Identification_Information: Citation: Citation_Information: Originator: Macpherson, A.E. Originator: Nicolsky, D.J. Originator: Suleimani, E.N. Publication_Date: 2014 Title: Digital elevation models of Skagway and Haines, Alaska: Procedures, data sources, and quality assessment Geospatial_Data_Presentation_Form: report and digital data Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 155 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 15 p. Online_Linkage: http://dx.doi.org/10.14509/29143 Description: Abstract: In May 2014 the Geophysical Institute at the University of Alaska Fairbanks (UAF) developed integrated bathymetric‐topographic digital elevation models (DEMs) of Skagway and Haines, Alaska, for the National Tsunami Hazard Mitigation Program (NTHMP). The DEMs are designed to fit within a nested hierarchy of similar DEMs of larger spatial extent but coarser resolution. The gridded DEMs will be used to support modeling of tsunami generation, propagation, and inundation. This report describes the various source datasets, data processing tasks and techniques, the surface interpolation, and quality assessment of the seamless 8/15-arc‐second (~15 m) bathymetric-topographic DEMs. The data files are provided as ASCII raster grids with an open end-user license. Purpose: In May 2014 the Geophysical Institute at the University of Alaska Fairbanks (UAF) developed integrated bathymetric‐topographic digital elevation models (DEMs) of Skagway and Haines, Alaska, for the National Tsunami Hazard Mitigation Program (NTHMP). The DEMs are designed to fit within a nested hierarchy of similar DEMs of larger spatial extent but coarser resolution. The gridded DEMs will be used to support modeling of tsunami generation, propagation, and inundation. Supplemental_Information: The DGGS metadata standard extends the FGDC standard to include elements that are required to facilitate our internal data management. These elements, referred to as "layers" group and describe files that have intrinsic logical or topological relationships and correspond to subdirectories within the data distribution package. The metadata layer provides an FGDC metadata file and may include other documentation files. Attribute information for each data layer is described in this metadata file under the "Entity_and_Attribute_Information" section. Data layer contents: >border: A polygon shapefile that provides a generalized outline of the geographic area described by this report. >haines-dem: bathymetric and topographic data in ASCII raster format >skagway-dem: bathymetric and topographic data in ASCII raster format Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2014 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -135.540082 East_Bounding_Coordinate: -135.283877 North_Bounding_Coordinate: 59.495481 South_Bounding_Coordinate: 59.188017 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: Bathymetry Theme_Keyword: Digital Elevation Model Theme_Keyword: Inundation Theme_Keyword: Modeling Theme_Keyword: Topography Theme_Keyword: Tsunami Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Haines Borough Coastal District Place_Keyword: Municipality of Skagway Coastal District Access_Constraints: This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below). Use_Constraints: Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: GIS Manager Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Electronic_Mail_Address: dggsgis@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Data_Set_Credit: The authors thank Kelly Carignan (Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder) for sharing her time and knowledge; and George Plumley (State of Alaska, Division of Community and Regional Affairs, DCRA) for providing data used in developing the Skagway DEM. This project was supported by the National Oceanic and Atmospheric Administration under Reimbursable Services Agreement ADN 0931000 with the State of Alaska's Division of Homeland Security and Emergency Management (a division of the Department of Military and Veterans Affairs). Data acquisition for this publication is sponsored by the Cooperative Institute for Alaska Research with funds from NOAA under cooperative agreement NA08OAR4320751 with the University of Alaska Fairbanks. We thank Ken Macpherson (Alaska Earthquake Center) for his help with the RTK GPS survey in Haines and Skagway, and Nicole Kinsman (Alaska Division of Geological & Geophysical Surveys) for her valuable comments and suggestions to improve the manuscript. Cross_Reference: Citation_Information: Originator: Hickman, P.J. Originator: Suleimani, E.N. Originator: Nicolsky, D.J. Publication_Date: 2012 Title: Digital elevation model of Sitka Harbor and the city of Sitka, Alaska: Procedures, data sources, and quality assessment Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 144 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 38 p Online_Linkage: http://dx.doi.org/10.14509/23964 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The accuracy of this elevation grid is dependent on the accuracy of its source data. The primary limiting factors include the scale, age, and resolution of the surveys. A significant amount of quality control was performed on the grid, using initial data points and other sources for comparison. Logical_Consistency_Report: We constructed two new 8/15-arc second bathymetric-topographic DEMs to support numerical tsunami wave inundation modeling and mapping in the communities of Skagway and Haines, Alaska. The spatial resolution of these grid cells satisfies NOAA minimum recommended requirements for computation of