Impact of different landform representations between aerial photographs and multi-resolution slope maps on landslide susceptibility assessment

Abstract

  This study systematically examined the effects of the topographic representation accuracy of aerial photographs and topographic maps on landslide interpretation and hazard evaluation based on the Analytic Hierarchy Process (AHP). Focusing on landslide landforms distributed in the Tohoku region, the visibility of aerial photographs was evaluated using the relative height differences of cracks and ridges extracted from 1-m DEM-based topographic maps as an indicator. The results confirmed that vegetation conditions strongly control the visibility of micro-topographic features. Furthermore, analyses using stepwise relative-height models enabled a systematic classification of the minimum relative height differences of micro-topography identifiable on topographic maps generated from DEMs of various resolutions. In addition, regression relationships between landslide width and the relative height differences of cracks and ridges were used to quantitatively clarify the landslide scales identifiable on each type of map and to evaluate the accuracy characteristics of AHP scores. The results indicate that the 1-m DEM-based topographic maps exhibit the highest topographic representation accuracy, whereas aerial photographs in forested areas and topographic maps derived from10-30-m DEMs tend to underestimate the hazard levels of small-scale landslides.