From: on behalf of Panel Registry Subject: FW: TNG registration of ...

XGCA. The importance of this change does not so much refer to changes in the amount of
rainfall, but more to a change in the ratio between rainfall and snow. In other words, the
transition from snow to rain during the colder months (as they will become warmer) may
cause complex changes in cryospheric regimes (glaciers, snowpack, lake ice) that may lead
to
subsequent changes in operation of reservoirs and in the seasonal shifts in timing of
streamflow.
The rest of this section provides a summary of the results of current research to date
concerning how climate impacts on snowpack, glaciers, streamflows and groundwater will
increasingly affect the pristine water resources of the XGCA. This section highlights how the
hydrology, and hence the water resources in the XGCA, are strongly influenced by
precipitation and temperature. For instance, the amount of precipitation falling as snow
versus rain, the amount of evapo‐transpiration, the sustainability of glacial inputs to rivers
and the timing of runoff are all potential impacts of climate change. 25
Snowpack 26
Snowpack is a critical seasonal water resource that is renewed each year at high elevations.
It retains freshwater during the cold winter months, after which it supplies streamflow to
soils, lakes and reservoirs during the warmer summer low‐flow periods. Snowpack is,
however,
utilized during most of the year after transformation in reservoirs, streamflow
and groundwater.
Snowpack projections in BC are still in their infancy, as snowpack is a difficult variable to
measure. Given that the projected changes to snowpack rely on both temperature and
precipitation, a great deal of uncertainty is associated with estimates. At present, a single
estimate has been produced by one RCM model. The results, however, are not sufficient to
produce a confident statement about future changes to snowpack in BC. The results do,
however,
demonstrate that a combination of scientific approaches is needed to provide
reliable
future estimates of changes to snowpack in BC.
While the findings are still tentative, the projections of spring snowpack for BC show
a decline by 2050s of ­200kg/m2. Significantly, the projected snowpack decline is
more pronounced in the Coastal Mountain ranges with ­500kg/m2. This is important
as while this area is more water­rich than the Chilcotin Plateau as mentioned above,
the decrease will impact the water resources in the vicinity of where the Xeni Gwet’in
reside.
In other words, the decrease in snowpack will impact the water resources that
supply the daily water use of the Xeni people.
The projected decreases were primarily caused by the change in snow‐to‐rain ratios
occurring
through December, which delayed snowfall into the later winter months and
reduced
annual snow water equivalent. 27
25 Dawson, R., A.T. Werner,
and T.Q. Murdock, (2008).
26 This section is primarily
prepared from information provided in PCIC (2007/revised 2009).
27 Sushama et al (2006).
25