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Earth Science

Speaker: Alex Kolker
Louisiana Universities Marine Consortium

Spring '13 Earth Science Thursday Speaker Series - Examining Pathways for Water and Sediment Transport in the Mississippi River Delta

Thursday, March 7, 2013
4:00 PM  to 5:00 PM

100  McMurtry College
Rice University
6100 Main St
Houston, Texas, USA

Abstract: The deltas of large rivers are among the most important interfaces on Earth. They are highly productive ecosystems that often serve as centers of population and commerce. Over long time periods, deltas also form important hydrocarbon reservoirs. Modern deltas are also under threat from rising sea levels, accelerated rates of subsidence, altered hydrological and sedimentological pathways, and a wealth of local factors. The Mississippi River Delta (MRD) exemplifies the threats that deltas face; it has lost nearly 4,900 km2 of land over the past century threatening lives, infrastructure and the nation’s economy. This presentation will examine three areas of active research in the MRD, subsidence, sediment distribution, and the potential for large groundwater pathways. Here we show how an understanding of dynamically-driven sea-level change can be used to determine improved rates of subsidence across the northern Gulf of Mexico. Results indicate that subsidence at key locations tracks patterns of fluid withdrawal and rates of land loss, indicating a close coupling between the three. Efforts to rebuild land in the MRD rely heavily on plans to partially divert the flow of the Mississippi River (MR), thereby reinitiating the natural land building processes that originally led to the genesis this system. Two sediment distribution systems are examined, a small crevasse splay in Cubit’s Gap during periods of “typical” high flow and the Atchafalaya River Shelf during the massive flood of 2011. Findings from these studies suggest that the smaller scale system in Cubit’s Gap makes a better diversion analogue than the larger scale system, emphasizing the importance of scale in diversion design and implementation. This talk will close by suggesting that the one of the largest pathways of water transport in the MRD actually occurs underground through series of buried paleochannels. During periods of elevated river stage, 10% or more of the Mississippi River’s water is transported from the main channel to the coastal bays, thereby influencing the geology and chemistry of both systems.

Biography of Alex Kolker: http://www.lumcon.edu/research/faculty.asp?name=akolker

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