In this Chapter, you will learn about:

• GeoBase, the primary source of framework data in Canada
• The important technical characteristics of GeoBase data
• Details of each of the currently available GeoBase data themes including: a description, online sources of documentation, metadata details, use and restrictions, available access data formats, and current status
• New data themes that are planned
• Navigating GeoBase and downloading GeoBase data to your own computer

GeoBase is a set of common, up-to-date and maintained framework data covering all of Canada. Multiple levels of government work together to collect and maintain the data.

In 2003, seven data themes or layers having national coverage were made available to the Canadian framework data user community via the GeoBase portal and in 2007 and 2008 the eighth and ninth data themes were added. By 2010, one additional data theme will be available. Other data themes are also under consideration for future additions <See New Data Themes>.

Currently the GeoBase portal contains the nine framework data themes or layers described in the following sections.

The Canadian Digital Elevation Data (CDED) layer consists of an ordered array of ground elevations at regularly spaced intervals. CDED plays a similar role to contours and relief shading on conventional paper maps (i.e., it allows users to see the differences in elevation between different features shown on the map) but is more powerful analytically. For example, you can use CDED for determining orientation and the slope of each point when used in GIS applications, for terrain modeling, for calculating the influence of the terrain on line-of-sight, for radar imaging, for simulating flooding, and similar applications.

The Canadian Geodetic Network contains horizontal and vertical geodetic control information for thousands of geodetic markers or monuments (i.e., permanent and stable survey markers for which precise coordinates have been established) distributed across Canada. The point information for each marker includes geographic and UTM coordinates, orthometric height, marker information description, and inspection data.

The Canadian Geographical Names Database (CGNDB) is the data bank of Canada's geographical names maintained by Natural Resources Canada, examples of which are shown in the following figure. The CGNDB stores the names and attributes of geographical locations (e.g., municipalities, rivers, lakes, etc.) that have been approved by the Geographical Names Board of Canada (GNBC). These authoritative records are made available for government and public use. Changes to the CGNDB are provided by naming authorities across Canada.

The Administrative Boundaries layer is currently made up of two types of boundaries:

• Canadian geopolitical boundaries
• Aboriginal lands

The National Hydro Network (NHN) is framework data representing the inland surface waters of Canada. The NHN is the evolution from a graphical representation of Canada’s inland surface waters (i.e., topographic maps that show only the locations and names of water features) to an intelligent network organized by drainage basins, or watersheds (i.e., data that includes not only locations and names of, but also the connections between, different water features). It provides geospatial vector data describing hydrographic features such as lakes, reservoirs, rivers, streams, canals, islands, obstacles (e.g. waterfalls, rapids, rocks in water) and constructions (e.g. dams, wharves, dikes), as well as a linear drainage network and the toponymic information (geographical names) associated with hydrography.

GeoBase offers access to over 1,000,000 kilometres of accurate, up-to-date road network data as illustrated in the figure below. The National Road Network (NRN) is a representation of the centerline of all non-restricted use roads in Canada (5 meters or more in width, drivable and with no barriers denying access). NRN data is composed of a network of line, point, and related descriptive attributes.