Dam breach reconstruction of the Blažňov pond caused by extreme hydrological event

Abstract

This article deals with the reconstruction of the dam breach of the Blaliov pond and consequent flood wave progress in the riverbed of the small brook. The dam breach occurred at the night from 28.3.2006 to 29.3.2006. The cause of the breach was above all increased inflow to the pond as a result of heavy rainfall together with intensive snowmelt. The earth-fill dam of the pond was in the time of breach corrupted by water rodents. The flood wave progressed through the brook valley with the length of 0.7 km. Consequently it fulfilled the Podoli pond, which is situated below the Blažňov pond. Podoli pond was in this time empty and the flood wave was completely transformed there. Measurements of the wave course and cross-sections through valley were made by total geodetic station. An extraction of flood sediments were carried out at three locations and their textures were analyzed. The reason was a description of the sedimentation process in the reach. For the modelling of the flood extremity and flood extent the hydrodynamic model HEC-RAS was applied (Hydrologic Engineering Centre - River Analysis System).