International Dredging Review

International Dredging Review

Moffatt & Nichol Engineers’ Raleigh North Carolina office is providing hydraulic and hydrologic engineering for the Black Bayou wetland project in Cameron Parish in southwest Louisiana. The project is funded under the Coastal Wetlands Planning Protection and Restoration Act (CWP-PRA) for the National Marine Fisheries Service and the Louisiana Department of Natural Resources.

The object is to restore hydrologic conditions over 3600 acres by using a numerical model to simulate and analyze alternative solutions affecting hydraulic conditions. The model encompasses approximately 650 square miles comprising fresh/intermediate marsh brackish marsh and open water.

Using the hydraulic numerical model MIKE 11 developed by the Danish Hydraulic Institute the engineers simulate hydrodynamic circulation patterns and salinity levels at key locations allowing evaluation of intrusion and spreading of saline waters into the marshes. The model tests the system’s response during “normal” and drought conditions as well as simulating inundation associated with hurricane storm surge. This provides a means to determine the effectiveness of the proposed structural improvements in achieving the project’s goals.

“The aim is to restore historical hydrologic conditions over a majority of the are increasing freshwater retention time and reducing saline water intrusion and tidal action” said Jeff Shelden Moffatt & Nichol project manager. “The ultimate objective of the restoration project will be to improve aquatic habitat conditions particularly for marine fisheries” he said.

The area in question has suffered wetlands loss due to hydrologic changes including reduced freshwater flow increased tidal fluctuations increased salinity high water levels excessive water exchange and artificial water circulation patterns.