Determination of the rockfall source in an urban settlement area by using a rule-based fuzzy evaluation

Abstract

Abstract. The evaluation of the rockfall initiation mechanism and the simulation of the runout behavior is an important issue in the prevention and remedial measures for potential rockfall hazards in highway protection, in forest preservation, and especially in urban settlement areas. In most of the studies in the literature, the extent of the rockfall hazard was determined by various techniques basing on the selection of a rockfall source, generally defined as zones of rock bodies having slope angles higher than a certain value, proposed by general practice. In the present study, it was aimed to carry out a rule-based fuzzy analysis on the discontinuity data of andesites in the city of Ankara, Turkey, in order to bring a different and rather systematic approach to determine the source areas for rockfall hazard in an urban settlement, based on the discontinuity and natural slope features. First, to obtain rock source areas (RSAs), data obtained from the field studies were combined with a rule-based fuzzy evaluation, incorporating the altitude difference, the number of discontinuities, the number of wedges and the number of potential slides as the parameters of the fuzzy sets. After processing the outputs of the rule-based fuzzy system and producing the linguistic definitions, it could be possible to obtain potential RSAs. According to the RSA maps, 1.7% of the study area was found to have "high RSA", and 5.8% of the study area was assigned as "medium RSA". Then, potential rockfall hazard map was prepared. At the final stage, based upon the high and medium RSAs, 3.6% of the study area showed "high rockfall potential", while areal distribution of "medium rockfall potential" was found as 7.9%. Both RSA and potential rockfall hazard map were in accordance with the observations performed in the field.Correspondence to: M. Ercanoglu

Rockfall characterisation and structural protection – a review

“…In landslide hazard assessment, many statistical or other modern techniques are now used (Van Westen, 2004); e.g., Aksoy and Ercanoglu (2006) classified the susceptibility of source areas using a fuzzy logic-based evaluation.…”

Identification of potential rockfall source areas at a regional scale using a DEM-based geomorphometric analysis

“…Similar attempts were limited to cliff faces (Krummenacher, 1995;Meissl, 1998) or active rockfall slopes only (van Dijke and van Westen, 1990). More evolved methods were developed by combining the slope geometry extracted from a DEM with datasets such as rock type, exposition, slope curvature and land cover for instance in an heuristic or probabilistic way (Marquinez et al, 2003;Aksoy and Ercanoglu, 2006;Acosta et al, 2007). Besides, high resolution DEMs (HRDEMs) have made possible the detection A. Loye et al: Potential rockfall source areas using a DEM-based geomorphometric analysis of discontinuities sets (Jaboyedoff et al, 2007).…”

Integrating field measurements, a geomorphological map and stochastic modelling to estimate the spatially distributed rockfall sediment budget of the Upper Kaunertal, Austrian Central Alps

“…For each group, a specific probability density function needs to be selected that effects higher or lower, more or less variable rockfall production rates. In a similar way, Aksoy and Ercanoglu (2006) use a fuzzy set of rules to assign a qualitative hazard (low-medium-high) to potential rockfall source areas. The rules for assigning nodes to such categories can be defined by experts, supported by field data and data from the literature.…”