| Citation |
Geertsema, M. (2000) Outburst floods at Tulsequah Glacier, northwestern British Columbia, Forest Sciences, Prince Rupert Forest Region, BC Forest Service. Extension Note #43, December, 2000. |
| Abstract/Description or Keywords |
Catastrophic floods resulting from the breaching of temperate, glacier-dammed lakes (glacial outbursts) are relatively common in the Canadian Cordillera, particularly in the Coast Mountains. Some lakes drain and fill frequently whereas others remain empty for years after self-dumping. The two lakes described in this paper are dammed by the Tulsequah Glacier and empty (often annually) through sub-glacial drainage channels. The physical signature of the Little Ice Age lies strong upon northwestern British Columbia. The self-dumping, ice-dammed lakes described in this paper are just one of its lingering effects. The lakes appear to be at different stages of development. Tulsequah Lake has increased in area earlier this century, and is now diminishing because of falling maximum lake levels. In contrast, the now larger Lake Nolake is still expanding in area because of ice ablation and calving, but its peak levels are also declining. Although the two lakes are similar, Lake Nolake may lag about 80 years behind Tulsequah Lake in evolutionary phase. As long s the outburst floods continue, the active floodplain of Tulsequah River will remain bare and river crossing structures will remain temporary. Nonetheless, if the glaciers continue to downwaste and recede, eventually the ice dams will vanish, and flow regimes on Tulsequah River will return to that of a more typical Holocene gravel bed river. |
