Tsankov Kamak Hydro Power Plant - Natural Landscape

Natural Landscape

The Tsankov Kamak arch dam, associated works and the HPP station are located on the Vacha River, which is the second longest river in Bulgaria. It raises in the Rhodope hill ranges which borders Greece. It is situated on the borders of Smolyan Province, Pazardzhik Province and Plovdiv Province, roughly 40 kilometres (25 mi) southwest of Plovdiv and downstream (north) of the town of Devin. The dam site is located about 400 metres (1,300 ft) downstream of the confluence of the Vacha River and the Gashnya River, in the valley known as Gashnya Valley. The catchment area at the dam site is 1,214 square metres (13,070 sq ft) and the annual flow is assessed to be approximately 650 million cubic metres with an average inflow of 69.5 cubic metres (2,450 cu ft) per second. The dam has been designed for a gross storage of 111 million cubic metres.

The hydropower potential in the river between Sredna and Vacha had remained unexploited under the five dams development initiative, but is now utilized through the Tsankov Kamak project. The reservoir submergence is in rocky terrain, which is deforested and has unproductive vegetation. The catchment is highly rugged and mountainous with high altitudes, high watershed flats, deep ravines and large tectonic kettles. The upper and lower course of the river flows through deep cut banks.

In the narrow valley stretch of the Vacha River where the project is located, the geological formation consists of sound granites and gneissic formations except for a small patch of about 7 metres (23 ft), which is the fractured zone of mylonites, which was filled up with concrete. The dam’s rock foundation has seven types of rocks with elastic modules values varying from 12,000 MPa to 72,000 MPa and a Poisson’s ratio varying between 0.24 and 0.27. The damping ratio of 10% for this foundation has been adopted in the dynamic analysis. The intake structure and the pressure tunnel pass through difficult geological formations. Due to this geological feature, particularly at the intake structure, an area of about 6,000 square metres (65,000 sq ft) was required to be plugged in the Gashnia Valley.