CHARACTERIZING RELICT SHORELINES TO ESTABLISH THE MOST DETAILED ACCOUNT OF LAKE-LEVELS IN THE PEACE ATHABASCA DELTA: A KEY HYDROLOGIC NODE OF THE MACKENZIE RIVER BASIN, NORTHWESTERN CANADA

The Peace-Athabasca Delta (PAD) is one of the largest freshwater deltas in the world. This important area contains Canada’s largest national park, Wood Buffalo National Park and has been designated a UNESCO World Heritage site and RAMSAR site or wetland of international significance. This is a difficult area to manage since it is a complex hydrologic system that is sensitive to changes in water level due to low topographic relief. In order to make informed long-term water-management decisions in the delta natural variations in water level must be fully understood. Here we present preliminary findings from relict shorelines on the west side of the PAD to evaluate whether these landforms can be used to create a paleohydrograph. We have identified 40 relict shorelines in this strandplain that are splayed laterally to the west of Lake Claire. Three ridges were visited during summer 2016 and accessed by helicopter because of the remote location and difficult terrain. The three ridges studied were among the youngest in the strandplain and ranged from 30 to 90 m in width and up to a few metres in height above adjacent wetlands, several with open water and floating mats with sedge or willow. A transect through the treed ridges was studied using a survey instrument to determine the morphology of the ridges, a geophysical instrument called ground penetrating radar to define subsurface stratigraphy, and hand-dug soil pits to investigate the type of sediment and stratigraphy as well as sample for age analysis using optically stimulated luminescence. Efforts are currently underway compiling and analyzing this data to characterize these well preserved relict shorelines and better understand this internationally recognized complex and dynamic system.