Assessment of Three Mapping Techniques to Delineate Lakes and Ponds in a Canadian High Arctic Wetland Complex
Keywords: High Arctic hydrology, High Arctic lakes, ponds and wetlands, LANDSAT, landscape mapping, RADARSAT, remote sensing
AbstractRecent evidence points to warmer and wetter conditions for Arctic regions. It is not clear how High Arctic environments, in particular extensive wetlands, will respond to these rapid changes. Sustainability studies of wetland complexes will require accurate mapping of water bodies (lakes, ponds, streams) over time. This information is critical to obtain reliable estimates of water inputs (e.g., snowmelt), outputs (e.g., evaporation), and storage, and to assess environmental change (e.g., pond desiccation, expansion, or both). Numerous tools and techniques are available to provide this information, though each approach has its benefits and limitations. In this study, we systematically explore the differences and similarities inherent in three different techniques used to delineate lakes and small ponds at an extensive wetland area near Creswell Bay, Somerset Island, Nunavut (72°43' N, 94°15' W). The mapping techniques compared are satellite mapping (extraction from a satellite-based land cover map), black-and-white aerial photography, and a topographic map sheet. Results indicate that while all three techniques could delineate large lake boundaries and their positions successfully, they differed in the number of ponds they delineated, as well as their boundaries and positions. A misrepresentation of water bodies can hinder hydrologic studies of Arctic water resources, and the results of this study emphasize the need to apply appropriate mapping techniques at different scales. The three mapping techniques are based on data from three different dates over several decades, so the different results also may indicate short- and long-term environmental change.