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  • Authors: The Pacific Climate Impacts Consortium Publication Date: Apr 2014
  • Authors: Nodelman, J. and co-authors [PCIC is a contributing author] Publication Date: Mar 2014
  • Source Publication: Hydrological Processes, 28, 14, 4294–4310, doi:10.1002/hyp.9997. Authors: Rajesh R. Shrestha, Daniel L. Peters and Markus A. Schnorbus Publication Date: Mar 2014

    It is a common practice to employ hydrologic models for assessing alterations to streamflow as a result of anthropogenically driven changes, such as riverine, land use, and climate change. However, the ability of the models to replicate different components of the hydrograph simultaneously is not clear. Hence, this study evaluates the ability of a standard hydrologic model set-up: Variable Infiltration Capacity (VIC) hydrologic model for two headwater sub-basins in the Fraser River (Salmon and Willow), British Columbia, Canada, with climate inputs derived from observations and statistically downscaled global climate models (GCMs); to simulate six general water resource indicators (WRIs) and 32 ecologically relevant indicators of hydrologic alterations (IHA). The results show a generally good skill of the observation-driven VIC model in replicating most of the WRIs and IHAs. Although the WRIs, including annual volume, centre of timing, and seasonal flows, and the IHAs, including maximum and minimum flows, were reasonably well replicated, statistically significant differences in some of the monthly flows, number and duration of flow pulses, rise and fall rates, and reversals were noted. In the case of GCM-driven results, additional monthly, maximum, and minimum flow indicators produced statistically significant differences. A number of issues with the model input/output data, hydrologic model parametrization and structure as well as downscaling methods were identified, which lead to such discrepancies. Therefore, there is a need to exercise caution in the use of model-simulated indicators. Overall, the WRIs and IHAs can be useful tools for evaluating changes in an altered hydrologic system, provided the skill and limitations of the model in replicating these indicators are understood.

  • Source Publication: International. Journal of Climatology, 34, 2, 326‐342, doi:10.1002/joc.3689 Authors: Whan, K., B. Timbal and J. Lindesay Publication Date: Feb 2014

    The intensity and position of the sub-tropical ridge (STR) have strong relationships with rainfall variability in southern Australia. The combined effect of intensity and position in March-April-May (MAM) and June-July-August (JJA) is the focus of this research. Linear statistics were used first: area-averaged and Australia-wide spatial correlations of STR intensity and position with precipitation in south-west eastern Australia reveal that STR intensity has a much stronger and more widespread relationship with precipitation in both seasons. Over time, these relationships vary in magnitude and spatial extent with the sign of the correlation changing between two 50-year epochs. These nonlinearities were investigated further using classification trees. Area-averaged precipitation data (terciles) for south-west eastern Australia was classified on the basis of STR intensity and position. In both seasons the classification trees identify STR intensity as the primary partition defining the dry group, supporting the linear analysis. In the transition season of MAM, the time of year when the mean position of the STR is more southerly, STR position is important in distinguishing between a ‘winter-like’ and a ‘summer-like’ wet groups, providing STR intensity is low. Vector wind analyses were computed to explain the composite seasonal precipitation anomaly results in terms of different circulation patterns associated with these two wet groups. The frequency of wet and dry cases in each group was examined with changes evident over the recent years. The research confirms that STR intensity is more important than STR position in explaining inter-annual rainfall variability across southern Australia but also demonstrates the additional role of STR position in MAM. These results explain the low correlation between rainfall and STR position and why this relationship has evolved during the 20th century as the mean location of the STR has shifted south in MAM.

  • Authors: PCIC Publication Date: Feb 2014
  • Authors: PCIC Publication Date: Jan 2014
  • Source Publication: Hydrological Processes, 28, 3, 1170‐1189, doi: 10.1002/hyp.9661 Authors: Schnorbus, M., A. Werner and K. Bennett Publication Date: Jan 2014

    Hydrologic modelling has been applied to assess the impacts of projected climate change within three study areas in the Peace, Campbell and Columbia River watersheds of British Columbia, Canada. These study areas include interior nival (two sites) and coastal hybrid nival–pluvial (one site) hydro-climatic regimes. Projections were based on a suite of eight global climate models driven by three emission scenarios to project potential climate responses for the 2050s period (2041–2070). Climate projections were statistically downscaled and used to drive a macro-scale hydrology model at high spatial resolution. This methodology covers a large range of potential future climates for British Columbia and explicitly addresses both emissions and global climate model uncertainty in the final hydrologic projections. Snow water equivalent is projected to decline throughout the Peace and Campbell and at low elevations within the Columbia. At high elevations within the Columbia, snow water equivalent is projected to increase with increased winter precipitation. Streamflow projections indicate timing shifts in all three watersheds, predominantly because of changes in the dynamics of snow accumulation and melt. The coastal hybrid site shows the largest sensitivity, shifting to more rainfall-dominated system by mid-century. The two interior sites are projected to retain the characteristics of a nival regime by mid-century, although streamflow-timing shifts result from increased mid-winter rainfall and snowmelt, and earlier freshet onset.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jan 2014
  • Authors: PCIC Publication Date: Dec 2013
  • Authors: PCIC Publication Date: Dec 2013
  • Authors: PCIC Publication Date: Dec 2013
  • Authors: PCIC Publication Date: Dec 2013
  • Authors: Hamlet, A.F., M.A. Schnorbus, A.T. Werner, M. Stumbaugh and I. Tohver Publication Date: Nov 2013
  • Authors: Hamlet, A.F., M.A. Schnorbus, A.T. Werner, M. Stumbaugh and I. Tohver Publication Date: Nov 2013
  • Authors: PCIC Publication Date: Nov 2013
  • Authors: PCIC Publication Date: Nov 2013
  • Authors: PCIC Publication Date: Nov 2013
  • Authors: PCIC Publication Date: Nov 2013
  • Authors: PCIC Publication Date: Nov 2013
  • Authors: PCIC Publication Date: Nov 2013

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