Comment: 22:44 - 24:06 (01:22)
Source: Annenberg/CPB Resources - Earth Revealed - 20. Running Water II: Landscape Evolution
Keywords: "Nancy Powell", "Old River", dam, "U.S. Army Corps of Engineers", "Old River Control Project", river, "Mississippi River", "Atchafalaya River", "bed load", flow-rate, "flow velocity", sediment, scouring, transportation
Our transcription: The effect on the Mississippi of the bed load remaining behind is a buildup of sediment in its channel.
So sediment flow, especially bed load as well as water flow, must be kept in check.
With this in mind, the Auxiliary Structure was strategically placed.
One of the goals of placing the Auxiliary Structure where it is to try to increase the amount of sediments being diverted from the Mississippi to the Atchafalaya.
One of the lessons we learned since the operation of the Low Sill Structure was that we were not diverting the same proportion of sediments through the Structure through Low Sill Structure, as we were water.
The Mississippi River was continuing to show evidence that it wanted to fill up, and the Atchafalaya was continuing to scour.
So we felt that if we increase the amount of sediments being diverted here at Old River that we would actually try to stabilize the Mississippi River and the Atchafalaya River, at least slow the trend down in the Atchafalaya.
So we located the Auxiliary Structure on the inside of a bend where there's actually more sediments.
And we angled it such that we would get the sediments moving along the bottom of the River.
These sediments would want to go into the inflow channel of the Auxiliary Structure and actually go through the Structure and on down to the Atchafalaya.
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