Jökull - 01.12.1974, Page 33

Fig. 3. Suspended sediment concentration of fine silt at the glacier outlets, in the rivers Skeidará,
Gígja and Súla.
Mynd 3. Aurburður af mélu í Skeiðará, Gígju og Súlu. Magn í Utra við jökulinn.
grain size of bottom material, which is mostly
sand in Gígja, but coarse gravel in Skeidará.
This problem was approached by sampling
floating small chips of glacier ice from the
jökulhlaup and measuring the sand content
along with other components in it. As a first
stage the floating glacier ice is assumed to re-
present the melted and eroded ice in the ice
tunnel which is the source of the sediment load.
The quantity of sand calculated on basis of
glacier ice content was 8,000,000 tons. The ratio
fine silt/coarse silt was of the same order of
magnitude in glacier ice as suspended in the
river.
The content in glacier ice was also used to
calculate the amount of gravel carried by the
jökulhlaup. The result is 2,000,000 tons of
gravel.
The total sediment load calculated in this
manner is 29,500,000 tons, whereof most of the
sand and all of the gravel is bedload.
JÖKULL 24. ÁR 3 1