Hydrographic Networks

Water is an important part of the Canadian landscape. It contains 20% of the world's total freshwater resources, and only 7% of which is considered renewable. To help with issues related to water management, Natural Resources Canada provides geospatial surface water data in the form of hydrographic networks. We also collaborate with the United States Geological Survey in cross-border harmonization efforts to offer a continuous network.

Available networks

Hydrographic or hydrospatial networks are datasets containing representations of surface water features. These features can include lakes, reservoirs, rivers, streams, islands, obstacles (e.g., waterfalls) and constructions (e.g., dams, wharves, dikes).

Natural Resources Canada maintains the following hydro networks:

Highlights and differences between the networks

Features	Canadian Hydrospatial Network	National Hydrographic Network
Follows Open Geospatial Consortium Hy-feature standards
Uses automatic extraction
Linear network including water flow direction
Based on high resolution data (where applicable)
Continuous national and international data	In progress
Full ability to traverse network
Value-added attributes for hydrologic modelling including stream order(s)
Hierarchical layers of drainage area (catchment, drainage area, work unit)
Integration of hydrometric stations from Environment and Climate Change Canada
Attributes integrating elevation values (Z)	In progress
Scale (best achieved, approximate)	1:2,000	1:20,000

Importance of hydro networks

Hydro networks have many applications. For example, showing surface water features, and their place names, on a map is key for better spatial comprehension of the map. So the hydro networks are often used as a base layer in simple cartography, but also in more complex analyses. Here are some other examples of how hydro networks are used:  

• Hydrologic and Hydraulic Modelling: networks can be used to model and understand water flow and drainage patterns.
• Environmental Analysis: scientists and technicians can use hydro networks to help with environmental analysis and monitoring.
• Decision-making Support: hydro networks can be used to aid in decision-making, including climate change mitigation, emergency management, and land-use planning.

Work Units – Areas of production and distribution of the networks

Natural Resources Canada’s hydrographic networks are produced and distributed by work units. Like watersheds, work units are different sizes and shapes as seen in Figure 1. They are created to represent different areas of the hydro network and can include different levels of sub-watersheds as seen in Figure 2. Like the surface water features, the work units change over time as data sources are updated.

Here is some technical information about the work units:

• There are more than 1,338 work units covering the entire Canadian landmass.
• Each work unit is a simple polygon without holes.
• The work units form a continuous layer.
• The original work units were created from the Water Survey of Canada Sub-Sub-Drainage Area and Fundamental Drainage Areas of the Atlas of Canada. They have changed over time and may be different from the source boundaries.

As the new Canadian Hydrospatial Network is developed, its work unit boundaries do too. Their shape will differ slightly from the National Hydrographic Network work units since the Canadian Hydrospatial Network and source data varies from the National Hydro Network. The work unit boundaries are available for the Canadian Hydrospatial Network and the National Hydrographic Network.

Find out more

• Use the National Hydrographic Network ready-to-use map
• View the National Hydrographic Network documentation
• See the latest data announcements
• Read the frequently asked questions on geospatial data
• Learn about flood mapping

Contact us

For more information, contact geoinfo@nrcan-rncan.gc.ca.