WATER QUANTITY
Indicators
- Water Levels
- Stream Flows
- Ice Phenology
- Sediment Load
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Current Knowledge
Baseline water quantities (natural amounts) of water in the NWT depend on the physical properties of the land, such as rock and soil, vegetation, slope and permafrost; and latitude. There are three main regions, and two lakes, which are studied: the Northern Cordillera (mountains), Interior Plains, the Precambrian Shield, and Great Bear and Great Slave lakes.
In the Northern Cordillera, streams flow fast, and lakes and wetlands are few. Steam flow peaks during spring snowmelt and immediately after summer rainstorms. In winter, stream flows can fall to very low or zero values. The Interior Plains and Precambrian Shield regions have many lakes and wetlands, which are able to store and release water slowly during the summer months. Peak flow in these regions occurs only in the spring when snow is melting. Great Bear and Great Slave Lakes, because of their size, are able to keep the amount of water flowing out of them relatively constant throughout the year.
There is a network of 75 stations for water quantity monitoring, 22 of which are studied for part of the year only. There is historic information from 50 other sites that are no longer monitored. Data from these stations shows that the amount of water in streams and lakes varies quite a bit from year to year, and from season to season. No trends indicating changes in stream flows have been noticed in the NWT except in the Slave River, Great Slave Lake and the Mackenzie River, which were affected by the Bennett Dam. In order to predict natural variations in river flow, at least 30 years of information are needed, and these records seldom exist.
Changes in timing of freeze-up and break-up, and river travel patterns and routes are unknown. Some information from trading posts and community residents may help, but this information must be interpreted carefully.
Current Monitoring
- Northwest Territories water quantity monitoring program - 75 stations operated by the Water Survey of Canada
- Global Energy and Water Cycle Experiment (GEWEX) - models water and energy cycles on the Mackenzie River
- Lower Carp Lake and Snare River - water balance studies as part of GEWEX
- Tibbit Lake - effects of forest fire, INAC
- Coppermine Cumulative Effects Monitoring Program - water quality and quantity, INAC, Wildfred Laurier University
- Dendrochronology (tree ring width) for stream flow and precipitation - INAC, EC, University of Regina
- Northern Rivers Ecosystem Initiative (NREI) - multiple partners working on pollution prevention, ecological management, contaminants, nutrients, long-range transport, and research in northern rivers
Gaps and Recommendations
In order to have data for comparison with future conditions, information is needed for East Bank tributaries of the Mackenzie River (along proposed gas pipeline route), the Liard basin, the Lockhart and Coppermine basins (related to diamond mine developments) and areas with no development. Specific areas with oil and gas or mineral development need to be monitored.
Long-term information, and links with weather and sediment information need to be improved. As well, recently closed monitoring sites need to be reopened and new ones need to be installed (along the east bank and proposed pipeline route). Tree ring studies need to continue and traditional knowledge of freeze-up and break-up dates and changes in travel patterns and routes needs to be documented.
This summary is based on: A Preliminary State of Knowledge of Valued Components for the NWT Cumulative Impact Monitoring Program (NWT CIMP) and Audit. February 1, 2002; updated February 2005.
For more details, you may also want to look at:
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