Modelling Streamflow in Present and Future Climates: Examples from the Georgia Basin, British Columbia
2002
Whitfield, Paul H. | Cannon, Alex J. | Reynolds, Christopher J.
The Georgia Basin is one of the most hydrologically complex areas of Canada. The form in which precipitation occurs in winter, either snow or rain, is the primary determinant of the hydrologic patterns of rivers. The region consists of mountains, valleys and plains, and has extensive variations in elevation. Variations in temperature and precipitation exert tremendous influence on the amount and form of water that reaches the land surface of the Georgia Basin. The amalgamation of the climatic and geographical factors creates homogenous zones in which distinctly different hydrological processes occur. Climate change could have major regional effects on temperature, precipitation, evapotranspiration and ultimately runoff. In previous work, zones of homogenous hydrologic processes in the Georgia Basin were delineated. In the present work, we used downscaled data from GCMs for future periods as inputs to a hydrologic model. These results are used to forecast the location of these zones in three periods in the 21st century. The results indicate important changes to the three hydrologic types found in the Georgia Basin: rainfall-driven streams demonstrate increased winter flows, snowmelt-driven streams demonstrate an increasingly early onset to spring snowmelt, and hybrid (mixed rain and snow) streams become increasingly rainfall driven. These large changes illustrate some of the impacts to which the Pacific Northwest may have to adapt in the near future.
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