Jökull - 01.12.1988, Blaðsíða 51

-1,600
- 1,400
- 1,200
- 1,000
-800
-600
-400
-200
1900 1920 1940 1960 1980
Fig. 9. Water consumption in Reykjavík
[1/inh.xday], average figures for the city (•) and for
different parts of the town (-).
Mynd 9. Vatnsnotkun í Reykjavík [l/íbúaxdag],
meðaltöl fyrir borgina í heild (•) og fyrir einstök
hverfi (-).
expensive.
As a thumb rule about 300 1/s of water is needed
for the production of one million salmon smolts per
year. In addition much water is needed for the coas-
tal pond- or tank-rearing stations during the initial
stages of salmon rearing. In Fig. 11 the actual and
foreseeable development in fish farming from 1970
to 1989 is shown (Rannsóknaráð ríkisins, 1986).
From the figure it can be estimated that in 1986
about 600 1/s of groundwater were needed, in 1988
about 3,600 1/s of groundwater will be needed for
the smolt production and in 1989 it is expected to
reach 4,500 1/s. The water flow for domestic use
through water works in Iceland has been estimated
as being about 3,000 1/s (Sigurðsson and Einarsson,
1986). Thus an increase of nearly 100 % in the har-
nessing of groundwater was needed in only 2 years
(1986 to 1988) to facilitate both an increase in the
production of previously existing stations and addi-
tional usage in new fish farming/hatching stations.
Still more will be needed if plans for the year 1989
come true. The quantity of groundwater needed by
about 20 coastal rearing stations, for the initial
stages of fish production, has not as yet been
estimated. However, it can be stated that it is vari-
able and dependent on many factors, such as initial
weight of the smolts, biomass load in the ponds or
Fig. 10. Average production of frozen fish
[thousand tons], 1942-1985.
Mynd 10. Meðal ársframleiðsla frystra sjávaraf-
urða [þús. tonna], 1942-1985.
tanks, methods of operation etc.
RESOURCES AND EXTRACTION
On the whole it can be stated that considerable
resources of good quality groundwater are to be
found in the Late Quatemary Volcanic Zone. Only
in recent years has the extraction locally reached the
stage of competition for the same water across mun-
icipal boundaries, with consequent needs for cen-
tralized administration.
On Tertiary and Early Quatemary rocks water
always has been seasonally limited, which is often
unfortunate during the slaughtering of sheep in the
autumn and the winter top in fishing.
The water is extracted from springs, boreholes
and dug wells, as shown in Fig. 12, and there are
still a few of villages dependent on surface water for
their water supply.
In Figs. 6 and 7 the distribution of the water con-
sumption, both regionally and by user groups, is
depicted. Large water works and hatching stations
are concentrated in, and on the borders of, the Late
Quatemary Volcanic Zone.
Limiting factors of water supply — The complex
picture of water abundance and shortage in Iceland
can be viewed and resolved by analysing its hydro-
logical, geological, historical and socio-economical
determinants. Some limiting factors can be isolated
and solved by investigations and appropriate
JÖKULL, No. 38, 1988 49