Degree
Doctor of Philosophy (PhD)
Department
The Department of Civil and Environmental Engineering
Document Type
Dissertation
Abstract
River deltas are valuable ecosystems that have been essential in supporting human populations and the economy across the world for centuries. However, climate change and human activities have caused significant land loss in delta areas. A prime example of a region that has suffered severe land loss is Louisiana in the United States. Coastal restoration is therefore essential for the livelihoods of its residents. To address this issue, the Lower Mississippi River (LMR) channel bar has been regularly dredged to rebuild degraded marsh areas. Additionally, sediment diversions off LMR have been designed to build marsh areas sustainably. This dissertation investigates the impact of channel bar dredging on the river's geomorphology, particularly near the diversions, and it also studies the water and sediment dynamics of the river delta using numerical models. The research first examines how the dredged borrow pits in the channel bar influence the sediment transport and geomorphology of the river. The study shows that the borrow pits are completely refilled within 4-8 years with periodic high flow conditions. The research concludes that channel bar dredging only impacts sediment diversion efficiency if it takes place immediately upstream of the intake. The second part of the research delves into the hydro-morphodynamic modeling of river delta, using the Wax Lake Delta (WLD) as an example to understand land building potential of sediment diversion in its receiving basin. The findings suggest that a sustained flow and sediment supply from the river, in conjunction with a directional shift in sediment distribution among deltaic channels under varying flow conditions, maintains a long-term equilibrium configuration of delta growth. Finally, Transfer Entropy (TE) is employed as a tool for hydrodynamic model validation, measuring directional information transfer between random variables to evaluate relationships between the variables across space and time. The proposed validation method is tested in the WLD model, which shows that the TE successfully measures the model’s performance of reproducing strength, timescale, and directional relationships of channel and island water levels, accurately tracking these dynamics over time. This indicates that TE can be a valuable addition to other validation metrics to evaluate numerical model performance.
Date
3-30-2024
Recommended Citation
Sadid, Kazi M., "SUPPLY AND DISTRIBUTION OF FLOW AND SEDIMENT IN RIVER AND DELTA SYSTEM" (2024). LSU Doctoral Dissertations. 6394.
https://repository.lsu.edu/gradschool_dissertations/6394
Committee Chair
Willson, Clinton S.