Characterizing groundwater flow in a translational rock landslide of southwestern China

Abstract

Characterizing the groundwater flow pattern in a landslide would help to establish a monitor-warning system to predict the movement of a highly concealed and extremely hazard translational landslide. The complex fracture network in this type of landslide affects the rainfall infiltration process and the groundwater flow. In this paper, multi-tracer tests, injection tests and electrical resistivity tomography were used to investigate the hydrogeological characteristics and groundwater dynamics of the Kualiangzi translational rock landslide, which is located in the northeast of the Sichuan Basin, China. The study results indicate that there are two kinds of groundwater flow mode, in the landslide, the concentrated mode and the dispersed mode. Tracer and injection test results indicate that the groundwater flow in the landslide is mainly controlled by a vertical preferential flow pathway (concentrated mode), of which the direction is approximately perpendicular to the sliding direction of the landslide. The main runoff direction in the middle of this landslide is southwest according to electrical resistivity tomography. The hydraulic conductivity in the preferential direction is more than 3750 times larger than that perpendicular to the direction. The groundwater flow along the weathered sandstone and mudstone media in the vicinity of the slip surface is very slow (dispersed mode). The results reveal the existence of a preferential flow pathway. The hydrogeological conceptual model is considered as an unbounded domain with an anisotropic medium in the whole area. This hydrogeological model clearly describes the hydrological conditions, and can help establish a monitor-warning system in a translational landslide.