TESTING THE SALINITY CONTROL DESIGNS IN CALCASIEU LAKE USING HYDRODYNAMIC AND SALINITY TRANSPORT MODELS

摘要

An in-house hydrodynamic and salinity transport model was used to test the performance of several salinity control designs in Calcasieu Lake, Louisiana. The 256 sq.km shallow water lake is located in southwest Louisiana, with a 5 mile waterway (Calcasieu Pass) connecting to the Gulf. The salt water in the lake comes from the Gulf due to daily high tide and due to storm surges. In the south west part of the lake, called West Cove, has unique flow circulations and has relatively high salinity concentration comparing to the other part of the lake. A deep Calcasieu Ship Channel is the eastern border of West Cove. The surrounding wetlands of West Cove are disappearing due to the salt water intrusion. The vegetation is dying due to the high salinity concentration, and the soils are eroded quickly without the surface vegetation. The design goal is to reduce the salinity concentration in West Cove without reducing too much flow. The proposed designs include installing a levee and flow and salinity control stations at the eastern border of West Cove separating the water body with Calcasieu Ship Channel. The optimal length and location of the levee and the flow control structure are the objectives of the research. The in-house code was used to simulate the hydrodynamics and salinity transport with the different designs. The results were used to show the effectiveness of the designs on reducing the average salinity concentration in the area and maintaining reasonable flow speed in and out of the area. In the implementation of the designs, the flow and salinity control stations were also included in the simulation. The main function of the stations is to block the salt water from the Gulf during high tide, and direct the fresh water from the north into the area during low tide. This action can keep maintain a single direction fresh water flow from north to south in order to keep salt water out of the system.