ASPECT of Newfoundland Watershed 02ZA000

The following data has been taken from the Canadian Digital Elevation Model: Product Specifications - Edition 1.1: The Canadian Digital Elevation Model (CDEM) for Newfoundland. The CDEM stems from the existing Canadian Digital Elevation Data (CDED). The latter were extracted from the hypsographic and hydrographic elements of the National Topographic Data Base (NTDB) at the scale of 1:50 000, the Geospatial Database (GDB), various scaled positional data acquired by the provinces and territories, or remotely sensed imagery. These product specifications apply to the Canadian Digital Elevation Model (CDEM). The CDEM is part of Natural Resources Canada's altimetry system designed to better meet the users' needs for elevation data and products. The CDEM stems from the existing Canadian Digital Elevation Data (CDED). The latter were extracted from the hypsographic and hydrographic elements of the National Topographic Data Base (NTDB) at the scale of 1:50 000, the Geospatial Database (GDB), various scaled positional data acquired by the provinces and territories, or remotely sensed imagery. In the CDEM data, elevations can be either ground or reflective surface elevations. A CDEM mosaic can be obtained for a pre-defined or user-defined extent. Derived products such as slope, shaded relief and colour shaded relief maps can also be generated on demand. The coverage and resolution of a mosaic varies according to latitude and to the extent of the requested area (see Sections 3.3 and 3.4 for further details). The North American Datum 1983 (NAD83(CSRS)) is used as the reference system for horizontal coordinates.1 Elevations are orthometric and expressed in reference to mean sea level. (Canadian Geodetic Vertical Datum of 1928 (CGVD28)). The CDEM plays the same role as contours and relief shading on conventional paper maps. The CDEM serves as key primary data in a range of applications critical to achieving sustainable development. These applications include environmental and ecological impact assessments, water flow and water quality analysis, climate change studies, forest regeneration planning and wildlife habitats. In addition, the CDEM can be used in the generation of three-dimensional graphics displaying terrain slope, profiles and lines of sight. Non-graphic applications include geoid calculations, terrain modelling, flood simulations and telecommunication studies. Spatial resolution within the CDEM data varies according to latitude and to the extent of the area requested by the user. For each of the three geographic areas shown in Figure 1, Section 3.3, there exists a base resolution. The base resolution for CDEM is 0.75 arc seconds along a profile in the south-north direction and varies from 0.75 to 3 arc seconds in the west-east direction, depending upon the geographic location. However, because of file size constraints, resolution be lower than that of the base resolution, at the time of extraction, depending on the extent of the region to be extracted. See Section 3.4 for further details. Elevations are orthometric and expressed in reference to mean sea level (Canadian Geodetic Vertical Datum 1928 (CGVD28)). CDEM elevations are recorded as either ground or reflective surface elevations.The metadata supplied with CDEM mosaics specify whether the elevations are reflective surface or ground. Data was extracted from the Geospatial Data Extraction Tool in NAD 1983 (CSRS). Data was extracted for each drainage area and was mosaiced in ArcPro 2.1.7. Section Pertaining to ASPECT: A relief-derived representation in which every pixel is attributed the value of the azimuth which the slope is facing. Such azimuth value is comprised between 0 and 360, measured in degrees, clockwise, from the north. The value -9999 can also be used in flat areas where the slope value is zero. The resulting product is a 32-bit raster image of azimuth values.