The Ventnor Undercliff: Landslide model, mechanisms and causes, and the implications of climate change induced ground behaviour and risk

The paper presents a calibrated ground model for the Ventnor Undercliff for the first time based on the results of two ground investigations carried out in 2002 and 2005. The ground model is supported by surface and sub-surface monitoring data which identify the most probable failure mechanisms and causes of ground movement in the Ventnor Undercliff. The results of the investigation have reduced uncertainty about the landslide mechanisms, causes and ground behaviour at Ventnor. This allows the implications of climate change induced ground behaviour and risk to be assessed with greater confidence; the results indicate that the risks are increasing and that accelerated ground movement and potential landslide events are more likely in the future. The implications of climate change induced ground behaviour and risk poses very significant challenges for the future. The local authority has been co-ordinating and implementing a landslide management strategy involving planning and building controls, engineering works, monitoring and dissemination of information. What is clear from the results of the recent investigations and stability analysis is that coastal landslide stabilisation will be needed to prevent a significant decline in stability of the Ventnor Undercliff; this could be achieved by preventing coastal erosion and deep drainage to reduce groundwater pressure beneath the landslide.