Storm-driven morphological evolution and sediment bypassing at a dynamic tidal inlet: A simulation-based analysis

This paper presents morphodynamic simulation results for Ancão inlet (Rio Formosa, Portugal), for two individual storms (ST01 and ST02), observed during the INDIA project in 1999. Despite similarities in maximum storm intensity and duration, variation in tidal range and hence tidal currents through the inlet during the storms result in very different morphodynamic response. ST01 occurs during a neap tide (range ~1.0m) when peak currents through the inlet are at a minimum, allowing wave action to move sediment onshore from the ebb delta, reducing inlet cross section and promoting closure. ST02 occurs between spring and neap tide (range ~ 2.0m), where ebb tidal currents are strong enough to inhibit wave action, causing tidal dominance within the channel, delta toe and inlet throat, and wave dominance on the up-drift and down-drift swash platforms and adjacent beaches. Analysis of aggregated volume change for each morphological element within the ebb delta suggests sediment bypassing efficiency increases with wave energy, and decreases in inverse proportion to grain size and tidal range due to wave blocking by ebb tidal current