The influence of reservoir filling on a preexisting bank landslide stability

Abstract

A new monitoring instrument (automatic GPS) was used to understand the relationship between the stability of landslide and the hydrological triggering factors in the process of reservoir filling. These factors were drawn from a study that reported on the relationship between surface movement and hydrological triggers of a typical reservoir landslide (Yanziping landslide) in Jiudian Gorge Reservoir (JGR). A Fast Moving Zone (FMZ) can be spatially identified from the Main Deformation Zone (MDZ), and the temporal evolution of the landslide consists of a progression in time with short periods of Fast Movement (FM) and longer periods of slower movement. The results indicate that three FMs could be identified, which are triggered by different factors. The continuous rapid water rise will definitely trigger FMs with the rainfall being the secondary role and the longer duration of rapid water rise is not conducive to the stability of landslide in the phase of 70～100 m. Rapid drawdown of reservoir water level also triggers FMs from 100 to 130 m. Besides, there is a lag time of approximately 5 days between FMs and rapid water rise. A most dangerous water level for the landslide movement also can be identified approximately 80 m. The sliding mode was changed by reservoir water storage. Near-real-time monitoring by GPS can provide more reliable and timely data, which is significantly important for disaster prevention and mitigation.