Application of dynamic contributing area for modelling the hydrologic response of the Assiniboine River Basin to a changing climate |
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Authors: | Yonas Dibike Ameer Muhammad Rajesh R Shrestha Christopher Spence Barrie Bonsal Laurent de Rham Jaden Rowley Grey Evenson Tricia Stadnyk |
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Affiliation: | 1. Environment and Climate Change Canada, Watershed Hydrology and Ecology Research Division, Victoria, BC V8W 3R4, Canada;2. Department of Civil Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada;3. University of Victoria, Department of Geography, Victoria, BC V8P 5C2, Canada;4. Environment and Climate Change Canada, Watershed Hydrology and Ecology Research Division, Saskatoon, SK S7N 1K2, Canada;5. Department of Food, Agricultural and Biological Engineering, the Ohio State University, Columbus, OH 44691, USA;6. Department of Geography, University of Calgary, ESB 458, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada |
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Abstract: | The Prairie landscape consists of numerous pothole depressions which produce complex fill-and-spill runoff generation processes that result in intermittent hydrologic connectivity and dynamic contributing areas (DCA). We investigated the effect of including DCA in the modified version of the Soil and Water Assessment Tool (SWAT) model and its implication on future streamflow projection for the pothole dominated Assiniboine River Basin (ARB). The fill-and-spill processes that lead to DCA were captured using a physically-based approach, with a volumetric threshold to reduce the computational demand. Despite the challenges in accurately simulating prairie pothole hydrology, both in terms of timing and volume of runoff, the modified approach improved streamflow modelling performance, and reduced model uncertainty. Further, we evaluated the effects of representing DCA on projecting future streamflow by using eight statistically downscaled CMIP5 GCMs, forced with the RCP4.5 and RCP8.5 scenarios. End of century projections indicate increases in annual precipitation and temperature across the ARB, with decreasing summer precipitation relative to the 1976–2005 baseline period. Compared to the standard SWAT setup that does not allow for DCA, the modified model was found to be more responsive to climatic change with relatively larger projected increases in seasonal and annual flows at the majority of evaluated stations. This advance in DCA modelling will facilitate longer-term large basin-scale simulations that are more representative for the Prairie region. |
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Keywords: | Assiniboine River Basin SWAT Prairie pothole Dynamic contributing area Fill-and-spill Climate change |
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