The Sima Power Station, located
south-west in the Sima Valley, utilizes water from two geographically
separated areas and is in reality two power stations, Lang-Sima and Sy-Sima,
which share the same machinery hall.
Lang Sima Power Plant
uses water which is stored in Rundavatn and Langavatn. Langavatn has 48m. of
working storage. Both dams are retained by rockfill dams, gathering water
from the rivers on the west side of the big glacier Hardangerjokulen.
Langavatn gave rise to the name Lang-Sima.
Sy-Sima Power Plant
Water from Bjoreio and the south side of Hardanger jokulen is diverted to
the main storage in Sysenvatn, where you now stand. Sysenvatn has 66 meters
of working storage and a top water level 940m. above sea level. The water is
retained by a rockfill dam and is among Norway's biggest. A tunnel leads the
water to the forebay Rembedaisval Sysenvatn gave rise to the name Sy-Sima
This drawing clear ly shows what is meant by "gathering water by the roof
guttet principle. Highlying
water, in part behind dams, is network of natural river basins or artificial
conduits tunnelled through the rock. The most important sluices and valves
may be opened and shut by remote control either from the Station control
room at Sima or the operating centre in Sauda. In this way it is possible to
"store" water until it is needed before releasing it down into the pover
The Sysenvatn lake is retained by a rockfilI dam with an impervious, moraine
core. The enormous weight of the rockfill keeps the reservoir water in
place. Both sides of the watertight core are provided with filter zones of
sand and gravel thus preventing the core from being washed away The huge
quantities of stone used in the backfill on both sides we e collected in
part from the tunnel operations nearby, and in part from reservoir areas now
under water. The backfill is faced with large, placed stones.