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Identifying Closed Depressions in the Hummocky Topography of the Waterloo and Paris-Galt-Guelph Moraines of Southwestern Ontario

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Title: Identifying Closed Depressions in the Hummocky Topography of the Waterloo and Paris-Galt-Guelph Moraines of Southwestern Ontario
Author: Ahrens, Beau
Department: Department of Geography
Program: Geography
Advisor: Lindsay, John
Abstract: Closed depressions, low elevation features in a landscape with no outlet point, play an important role in both surface and subsurface hydrology. These depressions, which are common in hummocky morainal landscapes, pool incoming surface flow, promoting infiltration and facilitating leaching of surface pollutants into vital groundwater resources. Due to the cost of ground based identification in large areas and difficulties with the identification of irregular depressions, remote identification using digital elevation models (DEMs) stands as a practical and effective tool for the mapping of these closed depressions. A modified stochastic depression identification algorithm was used in this study to characterize depressions in the Waterloo and Paris-Galt-Guelph moraines of Southwestern Ontario. The simulation output was a map of depressions in the study area. Depressions were corroborated using GRCA Wetlands data, Google Street View imagery, SWOOP 2006 orthophotos and field validation. Depression corroboration showed that the algorithm was able to accurately identify the location of closed depressions containing wetlands and closed depressions that are dry (largely due to wetland draining) in the hummocky topography of the study site. This research has implications for depression mapping in the field of digital terrain analysis as it enables the identification of real depressions in large study areas with a moderate resolution DEM. Providing a means of efficiently mapping closed depressions is important because of the role closed depressions play in the recharge of important groundwater stores.
URI: http://hdl.handle.net/10214/5246
Date: 2012-12


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http://creativecommons.org/licenses/by-nc/2.5/ca/ Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by-nc/2.5/ca/