Environmental Engineering Reference
In-Depth Information
tumn flood', albeit with less overall discharge than in spring, but also with re-
duced capacities to mitigate it, as the reservoirs, that serve to buffer the peak of
the flood discharge in spring, cannot be resorted to.
19.7 Dealing with a Flowing River
Such future scenarios, as well as the description of challenges around river ice,
might give the impression that hydroelectricity engineers would be particularly
worried during autumn and spring, or regarding the future. I have, however, not
found this to be the case. Quite on the contrary, these periods of increased atten-
tion blend in smoothly with their work throughout the rest of the year. When deal-
ing with the Kemi River, anything can happen - anytime. Part of a generator
might suddenly break, some electrical equipment might malfunction, or a few
rainy days might raise the water level at a particular reach to unforeseen heights.
Even if nothing unforeseen happens, the engineers' grip on the river is never to-
tally fast: no matter what they do, the river flows and if their dams are not opened
according to this constant stream of water, reservoirs and river will overflow. The
control room staff knows this and knows just as well that engaging with a river re-
quires much more than sitting in the control room watching screens and pushing
buttons. A leading figure of this staff, for instance, proposes to supplement the
numerical data constantly flowing into the computers with more visual and acous-
tic information from the power stations. For example, it can be decisive to actually
see the ice floes upstream from a power station, in order to sensibly decide how to
work the flood gates so that potential damage is averted. Similarly, installing mi-
crophones at the turbines should enable engineers to find out what is going on at
the particular plant more readily than - or at least complementary to - merely fig-
ures about electrical currents and circuits.
During winter, two members of staff regularly drive along the river throughout
the municipality of Rovaniemi in order to get a first-hand impression of the qual-
ity of ice cover. This is particularly relevant during late autumn and early winter,
when the ice is forming. For the public image of the hydropower company, the
stretch of the river around Rovaniemi is especially important, as about one third of
the entire population of the province of Lapland lives in this area. Here, direct ob-
servations of the river's surface can be more significant than data tables and com-
puter models. If - as has been the case for several weeks during the rather mild
winter of 2007-08 - the ice cover is too fragile or features too many open spots, all
the hydroelectricity engineers can do, is to not manage the river very much at all:
allowing the river to flow evenly and slowly is the best recipe for the formation of
stable ice.
Also during spring, in order to better estimate the extent of the coming flood,
hydroelectricity producers do not rely on figures and models retrievable on the
screens in the control room. The same two members of staff who drive along the
river in the winter embark upon a reconnaissance flight over the fringes of the wa-
tershed in spring. During the flight in a tiny propeller plane they closely watch and
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