29 Jul 2022

Investigation of Sources of Sediment Associated with Deposition in the Calcasieu Ship Channel

Abstract: The Calcasieu Ship Channel (CSC) is a deep-draft federal channel located in southwest Louisiana. It is the channelized lowermost segment of the Calcasieu River, connecting Lake Charles to the Gulf of Mexico. With support from the Regional Sediment Management Program, the US Army Corps of Engineers, New Orleans District, requested that the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, perform an investigation of the potential sources of sediment associated with dredging in the CSC. A previous study had quantified sediment from known sources, indicating that the known sediment sources contribute approximately only 21% of the volume that is regularly dredged from the channel. This technical report details the results of the current study, which employed multiple methods, including numerical analysis, to identify potential additional sources of sediment by first examining the available literature and the modeled energetics and flow pathways, and then estimating the quantities of sediment associated with these identified sources that may be contributing to the shoaling of the CSC. The results of these efforts were used to update the original sediment budget with estimates of the contributions from two additional sources: the erosion of interior wetlands and coastally derived sediments.

29 Jul 2022

Sediment Provenance Studies of the Calcasieu Ship Channel, Louisiana

Abstract: To maintain the navigability of the Calcasieu Ship Channel (CSC), the US Army Corps of Engineers annually dredges millions of cubic yards of sediment from the inland channel. To assess sources of channel shoaling, a previous study examined river and bankline erosion as inputs. Results from that study accounted for approximately 20% of dredged volumes. Through the support of the Regional Sediment Management Program, a follow-up investigation reviewed prior sediment budgets, identified potential missing sediment sources, modeled potential sediment pathways, and utilized geochemical fingerprinting to discern primary shoaling sources to the channel. The missing sediment sources from the original budget include coastally derived sediment from the Gulf of Mexico and terrestrially derived sediment from Lake Calcasieu and surrounding wetlands. Results from geochemical fingerprinting of various potential sediment sources indicate the Calcasieu River and the Gulf of Mexico are primary contributors of sediment to the CSC, and sediments sourced from bankline erosion, Lake Calcasieu bed, and interior wetlands are secondary in nature. These results suggest that engineering solutions to control shoaling in the CSC should be focused on sources originating from the Gulf of Mexico and river headwaters as opposed to Lake Calcasieu, channel banklines, and surrounding wetlands

30 Apr 2020

PUBLICATION NOTICE: Geochemical Fingerprinting of Sediment Sources Associated with Deposition in the Calcasieu Ship Channel

Abstract: This Regional Sediment Management Technical Note (RSM-TN) demonstrates how geochemical fingerprinting techniques were used to distinguish probable sediment sources to the Calcasieu Ship Channel (CSC). These methods were applied to sediment samples collected from suspected source areas identified in past sediment budget studies. The techniques can be used by managers and stakeholders to make more informed decisions on best practices for managing sediment and mitigating sediment deposition within the channel.