Effects of topography and geology on vegetation recovery after shallow landslides

Shallow landslides are instability events that lead to mass wasting of soil and vegetation in sloping areas and are commonly triggered by intense rainfall. Since vegetation is an important factor influencing the occurrence of rainfall-triggered shallow landslides and reduces the likelihood of landslides through different hydromechanical mechanisms, conducting in-depth research in this field for disaster risk management is meaningful. Investigating vegetation recovery processes after shallow landslides can provide significant insights for improving future disaster habitation works. However, vegetation recovery processes after shallow landslides and their influencing multivariate factors are not well known. Therefore, the objective of this study is to clarify the effects of geology and topography on vegetation recovery after shallow landslides in two research areas, the Shobara district, Hiroshima Prefecture, Japan, and the Obara district, Aichi Prefecture, Japan. Image analysis of historical aerial photographs was used to extract landslide-affected areas. Temporal changes in vegetation-condition indices were accessed from satellite imagery. GIS tools were used to extract topographic and geological indices. The relationships among those factors were quantified using a multivariate analysis of variance. Time series analysis was conducted by using the seasonal autoregressive integrated moving average. The change in time series, climate data, topographic, and geological characteristics were incorporated into a framework for mapping and modeling vegetation recovery. The results have quantitatively revealed both similarities and differences in vegetation recovery between the two areas in relation to geomorphological and geological conditions.