Plaquemines spillways : the impact of the lower Mississippi river levees on storm surge during hurricanes

The Mississippi river runs through Louisiana towards the Gulf of Mexico where it becomes a bird-foot delta. Various settlements of often no more than 2 km in width exist along the lower 125 km of this river; this area is known as Plaquemines Parish. Nowadays levees protect the Parish from storm surges and high Mississippi river discharges. During major hurricane events in the Gulf of Mexico the levees block the storm surge and this leads to a build-up of surge locally but also forces the water to flow upriver towards New Orleans. By creating spillways within the levees of Plaquemines Parish the maximum water levels in and around New Orleans can be reduced during hurricanes. To gain insight into the quantitative effects of the spillways on storm surge the Advanced CIRCulation flow model (ADCIRC) has been used to perform storm surge simulations.