Landform Evolution in the West Bay Mississippi River Diversion:
Implications for Deltaic Development and Coastal Restoration
Alexander S. Kolker1,2 , Alexander D. Ameen3,1 , Mead A. Allison 4,2, Michael D. Miner5,
Cyndhia Ramatchandirane 4, H. Dallon Weathers 4, Brendan Yuill4
1
Louisiana Universities Marine Consortium, Chauvin, LA 70344
Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118
3
Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118
4
The Water Institute of the Gulf, Baton Rouge, LA 70825
5
Bureau of Ocean Energy Management, US Department of Interior, New Orleans, LA 70123
2
Over the past century, Louisiana has lost nearly 5,000 km2 of land; plans to mitigate and
reverse this loss rely in part on partially diverting the flow of the Mississippi River to reinitiate
the natural delta-building processes that originally built the Mississippi River Delta. However,
there is relatively little field evidence regarding sedimentation processes in the kind of large
(>1,500 m3 s-1) diversion that are conceived of by the state's master plan. The West Bay
Mississippi River Diversion (WBMRD) one place to study such processes, as it is the largest
diversion operating in Louisiana that was specifically constructed for coastal restoration. Here
we present evidence on the short (seasonal) and long (decadal-centennial) scale evolution of the
WBMRD. Results indicate that West Bay (WB) evolved from multiple, overlapping deltaic
systems, including a crevasse in the Mississippi River levee that formed in 1838, recently (last
10 ~50 yr) evolved splays along a channels connected to this crevasse, and the diversion, which
was opened in 2002. Subsidence of the 1838 splay, and potentially earlier splays, created
accommodation space, which was subsequently infilled by the newer system. For much of the
past century, sedimentation rates in WB ranged from 0.5-5.0 cm/yr; rates that are geologically
rapid, but not necessarily fast enough to outpace the very high rates of relative sea level rise in
the region. Sedimentation patterns appeared to change with the construction of a series of
sediment retention devices (SREDs), which altered basin hydrodynamics and contributed to the
development of islands in the northern end of West Bay following the 2011 flood. Results from
this study suggest that river diversion strategies will be more effective if they focus on not only
on, "upstream" controls on sediment delivery, but also on, "downstream," controls on sediment
retention and coastal hydraulics.
Presenting author information. Dr. Alexander S. Kolker is a coastal geologist. His research
investigates the sedimentary dynamics in the coastal zone, the impacts of climate change and
sea-level rise on coastal systems, and pathways and processes associated with groundwater
discharge in large river deltas. He received his Ph.D. from Stony Brook University, State
University of New York. He now works at the Louisiana Universities Marine Consortium and
teaches at Tulane University. Contact info: akolker@lumcon.edu; (504) 579-2427.
An oral presentation is preferred, but a poster will be accepted.