engleski

Landslide hazard and risk assessment in Istria, Croatia

Paper presents landslide hazard and risk assessment in the central part of Istrian Peninsula, Croatia. Investigation area of about 550km2 is formed in Paleogene flysch deposits with expressed frequent instability phenomena followed by damages on local roads, buildings and other facilities, fortunately without casualties. Considering available data about landslide occurrences in the past, as well as results of preliminary analyses of sliding mechanism conditions and triggering factors, deterministic approach was used to analyse landslide hazard using 3D simulation model. High landslide susceptibility was identified in the north-eastern part of the investigated area, on the contact of flysch and limestone rock mass complex. Landslide susceptible areas are present in construction zones, protected forest, manufacturing and commercial zones, as well as other valuable parts on investigated area, established according to the existing urban plans. Furthermore, a coarse qualitative landslide risk analysis was performed. Elements at risk (assets) in the investigation area have been determined from the topographic maps and orthorectified photographs (1:5, 000) and they included following components: roads, smal road viaducts, residential houses and farm facilities, cultivated areas, protected forests and crude construction areas, as well as human lives and socio- economic activities. Vulnerability was defined as degree of loss for the certain element at risk threatened by landslide hazard inside defined hazard zone. Analysed area was divided in 20 hazard zones which were individually analysed regarding landslide risks, considering probability of hazardous event, vulnerability of elements at risk and temporal exposure to landslide hazard. Landslide hazard zones include zone of depletion, landslide path and zone of accumulation gained from the 3D simulation of landslide initiation and sliding mass propagation in LS-Rapid software. Temporal exposure of elements to landslide hazard was analysed considering a number of landslides inside the landslide hazard zone. Landslide intensity was considered in respect to landslide area. According to the present number of elements at risk inside the landslide hazard zone, four levels of impact on the total risk were determined. Single asset method was used in the vulnerability analysis where damage or loss for every element at risk were determined individually, paying attention on the elements inside or near the landslide hazard zones and landslides. Vulnerability was assessed inside the following levels: no damage, minor damage, functional damage or structural damage. Presence of human lives and social effects, as elements at risk, was considered in the way that vulnerability was raised for one level. Total risk was categorized into five levels: very low, low, medium, high and very high. Results of these analyses allow changes in existing urban plans and an improvement of future land use management. Cognitions about landslide hazard and risk in the area can be useful to many direct and indirect users, scientists and engineers, local government, developmental agencies, construction and utility service departments, as well as insurance companies. Analyses could give considerable contribution to sustainable land use development, if they would be included in the urban planning by limitation of construction on zones with acceptable landslide hazard and risk level.

landslide ; hazard ; risk ; susceptibility ; vulnerability

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