A Computational Investigation of Storm Impacts on Estuary Morphodynamics

Abstract

Global climate change drives sea level rise and changes to extreme weather events, which can affect morphodynamics of coastal and estuary systems around the world. In this paper, a 2D process-based numerical model is used to investigate the combined effects of future mean sea level and storm climate variabilities on morphological change of an estuary. Morphodynamically complex, meso-tidal Deben Estuary, located in the Suffolk at the east coast of the UK is selected as our case study site. This estuary has experienced very dynamic behaviors in history thus it might be sensitive to the future climate change. A statistical analysis of future storms around this area, derived from a global wave model, has shown a slight increase of storm wave heights and storm occurrences around the estuary in future as a result of global climate variations under medium emission scenario. By using a process-based model and by combining the forecast ‘end-of-century’ mean sea level with statistically derived storm conditions using projected storms over a time slice between 2075–2099, we determined hydrodynamic forcing for future morphodynamic modelling scenarios. It is found that the effect of increased sea level combined with future storms can significantly alter the current prevailing morphodynamic regime of the Deben Estuary thus driving it into a less stable system. It is also found that storm waves can be very significant to morphodynamic evolution of this tide-dominated estuary.

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“…Then, we applied the new scaled profile into the hydraulic model for validation simulation. For the seaside open boundaries, we combined the mean high water springs (MHWS, shift from Newlyn Ordnance to mean sea level) with different return periods of extreme water levels derived from McMillan et al [25], which was also applied by Yin et al [26]. For the seaside open boundaries, we combined the mean high water springs (MHWS, shift from Newlyn Ordnance to mean sea level) with different return periods of extreme water levels derived from McMillan et al [25], which was also applied by Yin et al [26].…”

“…For the seaside open boundaries, we combined the mean high water springs (MHWS, shift from Newlyn Ordnance to mean sea level) with different return periods of extreme water levels derived from McMillan et al [25], which was also applied by Yin et al [26]. For the seaside open boundaries, we combined the mean high water springs (MHWS, shift from Newlyn Ordnance to mean sea level) with different return periods of extreme water levels derived from McMillan et al [25], which was also applied by Yin et al [26]. The extreme water level is based on the skew surge joint probability method (SSJPM) analysis of tide-level data recorded at 40 Class A gauge sites (the periods of these sites vary between 10 years to 100 years).…”