tsunami inundation. Additional requirements are detailed by the NTHMP Mapping & Modeling Subcommittee. The new DEMs were also produced in accordance with NGDC best practices, using the highest-resolution and most current hydrographic surveys, and the best topographic datasets available to us at this time. We ensured that the horizontal geographic coordinates for all data points incorporated during the construction of this DEM are correctly referenced to the WGS84 horizontal datum and that all of the depth values are referenced to the MHHW vertical datum. A detailed discussion of the methods and sources used to generate these files can be found in the accompanying report. Completeness_Report: The completed Skagway and Haines DEMs were visually compared to nautical charts, topographic maps, and high-resolution imagery. A color classification was applied to the seamless DEM to separate positive and negative values. The coastline was meticulously scrutinized with respect to both the final coastline vector data and high-resolution imagery in GINA's Best Data Layer Web Mapping Service. Final DEMs were reviewed in three-dimensional (3-D) space using Quick Terrain Modeler software and ESRI ArcScene. The DEMs were also compared closely to the UAF GPS collection using a custom MatLab program to check for inconsistencies, to adjust contouring along the shore, and to improve the depiction of breakwaters and jetties where there were sparse source data points. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: A comparison of the UAF-surveyed GPS points to the existing NGDC 8/3-Arc Second DEM for Southeast Alaska versus the UAF GPS points as compared to the new Skagway and Haines DEMs shows a marked improvement for elevations at these surveyed areas. Histograms and specific summary statistics of these results are provided in figures 12-18 of the accompanying report. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: A comparison of the UAF-surveyed GPS points to the existing NGDC 8/3-Arc Second DEM for Southeast Alaska versus the UAF GPS points as compared to the new Skagway and Haines DEMs shows a marked improvement for elevations at these surveyed areas. Histograms and specific summary statistics of these results are provided in figures 12–18 of the accompanying report. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Caldwell, R.J. Originator: Eakins, B.W. Originator: Lim, E. Publication_Date: 2011 Title: Digital elevation models of Prince William Sound, Alaska-Procedures, data sources and analysis Series_Information: Series_Name: NOAA Technical Memorandum Issue_Identification: NESDIS NGDC-40 Publication_Information: Publication_Place: United States Publisher: National Geophysical Data Center, Marine Geology and Geophysics Division Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2011 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: Caldwell, R.J. and others, 2011 Source_Contribution: DEM Development Process_Step: Process_Description: Coastline - Digital MHW coastline positions were extracted from National Oceanic and Atmospheric Administration's (NOAA's) Office of Coast Survey (OCS) ENC (Electronic Navigational Chart) Direct-to-GIS online extraction service1. A cartographic coastline dataset created by the Alaska Department of Natural Resources, Information Resource Management Section, at a scale of 1:63,3602, was downloaded from the Alaska State Geo‐Spatial Data Clearinghouse (ASGDC). The coastlines were compared and edited to match high-resolution imagery and topographic data provided by the Alaska Mapped3 program and the Geographic Information Network of Alaska's (UAF-GINA's) Best Data Layer Web Mapping Service to create a final coastline product. The ENC coastline conformed most closely to the imagery but did contain some gaps that required manual, heads‐up digitizing from the imagery at a scale of roughly 1:3,000. A complete list of references can be found in the accompanying report. Process_Date: 2014 Process_Step: Process_Description: Bathymetry - We assembled various bathymetric data. Bathymetric data were transformed to WGS84 and MHHW datums as needed. Where recent, higher-resolution data exist, older data were ignored. Vertical datum transformations were conducted with a sole-station offset based on the NOAA tide station (tidal station # 9452400) in Skagway. Because Haines is in close proximity to Skagway, connected by deep water, and has no independent tide station, we infer the local MHHW datum for Skagway as a best-available approximation for the local MHHW datum in Haines. A complete list of references can be found in the accompanying report. Process_Date: 2014 Process_Step: Process_Description: Topography - We evaluated several sources of topographic data for use in this project. Alaska's Division of Community and Regional Affairs (DCRA) provided topographic data for Skagway. No comparable DCRA dataset exists for Haines and further research did not reveal any other suitable topographic data. ArcGIS was used to transform the CAD files (DCRA dataset) to shapefiles. The National Elevation Dataset (NED) DEM provided full topographic coverage at 1/3-arc second. Vertical datum transformations were based on the NOAA tide station in Skagway. Topographic data used in developing the Skagway and Haines DEMs is listed in table 4 of the accompanying report. Process_Date: 2014 Process_Step: Process_Description: RTK GPS Data Collection - The available topographic datasets are augmented with a real-time kinematic (RTK) GPS survey in the harbor areas and along nearshore areas in Skagway and Haines. The survey in Skagway was