Terrestrial laser scanning for monitoring the process of hard rock coastal cliff erosion

Hard rock cliffs represent approximately 75% of the world's coastline. The rate and nature of the mechanisms that govern the retreat of these cliffs remain poorly constrained, primarily because conventional approaches employed to monitor these processes are generally inadequate for describing cliff erosion processes directly. These techniques are usually centred upon the interpretation of data collected periodically from aerial sensors, including stereographic aerial photographs and more recently air-borne LIDAR. These methods are generally not capable of assessing the pattern of erosion on the cliff face due to the oblique viewing angles, and hence tend to concentrate upon the resultant recession of the cliff top rather than change on the cliff face. Thus, processes of undercutting and small scale iterative failures of localized sections of the cliff face are generally not recorded. It is only when a failure affects the cliff top that any retreat is recorded. It is therefore unsurprising that cliff erosion is commonly deemed to be episodic.