Hydrological conditions (see table)

Gravity dam
The concrete gravity dam rises to a height of 18.0 m above the valley bottom and 33.0 m above the footing bottom. The dam crest is 472.0 m long. The maximum width of the dam crest is 7.75 m and that of the dam footing is 31.90 m. The volume of the dam is 347,000 m3.

The concrete gravity dam consists of 31 blocks 6.5 to 16 m wide which are of identical design and are embedded in the same rock. Three pillars, inflow and outflow wings of the discharge facility rest on caissons. The other pillars, foundation slab and stilling pool are in an open building pit protected by a steel sheet wall.

Dilatation joints between blocks are sealed on the waterside by a V-shaped rubber rope protected by a vedge of reinforced concrete. Another sealing is a 15-cm-wide rubber band deposited in a joint in a special shaft.

Through the whole body leads an inspection corridor which also had the function of a grouting gallery. Grouting was made through a grid of drillholes to which additional holes were progressively added on the basis of previous results of water pressure tests. A grouting curtain was made of a stabilized clay-cement suspension.

Because of the presence of alkaline mineral water in the foundations of the dam blocks and discharge facility it was necessary to take measures for protecting the foundation concretes. The protection is provided by an insulation basalt pavement of cobble stones embedded in mortar of terrazzo cement and basalt sand.

The dam holds back a water reservoir which serves for daily and weekly flattening of water flows. The reservoir has a total volume of 36.0 million m3, of which reserve volume accounts for 24.0 million m3 and permanent volume for 12.0 million m3. The reservoir‘s backwater stretches for 12.0 km and the maximum inundated area is 7.0 million m3 with the maximum water depth of 15 m.

Functional facilities are situated in five blocks of the dam. They include crest spillways and bottom outlets. The crest spillways are closed by 17.3x3.5-m gates with a capacity of 1,200 m3.s-1. The bottom outlets are closed by segments 14.0x4.8 m in size whose capacity is 3,500 m3.s-1. The gates and segments are controlled from an engine room on a dam girder whose total height is 9.7 m.

On the left bank below the dam is the hydroelectric power plant. It has three vertical Kaplan turbines, each with a throughput of 130.0 m3.s-1, and 10.5 kV generators. Each aggregate is located in a separate block 21.0 m wide. An engine room is enlarged by an assembly area. Turbine inlets can quickly be closed – by shutters and also by auxiliary damming panels. Inlets to spirals are protected by fine bar screens.

The power plant‘s rated capacity is 3 x 22.5 MW, i. e. 67.5 MW, with an average annual production of 151.9 GWh and guaranteed duration of peak hours 4.4 hours a day. The maximum head is 22.5 m and the minimum one 11.5 m.

Waste water canal from the power plant is 2.65 km long, has a trapezoidal cross-section, bottom width 48 m and a capacity of 400 m3.s-1.

Information & Contact:

Research Institute of Water Management,
Nabr. arm. gen. L. Svobodu 5,
811 02 Bratislava,
tel.: 00421 (2) 59343111,
fax: 00421 (2) 54415743