Deciphering the evolutionary history and depositional processes of meandering rivers

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Rivers are essential aspects of transport systems that deliver sediment from erosional highlands to depositional basins. Rivers also play a significant role in society, from irrigation and navigation, to wildlife habitat and sources of drinking water. Drastic changes in river system behavior can also significantly impact infrastructure and human lives (e.g., floods). There is considerable uncertainty in predictions of the magnitude and frequency of future flood events and how river systems will respond to environmental change. Investigation into the deposits of past floods and the evolutionary history of river systems provides insight into these uncertainties. By documenting ongoing processes in modern river systems, we learn how and under what conditions sediment is deposited, and define criteria for recognition of associated sediments in the depositional record. The proposed research program aims to better understand how rivers respond to internal (e.g., floods) and external (e.g., climate) forcing by studying the processes of modern rivers, and their resulting deposits in the fossilized record.***The surficial sediment cover of southwestern Manitoba records the de-glaciation history of the area, beginning around 20,000 years ago. This includes the deposition of the Assiniboine Delta into glacial Lake Agassiz, which once covered much of the province. As the lake drained, fluvial incision into the deltaic deposits created the modern Assiniboine River valley. It is within these river deposits that an archive of past floods, changing lake levels, and varying climatic conditions is recorded. The proposed research program will investigate these deposits to yield insight into the magnitude and frequency of flood events, and more generally, how rivers respond to changing Earth conditions. To expand the window of observation, fossilized river deposits exposed in the “badlands” of southeastern Alberta will also be examined. Ancient fluvial deposits are an underutilized record of changing Earth conditions, and they represent a much longer archive (>104 yrs) than human observation. This integrated analysis will provide a holistic understanding of river processes and sedimentary products, which will inform predictions of future flood events and river response to a changing climate. The proposed research program will train 14 HQPs and produce results that are directly applicable to flood mitigation efforts, as well as the development of oil and gas resources contained in fluvial deposits.