Measurements of the time-varying free-surface profile across the swash zone obtained using an industrial LIDAR

The use of an industrial LIDAR instrument to measure time-varying water-surface elevations within the swash zone is investigated. The propagation of the swash lens across the beach face was measured simultaneously by a LIDAR instrument and a network of precision ultrasonic altimeters at a sandy beach. Comparison of the two datasets indicates that the time-varying swash free-surface profile obtained using a LIDAR compare favourably with point measurements obtained using ultrasonic altimeters. Significantly, the use of a continuously scanning laser beam enables a single LIDAR instrument to obtain measurements of free-surface elevation near-synchronously at several hundred points throughout the swash zone. This high spatial resolution permits small-scale flow features such as the swash-front gradient and the presence of secondary bores to be detailed, and negates the need for the deployment of a large, multi-sensor array.