Effective LiDAR-based modelling and visualisation of managed retreat scenarios for coastal planning: An example from the southern UK

This study presents a visualisation of proposed managed retreat options for a scientifically important estuarine area within the South Downs National Park, United Kingdom. A range of GIS and remote sensing techniques are used to facilitate the manipulation of LiDAR data for landscape visualisation. Landscape and flood modelling methods are incorporated and developed. The extent of inundation and tidal prism are assessed following proposed coastal planning and landscape changes. Ground-truthed LiDAR elevation data are used to model a series of proposed managed retreat scenarios (scenarios A, B, Cand D) for the river Cuckmereestuary. Following detailed landscape visualisation and manipulation, a 'pour-point' flood modelling method is used to simulate tidal inundation and calculate the tidal prism for proposed managed retreat scenarios using current tidal data. Further analysis was undertaken to assess the potential impact of sea level rise (for the years 2025, 2050, 2075 and 2100) in this estuarine area if the managed retreat proposals are actioned. The use of GIS-based techniques to alter and visualise landscape features under proposed managed retreat alternatives proved successful. Clear differences in tidal inundation and the tidal prism were observed following the modelling of large scale engineering features. These differences in inundation were apparent both using current tidal data and predicted sea level rise data. The tidal prism was strongly affected by the choice of the managed retreat scenario. Subtle changes in landscape features were shown to strongly affect the water accommodation potential of the estuary. The study demonstrates that high resolution data facilitated the detailed visualisation and modelling of fine-scale landscape change. Furthermore, the alteration of landscape features suggested that the area of inundation could potentially vary by over 20% (>100 ha); and that these landscape changes would noticeably alter tidal impact in this estuary.