance.png26Summary table showing percentage of difference surface nodes between H12519 and junctioning survey H12518 that meet allowable IHO accuracy standards for the associated depths.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_X3b_H12518_Junction_IHO_table.png27Subset view of sonar data between H12519 (red) and junctioning survey H12518 (yellow).file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_3_Junction_subset.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.Sound Speed ArtifactsDespite the attempts of the survey crews to spatially and temporally collect sound speed profiles, artifacts were seen within the data in the form of 'smiles' or 'frowns', particularly in areas of fresh water inflow near rivers and streams (Figure 28). In these areas, the outer beams were flagged as rejected to assist the gridding algorithm in bringing the surface back to the 'true' seafloor and within the accuracy specifications defined in the HSSDM (Figure 29).28Example of sound speed artifact seen within H12519 prior to cleaning.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_SV_issue.png29Example of sound speed artifact within H12519 after cleaning.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_SV_fixed.pngEllipsoid-to-Tidal surface comparisonUsing the GPS height determined from the SBET file, data from H12519 was referenced to the ellipse and gridded. By differencing this ellipsoidally-referenced surface (ERS) from the traditional tidally-referenced surface, one should only see the ellipsoidal slope across the length of the survey. Any deviations from this slope would therefore be the result of an error intrinsic to either the ERS or tidal processing work flow. For example, misprojected SBETs, current-induced dynamic draft, incorrect waterline measurements, corrupt True heave files, or poorly-modeled water levels are all examples of artifacts that can be identified through the difference of the ERS and tidally-referenced surfaces. Figure 30 shows the gentle slope of the ellipse from north to south in the vicinity of survey H12519. There were some small (less than 0.20 meters) steps seen in the difference surface (dark blue patch in NW corner of survey), which are likely the correction of tidal artifacts. Given there were no other major "bright spots" in the difference surface, none of the other artifacts mentioned in the previous paragraph are likely present, in any substantial amount, in survey H12519.30Difference surface between the ellipsoidally-referenced and tidally-referenced surfaces.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_2_6_X1_ERS_diff_MLLW.pngFor data collected by launches, sound speed profiles were acquired using the SBE 19plus CTDs at discrete locations within the survey area at least once every four hours, when large changes in surface sound speed were apparent, and when moving to a new area. For data collected on S221 (RAINIER), sound speed profiles were acquired using the Rolls Royce MVP200 approximately every 15 minutes or when recommended by "CastTime", a cast frequency program developed at the University of New Hampshire. All casts were concatenated into a master file for each vessel and applied to lines using the "Nearest in distance within time (4 hours)" profile selection method (Figure 31). 31Sound speed profiles acquired for H12519. Ship profiles are in red, and launch profiles are in green.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_SV_Casts.pngAll equipment and survey methods were used as detailed in the DAPR.True Heave could not be applied to Launch 2802 (RA-5) on DN168 due to an isolated data corruption issue. The affected data was examined in CARIS Subset Editor and found to be in agreement with surrounding data.In cooperation with University of New Hampshire and The Center for Coastal and Ocean Mapping, a new vessel file was created for S221 to resolve a recurring artifact seen in data collected by the Kongsberg EM710 on the RAINIER. On 25 May (DN146), the ship's system integration was reconfigured, moving the reference point for both the IMU and the sonar to the center of the sonar's transmit array. This implies that both real-time and logged data is in the ship's reference frame, with the EM710 transmitter as the origin. Necessarily, this new vessel file (S221_Simrad-EM710_TxRef.hvf) contains new patch test values as well as the change to the vessel's reference frame. Two lines (0004_20130617_183401_Rainier and 0005_20130617_184559_Rainier) were acquired using this new configuration. This configuration is further described in the DAPR. It should be noted that the aforementioned EM710 artifact was associated with the ship acquiring data in heavy seas. For the duration of survey H12519, flat calm conditions were prevalent. Thus, data acquired by S221 prior to the configuration change is artifact-free.Patch Test2013-05-25Update of system configuration.Backscatter data was acquired, but not formally processed by RAINIER personnel. However, periodic spot checks were performed to ensure backscatter quality. A preliminary backscatter mosaic of data acquired by S221 is shown in Figure 32. Backscatter was logged as 7k or .ALL files and submitted to NGDC, but is not included with the data submitted to the Branch.32H12519 backscatter mosaic of S221 lines.