Jökull - 01.12.1967, Blaðsíða 24

TABLE I. Advance ol the hlaup down to Markarfljótsbrú (= Brú)
TAFLA I. Ferð lilaupsins frd upptökum að Markarfljótsbrú (—Brú)
Locality Distance from Time from set Distance Interval Average velocity
or section source, km off, min. km min. m/sec km/hour
Staður Leið frá upp- Tími frá byrj- Lengd kafla Timi á kafla, Meðalhraði
eða kafli tökum, km un, min. km mín. m/sek. km/klst.
Innstihaus Innstih -Thórólfsf ell 0 0 9.5 18 8.8 32
Thórólfsfell Thórólfsfell-Brú .... 9.5 18 15 90 2.8 10
Brú Innstihaus-Brú 24.5 108 24.5 108 3.8 13.6
of the flood was estimated at Thórólfsfell, be-
tween 5 and 15 minutes, and at Markarfljóts-
brú between 15 and 20 minutes.
ORIGIN OF THE FLOOD WATER
At Markarfljótsbrú, a section of the hlaup
track was investigated and levelled by Sigurjón
Rist (pers. comm.). Applying the Manning for-
mula, he found the maximum discharge of the
hlaup to have been 2100 m3/sec and estimated
the total volume of the lilaup water at 1.5 • 10°
to 2.5 • 106 m3, excluding the water of the
Markarffjót which was in great flood.
Most of the hlaup water was certainly de-
rived from Steinsholtslón. Tliis lake hacl an
Fig. 10. Left foreground: heap of ice and rock fragments. Right in the middle: Steinsholtsjök-
ull covered with debris. Background: mountain side with an undulating wliite stripe, consisting
of ice blocks, marking the reach of the hlaup. — Photo G. Kjartansson, January 23, 1967.
10. myncl. Fremst og t. v.: Jakahrönn blönduð grjóti við Steinsholtslón. T. h.: Steinsholtsjökull,
þakinn aur. Fjær: Skaratungur með Rjúpnafelli, og í hlið þeirra hvit rdk, öldótt, sem er hrönn
d hlaupmörkum.
258 JÖKULL 17. ÁR