Abstract
This study explores the impact of rainfall on the followed-up landslides after a severe typhoon and the relationship between various rainfall events and the occurrence, scale, and regional characteristics of the landslides, including second landslides. Moreover, the influence of land disturbance was evaluated. The genetic adaptive neural network was used in combination with the texture analysis of the geographic information system for satellite image classification and interpretation to analyze land-use change and retrieve disaster records and surface information after five rainfall events from Typhoon Morakot (2009) to Typhoon Nanmadol (2011). The results revealed that except for extreme Morakot rains, the greater the degree of slope disturbance after rain, the larger the exposed slope. Extreme rainfall similar to Morakot strikes may have a greater impact on the bare land area than on slope disturbance. Moreover, the relationship between the bare land area and the index of land disturbance condition (ILDC) is positive, and the ratio of the bare land area to the quantity of bare land after each rainfall increases with the ILDC. With higher effective accumulative rainfall on the slope in the study area or greater slope disturbance, the landslide area at the second landslide point tended to increase.
Highlights
Accepted: 23 March 2021Taiwan is prone to typhoons and heavy rainfall
Some of the original cartographic information in this study was based on data from Chue et al [14], including the satellite image maps, digital elevation maps (DEMs), and geological maps of Formosat-2 (FM2) before and after the six storms during
This study explored the impact of rainfall on the second landslide and evaluated the relationship between the various rainfall events and the occurrence, scale, and regional characteristics of the landslide
Summary
Accepted: 23 March 2021Taiwan is prone to typhoons and heavy rainfall. Because of steep terrain and unfavorable geological conditions in mountainous areas of Taiwan, concentrated rainfall during typhoons or rainstorm attacks leads to landslide and debris flow [1]. The Morakot Typhoon in August 2009 hit Taiwan with heavy rain, causing severe landslides, debris flow, and flooding in the southern, central, and eastern regions [2,3]. Such heavy rainfall that accompanies typhoons has caused frequent disasters in various hillside areas and affected people in those regions. Such disasters greatly affect the safety of people’s lives, property, and the living environment in the region, presenting a threat to the construction of major public projects. Even after the reconstruction, these regions face the risk of repeated sediment disasters on the slopes
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