FACTORS CONTROLLING RAINFALL-INDUCED SLOPE INSTABILITY OF NATURAL SLOPES IN NORTH MALENY, QUEENSLAND

Abstract

Rainfall infiltration is a significant triggering factor of slope failures as major landslide events have occurred during or immediately after rainfall. The rainfall-induced slope instability is governed by a complex interaction of topographical, hydrological and geological conditions of the slopes; hence these properties are critical parameters in determining slope stability under rainfall. The slopes in reservoirs catchments areas are constantly subjected to heavy rainfall with high intensity; thus, investigating the effect of rainfall on slope failures is vital to mitigate the adverse consequences. In this study, two critical slopes were identified based on high rates of erosion, sediment run-off, and elevated risk in Eden Road and Newsham in Lake Baroon Catchment, North Maleny, Queensland, Australia. The effect of slope geometry was analyzed by parametric analysis with the parameters; of soil's initial moisture content, rainfall intensity, and intermittent rainfall on landslide initiation in these two critical slopes by employing seepage and slope stability. The stability of the slopes was evaluated by the factor of safety, based on the produced seepage conditions from seepage analyses. The outcomes of the parametric studies are involved in identifying critical slope regions and rainfall conditions to mitigate the potential risk of rainfall-induced slope failures on Baroon Pocket Dam, Queensland.