Geologija (Jun 2009)
Debris-flow susceptibility model of Slovenia at scale 1 : 250,000
Abstract
For the area of Slovenia (20.000 sqr. km) a debris-flow susceptibility model at scale 1 : 250,000 was produced.To calculate the susceptibility to debris-flow occurence using GIS several information layers were used such as geology (lithology and distance from structural elements), intensive rainfall (48-hour rainfall intensity), derivates of digital elevation model (slope, curvature, energy potential related to elevation), hydraulic network (distance to surface waters, energy potential of streams), and locations of sixteen known debris flows, which were used for thedebris-flow susceptibility models’ evaluation. A linear model weighted sum approach was selected on the basis of easily acquired spatio-temporal factors to simplify the approach and to make the approach easily transferable toother regions. Based on the calculations of 672 linear models with different weight combinations for used spatio temporal factors and based on results of their success to predict debris-flow susceptible areas, the best factors’weight combination was selected. To avoid overfitting of the prediction model, an average of weights from the first hundred models was chosen as an ideal combination of factor weights. For this model also error interval was calculated. A debris-flow susceptibility model at scale 1 : 250,000 represents a basis for spatial prediction of the debris-flow triggering and transport areas. It also gives a general overview of susceptible areas in Slovenia andgives guidance for more detailed research areas and further spatial and numerical analyses. The results showed that approximatelly 4 % of Slovenia’s area are extremely high susceptible and approximatelly 11 % of Slovenia’sarea of susceptiblity to debris-flows is high. As expected these areas are related to mountainous terrain in the NWand N of Slovenia.
