Jökull - 01.12.1988, Page 39

High precipitation and permeability
llllll 1 lllllllll 2 ---------- 3 4
Fig. 1. Where high permeability of the bedrock coincides with high precipitation, groundwater is abundant,
as in southwest Iceland. Areas without permeable bedrocks and sufficient precipitation may be deficient in
groundwater for exploitation.
Mynd 1. Gnótt er af grunnvatni, þar sem saman fara lekur berggrunnur og mikil úrkoma, eins og á
Suðvesturlandi. Annars staðar geta lítil lekt bergs og takmörkuð úrkoma leitt til skorts á neyzluvatni.
Explanations / Skýringar:
1. Precipitation > 1,600 mm / Úrkoma > 1600 mm
2. Precipitation > 3,200 mm / Úrkoma > 3200 mm
3. Permeable bedrocks / Lekur berggrunnur
4. Permeable bedrocks and limited surface runoff / Lekur berggrunnur og takmarkað afrennsli á yfiborði
open fissure swarms are absent and the extractable
groundwater is restricted to Recent sediments of a
limited extension and with strong seasonal fluctua-
tions in the discharge of the springs (Fig. 2).
The real conditions are much more diversified
than this simplified general classification, but the
deviations are varying and are in each case res-
tricted to limited areas (Hjartarson et al., 1980).
A notable degree of regularity can be detected in
the chemical composition of the groundwater. The
JÖKULL, No. 38, 1988 37