High resolution lidar-derived elevation data for Barry Arm landslide, Southcentral Alaska, June 26, 2020

Daanen, R.P. Wolken, G.J. Wikstrom Jones, Katreen Herbst, A.M. 2021 High resolution lidar-derived elevation data for Barry Arm landslide, Southcentral Alaska, June 26, 2020 report, point cloud, GeoTIFF Raw Data File RDF 2021-3 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 9 p. https://doi.org/10.14509/30593 The Alaska Division of Geological & Geophysical Surveys (DGGS) used aerial lidar to produce a classified point cloud and high-resolution digital terrain model (DTM), digital surface model (DSM), and intensity model of the Barry Arm landslide, northwest Prince William Sound, Alaska, during near snow-free ground conditions on June 26, 2020. The survey's goal is to provide high quality and high resolution (0.10 m) elevation data to assess potential landslide movement. Aerial lidar and ground control data were collected on June 26, 2020, and subsequently processed in Terrasolid and ArcGIS. Ground control was collected on June 26, 2020, as well. This data collection is released as a Raw Data File with an open end-user license. All files can be downloaded free of charge from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30593). The survey's goal is to provide high quality and high resolution (0.10 m) elevation data to assess potential landslide movement. >classified point cloud data: Classified point cloud data is provided in this collection in compressed LAZ format. Data are classified in accordance with ASPRS 2014 guidelines and contain return and intensity information. The average pulse spacing was 1.8 cm and the average density was 53.8 pts/m2 (figure 2). >digital surface model: The DSM represents surface elevations, including heights of vegetation, buildings, bridges, etc. The DSM is a single band, 32-bit GeoTIFF file, with a ground sample distance of 10 centimeter. No Data value is set to -3.40282306074e+038. >digital terrain model: The DTM represents surface elevations of ground surfaces, excluding vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of 10 centimeters. No Data value is set to -3.40282306074e+038. >lidar intensity image: The lidar intensity image portrays the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is largely a function of scanned object reflectance in relation to the signal frequency, is dependent on ambient conditions, and is not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit float GeoTIFF file with a ground sample distance of 10 centimeters. No Data value is set to -3.40282306074e+038 (32-bit, floating-point minimum). 20200626 ground condition complete None planned -148.182397 -148.114463 61.176522 61.122558 ISO 19115 Topic Category geoscientificInformation Alaska Division of Geological & Geophysical Surveys Aerial Aerial Geology Aerial Photography Debris Avalanche Debris Flow Digital Elevation Model Digital Surface Model (DSM) Digital Terrain Model Elevation Engineering Engineering Geology Geologic Geologic Hazards Geological Process Geology Geomorphology Geotechnical Glacial Glacial Deposits Glacial Geology Glacial Geomorphology Glacial Processes Landslide Landslide Susceptibility LiDAR Point Cloud Data Remote Sensing Rock Avalanche Rockfall Slope Slope Instability Surface Surficial Surficial Geology Topography Tsunami Unconsolidated Deposits Web Service Alaska Division of Geological & Geophysical Surveys Barry Arm Barry Glacier College Fjord Esther Island Harriman Fiord Passage Canal Port Wells Whittier 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). 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. Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5020 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible. These data products were funded by the State of Alaska and collected and processed by DGGS. We thank Clearwater Air and Alpine Air for their aviation expertise and contribution to these data products. Daanen, R.P. Wolken, G.J. Wikstrom Jones, Katreen Herbst, A.M. 2021 Lidar-derived elevation data for upper Barry Arm, Southcentral Alaska, June 26, 2020 Raw Data File RDF 2021-1 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 9 p https://doi.org/10.14509/30589 Stevens, D.S.P. Wolken, G.J. Hubbard, T.D. Hendricks, K.A. 2018 Landslides in Alaska Information Circular IC 65 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 2 p https://doi.org/10.14509/29849 Stevens, D.S.P. 2019 The Engineering Geology section at DGGS Information Circular IC 76 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 2 p https://doi.org/10.14509/30122 Timm, Kristin Wolken, G.J. 2017 Deglacierization and the development of glacier-related hazards Information Circular IC 63 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 3 p https://doi.org/10.14509/29752 Wolken, G.J. Hendricks, K.A. Daanen, R.P. Overbeck, J.R. Stevens, D.S.P. Masterman, S.S. 2017 Alaska & climate change Information Circular IC 64 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 2 p https://doi.org/10.14509/29781 Not applicable Relative accuracy for this dataset was evaluated as the interswath overlap consistency and was measured at 8.3 cm RMSE. The data quality is consistent throughout the survey. The tests and processing methods used to ensure data consistency are further described in the accompanying report. This data release is complete, and there is no over collect, except for the aircraft turns that were eliminated from the dataset. Horizontal accuracy was not measured for this collection. A mean offset of -19.7 cm was measured between 84 control points and the point cloud (appendix 1). This offset was reduced to -0.6 cm by performing a vertical transformation of the lidar point