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_4_X1_Backscatter_mosaic.pngNOAA Extended Attribute Files Version 5_3_2All data was processed using CARIS HIPS and SIPS 7.1.2.6. It should be noted that all Kongsberg EM710 data was intentionally processed without the Simrad Sound Velocity Correction (SVC) module. This was done in order to avoid a known error in the SVC module associated with reverse-mounted transducers. To accomplish this, a custom CARIS license file was used, which excluded the licensing for the Simrad SVC. For further details, refer to the DAPR.H12519_1mCUBE10600NOAA_1mComplete MBESH12519_2mCUBE20600NOAA_2mComplete MBESH12519_4mCUBE40600NOAA_4mComplete MBESH12519_8mCUBE80600NOAA_8mComplete MBESH12519_16mCUBE160600NOAA_16mComplete MBESH12519_32mCUBE320600NOAA_32mComplete MBESH12519_1m_0to40_FinalCUBE1040NOAA_1mComplete MBESH12519_2m_18to80_FinalCUBE21880NOAA_2mComplete MBESH12519_4m_36to160_FinalCUBE436160NOAA_4mComplete MBESH12519_8m_72to320_FinalCUBE872320NOAA_8mComplete MBESH12519_16m_144to500_FinalCUBE16144500NOAA_16mComplete MBESH12519_32m_288to600_FinalCUBE32288999NOAA_32mComplete MBESH12519_Combined_32mCUBE320600NOAA_32mComplete MBESIn order to prevent apparent coverage gaps resulting from the gridding algorithm in the "steep and deep" bathymetry found in H12519 (Figure 33), finalized surfaces were extended beyond the depth thresholds specified in the HSSDM. For example, rather than gridding the data at a 2-meter resolution between 18 and 40 meter depths; the depth range was extended to between 18 and 80 meter depths. All other finalization depth ranges are stated in Table 10.33(Top) Finalized surfaces created using depth thresholds specified in the HSSDM; notice the gaps between depth resolutions. (Bottom) The same region gridded at the finest resolution shows the data is free of coverage gaps.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_B_5_2_X1_Surface_Resolutions.pngAdditional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterDiscrete ZoningKetchikan, AK9450460Burroughs Bay, AK94509179450917.tidVerified ObservedH12519CORF.zdfFinal2013-06-212013-08-02The operating NWLON primary tide station in Ketchikan, AK (9450460), as well as a subordinate tide station installed by RAINIER personnel at Burroughs Bay, AK (9450917) served as the controls for datum determination and water level reducers for survey H12519. A complete description of the vertical and horizontal control for this survey can be found in the accompanying OPR-O193-RA-13 Horizontal and Vertical Control Report (HVCR), submitted under a separate cover. Preliminary zoning was updated by CO-OPS to include Walker Cove within the ZDF and to make the subordinate tide station (9450917) the primary tide station for the project.North American Datum of 1983 (NAD83)UTM - 09 NorthSingle BaseChannel Island, AKN/AIn conjunction with this project, a GNSS base station was established by RAINIER personnel on Channel Island near the center of the survey area. Vessel kinematic data was post-processed using Applanix POSPac processing software as described in the DAPR. Single Base processing was used from DN128 to DN134 while the site was installed. On DN131, the POS file was cut short during acquisition on S221. The result is that two lines (0019 and 0020) do not have processed SBETs, and line 0018 has only partial coverage. The data was examined in CARIS Subset Editor and the affected lines showed good correlation with surrounding data.The PPK base station on Channel Island was removed on DN135 to relocate to the next project area. Therefore, a PPK solution was not possible for DN135, DN167, and DN168. To provide enhanced positioning data, a PPP solution was used for those days. Data processed by PPP correlated well with surrounding data processed with PPK.Biorka Island, AK (305 kHz)Level Island, AK (295 kHz)Annette Island, AK (323 kHz)DGPS was used for primary positioning during acquisition. Following PPK or PPP processing, DGPS position data was replaced with improved SBET navigation data. For Launch 2802 DN168, DGPS was used for final positioning (see Section B.3.1 - Corrections to Echo Soundings). DGPS was also used for final positioning for RAINIER (S221) lines "0019_20130512_001115_Rainier" and "0020_20130512_004137_Rainier" as processed SBETs did not encompass the time extents of the line. DGPS positioning was in agreement with surrounding data.Two principle methods were used in comparing survey H12519 to the contemporary charts. From the survey data, contours and soundings were generated and compared to the raster chart. For the Electronic Navigation Chart (ENC), a TIN was generated from all soundings and contours within the ENC (Figure 34). From this TIN, an interpolated surface was generated, which was then differenced from the survey data for the purposes of visualization and computing statistics. For specific details on the chart comparisons for survey H12519, refer to Section D.1.1 - Raster Charts, and Section D.1.2 - Electronic Navigation Charts.34TIN and interpolated surface generated from ENC US4AK44M for the purposes of a chart comparison to survey H12519.