Author(s): M. Cetina; R. Rajar; T. Hojnik; M. Zakrajsek; M. Krzyk
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Keywords: Debris flows; Mathematical models; Non-Newtonian fluids; Torrent control; River engineering; Hazard zones
Abstract: Numerical simulations of a landslide-debris flow, which occurred in November 2000, and destroyed a part of the village Log pod Mangartom, have been carried out. Onedimensional model DEBRIF1D was first used for simulations along the upper part of the affected region, where the debris flow was in a narrow canyon. Hydrographs of the debris flow discharge at the upstream end of the affected village were thus determined for chosen cases of possible future landslides; these were used as the upstream boundary condition for simulations carried out by two two-dimensional models: PCFLOW2D, developed at the University of Ljubljana and a commercial model FLO-2D. The three models were calibrated by field measurements and then used efficiently to determine the necessary measures for the future protection of the village. The most effective measures are: (1) removal of the debris mass, deposited after the last landslide in the stream along the village, to allow the future debris flows to move through or to be deposited; (2) construction of four dams which will partly accumulate the mass and partly dissipate the energy; (3) construction of an alongstream wall to deflect the debris flow at the upstream border of the village. A special feature of the DEBRI1D model enables direct computation of the initial hydrograph. The validity of the quadratic equation expressing resistance was roughly confirmed by field measurements even for changing flow regimes. Some interesting comparisons of the properties and the results of the three models are described.
Year: 2003