The National Hydro Network (NHN) project produces the geospatial hydrography data that forms an information layer for the GeoBase initiative. The GeoBase initiative is a federal, provincial and territorial government initiative that ensures availability and access to a common, up-to-date and maintained set of geospatial data for all of Canada.

Federal and interested provincial and territorial partners carry out the production of the NHN datasets. These partners are selected for their interest and capacity to provide a homogeneous view of the Canadian landmass using the best available data. GSDNR and NRCan's Centre for Topographic Information (CTI) are now working with these partners to develop a national standard for the NHN and to populate the hydrography data layer in GeoBase. The national standard will comply with existing international standards and with new technologies. It will also address issues related to the representation and management of topographic data under the theme of hydrography.

The project is co-funded by GeoConnections, a national partnership working to build the Canadian Geospatial Data Infrastructure to make Canada's geographic data, tools and services readily accessible on-line.

Because this project encompasses key concepts of both hydrography and hydrology to describe Canada's surface water system, the NHN model is flexible enough to support several applications including cartographic representation and data analysis in order to satisfy the requirements of a varied user base.

The NHN is developing two representations of Canada's water supply. The first is a linear hydrographic network that logically links all connected water bodies through their centerlines. The second representation is a more traditional cartographic one that depicts the boundaries of various water bodies. The NHN content includes five key elements: the linear representation of Canada's water supply, the traditional cartographic representation of the network, the events (attribute information), the toponymy and the metadata. The event elements contain class and attribute information that allow the association of hydrographic phenomena with the other network elements.

GSDNR will produce the first version of the NHN with complete national coverage in collaboration with territorial and provincial partners within the next five years. The NHN will be produced from the best available data sources, depending on the region, data resolution, data availability, and data accuracy. Some data will come from provincial and territorial sources with an expected resolution to be at a scale of 1:10,000 or 1:20,000. Accuracies are expected to range from 5 to 25 m. Data coming from federal sources will be at a scale of 1:50,000, with accuracies meeting the national orthoimage framework, i.e.better than 30 m. in accuracy.

Project Priorities:

• Refine the definition of the federal requirements through direct and detailed consultations;
• Establish partnership agreements with other federal, provincial and territorial partners;
• Produce the hydro network in accordance with the national standard using the best available provincial and federal data.

For more information, please contact the project leader: Yves Belzile or the

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