TOPOGRAPHIC MAPPING OF SURFACE WATER DRAINAGE PATTERN AND HYDROLOGICAL CONNECTIVITY ON THE CANADIAN SHIELD
Nimisha A. Wagle, Brown University, nimisha_wagle@brown.edu (Presenter)
Laurence C. Smith, Brown University, laurence_smith@brown.edu
Jessica V. Fayne, University of California, LA, jfayne@g.ucla.edu
The Canadian Shield (CS) contains the world’s highest density of lakes but its surface drainage pattern is poorly known. Furthermore, under a wetter future climate, the extent and hydrological connectivity of CS surface drainage may increase. Traditional digital elevation model (DEM) based drainage pattern delineation treats topographic depressions as artifacts that must be removed to model overland hydrologic flow paths. However, the CS contains many true topographic depressions, some of which impound surface water until their outlet bedrock sills are overtopped (called “fill-and-spill” hydrology). We perform DEM analyses retaining topographic depressions, to assess current CS depression storage and drainage patterns and their potential sensitivity to a wetter climate. First, depressions are quantified by filling the Merit DEM and then subtracting it from the original Merit DEM. Next, the surface drainage pattern is mapped by quantifying the sensitivity of depression storage to regional P-E (precipitation minus evapotranspiration) and developing a relationship between depth and volume for each depression in the landscape. Our results suggest a large unfilled capacity of depression storage, with only approximately one-fourth of depression storage (by area) likely to fill and spill under an, assumed 150 mm increase in regional water balance. Future work will explore the potential sensitivity of CS drainage patterns to changing future water balance as projected by climate models. Such research will identify physically realistic current and potential overland flow paths necessary for hydrologists and decision-makers to assess CS drainage patterns and their sensitivity to climate change.
Keywords: Canadian Shield, Drainage Pattern, Topographic Depressions, Hydrological Connectivity
Presentation: RH_Wagle__118_31.pptx
Associated Project(s):
Presentation Type: Research Highlight
Session: Permafrost and Hydrology
Session Date: Tuesday (5/10) 10:30 AM