Surge generation mechanisms in the lower mississippi river and discharge dependency
The Lower Mississippi River protrudes into the Gulf of Mexico, and manmade levees line only the west bank for 55 kmof the Lower Plaquemines section. Historically, sustained easterly winds from hurricanes have directed surge across Breton Sound, into the Mississippi River and against its west bank levee, allowing for surge to build and then propagate efficiently upriver and thus increase water levels past New Orleans. This case study applies a newand extensively validated basin- to channel-scale, high-resolution, unstructured-meshADvancedCIRCulationmodel to simulate a suite of historical and hypothetical storms under low to high river discharges. The results show that during hurricanes, (1) total water levels in the lower river south of Pointe à La Hache are only weakly dependent on river flow, and easterly wind-driven storm surge is generated on top of existing ambient strongly flow-dependent river stages, so the surge that propagates upriver reduces with increasing river flow; (2) natural levees and adjacentwetlands on the east andwest banks in the Lower Plaquemines capture storm surge in the river, although not as effectively as the manmade levees on thewest bank; and (3) the lowering ofmanmade levees along this Lower Plaquemines river section to their natural state, to allow storm surge to partially pass across the Mississippi River, will decrease storm surge upriver by 1 to 2 m between Pointe à La Hache and New Orleans, independent of river flow. © 2013 American Society of Civil Engineers.
Journal of Waterway, Port, Coastal and Ocean Engineering
Digital Object Identifier (DOI)
Kerr, Westerink, J. J., Dietrich, J. C., Martyr, R. C., Tanaka, S., Resio, D. T., Smith, J. M., Westerink, H. J., Westerink, L. G., Wamsley, T., van Ledden, M., & de Jong, W. (2013). Surge Generation Mechanisms in the Lower Mississippi River and Discharge Dependency. Journal of Waterway, Port, Coastal, and Ocean Engineering, 139(4), 326–335. https://doi.org/10.1061/(ASCE)WW.1943-5460.0000185