Influence of high resolution elevation data on storm tide modelling outcomes

This investigation assesses the significance of high resolution near-shore bathymetric and coastal topographic data (LiDAR) to the outcomes of storm tide inundation modelling. In particular potential improvements to simulations in terms of accuracy, reliability, spatial resolution and magnitude, when compared with results from models that use coarser data such as navigational chart data, for example. Numerical simulations were undertaken to assess effects of the bathymetric data resolution on a) storm surge and b) wave set-up using the Delft3D and SWAN modelling systems, respectively. Initial investigations simulated these processes independently to assess which was the most sensitive upon grid and bathymetry resolution. Further analysis utilised coupled wave-current simulations to assess the effect of bathymetry on overall storm tide level and inundation at or near the coastline. The sensitivity of model results to numerical grid cell size, especially in the near-shore area, was also investigated. A number of conclusions are drawn based on the simulation results: Primarily, that the storm surge component of storm tide prediction is not particularly sensitive to the bathymetry used or, significantly, the grid cell size of the model. However, the wave set-up component of storm tide prediction was shown to vary significantly with near shore bathymetry and grid cell size. As a result simulations of overall storm tide magnitudes and hence predictions of coastal inundation, can differ significantly with the use of different bathymetric datasets, and grid cell resolutions.