Jökull - 01.12.1983, Page 126

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Fig. 3. Elliðaár river. Large flood 28th February 1968, a flood of type 3 + 6 i.e. rain- and meltflood with
the addition of man-made flood. The picture is taken towards Blesugróf. The river threatens a 60 kV main
transformer station for Reykjavík. (Photo. Landsv.).
3. mynd. Elliðaár. Ofsaflóð 28. febrúar 1968, flóð af tegundinni 3+6, þ.e. regn og leysingaflóð að viðbœttu
mannvirkniflóði. Myndin er tekin vesturyfir til Blesugrófar. Ain ógnar 60 kVaðalspennistöð Reykjavíkurborgar. (Ljósm.
Landsvirkjun).
former in the desertion of two parishes for some
decades.
In spite of large and sudden floods in the past
centuries only a few people have lost their lives as a
result offloods in Iceland. This is due to the dispers-
ed nature of the settlement and to the fact that there
has been almost no human traffic while the floods
were in spate. In the last century a shepherd from
Núpstadur lost his life on Skeidará sandur when a
jökulhlaup came from the Grænalón lake. A couple
from Oddagardur in Flói were drowned while try-
ing to save their livestock from floods in the Hvítá
river shortly after 1700. Floods have harmed
farmers’ stock from time to time and now in this
century roads and bridges can be added to the
misfortunes due to floods. On leap year’s day 1%8
the Ölfusá river flooded 35 houses in Selfoss. This
represents considerable damage in a country with
as small a population as Iceland.
The Hvítá river in Amessýsla
No doubt the river Hvítá/Ölfusá is the most
dangerous flood river in Iceland; there are many
reasons for this. There are, however, two main
causes. The first is that the left bank, i.e. to the east
of the river, is low, as if there was in fact a floodplain,
although geologically the land is quite different.
The other reason is that: this is one of the mosl densely
populated areas in the country.
The winter floods are the most dangerous. They
are rain- and meltfloods on frozen ground, when the
channel is half dammed up by ice and slush ice.
Floods have also proved to be destructive in late
summer- and autumn- rains. Spring floods however
do not occur in the Ölfusá river; for that to happen
the climate would need to cool considerably from
the present (Rist 1969).
1 he Thjórsá lava pushed the Hvítá river west of
Vördufell only a few thousand years ago. (Kjartans-
124 JÖKULL 33. ÁR