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_D_1_1_TIN.png1742427378000092009-102013-06-112013-03-30A comparison was performed between survey H12519 and Chart 17424 (1:80000) using CARIS sounding and contour layers derived from the 32-meter combined surface. The contours and soundings have been overlaid on the chart, and representative areas are shown in Figures 35 and 36. Throughout the survey, the 100-fathom contour is very closely modeled by the survey data; however the 3-fathom contour has likely been pulled offshore for cartographic reasons and is seldom correctly modeled. Likewise, in the narrow band often seen along the shoreline of Chart 17424 (i.e. blue tint), most soundings between the 3-fathom and 100-fathom contour have been pulled offshore for cartographic reasons. Given the extreme steep and deep nature of the bathymetry, the 3-fathom contour is inappropriate for this area and the Hydrographer recommends removing it from the chart. For a further discussion of the sounding by sounding comparisons, refer to Section D.1.2 - Electronic Navigation Charts. It is recommended that H12519 data supersede all charted depths on Chart 17424. 35Close-up of Channel Island and Walker Cove, showing comparison of contours derived from survey H12519 and those depicted on Chart 17424.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_D_1_1_X2_Chart_Compare_Raster_N.png36Close-up of Sargent Bay and Manzanita Bay, showing comparison of contours derived from survey H12519 and those depicted on Chart 17424.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_D_1_1_X2_Chart_Compare_Raster_S.pngUS4AK44M8000022011-12-122011-12-12falseENC US4AK44M coincides with raster Chart 17424. To compare soundings, a TIN surface was created from the ENC depth features (soundings and contours). A 16-meter surface from H12519 was then differenced from the ENC TIN (Figure 37). Positive (red) values show where survey H12519 is shoaler than the TIN and negative (blue) values show where survey H12519 is deeper than the TIN. Overall, the surveyed depths and charted soundings agree well in the center of the channel; otherwise, there is a tendency for the chart to express a shoal biasing in the soundings (sometimes by over 10 fathoms). Figure 38 shows a close-up of the depth comparisons in the vicinity of Channel Island. One can see how all the soundings near shore (shoaler than 100 fathoms) are typically much shoaler than H12519 depths (likely because the soundings were pulled offshore for cartographic reasons). Figure 38 also shows that, generally, the survey and chart agree in the immediate vicinity of most of the charted depths (the areas of gray around all the charted soundings); suggesting that most of the discrepancies between the two sources may be an artifact of the interpolation process used to create the TIN surface.37Difference surface between depth estimates from survey H12519 and an interpolated surface created from the soundings and contours of ENC US4AK44M.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_D_1_1_Chart_Compare_ENC_diff.png38Close-up view of Channel Island and difference surface between depth estimates from survey H12519 and the TIN surface. Charted nearshore soundings appear to have been pulled offshore for cartographic reasons; otherwise, there is good general agreement in the immediate vicinity of the charted soundings.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/Figure_D_1_1_X3_Chart_Compare_ENC_diff_inset.pngNo AWOIS items were assigned for this survey.No Maritime Boundary Points were assigned for this survey.No charted features exist for this survey.No uncharted features exist for this survey.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.Twenty one bottom sample locations were identified in the Project Reference File. Thirteen assigned bottom samples, where depths exceeded 100 meters, were not acquired due to equipment limitations. Eight bottom sample locations were selected based on feasibility and distribution throughout the survey area (Figure 39). Acquired bottom samples are addressed, as required, with S-57 attribution and recorded in the Final Features File accompanying this submission.39Bottom samples in H12519.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_bottomsample_pic2.pngShoreline verification was conducted near predicted low water in accordance with the applicable sections of the NOAA HSSDM and FPM. There were 56 assigned features for this survey. All features were addressed as required with S-57 attribution and recorded in the H12519 Final Features File to best represent the features at chart scale.No prior survey comparisons exist for this survey.No Aids to navigation (ATONs) exist for this survey.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.A large underwater feature, which appears to be a volcano, was discovered at the southern region of H12519 near Sargent Bay (Figure 40). The feature rises over 150 meters from the seafloor to a least depth of 62 meters. 40Volcano-like feature discovered in the southern region of H12519.file:///K:/Projects/2013_Projects/OPR-O193-RA-13,%20Behm%20Canal,%20AK/Surveys/H12519/Descriptive_Report/Report_Body/Images_DR/H12519_MtBuesseler.pngNo 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.Richard T. Brennan, CDR/NOAACommanding Officer, NOAA Ship RAINIER2013-08-09Michael O. Gonsalves, LT/NOAAField Operations Officer, NOAA Ship RAINIER2013-08-09James B. JacobsonChief Survey Technician, NOAA Ship RAINIER2013-08-09Bart O. Buesseler, LTJG/NOAAJunior Officer, NOAA Ship RAINIER2013-08-09