Jökull - 01.12.1969, Side 106

On the Recession of Vatnajökull'
GUTTORMUR SIGBJARNARSON,
NATIONAL ENERGY AUTHORITY, REYKJAVÍK, ICELAND
S U M M A R Y
There is a certain discrepancy between pre-
cipitation maps and run-off maps of Iceland
now available in the way that the run-off
seems to have been greater than the precipita-
tion. An attempt is made to calculate to what
degree the glacier recession is responsible for
this discrepancy. Measurements of the recession
of Breidamerkurjökull were gathered. During
the period 1894—1968 the glacier front retreat-
ed up to 2300 m, exposing 52 km1 2 of de-
glaciated area. During the same span of time
Breidamerkurjökull lost in volume 49 km3,
which corresponds to an increase of 19 m3/sec
in the average run-off.
In this period the shrinkage of Vatnajökull
was approximately 270—350 km3 which amounts
to 8—10% of its total volume of ice. With a
comparable recession to that of the years 1932—
1968 it would take 500—600 years to waste the
whole of this ice mass away. Calculated as
annual increase in run-off the total glacial re-
cession in Icelancl during the period 1931 —
1960 approximates to 7—8 • 109 m3. It partly
explains the above discrepancy but is far from
being a complete explanation.
1) Tliis paper will be published in Jökull
1970.
102
JÖKULL 19. ÁR