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Modeling Climate Change Impacts on Hydrology and Nutrient Loading in the Upper Assiniboine Catchment

Authors

  • Rajesh R. Shrestha,

    1. Respectively, Visiting Fellow, Water and Climate Impacts Research Centre, Environment Canada and University of Victoria, Victoria, V8W 3R4, Canada, now at Pacific Climate Impacts Consortium, University of Victoria, Victoria, BC, V8W 2Y2, Canada
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  • Yonas B. Dibike,

    1. Physical Scientist, Water and Climate Impacts Research Centre, Environment Canada and University of Victoria, Victoria, V8W 3R4, Canada
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  • Terry D. Prowse

    1. Professor and Research Chair, Water and Climate Impacts Research Centre, Environment Canada and University of Victoria, Victoria, V8W 3R4, Canada
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  • Paper No. JAWRA-10-0188-P of the Journal of the American Water Resources Association (JAWRA). This article Modeling Climate Change Impacts on Hydrology and Nutrient Loading in the Upper Assiniboine Catchment was written by Rajesh R. Shrestha, Yonas B. Dibike, and Terry D. Prowse of the University of Victoria, Victoria, Canada. It is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Discussions are open until six months from print publication.

(E-Mail/Shrestha: rshresth@uvic.ca).

Abstract

Shrestha, Rajesh R., Yonas B. Dibike, and Terry D. Prowse, 2011. Modeling Climate Change Impacts on Hydrology and Nutrient Loading in the Upper Assiniboine Catchment. Journal of the American Water Resources Association (JAWRA) 48(1): 74-89. DOI: 10.1111/j.1752-1688.2011.00592.x

Abstract:  This paper presents a modeling study on climate-induced changes in hydrologic and nutrient fluxes in the Upper Assiniboine catchment, located in the Lake Winnipeg watershed. The hydrologic and agricultural chemical yield model, Soil and Water Assessment Tool (SWAT) was employed to model a 21-year baseline (1980-2000) and future (2042-2062) periods with model forcings for future climates derived from three regional climate models (RCMs) and their ensemble means. The modeled future scenarios reveal that potential future changes in the climatic regime are likely to modify considerably hydrologic and nutrient fluxes. The effects of future changes in climatic variables, especially precipitation and temperature, are clearly evident in the resulting snowmelt and runoff regimes. The future hydrologic scenarios consistently show earlier onsets of spring snowmelt and discharge peaks, and higher total runoff volumes. The simulated nutrient loads closely match the dynamics of the future runoff for both nitrogen and phosphorus, in terms of earlier timing of peak loads and higher total loads. However, nutrient concentrations could decrease due to the higher rate of runoff increase. Overall, the effects of these changes on the nutrient transport regime need to be considered together with possible future changes in land use, crop type, fertilizer application, and transformation processes in the receiving water bodies.

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