Peace-Athabasca Delta
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The Peace-Athabasca Delta is a large freshwater, inland delta in northeastern Alberta located where the Peace and Athabasca Rivers join the Slave River at the western end of Lake Athabasca.
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[edit] Conservation
The marshes, lakes and mud flats of this area are an important habitat for waterfowl nesting and provides a staging area for migration.[1] As many as one million ducks, geese and swans pass through this area in the fall. The grass and sedge meadows of this area provide habitat for several thousand Wood and Plains Buffalo. The endangered Whooping Crane migrates through the delta on its way to its nearby nesting area.
Much of this area falls inside Wood Buffalo National Park. This delta was recognized on 24 May 1982 as a wetland of international significance under the Ramsar Convention, for its undisturbed nature and for being the largest boreal delta of the world.[2]
[edit] Influence of Bennett Dam
In the late 1960s, the W.A.C. Bennett Dam was constructed on the Peace River in northern British Columbia by BC Hydro, a major hydropower utility. The role of the dam has been disputed. Initial drops in water levels were mitigated by the construction of three rock-fill weirs on the Chenal des Quatre Forches, Revillon Coupé, and Riviere des Rochers, the first of which was later removed due to complaints from muskrat trappers. The weirs restored mean open-season water levels nearly to pre-regulation levels.
Critical to the delta are spring ice-jam floods that play a critical role in refilling perched basins and wetlands outside of the permanently connected channels and lakes. It has been claimed that the dam reduced ice-jam floods, but the recent studies are not able to verify this claim. Sediment records were used to reconstruct the history of flooding for the past 300 years[3]. Maximum flood frequency was seen to reach a maximum in the early 1900s and declined in the 1940s and 1950s prior to the construction of the dam. Between 1975 and 1995 there were no major ice-jam floods and this could be a result of the dam. In 1996 and 1997 major ice-jam floods occurred. There have been similar prolonged periods lacking major flooding including 1813 - 1839 and 1705 - 1786.
Studies of the climate and ecology of the Peace-Athabasca Delta have been carried out to understand the effect of the dam on delta[4]. It was found that the recent decades are neither the driest nor the wettest that the delta has experienced in the past three hundred years. The early 1900s were some of the wettest conditions experienced by the delta and during the early- to mid-1900s there has been a general trend of drying. While the delta is drier today than it was in the early parts of the 1900s, there is no clear indication that the dam is responsible. The Peace-Athabasca is still well within the range of naturally variability due to natural changes in climate seen within the past few centuries.
An ongoing lawsuit between BC Hydro and local First Nations bands relates to the effects of Bennett Dam on Delta water levels and associated traditional lifestyles.
[edit] Waterways
The Birch River flows into Lake Claire, the largest lake completely in Alberta, which is an important part of the delta. Other lakes developed in the region are Baril Lake, Mamawi Lake, Hilda Lake, Otter Lake, French Lake, Pair Lakes, Welstead Lake, Four Forks Lake, Galoot Lake, Pushup Lake, Jemis Lake, Richardson Lake, Flett Lake, Blanche Lake and Limon Lake.
The waterway connecting Lake Athabasca and the point where Peace River flows into the Slave River is called Riviere Des Roche.
Other rivers draining the wetlands through the Peace-Athabasca Delta include Swift Current Creek, Carolyn Creek, Modere Creek, Steepbank River, McIvor River, Buckton Creek, Frog Creek, Sall River, Bolton Creek, Edra Creek, Peel Creek, Alice Creek, Mamawi Creek, Embarras River, Horse Island Creek, Chilloneys Creek, Claire River, Dempsey Creek, Baril River, Peltier Creek, Scow Channel, Powder Creek, and Revillon Coupe.
[edit] References
- ^ Environment Alberta - Northern River Basins Study Final Report - The Peace-Athabasca Delta
- ^ Environment Canada - Peace-Athabasca Delta, Alberta - Ramsar Site
- ^ Wolfe, B.B., Hall, R.I., Last, W.M., Edwards, T.W.D, English, M.C., Karst-Riddoch, T.L., Paterson, A., and Palmini, R. 2006. Reconstruction of multi-century flood histories from oxbow lake sediments, Peace-Athabasca Delta, Canada. Hydrological Processes, 20: 4131-4153.
- ^ Wolfe, B.B., Kart-Riddoch, T.L., Vardy, S.R., Falcone, M.D., Hall, R.I., and Edwards, T.W.D. 2005. Impacts of climate and river flooding on the hydro-ecology of a floodplain basin, Peace-Athabasca Delta, Canada since A.D. 1700. Quaternary Research, 64: 147-162.
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