Landslide risk for the territory of Bulgaria by administrative districts

An assessment of the landslide risk (R_ls) for the territory of Bulgaria by administrative districts has been made by combining the vulnerability (V) and landslide hazard (H_ls) maps. Landslides are a significant part of geological hazards and are widespread throughout the country. In order to assess the landslide risk for the territory of Bulgaria, it is necessary to take into account not only all landslides for a given region, but also its vulnerability, and thus to assess the level of landslide risk for this region, R_ls = f (V, H_ls). Landslide risk is determined by a risk matrix, using selected indicators and weighting coefficient of vulnerability and landslide hazard. Assessing the vulnerability of a region subjected to geological hazards is a key component of risk assessment. These include the exposure of infrastructure, industrial facilities and production capacity, residential buildings, regional GDP per capita and potential for human disability (defined by population density in the district). The data used is combined to create a map showing the vulnerability of each administrative district. Indicators of population density, GDP, length of road and railway networks and number of residential buildings were used to assess the vulnerability. The landslide hazard in each administrative district is determined by the intensity of landslide processes in the district, depending on the level of their activity and the affected area. The normalized (distributed) hazard of landslides for an administrative region is given depending on the area of the given administrative region. Landslides are categorized as active, potential and stabilized. The results express the weighted average hazard. Landslide hazard is rated from 1 to 5, where 1 means no landslide hazard and 5 means that landslide hazard has a very high intensity (very high hazard). The high degree of landslide hazard in turn leads to possible economic losses, social and environmental consequences (landslide risk). The intensity (level) of landslide vulnerability, hazard and risk is assessed as very low, low, medium, high and very high, and is shown on the relevant maps.