A HOLISTIC MODEL TO SIMULATE LONG-TERM EVOLUTION OF CATCHMENT- ESTUARY-COASTAL SYSTEMS

Long-term (i.e., multi-decadal to century periods) evolution of inlet-interrupted coasts can be assessed in relation to the variation of sediment volume exchange between the inlet-estuary system and its adjacent coastal zone (Ranasinghe et al., 2013; Bamunawala et al., 2020a). The oceanic (e.g., sea-level-rise) and terrestrial processes (e.g., change in fluvial sediment supply) contribute to the long-term evolution of inlet-interrupted coasts. These contributing processes are affected by climate-change-driven impacts and anthropogenic activities. Thus, it is necessary to consider the holistic behaviour of Catchment-Estuary-Coastal (CEC) systems when assessing the evolution of inlet-interrupted coasts under the impacts of projected climate change and increasing pressures due to anthropogenic activities. Such a holistic assessment of the long-term evolution of CEC systems can be achieved via reduced-complexity modelling techniques, which also ably quantify the uncertainties associated with the projections due to their lower simulation times (Bamunawala et al., 2020b; Ranasinghe, 2020). The Generalised Scale- aggregated Model for Inlet-interrupted Coasts (i.e., G-SMIC) presented by Bamunawala et al. (2020b) is one such model that can probabilistically assess the long-term evolution of inlet-interrupted coasts while considering the holistic behaviour of Catchment- Estuary-Coastal systems. However, G-SMIC does not consider the presence of ebb-delta systems when considering the sediment budget at tidal inlets. Here, we present an improved version of G-SMIC by incorporating the ebb-delta dynamics into its computations. The updated model is piloted at two selected case study sites in Vietnam and United Kingdom, and the preliminary results are presented, along with the overall modelling concept.