Water Governance in the Context of IWRM: Chile - Climate Change and Water Governance: Adaptive Capacity in Chile and Switzerland - page 157

With the Mattmark reservoir, extra storage capacity can be created by pumping water
out of the reservoir to prepare for higher precipitation volumes as and when is needed.
In 2000, a debris flow ( murgang ) caused extensive damage to the Vispa in Stalden.
During this event the extra storage volume was used to ensure that excessive amounts
of water did not flow into Visp, hence avoiding more serious flooding impacts,
although some damage still occurred.
The Third Rhône Correction plan was outlined in the aftermath of the earliest of
these events, and agreed upon after the later events, as the impacts of the floods
highlighted how the earlier remediations on the Rhône (the first and second
Rhône corrections) could no long ensure sufficient security for the Rhône flood
plain. In the central Valais, there are a number of priority measures (e.g. at Alcom)
because it is an industrial zone where they produce aluminium, and the damage
potential is millions of franks worth. The 2000 flood was a prime example of the
increasingly aggressive autumn floods that occur between September and October,
when a cold snow spell is followed by higher than average temperatures.
While the elevation of the snow line has significant implications on the alpine
tourism industry, there are also severe ramifications for water quantity and timing
and the impacts from heavy precipitation events. For example, in the Valais above
2,000 m the terrain tends to be mainly glacial or rock and cliff. When the 0°C iso-
therm is only at 4,000 m as opposed to about 2,000 m, then most of the precipitation
falls as rain, rather than snow, with repercussions for the amount that is stored for
later melt (Beniston 2006 ), and that which flows down directly through the streams
and off the cliffs (a 2,000 m difference can increase or reduce the volume by half).
Increasing flows of water from rapidly receding glaciers is not only an influencing
factor on the increasing flooding events, but also provides certain benefits to the
hydropower operators, who have more seasonal production than when the 0°C iso-
therm is lower. Changing patterns in glacial melt have had repercussions on spring
levels, which are fed by seasonal glacier and snow melt. At the commune level, the
largest source of water for domestic supply is from glacier melt (in that it feeds the
springs and groundwater from which domestic use is supplied). In the Zermatt
region, the rapidly reducing Findler Glacier is negatively affecting spring recharge,
which the communes rely upon for domestic water supply.
In other areas of the Valais, there are situations where levels of melt water are
insufficient to meet demand from mid-August (but mainly on the northern alpine
side). Low snow levels in winter and periods of low precipitation in summer, also
negatively impact spring levels, which can lead to an increasing exploitation of
groundwater sources. Spring and groundwater levels are dependent on a number of
variables, including precipitation levels in winter, whether precipitation falls as
rain or snow, and when the melt period begins. In general, if the months after
March are very dry, then the dual impact of less melt and less precipitation reduces
the replenishment of the springs (April 2010 and 2011 were both extremely dry).
These compounding impacts have reportedly led to situational increases in compe-
tition at the commune level, for which the canton has no oversight. However, while
utilities have diversified supply from precipitation (rain/snow) and melt water to
recharge springs, hydropower operators rely solely on glacier melt.