A New Lake Classification Scheme for the Peace-Athabasca Delta (Canada) Characterizes Hydrological Processes that Cause Lake-level Variation

Recent drawdown of the delta’s abundant shallow lakes and rivers has deteriorated
vital habitat for wildlife and impaired navigation routes. Here, we report continuous measurements at ~50 lakes during open-water seasons of 2018 and 2019 to improve understanding of hydrological processes causing lake-level variation.
New hydrological insights for the region: Analyses reveal four patterns of lake-level variation attributable to influential hydrological processes, which provide the basis for a new lake classification scheme: 1) ‘Drawdown’ (≥15 cm decline) by evaporation and/or outflow after ice-jam floods, 2) ‘Stable’ lake levels (<15 cm change) sustained by rainfall, 3) ‘Gradual Rise’ by inundation from the open-drainage network, and 4) ‘Rapid Rise’ by input of river floodwater. River flooding during the open-water season is an under-recognized recharge mechanism yet occurred extensively in the Athabasca sector and appears to be a common occurrence based on the Athabasca River hydrometric record. Lake-level loggers show strong ability to track shifts in
hydrological processes, and can be integrated with other methods to decipher their causes and ecological consequences across water-rich landscapes.