Impact of Intertidal Areas on Tidal Propagation in Tidally Dominated Estuaries. Part II: A Comprehensive Sensitivity Study

This is Part II of a two-part theoretical study on the impact of intertidal areas on tides in tidally dominated estuaries. Part I developed an analytical model that resolves tidal motions in the channel and intertidal regions which are dynamically coupled through the water exchange between both regions. This model considers both effects of water storage (IWS) and longitudinal currents (ILC) over intertidal areas. Part II applies the model to a broad range of parameter space to systematically investigate how the strength of currents over intertidal areas and the significance of ILC effects on tides respond to changes in estuary characteristics and forcing conditions. Our results demonstrate intertidal areas amplify tides in systems with large channel depths, short lengths, weak friction in the channel, and strong width convergence, while causing tidal damping under contrary conditions. Model experiments show significant currents over intertidal areas in tidally dominated estuaries over a large range of parameter spaces, particularly under conditions of small channel depths, strong channel bed friction, and weak intertidal bed friction. These currents over intertidal areas reach up to 60% of channel flow velocities. The ILC-induced water exchange is almost out of phase with that induced by IWS. Therefore, the ILC effect reduces the total channel-intertidal water exchange and counterbalances up to 45% of the above-mentioned effects of intertidal areas on tides. This highlights the potential importance of currents over intertidal areas in shaping tidal dynamics in tidally dominated estuaries, emphasizing the need for improved monitoring and modeling of these processes.