Fourth Study Conference on BALTEX Scala Cinema Gudhjem

6. Results
There are many possible developments. The maximum
sea water level in relation to today's mean value is about
the same as today, if we look at the ensemble mean value.
Figure 2. Modelled seasonal inflow to the Lake
Mälaren for present-day conditions (dark blue) and
two climate change scenarios. Shown are means
over the 30-year modelling period.
On the other hand, the "worst case scenario", as defined
within the project, shows an increase of about 50 cm. The
hydrological scenarios present higher flows during
autumn and winter and reduced flow during the extended
summertime. Noticeable is that the high flow in
wintertime coincides with a period of normally high sea
water level. There is also the question on regulations.
There are about five places where regulations are made
according to a judicial decision from 1989. The
regulation system is at least partly controlled by man and
thus it is vulnerable to know what actions will actually be
taken and at what time. Different combinations are
possible to test in theory with a model developed at
SMHI.
Figure 3. An example of a possible change in water
level comparing today's situation and tomorrow.
The blue line shows the actual condition from July
2000 to June 2001, including regulations. The pink
- 173 -
line shows a future scenario (RCAO-H/A2) with
the assumption of an increased sea water level of +
46 cm and with the same regulations as was the
case with the blue line.
7. Conclusions
The results so far show that the land uplift and the
eustatic water level change are the most important factors
regarding sea water level. The elevated risk of flooding is
strongest for the eastern and southern part of the Baltic
Sea. The hydrological results points at higher flows half
of the year and lower flows during the other half. These
conditions may lead to diverse problems; flooding but
also too low water levels for transportation. The main
conclusion is though that climate change strengthens the
need for increased outflow from the Lake Mälaren and
that high flow periods tend to last longer.
References
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