Assessing climate change impacts on the stability of small tidal inlet systems: Why and how?

Coastal zones in the vicinity of tidal inlets are commonly utilised for navigation, fishing, sand mining, waterfront development and recreation and are under very high population pressure. Any negative impacts of climate change (CC) on inlet environment are therefore very likely to result in significant socio-economic impacts. CC driven variations in mean water level (i.e. SLR), wave conditions and riverflow are likely to affect the stability of, particularly, the thousands of Small Tidal Inlets (STIs, or bar-built/barrier estuary systems) around the world. The combination of their predominant occurrence in developing countries, socio-economic relevance and low community resilience, general lack of data, and high sensitivity to seasonal forcing makes STIs potentially very vulnerable to CC impacts.\ud \ud This article summarises potential CC impacts on the stability of STIs and discusses means by which these CC impacts maybe quantified using existing modelling tools. As presently available process based models cannot be confidently applied with concurrent time varying water level, wave and riverflow forcing over typical CC impact assessment time scales (~ 100 years), a ‘snap-shot’ simulation (~ 1 year duration) approach using process based coastal area morphodyamic models is proposed for qualitative assessments of CC impacts on STIs. As the modelling approach will by necessity depend on the level of data availability, two different ‘snap-shot’ modelling frameworks for ‘data rich’ and ‘data poor’ environments are presented. Process based multi-scale coastal area morphodynamic models and scale aggregated (or reduced complexity) morphodynamic models are identified as modelling approaches that may be pursued in the future to obtain more reliable assessments of CC impacts on STI stability