| dc.description.abstract | Large landslides usually caused severe damage to people and properties. The disaster scales of dip-slope landslides were more severe than other types of landslides. Therefore, the dip-slope mapping becomes one of the important works for preventing landslides. According to Soil and Water Conservation Technical Regulations Article No. 31, the dip slopes are defined such that the angle between the strikes of the slope surface and the bedding or the angle between the strikes of the slope surface and the weak plane is less than 20 degrees with the same dip directions. In the past, dip-slope mapping methods were usually acquired by manual mapping. The results were subjective and time-consuming. Now, with the advanced development of remote-sensing technology and computing power, the dip-slope mapping could be automatically interpreted by fast computer program analysis. This technology makes dip-slope mapping more objective and efficient.
The study proposes to input the high-resolution digital elevation model (DEM) and the attitudes of the bedding planes from field investigation into Geographic Information System (GIS). We intended to identify the ranges for dip slopes by executing series of automated identification program. First, the study uses GIS to obtain dip direction of bedding information raster data from the trend surface method and kriging by the actual bedding attitude data, respectively. Afterward, we overlaid two kinds of dip direction raster data respectively to obtain the dip-slope cell raster with aspect and slope raster data from DEM data. Then, we execute “Point-Density” algorithm to automatically finish the dip-slope mapping by choosing the appropriate Point Density (PD) value. Last, we take the results of dip-slope mapping to compare with the dip-slope raster data by CGS and the landslide cases in the study area. We consider that the attitude raster data making by kriging have higher accuracy than the other one in the study area.
Based on the dip-slope mapping result in this study, we further consider the distribution of the cells of which slope angles are bigger than dip angles, and we called the involved dip-slopes the cells “the daylighted dip-slopes with potential hazard”. Finally, we try to explore the evidence about whether the mapped dip-slopes are danger dip-slopes by field investigation. In the future, we hope the automated program in our study can effectively and rapidly find the possible distribution of the dip-slopes with potential hazards, and also reduce the cost and time about the geological field investigation for dip slope mapping. | en_US |