Hurricanes in southeastern Louisiana develop significant surges within the lower Mississippi River. Storms with strong sustained easterly winds push water into shallow Breton Sound, overtop the river’s east bank south of Pointe à la Hache, Louisiana, penetrate into the river, and are confined by levees on the west bank. The main channel’s width and depth allow surge to propagate rapidly and efficiently up river. This work refines the high-resolution, unstructured mesh, wave current Simulating Waves Nearshore + Advanced Circulation (SWAN+ADCIRC) SL16 model to simulate river flow and hurricane-driven surge within the Mississippi River. A river velocity regime–based variation in bottom friction and a temporally variable riverine flow-driven radiation boundary condition are essential to accurately model these processes for high and/or time-varying flows. The coupled modeling system is validated for riverine flow stage relationships, flow distributions within the distributary systems, tides, and Hurricane Gustav (2008) riverine surges.

RC Martyr, JC Dietrich, JJ Westerink, PC Kerr, CN Dawson, JM Smith, H Pourtaheri, N Powell, M van Ledden, S Tanaka, HJ Roberts, HJ Westerink, LG Westerink (2013). “Simulating Hurricane Storm Surge in the Lower Mississippi River under Varying Flow Conditions.” Journal of Hydraulic Engineering, 139(5), 492-501, DOI: 10.1061/(ASCE)HY.1943-7900.0000699.