Debris flows in Kazanlak valley, south slopes of the Balkan mountain range, Bulgaria

Abstract

Along the Balkan slope of Kazanlak valley there are active debris flows. They are formed in small basins and increase the relief-dissection rate. Their activity is related with deforestation of this area, especially strong during the end of the Medieval period. The fortification of the streams along the south slope of the Balkan Range was a state policy when a Department of Forestation was founded (as department of the National Agency for Torrents Control) in 1904 in Kaznalak town. This research was taken during archeological excavations, when layers stratification around Thracian moulds showed typical alluvial fan gradation. The aim of this study was to characterize the streams, their type, their deposits and their forms of accumulation (using grain size analysis), and to estimate the forestation as prevention activity. The results showed that debris flows in Kazanlak valley are incoherent, the size of their sediment forms is not large but they were fortified very effectively and in present days they are not active.

Keywords

• Kazanlak valley
• colluvial fan
• debris flow
• erosion
• forestation