Náttúrufræðingurinn - 1981, Blaðsíða 20

4) Kanna þyrfti seltu og hita á mis-
munandi árstíma, bæöi innan
fjarðarins og utan við Röstina, og
skoða þær niðurstöður í tengslum
við strauma og ferskvatnsrennsli.
5) Rannsaka þarf lífríki fjarðarins,
bæði plöntu- og dýralíf. í því sam-
bandi væri sérstaklega fróðlegt að
kanna fiskigöngur um Röstina.
Það er von okkar, að þessi skýrsla um
byrjunarathuganir í Hvammsfirði niegi
örva frekari rannsóknir af jtví tagi, sem
hér hefur verið nefnt.
HEIMILDIR
Den Islandske Lods, Kaupmannahöfn 1903.
Ilauksson, Erlingur. 1977. Utbreiðsla og kjör-
svæði fjörudýra í Breiðafirði. Náttúru-
fræðingurinn. 47: 88—98.
Leiðsögubók fyrir sjómenn við Island, I,
Vesturland. Vita og hafnamálaskrif-
stofan 1949.
Rist, Sigurjón. 1956. íslenzk vötn 1, Raforku-
málastjórn, Vatnamælingar.
Stefánsson, Unnsleinn & Guðmundur Guðmunds-
son. 1978. The Freshwater Regime of
Faxaflói, Southwest Iceland and its
Relationship to Meteorological
Variables. Estuarine & Coastal Mar.
Science. 6: 535—551.
Sverdruþ, II.U. et al. 1946. The Oceans, their
physics, chemistry and general biology.
New York 1946.
Þórðardóttir, Þórunn & Unnsteinn Stefánsson.
1977. Productivity in Relation to
Environmental Variables in the Faxaflói
Region, 1966—1967. ICES, C.M.
1977/L: 34.
SUMMARY
Hvammsfjörður — Its renewal
and water budget
by Unnsteinn Stefánsson
University of Iceland, and
Marine Research Institute, Reykjavík and Pétur
Þorsteinsson, Búðardal, Iceland
This paper describes preliminary studies
of the hydrographical features and water
budget of the fjord Hvammsfjörður, West
Iceland. It is about 350 km2 in area, with a
maximum depth of 51 m, and is separated
from the bay Breiðafjörður by a great
number of small islands and reefs in the
mouth of the fjord (Fig. 1, Table II). Results
of observations made in July 1979 are given
in Tables I and III. Tidal currents in the main
channel through the mouth (Hvammsfjarð-
arröst) are computed from information on
the area and volume of the fjord, the range
of the tide and the cross section area of the
channel, through which at least 90% of the
water exchange is assumed to take place.
The results indicate a range between 4 and
20 Knots (Table IV). On the basis of salinity
values for the fjord and the bay outside, the
fresh water fraction for different depths is
computed, and the total fresh water volume
found by numerical integration (equation
(4) and Table V). From hydrological data on
the average discharge of fresh water into the
fjord and the total fresh water volume, the
flushing time for fresh water in the fjord is
estimated to be between 21 and 46 days.
Finally, by comparing the net fresh water
discharge with the water volume trans-
ported through the mouth of the fjord, it is
concluded, that about Vt—8/9 of the sea
water exchanged during each tidal cycle is
derived from water which was exchanged
during the previous tidal cycle.
98