| Summary: | Hydrological monitoring in complex, dynamic northern floodplain landscapes is challenging but increasingly important as these ecosystems come under threat from multiple stressors, including climate-driven decline in freshwater supplied by rivers draining the hydrographic apex of western North America. Sustainable approaches capable of tracking status, trends and drivers of lake water balances in complex, remote landscapes are needed to inform ecosystem stewardship and water-security actions. The Peace‐Athabasca Delta (PAD) in northern Alberta, Canada, is a Ramsar Wetland of International Importance reliant on episodic river ice‐jam flood events to recharge abundant perched lakes and wetlands. However, the frequency of these floods has been in decline for decades over much of its area. Compounding concerns about water-level drawdown have prompted the need to improve knowledge of lake water balances and establish a lake monitoring program. Yet, the delta’s remoteness and dynamic nature present challenges to these goals. In this thesis, I address hydrological knowledge gaps essential to understanding spatial and temporal patterns of hydrological processes and their influence on lakes in the PAD. First, we assess the legacy influence of a large-scale ice-jam flood in 2014 on hydrological and limnological status of lakes in the PAD by integrating spatial and temporal data. Analysis of water isotope compositions and water chemistry measured at numerous lakes across the delta shows that hydro-limnological effects of the flood event of 2014 failed to persist beyond the early ice-free season of 2015. Isotope-inferred paleohydrological records from five hydrologically representative lakes in the PAD indicate that periodic desiccation during the Little Ice Age occurred at the most elevated basin in response to locally arid climatic conditions and reduced flood frequency, yet other lower elevation sites were influenced by high water level on Lake Athabasca owing to increased snowmelt- and glacier-derived river discharge. In ...
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