Economic assessment of landslide risk for the Waidhofen a.d. Ybbs region, Alpine Foreland, Lower Austria

This research aims to assess potential risk and estimate economic damage caused by landslides. The study area is located in the Ybbs valley, Lower Austria (Fig.1). Methodology consists of Arc GIS based spatial analysis and estimation of the potential monetary losses caused by landslides. Spatial analysis was used for defining elements at risk located in the risk zone of 100 m near landslides, and assessment of potential consequences. Results: calculated possible losses caused by the destruction of immobility and transport: costs for buildings demolition, restoration, roads rebuilding, debris transport, excavation and removal. Research Area. The region of Ybbs valley is located in mountainous Alpine Foreland, Austria. It covers a total area of 131.3 km2. The environmental conditions of the the Ybbs valley are especially prone to landslides: Geology: deposits of gravel, sand, marl, conglomerate, calcareous sandstone and clay. Most of the region is used as pasture, agricultural land, and large forests. Climatic humid to continental. Intensive rainfalls in spring and autumn months. The region is attractive for tourists due to its environmental and historical value. Methods. The geographic location of the landslides within the Ybbs valley was used to define risk zones. Risk zone: 100-meter buffer area surrounding all landslides downwards, as a landslide with volume of 1 km3 may reach 100 meters while moving. Elements at risk: The objects located in the 100 meter distance downwards the landslides are regarded as elements at risk. Estimation of the economic losses: The methodology is proposed by Giacometti (2005) was applied for Ybbs valley using real estate prices for common goods (immobility, roads). Calculations of the economic losses (in €) was done based on the average real estate prices for various aspects of renovation, reconstruction and rebuilding of the destroyed objects. Defining elements at risk The elements at risk were selected in 100-meter buffer area near the landslides. The length and number of the elements at risk within the distance of 100 m near landslides totals to 20.9 km of railway lines, 13.5 km of roads and 641 buildings. Calculation the economic losses. The calculation of the real estate losses is computed from the calculation of five different types of costs: demolition, transport and disposal debris, restoration of inner walls, furniture restoration and house construction. The average volume to demolish damaged buildings indicated the dimensions of the losses of ca. 13.65 M €. The estimated price for the debris removal is approx. 3.6 M €, in case buildings are totally affected and covered. The restoration of the inner walls is based on average prices for building restoration and approximate surface of the walls, which totally estimates 2.73 M €. Using approximate prices of the furniture costs in a typical house the costs for furniture renovation is € 190,500. Cost for house construction is computed using real estate prices and average house area in m2 which sums up to € 349,250. The losses for transport include costs to rebuild a road, a railway, and a restoration of the roads. A total of almost 140 M € would have to be invested for the renovation of the Ybbs valley in case of a landslides disaster