Water Stewardship Information Sources

Citation Schnorbus, M. 2012. Hydrologic Impacts Research Plan for 2012-2016. Pacific Climate Impacts Consortium.
Organization PCIC
URL http://www.pacificclimate.org/sites/default/files/publications/Schnorbus.HI_Plan_April2012.pdf
Abstract/Description or Keywords The hydro-climatology of British Columbia (BC) is complex, in part due to its close proximity to the
Pacific Ocean, mountainous terrain and large latitudinal expanse. Historical changes to climate and
hydrology have been documented in British Columbia and western North America by Rodenhuis et al.
(2009). Historical changes are in part attributable to climate variability on annual to decadal timescales,
such as teleconnection patterns coming from El Niño/Southern Oscillation (ENSO) or the Pacific Decadal
Oscillation (PDO). In addition, recent hydro-climatic trends in western North America have also been
affected by anthropogenic climate change, predominantly in the form of increased regional warming
(Barnett et al. 2008; Bonfils et al. 2008; Pierce et al. 2008). The regional response to climate variability
and trends can potentially affect all aspects of the hydrologic cycle, including the hydrologic extremes of
flood and drought (Hamlet and Lettenmaier 2007; Sheffield and Wood 2008). Ultimately it is recognized
that the hydro-climatic system can no longer be considered stationary, and from a management
perspective the past may become progressively less informative of future conditions (Milly et al. 2008).
Consequently, the aim of the Hydrologic Impacts (HI) theme at the Pacific Climate Impacts Consortium
(PCIC), and the purpose of the proposed applied research, is to quantify the effects of climate change and
variability on water resources within the Pacific and Yukon region (PYR) of western Canada. The main
purposes of HI theme products are to:
 Inform and support the sustainable use of the region’s water resources in order to help reduce
society’s vulnerability to climate change and climate variability; and
 Raise awareness of potential hydrologic implications of climate change and climate variability.
All this is to be accomplished at spatial scales relevant to regional and local management and over
multiple planning and adaptation time frames. Spatial scales range from several hundreds of thousands of
square kilometres (e.g. the Fraser River basin) to several hectares (e.g. drainage culvert design) and
timeframes vary from monthly to century. Of particular interest for management and planning is a greater
emphasis on knowledge regarding changes in hydrologic variability and changes in extremes, such as
flood and drought, and phenomena that affect that variability, such as changes in the frequency and
intensity of storms affecting the PYR.
Climate, and subsequently hydrology, varies over a wide range of space and time scales as a result of
processes both internal and external to the Earth’s climate system (Keenlyside and Ba 2010). External
forcing includes climate variations caused by factors external to the climate system, such as changes in
radiative forcing as a result of human-derived greenhouse gas (GHG) emissions. Internal processes are
reflected by internal climate variability, which arises from natural interactions within the earth-oceanatmosphere
climate system, such as manifested in the ENSO or Pacific Decadal Oscillation phenomena.
Different time frames can be organized and distinguished by characterizing them by the degree to which
the driving climate is dominated by internal climate variability versus external forcing. Therefore, in order
to assess the possible hydrologic effects of both climate change and climate variability over a broad range
of time scales, the work of the HI theme will be organized along the following three time frames (Figure
1):
 Short-term - monthly to annual;
 Near-term - annual to multi-decadal; and
 Long-term - multi-decadal to century.
Over the short term, hydro-climatic processes are governed predominantly by internal climate variability,
whereas over the long-term these processes are strongly affected by external forcing (Figure 1). In the
near-term, hydro-climatic processes are affected by both internal variability (particularly for time frames
of a decade or less; Keenlyside and Ba 2010) and, over multiple decades, by external forcing. The activities with which the HI theme intends to address and estimate hydrologic impacts within the
short-, near- and long-term timeframes are classified into forecasting, prediction and projection,
respectively. A forecast is the estimation of values or magnitude of hydro-climatic conditions (or their
probabilities) at a specific future time, or during a specific time interval (e.g. reservoir inflow over the
coming six months; Lettenmaier and Wood (1993)). A prediction is the estimation of future hydroclimatic
conditions, but is herein distinguished from forecasting in that it is not referenced to a specific
date or time, but instead seeks to predict the statistical characteristics of hydro-climatic conditions over
some defined time period (e.g. the frequency of flood events over the next five years). A projection is the
estimated response of the hydro-climate system to changes in radiative forcing. As projections must be
explicitly tied to assumptions of how future greenhouse gas emissions may evolve in response to human
activities (in the form of emissions scenarios), they are neither forecasts nor predictions (Bray and von
Storch 2009). Projections aim to provide a set or range of plausible, but not necessarily likely, outcomes.
Over the short-term, forecasts are an “initial value” problem in that forecast results and skill are sensitive
to specified initial states (climatologic and hydrologic) and radiative forcing can be set to reflect present
conditions. Long-term projections are “boundary value” problems in that the evolution of hydroclimatology
is strongly affected by assumptions regarding the evolution of greenhouse gas concentrations
and consequent radiative forcing. Near-term decadal to multi-decadal predictions can be considered a
hybrid problem, in that predictions are expected to be sensitive to some aspects of both the initial states
and assumptions regarding future greenhouse gas concentrations and other external factors affecting the
climate system. climate change, streamflow, water supply, peak flow, low flow
Information Type report
Regional Watershed Province
Sub-watershed if known
Aquifer #
Comments
Project status complete
Contact Name Markus Schnorbus
Contact Email [email protected]