A Numerical Modeling Approach to Predict the Effect of a Storm Surge Barrier on Hydrodynamics and Long-Term Transport Processes in a Partially Mixed Estuary

Abstract

Floodgates or storm surge barriers are increasingly being considered as feasible climate change adaptation strategies to mitigate flooding risk. We developed a numerical modeling approach for a partially mixed estuary to simulate long-term alterations to hydrodynamics and transport processes induced from human modifications; two types of partially embanked storm surge barriers across the mouth of Chesapeake Bay were examined. Under modeled scenarios, surge barriers exerted a significant influence on the tide, salinity, residual current, and transport processes. The surge barrier caused (1) a reduction of tidal range inside the estuary, (2) stronger stratification and further salt intrusion, weaker vertical mixing and larger vertical exchange time, and (3) a decrease of bottom inflow in the mainstem and weakened horizontal water exchange. The change of horizontal water exchange and residence time was not a linear response with the barrier size and it varied at different regions of the estuary. The modeling approach is suitable to assess large-scale long-term ecosystem changes induced by human modifications or adaptations under a changing system.