We are excited to announce that our collaborative proposal with Jeff Nittrouer of Rice University was recently funded by the Geomorphology and Land-use Dynamics program of NSF. The project will focus on changes that mud flocs under go as they move from the confined freshwater fluvial sections of the Mississippi River to the vertically stratified and laterally unconfined conditions in the Gulf of Mexico (see figure and abstract below).
Rivers deliver fine muddy sediment eroded from upstream landscapes to coastal regions. Upon arrival, mud can deposit in or move through the rivers, bays, estuaries, marshes, and deltas of the region. Forecasting where the mud goes when it arrives is important for society. For example, accurately forecasting the movement and deposition of mud in these regions is important for predicting and evaluating the effectiveness of river diversion projects aimed at using sediment deposits to build deltaic landscape, fostering healthy water quality, and/or evaluating how mud deposits shoal waterways and therefore impede vessel navigation. Yet, the prediction of mud movement through coastal waters is difficult. The difficulty is due in large part to the limited ability to measure and model how mud particles change when suspended in water. Small mud particles tend to clump together and form aggregates known as flocs, which grow or shrink depending on turbulence levels in the flow and the salinity, biological content, and amount and type of sediment in the water. The settling speed of muddy sediment is directly related to the size and density these flocs. This research will evaluate the nature of mud particle movement in river and coastal waterways by collecting detailed measurements that will inform and validate physically-based models of floc dynamics. The research pairs laboratory experiments and comprehensive field surveys from one of the largest coastal deltas in the world, the lower Mississippi River in Louisiana.