Instability of Rock-Fill Spur-Dykes Downstream of Hydropower Station and Countermeasures

Breakdown of rock-fill spur-dykes occurs very often in natural streams downstream of hydropower station due to rapid flows. In this paper the laboratory investigations in an open-channel flume have been presented, showing how the stability of the dykes is influenced by the flow downstream of hydropower station. The main factors, which results in the breakdown of the spur-dykes, are analyzed and the countermeasures against the collapse are summarized. Furthermore, the layout of geotextile soft mattress as a countermeasure against the indirect damage is suggested based on the measurements of turbulent flows around the spur-dyke. Also, modification in cross-section of spur-dykes is proposed as a countermeasure against the direct damage.