data. Twenty-two check points were used to determine the non-vegetated vertical accuracy (NVA) of the point cloud ground class, using a tin-based approach. Project NVA was calculated to have a root mean square error (RMSE) of 7.7 cm (appendix 2). See accompanying report for more detail. Airborne survey - The aerial survey was flown on June 26, 2020, with a Cessna 180. Flight take-off occurred at 10:15 am from Merrill Field airport in Anchorage, Alaska, and landing occurred at 4:00 pm. The aircraft landed at the airstrip in Girdwood, Alaska, once during the survey. The weather throughout the survey was overcast. DGGS used a Riegl VUX1-LR laser scanner integrated with a global navigation satellite system (GNSS) and Northrop Grumman LN-200C inertial measurement unit (IMU). Phoenix LiDAR Systems designed the lidar integration system. The sensor is capable of collecting up to 820,000 points per second over a distance of 150 m. This survey was flown with a pulse refresh rate between 200,000 and 600,000 pulses per second at a scan rate between 80 and 150 lines per second. This survey was flown with an average elevation of 200 m above ground level and a ground speed of approximately 36 m/s with a fixed-wing aircraft configuration, using a Cessna 180 aircraft. The scan angle was set from 80 to 280 degrees. The total area surveyed on the mission was approximately 40 km2. The focused area of interest depicted in the location map is approximately 6.1 km2 and, to achieve a higher pulse density and hence a higher resolution product for this section, was flown with the highest pulse refresh rate and scan rate from the above mentioned ranges. 20200626 Ground survey - Ground control and check points were collected on June 26, 2020. A Trimble R10-2 GNSS receiver with internal antenna was deployed on a ridge near the center of the study area and provided a base station occupation and real-time kinematic (RTK) corrections to points surveyed with a rover Trimble R10-2 GNSS receiver (internal antenna). A total of 106 ground control points and check points were collected to be used for calibration and assessment of the vertical accuracy of the point cloud. All points were collected on bare earth or minimally vegetated surface. 20200626 Lidar dataset processing - Point data were processed in SDCimport software for initial filtering and multiple-time-around (MTA) disambiguation. MTA errors, corrected in this process, result from imprecise interpretations of received pulse time intervals and occur more frequently with higher pulse refresh rates. IMU and GNSS data were processed in Inertial Explorer and used to integrate flightline information with the point cloud in Spatial Explorer software. The point data were calibrated at an incrementally precise scale of sensor movement and behavior, incorporating sensor velocity, roll, pitch, and yaw fluctuations throughout the survey. Points were classified in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) 2014 guidelines, using macros designed in Terrasolid software. Careful attention was given to the interpolation of the project's ground surface to compensate for inconsistent penetration through low vegetation as a function of the scan angle. Once classified, points underwent a geometric transformation and were converted from ellipsoidal heights to GEOID12B (Alaska) orthometric heights. Raster products were derived from the point cloud, using ArcMap. The DTM was interpolated from all ground class returns using a tin-based method. The DSM was interpolated from only the first return points using a tin-based method. An intensity image was also produced in ArcMap, using closest-to-mean binning. 2020 raster Universal Transverse Mercator 6 0.999600 -147 0 500000.000000 0 coordinate pair .00000001 .00000001 Meters NAD83 (2011) GRS 80 6378137 298.257222101000025 NAVD88, GEOID12B 0.001 meters Explicit elevation coordinate included with horizontal coordinates classified point cloud data Classified point cloud data is provided in this collection in compressed LAZ format. Data are classified in accordance with ASPRS 2014 guidelines and contain return and intensity information. The average pulse spacing was 1.8 cm and the average density was 53.8 pts/m2 (figure 2). Alaska Division of Geological & Geophysical Surveys (DGGS) classified point cloud data digital surface model The DSM represents surface elevations, including heights of vegetation, buildings, bridges, etc. The DSM is a single band, 32-bit GeoTIFF file, with a ground sample distance of 10 centimeter. No Data value is set to -3.40282306074e+038. Alaska Division of Geological & Geophysical Surveys (DGGS) digital surface model digital terrain model The DTM represents surface elevations of ground surfaces, excluding vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of 10 centimeters. No Data value is set to -3.40282306074e+038. Alaska Division of Geological & Geophysical Surveys (DGGS) digital terrain model lidar intensity image The lidar intensity image portrays the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is largely a function of scanned object reflectance in relation to the signal frequency, is dependent on ambient conditions, and is not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit float GeoTIFF file with a ground sample distance of 10 centimeters. No Data value is set to -3.40282306074e+038 (32-bit, floating-point minimum). Alaska Division of Geological & Geophysical Surveys (DGGS) lidar intensity image Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5020 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. 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. https://dggs.alaska.gov/metadata/dggs.ext dggs metadata extensions