Hydrogeochemistry in landslide research: a review

This review aims to give an overview of the potential hydrogeochemical information can have for landslide research and analyses the use of hydrogeochemical information to unravel the hydrological processes in landslide triggering. Landslides are well known for their data shortage; especially in case the hydrogeology is heterogeneous and difficult to measure. In this article we analyse the impact hydrogeochernical processes has on physical properties of the soil material and rock slopes, i.e. the relation with deformation rate and the relation of pore fluid composition and residual shear strength of soil material. Furthermore, the paper looks at the subsurface information that can be gained, i.e. the geological information of subsurface architecture and the hydrological information on origin of water, flow paths and travel times (using isotope analyses). Hydrochemical information used in both hard and soft rocks enables the display of clusters of water types, which is useful to identify contribution of different aquifers to the landslide area. Moreover, it can demonstrate the existence of lithologies and structures that are not visible with surface based geological investigations. Kinetic-based modelling is shown to be very useful in the interpretation of hydrogeochernical information. Lastly, it is shown that chemical information such as cation exchange properties coming from cored drilling is worthwhile for hydrological interpretations of landslides.