2016 USGS Lidar DEM: Yukon - Kuskokwim River Delta (AK)

Product: These are Digital Elevation Model (DEM) data for AK Yukon-Kuskokwim as part of the required deliverables for AK Yukon-Kuskokwim Lidar 2016 project. Class 2 (ground) lidar points in conjunction with the hydro breaklines and bridge breaklines were used to create a 1 meter hydro-flattened Raster DEM. Due to temporal issues related to tidally influenced streams within the AOI, water heights found in the interior of the project are occasionally higher than heights found along the coast. Occasionally, this will be evident in the digital elevation model.

Geographic Extent: AOI is located in the Yukon-Kuskokwim River delta between the communities of Chevak and Newtok in Western Alaska. Additional satellite areas of interest are located neat the communities of Emmonak, Scammon Bay, and Mekoryuk Alaska. The areas of interest covers approximately 1,650 square miles.

Dataset Description: AK Yukon-Kuskokwim Lidar 2016 project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83, Universal Transverse Mercator, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files, formatted to 4877 individual 1000 m x 1000 m tiles as tiled Intensity Imagery, and as tiled bare earth DEMs; all tiled to the same 1000 m x 1000 m schema. Please note that delivery tiles 03VVH800710 and 03VWH110340 do not contain lidar points. The data boundary minimally intersects these tiles and a hydro breakline was digitized and subsequent DEM and Intensities TIFs were generated. There is no LAS 1.4 for tiles 03VVH800710 and 03VWH110340. The DEM IMG/Intensity tiff file count is 4879. The LAS 1.4 count is 4877.

Ground Conditions: Lidar was collected in late 2016 by Kodiak Mapping of Palmer Alaska , while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Kodiak Mapping established a total of 94 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 165 independent accuracy checkpoints, 117 in Bare Earth and Urban landcovers (117 NVA points), 48 in Tall Grass and Brushland/Low Trees categories (48 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

The NOAA Office for Coastal Management (OCM) downloaded 4879 img files from the USGS site: ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/OPR/AK_Yukon-Kuskokwim_2016/ and processed the data to be available on the Digital Coast Data Access Viewer (DAV).

In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEMs were created from, are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Breakline data are also available. These data are available for download at the link provided in the URL section of this metadata record. These products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

The massive Yukon-Kuskokwim River Delta (the delta) in western Alaska is one of the flattest and most vulnerable regions in Alaska. The delta is roughly 50,000 mi2 and is home to 35+ villages including some of the most imperiled communities in Alaska. The delta is highly vulnerable to coastal flooding associated with storm surges due to its shallow bathymetry, orientation, and low relief. This LIDAR data will be used for many purposes but the primary need is to create digital elevation maps that can meet the needs of emergency response planning, community planning for trails and future infrastructure, and of the resource managers managing this critical habitat. A partnership of six State and Federal entities (U.S. Fish & Wildlife Service; Federal Emergency Management Agency, Natural Resources Conservation Service, Alaska Ocean Observing System, Alaska Division of Geological and Geophysical Service, and the Western Alaska Landscape Conservation Cooperative), combined their resources with the U.S. Geological Survey to obtain LIDAR data for seven rural communities and a large section of critical waterbird habitat. Rural communities covered by the LIDAR acquisition include Emmonak, Scammon Bay, Hooper Bay, Chevak, Mekoryuk, Newtok and the new village site of Mertarvik. The LIDAR data was collected to such that data for immediate coastal areas were acquired at or below mean high tide to improve tidal coordination. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Intensity Images, Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 1 meter cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, hydro-flattened DEMs as necessary.

USGS Contract No. G10PC00057 CONTRACTOR: WoolpertInc. SUBCONTRACTOR: Kodiak Mapping Inc. Lidar data were acquired, calibrated, and filtered to bare earth Kodiak Mapping Inc. All follow-on processing was completed by the prime contractor.

Raster File Type = IMG Bit Depth/Pixel Type = 32-bit float Raster Cell Size = 1 Meter Interpolation or Resampling Technique = Triangulated Irregular Network Required Vertical Accuracy = 19.6 cm NVA

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Lidar Specification v1.2",

"ldrsens" : "Riegl LMS Q780",

"ldrmaxnr" : "7",

"ldrnps" : "0.7",

"ldrdens" : "2",

"ldranps" : "0.7",

"ldradens" : "2",

"ldrfltht" : "2100",

"ldrfltsp" : "110",

"ldrscana" : "60",

"ldrscanr" : "variable",

"ldrpulsr" : "500",

"ldrpulsd" : "3",

"ldrpulsw" : "1.2",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25",

"ldrswatw" : "2200",

"ldrswato" : "50",

"ldrcrs" : "NAD 1983 UTM Zone 3N Meters",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B"

},

"ldraccur" : {

"ldrchacc" : "0.358",

"rawnva" : "0.086",

"rawnvan" : "117",

"clsnva" : "0.086",

"clsvva" : "0.167",

"vvan" : "48"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld (ignore) points were identified in these files using the standard LAS Withheld bit.",

"lasolap" : "Swath "overage" points were identified in these files using the standard LAS overlap bit.",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

Woolpert prepared the original data as set forth in the Scope of Services, in accordance with reasonable care and due diligence as set forth in this Agreement, however, due to the easily alterable nature of electronic media, files, documents, and other deliverables, Woolpert, Inc. makes no warranties, either expressed or implied, with respect to the accuracy, completeness, merchantability, or fitness for any particular purpose, including, but not limited to, use of any/all data as described within this metadata file, by any user of this data. Any use will be at the end-user’s sole risk.

Any conclusions drawn from the analysis of this information are not the responsibility of USGS, Woolpert, Inc., NOAA, the Office for Coastal Management or its partners

Data is available online for custom and bulk downloads.

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.

Not Provided

LAS data covering the AK Yukon Kuskokwim QL2 Lidar Task Order was compared to independent survey control points to determine the NVA of the LAS Swath and of the Bare-Earth DEM. In addition, this LAS data was compared to independent VVA points.

Raw Swath Non-Vegetated Vertical Accuracy (NVA) Tested 0.086 Meters Non vegetated vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported against 117 NVA points using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the TIN using all lidar points.

LAS Swath Non-Vegetated Vertical Accuracy (NVA) Tested 0.076 Meters Non vegetated vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using 0.039 Meters (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines.

Bare-Earth DEM Non-Vegetated Vertical Accuracy (NVA) Tested 0.086 Meters Non vegetated vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using 0.044 Meters (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines.

Vegetated Vertical Accuracy (VVA) Tested 0.167 Meters at the 95th percentile reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM using 48 VVA points. VVA Errors larger than 95th percentile include: Point 2938, Easting 514415.057, Northing 6950578.994, Z-Error 0.169 Meters Point 3212, Easting 430638.430, Northing 6693915.059, Z-Error 0.293 Meters.

These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Data covers the entire area specified for this project.