CGRG Bibliography of Canadian Geomorphology
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Author : Brook, G.A.
Date : 1983
Title : Hydrology of the Nahanni, a highly karsted carbonate terrain with discontinuous permafrost
Publication : Permafrost : Fourth International Conference, proceedings, July 17-22, 1983. - Washington, D.C. : National Academy Press
Issue :
Page(s) : 86-90
Abstract
Groundwater recharge rates are usually low where permafrost is present. However, in carbonate regions where a karst drainage system predates permafrost development, groundwater recharge and circulation may be vigorous. This is the case in the Nahanni north karst of northwestern Canada. Not only is the volume of groundwater flow in this permafrost region considerable--102 X 1,000,000 of water flows annually to each of two springs which drain the area--but hydrologic activity is spectacular. Between July 19 and 31, 1972, an extreme summer storm deposited 224 mm of rain on the area. First, Second, and Third poljes flooded; maximum water depths were 8.5, 25, and 8 m, respectively; and Third Polje overflowed. The level of Raven Lake (0.25-0.50 km long) rose 49 m at an average 2.9 m/day. Field observations and evidence from LANDSAT images have provided a hydrologic record for the karst for the years 1972-1978. These data indicate that immediately priorto spring snowmelt depressions are dry, and that when snow and ice melts in May, several depressions may flood temporarily because their drainage routes are blocked by ice. The major surface and groundwater activity in Nahanni is not induced by snowmelt but results from unusually high rainfall in the months of June-August.
Bibliography of Canadian Geomorphology