ABSTRACT: Application of LANDSAT imagery to flood studies in the remote Nahanni Karst, Northwest Territories, Canada

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Abstract

LANDSAT imagery has provided important new data about the spectacular hydrology of the Nahanni north karst, one of the most complex subarctic karst landscapes known. Near-infrared band-6 (700-800 nm) and band-7 (800-1100 nm) LANDSAT images are the most suitable for hydrologic investigations. Images have revealed that prior to spring snowmelt the three poljes and other depressions in the north karst are dry. This suggests that water remaining in depressions in October, when lakes freeze over, drains underground before the following spring. When snow and ice melts in May, several depressions flood because their ponor systems are blocked by ice. Spring snowmelt is not the major hydrologic event of the year; the most intense hydrologic activity results from heavy rainfall in the months June-August. Nahanni depressions flood when there is above-average rainfall in any of these months. In years with no unusually high monthly precipitation, depressions may remain dry or suffer only minor inundation. Continuation of the LANDSAT program of earth resource data acquisition provides a means of monitoring hydrologic conditions in the north karst in the future

Bibliography of Canadian Geomorphology