Review of disastrous torrent flood on the vlasina river on June 26, 1988 — Including analysis of flood and the obtained results

Abstract

A disastrous torrent flood on the Vlasina River of 26 June 1988 was of unprecedented intensity in Yugoslavia. The catchment area affected by the catastrophe covered more than 1000 km2 and the damage was estimated to one billion dollars. It is interesting to note that this area was treated with erosion control works and that percentage of eroded land (soils) was negligible. According to the experts opinion, or should we say delusion, torrent flood could not possibly occur in thus protected catchment. However, we have to admit that impossible did happen. The analysis of the flood yielded significant results that revealed that experts were mistaken in many points. Those results indicated a need to find different analytical approach because, besides visible traces, the actual records of flood were sparse. Rain gauging stations in the zone affected most seriously were completely destroyed as well as water level gauges. Since the torrent flood computations on the base of flood traces are not reliable, the causes of flood occurrence and development of flood itself had to be reconstructed. In that respect, meteorology — radar surveys were used for reconstruction of rainfalls. Using these data, as well as those obtained by torrent bed survey, by grain size analysis and by determination of peak flood on some tributaries and along the river itself, the flood could be analysed. In addition, the efficiency level of erosion control works was analysed and also the importance of torrent control as basic element of complex erosion and torrent control works.