Fuzzy logic Application in compiling geohazard macro-zone maps

摘要

Geohazards in Iran can cause widespread damage to property and human lives. In this study, we describe a new method of fuzzy logic applied to geohazard macro-zone maps. The basic steps are (i) compilation of macro-zone maps for each type of geohazard phenomenon, such as landslides, rock falls, sink holes, asymmetric subsidences, liquefactions, erosion and water washing in various situations, large-scale ground failures, floods, and avalanches, to name a few. Each phenomenon is then assigned one of seven geohazard zones: very low, low, relatively low, moderate, relatively high, high, and very high; (ii) definition of a membership function using a fuzzy logic algorithm to quantify the qualitative data, estimate a geohazard grade for each mesh point, and to convert qualitative maps to quantitative maps; (iii) computation of the summed hazard grade for each mesh point and compilation of a cumulative geohazard map; and (iv) compilation of a geohazard macro-zone map by defining a mathematical algorithm and again using fuzzy logic. In this paper, in addition to introducing the method outlined above, we also describe a mechanism that takes subjective engineering judgments into account. Finally, a geohazard map with a scale of 1:25,000 (in Iran) was compiled and presented.