Projected Changes to Streamflow Characteristics over Western Canada as Simulated by the Canadian RCM

Abstract

Intensification of the global hydrological cycle and increase in precipitation for some regions around the world, including the northern mid-to high latitudes, is expected in a changing climate. Changes in the amount of seasonal precipitation and the intensity and frequency of extreme precipitation events directly affect the magnitude of seasonal streamflows and the timing and severity of floods and droughts. In this study, the Canadian Regional Climate Model (CRCM) projected changes to streamflow characteristics (i.e., hydrologic regime, mean annual streamflows, and the timing, frequency, and magnitude of extreme flows-low and high) over selected basins in western Canada and assessment of errors associated with these characteristics in the current climate are presented. An ensemble of five current (1961-90) and five future (2041-70) simulations, corresponding to the Special Report on Emissions Scenarios (SRES) A2 scenario, are used in the assessment of projected changes; the ensemble of simulations allows better quantification of uncertainty in projected changes. Results of the study suggest an increase in the magnitude of winter streamflows and an earlier snowmelt peak for the northern basins. In addition, study of selected return levels of extreme flows suggest important changes to the timing, frequency, and magnitude of both low and high flows, with significant increases in 10-yr 15-day winter and fall low flows and 1-day high flows, for all the high-latitude west Canadian basins. The level of confidence in projected changes to mean annual streamflows is relatively higher compared to that for extreme flows for most of the basins studied.

On improving cold region hydrological processes in the Canadian Land Surface Scheme

“…Free vertical drainage is assumed at the lower boundary of the permeable part of soil column, which is the sub-surface runoff. The CLASS-simulated total runoff (surface and sub-surface) is transformed into streamflows using the modified routing model WATROUTE (Soulis et al 2000;Poitras et al 2011). The routing scheme solves the water balance equation at each grid cell and relates the water storage to outflow from the grid cell using Manning's equation.…”

“…The land surface model used in CRCM5 is the Canadian Land Surface Scheme (CLASS; Verseghy 2012), which is a physically based model. Studies that validated CRCM5/ CLASS simulated spring streamflows have reported systematic biases (Poitras et al 2011;Huziy et al 2012). For example, the study by Huziy et al (2012) suggests underestimation of spring peak flows for the province of Quebec.…”

Prediction of soil and water conservation structure impacts on runoff and erosion processes using SWAT model in the northern Ethiopian highlands

“…Insufficient information on soil erosion and streamflow could lead to inefficient planning and inadequate design and operation of soil and water resource management projects (Poitras et al 2011). Changes in the extent of seasonal precipitation, frequency, and intensity of extreme precipitation events directly affect the amount of seasonal streamflow (Poitras et al 2011).…”

“…Changes in the extent of seasonal precipitation, frequency, and intensity of extreme precipitation events directly affect the amount of seasonal streamflow (Poitras et al 2011). The prediction and assessment of streamflow and sediment yield using a watershed model are important for agricultural watershed management in the Ethiopian highlands as watershed models are crucial tools to illustrate hydrological processes and to scale up the model results.…”

Investigation of the 2013 Alberta flood from weather and climate perspectives

“…Streamflows are generated for the BRB from the CRCM5 simulated runoff with the WATROUTE hydrological routing scheme (Poitras et al 2011;Soulis et al 2000). The flow directions, river lengths and slopes required by the routing scheme are derived from the HydroSHEDS database (Lehner et al 2008), available at 30-s spatial resolution, following the upscaling method employed by Huziy et al (2013).…”