4.3
FIGURE 3
Drought conditions in the
U.S. on September 24,
2002, after a summer of
low precipitation and
extremely high
temperatures
and floods, are expected to increase (Prowse et al).  These
summer recharge.  This recharge may be able to bring
changes are amplified when human activities are consid-
ground water back to “normal” levels, but due to the added
ered.  Higher temperatures and evaporation will lead to an
stress from summertime withdrawal increases and in-
increased need for irrigation for drier soils and lawns.
creased evaporation, it may be too late to reverse the
Hotter summers will lead to an increased demand for
damage.
electricity for air conditioning, causing more water to be
withdrawn for cooling purposes and placing more pressure
Many of the  General Circulation Models and Regional
on declining ground water resources.  Overall, an increase
Climate Models have predicted an increase in severe storms
in summer water demand of five percent is predicted
and extreme weather, possibly with more intense rainfall.
(Environment Canada 1995).
This does not bode well for ground water recharge, as
more of the water is likely to run straight into surface water
Increases in evaporation will reduce the amount of water
courses instead of recharging aquifers.  Infiltration can only
infiltrating the soil and reaching the water table.  An
occur at a set rate.  If more rain falls than can be absorbed,
increase in temperature at the Experimental Lakes Area,
most of it will run off, increasing the chances of  flooding
north of the Great Lakes region, from 14 to16 degrees
(United Nations Framework Convention on Climate
Celsius led to an increase in evaporation of 30 percent
Change 2002).
(Schindler 2001).  On the southern Great Lakes, increases
in evaporation are expected to result in drier soils, thus
Additionally, the frequency of droughts is expected to
reducing runoff and ground water recharge (Environment
increase, which could also contribute to ground water
Canada 1995).  The predicted reduction in runoff would
shortages.  For the past two years, North America has
make ground water base flow an even more important
experienced lower than average precipitation that has
component of stream flow.
resulted in extreme drought conditions in parts of the
continent.  As seen in Figure 3, drought in the Great Lakes
Increases in ground water recharge are predicted for
region has not been as devastating as in other regions, but
certain times of the year.  Higher temperatures will alter the
the lack of precipitation and extremely high temperatures
timing of snowmelt, causing ground water recharge to
over the summer of 2002 have forced municipalities to
occur earlier in the spring.  The ground would likely freeze
issue water restrictions in most communities to conserve
at a later date, allowing early winter rains to penetrate the
water.  During drought conditions the soil is so dry it
soil and recharge ground water supplies.  The timing of
becomes hydrophobic and will not absorb the rainwater
recharge would shift to earlier in the spring and later into
easily.  If the frequency or intensity of droughts increases, as
the winter, possibly compensating for the decrease in
is expected with climate change, we will see a reduction in
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