The Effect of Sea Level Rise on Tidal Dynamics in Chesapeake and Delaware Bays

An outstanding question on coastal inundation is whether rising mean sea levels will increase or decrease tidal ranges in coastal oceans and estuaries. We address this question for Chesapeake and Delaware Bays, two major estuaries on the U.S. East Coast. They are located in a region subject to high rates of relative sea level rise but have very different tidal characteristics. A three dimensional hydrodynamic model (FVCOM) is utilised to investigate the relationship between sea level rise and tides in the two estuaries. To replicate changing estuarine geometry, land up to 5m above mean sea level was included in the model domain. Simulations assuming both a moving and fixed shoreline were conducted. It is found that tidal ranges in Delaware Bay decrease under higher sea levels when low-lying land is allowed to flood and tidal ranges mostly decrease under higher sea levels in Chesapeake Bay. Tidal energy budget analysis revealed that reduced friction in deeper water is offset by dissipation in newly-flooded lands, with the net result that less tidal energy is propagated to the upper parts of the estuaries.