Dewberry 20210429 raster digital data Product: These are Digital Elevation Model (DEM) data for Niagara , New York, as part of the required deliverables for the 2019 New York FEMA Central Lidar WUID 172460 project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened Raster DEM. Geographic Extent: Niagara County, New York, covering approximately 577 square miles. Dataset Description: 2019 New York FEMA Central Lidar WUID 172460 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 1.3. The data was developed based on a horizontal datum/projection of NAD83 (2011), Universal Transverse Mercator, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 740 individual 1500 m x 1500 m tiles, as tiled bare earth DEMs; all tiled to the same 1500 m x 1500 m schema. The tile grid contains 740 tiles and there are 740 DEMs delivered. There are 739 LAS delivered due to one LAS tile having no lidar points within the boundary due to 100% water within a tidal area. All tiled to the same 1500 m x 1500 m schema. Ground Conditions: Lidar was collected in early 2019, 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, Dewberry established a total of 219 ground control points that were used to calibrate the lidar to known ground locations established throughout the NY FEMA Central project area. An additional 19 independent accuracy checkpoints, 11 in Bare Earth and Urban landcovers (11 NVA points), 8 in Tall Grass and Brushland/Low Trees categories (8 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. 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. Raster File Type = TIFF 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 20190104 20190104 ground condition Complete None planned -79.086603 -78.438332 43.394979 43.001402 655925.152274 707501.560021 4806478.290546 4764115.525302 None Model Raster DEM Remote Sensing Elevation Data Lidar None New York Niagara County No restrictions apply to these data. None. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these 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. Data covers the entire area specified for this project. Datasets contain complete coverage of tiles. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. There are no void areas or missing data. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications. This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class. Hydro Flattened Raster DEM Process: Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened Raster DEM. Using LP360, a GeoTIFF file was created for each tile. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface. 20210401 Raster Pixel 1500 1500 Universal Transverse Mercator 17 0.9996 -81.000000 0.0 500000 0.0 row and column 1 1 meters North American Datum of 1983 (2011) Geodetic Reference System 80 6378137 298.257222101 North American Vertical Datum of 1988, Geoid 12B 1 meters Explicit elevation coordinate included with horizontal coordinates 20230309 20230309 Dewberry mailing and physical

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