Stability of the White Horse Slopes in Wiltshire: Broad Town

Landslide occurrence is influenced by many factors, including bedrock geology, slope angle, slope aspect, and rainfall events, and threatens the historically significant chalk hill figures synonymous with Southern England. This study investigates how landslide risk varies throughout the Wiltshire White Horses region, utilising historical landslide data and a GIS-based approach. Here it is demonstrated that bedrock geology, slope angle, slope aspect, and rainfall events are all factors influencing the susceptibility of slopes to landslides which can be used to assess if slopes are at risk of landslide occurrence. Slopes which sit along the Gault Clay / Grey Chalk interface were found to be at an elevated risk of landslides. Where this occurs, slope angles in the range of 25° to 40° and with aspect facing North, North-West, or West were also judged to be at increased susceptibility to landslides. Extreme rainfall events commonly occurred within a 12-hour period preceding the landslide, as did similarly intense events a few days prior. When compared to other Wiltshire White Horses, Broad Town and Westbury are assessed to be at the most risk to landslide occurrence.