Jökull - 01.12.1988, Blaðsíða 52

Fig. 11. Development in fish farming from 1970 to
1989. Number of hatching stations (plotted as •) on
the left scale and number of salmon smolts [mil-
lions] (plotted as x) on the right scale.
Mynd 11. Þróun fiskeldis á árunum 1970 til 1989.
Fjöldi seiðaeldisstöðva (táknaður með •) sýndur til
vinstri, fjöldi seiða [milljónirj (táknaður með x)
sýndur til hægri.
measures. New factors will shortly emerge in their
place and become more important.
The main limiting factors of water supply emerge,
as the seasonal changes in water demand are viewed
against the background of seasonal changes in
groundwater availability. The former is a socio-
economical factor, the latter a hydrological - geo-
logical one. And a new limiting factor is emerging
now, that of the competition for the total regional
resource, as a new, fast evolving and water consum-
ing industry clashes with older, domestic needs,
placing demands on a resource that was plentiful but
can not now fulfill all the wishes for its use.
Shortage areas — The populated areas with the
strongest seasonal fluctuations in water consumption
(fishing season, sheep slaughtering), coincide
roughly with the hydrogeological areas with the
strongest seasonal fluctuations in the hydrological
regime, i. e. the older rock formations of the
westem, northem and eastem coastal regions. The
municipal water supply has been a problem for a
long time in these regions, but it has been steadily
intensified in the last few decades, with increasing
population and demands from the fish industries.
The latest technical know-how often diffuses slowly
to the somewhat isolated communities, partly due to
the lack of a central information agency.
Where the local auhorities have concentrated on
longtime solutions and enjoy the assistance of a
capable and progressive technical staff, with a
proper geological - hydrological advice, adequate
solutions have usually been found. They may
include water conduits from distant springs or exten-
sive drainage wells in river gravels, but above all the
construction of sufficient storage facilities. A combi-
nation of natural water flow from springs, plentiful
for the greater part of the year, and seasonal pump-
ing of water from wells in river gravel for a few
months, is a promising solution in many places.
Surplus areas — The explosive expansion of the fish
farming and its water demands has changed the
situation of the freshwater reserves drastically, even
in the most affluent groundwater regions. On the
westem part of the Reykjanes peninsula the ground-
water reserves were only few years ago estimated to
be ten- or fifteenfold the extraction at that time and
then sufficient for at least decades to come. Now the
planned demands of the fishfarms in this region
probably exceed the known reserves. This illustrates
clearly how the situation has changed. The fishfarms
are a source of pollution, despite all care and cau-
tion. In any case some dissolved organic compounds
are conducted to rivers and other surface water, and
from there to the groundwater or to the sea. This in
tum may restrict the use of those waters, thus further
reducing the available surplus.
Plentiful freshwater may still be exploited in the
vicinity of Reykjavík, but there the danger of con-
tamination is also rapidly increasing. Other very
potent groundwater and/or spring regions are
situated at the interior highland margin. They have
been too remote for an economic exploitation, but
this aspect might also be changing as more sites for
fish farming are brought into the discussion. Some
of them are located in areas of historic monumental
50 JÖKULL, No. 38, 1988