Pathways to Realistic Impact Modelling in Estuarine Areas

The interconnected nature of land and marine processes has led to the development of fully coupled climate models combining atmospheric, terrestrial, riverine and oceans dynamics, such as the UKC3 UK national climate model created by the Met Office. Although highly resolved at the order of ~1.5 km, UKC3 may not capture estuarine and intertidal processes accurately, such as surge propagation and interactions with river flows. Using hyper resolution (<20 m) unstructured grids, a Delft-3D Flexible Mesh Suite model has been created to identify the importance of resolving these features for impact studies such as coastal flood risk. To further improve on the resolution of previous models, 15-minute river discharge was included as well as wetting and drying for coastal zones. Using a case study of the eastern Irish Sea, which is hyper-tidal and includes eight estuaries and a significant intertidal zone, the Delft model has been compared against UKC3 for simulations of the 2013-2014 extreme winter storm season. Analysis of the UKCP18 climate scenarios will be implemented to the new Delft model to investigate for future climate change variations. It is shown that there are clear differences in sea level variability between the models as well as differences in the salinity, storm surge frequency and flood severity. This research will allow us to optimise mesh resolution to accurately model the coastal environment for flood risk.