conducted October 18-20, 2013, and the survey in Haines October 22-24, 2013. The collected GPS measurements had 0.03-0.05 m (1.2-2 in) horizontal and vertical accuracy with respect to the base station (Leica Geosystems AG, 2002). To achieve sub-meter accuracy for all GPS measurements relative to the MHHW datum, the base station must be linked to the MHHW datum with sub-meter accuracy. This level of accuracy can be achieved if the base station is set up at an established tidal benchmark with a known geodetic elevation. No conveniently located tidal benchmark was available in Skagway for this survey, and there are no listed tidal benchmarks in Haines8. Therefore, we converted the collected GPS measurements to the MHHW datum using a technique described in the the accompanying report. Process_Date: 2014 Process_Step: Process_Description: DEM Development - After horizontal and vertical transformations were applied in ArcGIS, the resulting ESRI shapefiles were reviewed in ArcMap and QT Modeler for consistency among datasets. Problems and errors were identified and resolved before proceeding with subsequent gridding steps. Some fixes and preliminary steps included: Where there were inconsistent, overlapping bathymetry and topography datasets, older data were clipped to newer data and only used in those areas where gaps in newer data coverage existed. The NED topographic data were clipped to the adjusted ENC coastline. A careful visual inspection of the bathymetric/topographic interface was conducted to ensure there were no artificial cliffs in the DEM. This area displays a rugged coastline with some steep cliffs along the shore and the DEM was inspected to confirm these also appeared correctly in the final dataset. Bathymetric data were lacking in the delta region of McClellan mudflats, so MHW elevations were pulled from existing NOAA DEM at 8/3-arc‐second resolution, transformed, and edited to more smoothly transition to the boundary with NOS survey data and topographic data. The central flat area was adjusted to zero elevation and then interpolated toward the coast and deeper waters where survey data existed. Elevations at Haines Airport runway were adjusted minimally (less than 1 m) to match documented survey elevations. We used the shapefiles discussed in the preceding sections of this report as input into the Tensioned Spline function of ArcGIS' Spatial Analyst extension to construct the seamless bathymetric-topographic DEM. The Tensioned Spline tool performs a spline interpolation of input data‐point values to create a raster dataset in which the surface passes exactly through the input x-y-z data and interpolates values for cells with no data. A weight parameter of 1 was used in order to create a surface that closely fits the input control points. The use of this interpolation method conforms to techniques used for the creation of other NGDC DEM products. Source_Used_Citation_Abbreviation: Caldwell, R.J. and others, 2011 Process_Date: 2014 Process_Step: Process_Description: DEM Analysis - The completed Skagway and Haines DEMs were visually compared to nautical charts, topographic maps, and high-resolution imagery. A color classification was applied to the seamless DEM to separate positive and negative values. The coastline was meticulously scrutinized with respect to both the final coastline vector data and high-resolution imagery in GINA's Best Data Layer Web Mapping Service. Final DEMs were reviewed in three-dimensional (3-D) space using Quick Terrain Modeler software and ESRI ArcScene. The DEMs were also compared closely to the UAF GPS collection using a custom MatLab program to check for inconsistencies, to adjust contouring along the shore, and to improve the depiction of breakwaters and jetties where there were sparse source data points. Process_Date: 2014 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: raster Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.000411 Longitude_Resolution: 0.000411 Geographic_Coordinate_Units: decimal degrees Geodetic_Model: Horizontal_Datum_Name: World Geodetic System of 1984 Ellipsoid_Name: WGS 84 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257223563 Vertical_Coordinate_System_Definition: Depth_System_Definition: Depth_Datum_Name: Mean Higher High Water Depth_Resolution: 1.0 Depth_Distance_Units: meters Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: border Entity_Type_Label: mp155-border Entity_Type_Definition: A polygon shapefile that provides a generalized outline of the geographic area described by this report. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (DGGS) Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: haines-dem Entity_Type_Label: mp155-haines-dem Entity_Type_Definition: Bathymetric and topographic data in ASCII raster format Entity_Type_Definition_Source: Alaska Earthquake Center, University of Alaska Fairbanks Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: skagway-dem Entity_Type_Label: mp155-skagway-dem Entity_Type_Definition: Bathymetric and topographic data in ASCII raster format Entity_Type_Definition_Source: Alaska Earthquake Center, University of Alaska Fairbanks Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Facsimile_Telephone: (907)451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Contact_Instructions: Please view our website (http://www.dggs.alaska.gov) for the latest information on available data. 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User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys. Metadata_Extensions: Online_Linkage: http://www.dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions