Impacts of Storm Surge Barriers on Drag, Mixing, and Exchange Flow in a Partially Mixed Estuary

Storm surge barriers are increasingly being considered as risk mitigation measures for coastal population centers. During non-storm periods, permanent barrier infrastructure reduces the flow cross-sectional area and affects tidal exchange. Effects of structures on estuarine salinity dynamics have not been extensively examined, particularly partially mixed estuaries. A nested, high-resolution model is used to characterize impacts a potential storm near mouth Hudson River estuary. Maximum velocities through openings more than double those in base case. Landward barrier, amplitude decreases average by about 6% due increased drag. The drag coefficient with 5 times greater case primarily form from separation at rather bottom friction. scales geometry similar previous studies around headlands. Tidal water levels reduced during spring tides, such that marsh inundation frequency up 25%. Strong enhance mixing locally, but overall estuary velocities. Correspondingly, stratification increases landward intrusion length 5%–15% depending discharge decreased exchange flow. Exchange reflux into lower layer mixing, which has increase residence times.