Jökull - 01.01.2004, Page 32

Eyjólfur Magnússon et al.
Figure 10. A part of Köldukvíslarjökull (corner image) in the DEM from 1998 viewed as relief image with 20
m contour lines. The circle indicates a depression, probably created by geothermal activity. The balance and
ice velocity have been measured in K01, K02 and K03 since 1991. - Staðsetning sigketils í jaðri Köldukvíslar-
jökuls.
the geothermal area forming this depression could be
some tens of MW but not higher.
CONCLUSIONS
The EMISAR DEM along with a DEM from 1997 of
Skeiðarárjökull and the sub-ice topography of Vatna-
jökull were used to model the basal water poten-
tial under W-Vatnajökull assuming the water pressure
equals the ice overburden pressure. From that static
potential the water divides were delineated for all the
main rivers of W-Vatnajökull, between Skeiðará and
Jökulsá á Fjöllum as well as for the Gjálp eruption
site, Grímsvötn and the Skaftá cauldrons.
Some critical points exist in the predicted water
potential where it is not possible to say with certainty
into what river the water passing these points would
drain. The most crucial point is located at the di-
vides between the rivers Hverfisfljót and Djúpá. The
water that passes this point drains from a 270 km2
32 JÖKULL No. 54