Nola.com
The diversion’s location was chosen in part because the Mississippi’s water would pass over one or more sand bars between the river’s navigation channel and the West Bank levee, capturing a greater share of bar sand just before entering the diversion structure.
The researchers also had to determine the best time of year to open and close the diversion, based on records of the amount of sediment in river water during a 50-year period from 1964 through 2013.
“At low flow, there’s no sand in suspension in the river,” said Ioannis Georgiou, director of coastal and deltaic systems modeling at The Water Institute of the Gulf and formerly director of the University of New Orleans’ Pontchartrain Institute for Environmental Sciences. “The sand gets trained [in the water] as the flow transitions from low to high.”
The trigger delivering the most large sand grains is when the river’s flow reaches 450,000 cubic feet per second upstream at Belle Chasse. At that point, the diversion gates are opened and 25,000 cfs of water and sediment will flow into Barataria Basin. As the river speeds to 1 million cfs, the amount diverted will increase to a maximum of 75,000 cfs. Read the full story here.