Clogged Sieve? – Floodplain sedimentation above the deltaic apex of the Lower Mississippi River

Frank Heitmuller, University of Southern Mississippi

The Lower Mississippi River near Natchez, USA, has experienced a prolific series of floods over the past 15 years that have resulted in overbank sedimentation in the embanked floodplain. Analysis of overbank sediment samples following floods coupled with floodplain sediment cores indicates that depositional thicknesses, rates, grain sizes, organic carbon, and nutrient concentrations vary with sub-basin inputs, flood magnitude and duration, and historical trends associated with land-use and flood mitigation efforts.