Description: This dataset is derived from the multi-resolution National Elevation Dataset (NED), at resolutions of both 1/3 arc-second (approx. 10 meters) and in limited areas, 1/9 arc-second (approx. 3 meters). Contours derived from this data may appear to have “shifted” when compared to the 7.5 minute USGS Quad Maps, i.e., Digital Raster Graphics, for a variety of reasons: 1) The NED is a multi-resolution dataset, e.g., areas with LiDAR source data have superseded the original "quad" contours; 2) A result of the original contour vectors undergoing a NAD27 to NAD83 conversion, then the contour vector-to-raster resampling that produced the initial grid, followed by a resampling of that initial 10m grid to the 1/3 arc-second NED (~10.29m) and finally the raster-to-vector conversion yielding the current contours. VCGI extracted the Vermont portion of the NED and re-projected into Vermont State Plane Meters NAD83 (vertical units in feet). Production artifacts were filtered out of this source data prior to acquisition resulting in a much-improved base of elevation data for calculating contours, slope and hydrologic derivatives. The NED is the primary elevation data product produced and distributed by the USGS. The NED provides the best available public domain raster elevation data of the conterminous United States, Alaska, Hawaii, and territorial islands in a seamless format. The NED is derived from diverse source data, processed to a common coordinate system and unit of vertical measure. The source data are distributed in geographic coordinates in units of decimal degrees, and in conformance with the North American Datum of 1983 (NAD 83). The source elevation values are provided in units of meters, and are referenced to the North American Vertical Datum of 1988 (NAVD 88) over the conterminous United States. The NED is updated on a nominal two month cycle to integrate newly available, improved elevation source data.
Name: VT Data - Hydro-Flattened/Hydro-Enforced Breaklines from QL2 Lidar
Display Field: B_LINE_TY
Type: Feature Layer
Geometry Type: esriGeometryPolyline
Description: This metadata applies to hydrologic break lines derived from Quality Level 2 (QL2) Lidar 'collections' with a resolution (RESCLASS) of 0.7m. For an overview of the VCGI Lidar Program please see 'VCGI.VERMONT.GOV/LIDAR'. For specific details on each project extent's 'point cloud', e.g., flight dates, nominal pulse spacing and RMSEz etc., see the VCGI LiDAR data product page for links to each extents vendor based metadata - http://vcgi.vermont.gov/warehouse/products/ALL-LDR_MIX_LIDAR_STATE_ALL. NOTE - QL2 hydrologic breaklines were produced from 5 individual collections possessing slightly different datums: 2017 Western VT - NAD 83 (2011); 2016 Mid-CT River VT - NAD 83 (2011); 2015 Windham_VT - NAD 83 (NSRS 2007); 2014 'Eastern' VT - NAD 83 (2011); 2013 Rutland_VT_Lidar_Data - NAD 83. Refer to vendor based metadata for detailed coordinate reference information. For the range of ground collection dates, by collection, see the various "Source Citation" sections below.
Copyright Text: The following Federal, State and Local partners of the VCGI Lidar Program: U.S. Geological Survey, National Resource Conservation Service, U.S. Forest Service, FEMA, USACE, UVM Spatial Analysis Lab, VT Assoc. of Planning & Dev. Agencies, Chittenden County RPC, Southern Windsor County RPC, Two Rivers-Ottauquechee Regional Commission, VCGI, VT Agencies of Agriculture, Natural Resources & Transportation and the Lake Champlain Basin Program.