Bozkovské Dolomite CavesBozkovské Dolomite Caves

The dolomite caves with the largest underground lake in Bohemia.

Prachovské skály (rocks)Prachovské skály (rocks)

The Prachovské Skály nature preserve is one of the most popular regions in the Czech Republic. It is one of the oldest nature preserves in the country. 


The Hruboskalsko is one of the best-known rock formations. It is characterised by impressive towers reaching up to 55 m and also by steep canyons. 


Protržená Přehrada - Dam that burst open

Jizera Mountains

Desná v Jizerských horách, 468 41

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The dam on the Bílá Desná River is situated near the village of Desná, 806 metres above sea level. The structure was completed in 1915; however, in September of the following year, it burst open.

The accident was a real catastrophe since the flood wave not only caused immense damage on the property but killed 65 people as well. The preserved parts of the burst dam were used as an example of improper technology in order to make computations for other similar constructions, built after 1916, safer. In 1996 the dam that burst open was declared the cultural monument. At the present time, you can see the preserved slide tower, relics of the dike and the underground tunnel that was used to direct the water in the neigbouring reservoir named Souš.

The Breached Dam – the historical context

The reservoir on the White Desná (nowadays known as the Breached Dam area) was built together with the Souš Valley Reservoir as part of a hydro-engineering system. The design project was drawn up at the instigation of the Water Cooperative in Dolní Polubný with the participation of Professor Dr Otto Intze. The design engineer was Ing. Wilhelm Plenkner. Construction commenced on 17th October 1911, less than two months after the commencement of the construction on the Souš Reservoir. Both hydro-engineering structures were connected by a 1104.8 m long tunnel with a longitudinal gradient of 1%0. It was supposed to be used to transfer water from the reservoir on the White Desná to the Souš Reservoir. Both reservoirs were given final approval for use on the same day – 18th November 1915. The dam on the White Desná breached exactly ten months later. The volume of water in the reservoir was 290,000 m3, meaning that it was up to three-quarters full (its total capacity was supposed to be 400,000 m3).

The first leak was noticed at 3:30 pm on 18.9.1916 (about a two centimetre trickle). By 3:55 pm, the water was already pouring through strongly. At 4:15 pm, the tiles on the upstream side began to subside and the dam breached completely at 4:45 pm. The water gushed down a 40 m wide rift and took everything in its path with it. The dam lies in the cadastral territory of the Municipality of Albrechtice v Jizerských horách, but the consequences of the breach were mainly catastrophic for the area of what is now Desná I.

The reservoir’s planned technical parameters:

The dam: an earth dam, width at the base: 54 m, height above the terrain: 14.6 m, width at the crown: 5.2 m with an elevation of 1.6 m above the highest water level in the reservoir

The reservoir volume: 400,000 m³


It is prohibited to ride motorcycles to the Breached Dam.

Likewise, it is also prohibited to stop or park your vehicle anywhere in the 1st Protection Zone of the Souš Water Reservoir (in accordance with the “Water Act”). This is apparent from the traffic signs placed throughout the entire section from Souš to the intersection with the Barracks Trail (Kasárenská cesta).

Protržená přehrada, author: Milan Drahoňovský

Technical Monuments: Other technological sites

Protržená přehrada, author: Milan Drahoňovský
Protržená přehrada, author: Milan Drahoňovský
Protržená přehrada, author: Milan Drahoňovský


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