Rockfall hazard zoning for land use planning
Rockfall constitute a serious threat to communities living in mountainous areas all over the world, and their potential hazard must be taken into account for an appropriate land use planning and for establishing risk mitigation measures. This chapter deals with guidelines and methodologies for assessing and zoning rockfall hazards for urban development planning. Depending on the purpose of the study, on the scale, as well as on the availability and quality of data, several methods are available, each based on specific approaches and assumptions. An overview of currently available guidelines and of zoning methodologies at the regional scale is first given. Then, as a detailed hazard zoning is required at the local scale for the purpose of planning urban areas, particular attention is paid to methodologies whose degree of detail and amount of information are suitable for this implementation. Precisely, methodologies based on trajectory modelling and, according to the definition of hazard, on the characterisation of rockfall intensity and frequency, fulfil these requirements. Several methods are presented and their differences highlighted. It is pointed out that is not straightforward to pass from trajectory simulation results to hazard zoning. The last but one section presents further uncertainties and difficulties which emerge in the elaboration of hazard maps. They are related to both departure zone characteristics and trajectory modelling results. Finally, the last part emphasises how national guidelines have conditioned the development of zoning methodologies, which allows understanding some reasons/sources of non-homogeneity in the approaches currently used worldwide. These considerations underline how social and political criteria (i.e. risk acceptance and risk management) must be carefully taken into account when comparing methodologies used in different countries and/or when transferring knowledge or approaches for hazard zoning from one country to another.
Record created on 2011-06-24, modified on 2016-08-09