Jökull - 01.12.1983, Blaðsíða 127

son 1943). The channel from Vördufell to the sea is
therefore young and hardly fully developed. A few
hindrances are clearly seen during large floods; they
force the river out of its channel and eastwards over
the level land at Skeid and Flói. A continuous lake
forms there over a large area. I do not know of
anywhere else in the country where farmers have
had to save their sheep on the roofs of the sheep
houses to prevent them being drowned, when not a
single area was left standing above water. A similar
situation can thus occur in the Hvítá river area as on
a floodplain.
The northernmost and also the first obstacle in
the geologically young channel of the Hvítá is at the
western corner ofVördufell at the cliífs of Ida and
Skálholt, where the bridge is today. To the north of
the obstacle a large lake forms in large floods. It is
said that in the large flood of 2nd March 1930 the
water managed to trickle eastwards of Vördufell.
(Thordarson 1970). The second obstacle is east of
Hestfjall near the deserted farm Arhraun. In large
floods a continuous lake forms from Lake Hestvatn
along the Hvítá, through Utverkabakki and east-
wards to Olafsvallahverfi. From this reservoir a lot
of water flows southwards along Merkurlaut down
to Flói and to the sea (see Fig. 1 and 4).
From the southem end of Lake Hestvatn it is a
short and easy route to the River Hvítá. It would be
possible to build a construction to let the flood water
carry on and thus make full use of the channel in the
lowest part of the river, one to two days earlier than
occurs at present, and thus break down the highest
flood peak. Such constructions are not usually built
unless in connection with the total exploitation of
Fig. 4. Water level of the
Hvítá river for different flow
values, section from Ida
bridge to Árhraun farm (Hyd-
rol. Survey drawing 5326,
17thjanuary 1961).
4. mynd. Vatnsborð Hvítár við
mismunandi rennsli, kaflinn frá
Iðubrú að Árnahrauni (Vatnam.
teikn. 5326, 17.jan. 1961).
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JÖKULL 33. ÁR 125