Sunday, August 15, 2021
Friday, April 23, 2021
The Water Comes Faster, Deeper & Drains Slower … Residents Are Getting Sick And Tired It…
Parker Conrad Flood Control Plan Map c 1980
OverBank Flooding at Bayou Pigeon 1974
The Atchafalaya Floodway System Levees
Unintended Consequences - The Lafourche - Terrebonne Drainage Basin
USACE Flood Control Strategy / Plan For Entire Mississippi River Valley
Mind Boggling proposals of the Parker Conrad plan :
Parker Conrad plan - A Bigger Outlet to the Gulf at Wax Lake
2021 - Current Project At Avoca Island Cutoff / Bayou Chene To Reduce Backwater Flooding
Diagram of Backwater flow through Avoca Island Cutoff / Bayou Chene
Problem Solved For Bayou Sorrel, Bayou Pigeon, Likely Not
Problem #1 Water / Sediment Management...
Lower Grand River in Iberville and Iberia parish have experienced rapid and substantial amounts of sediment deposition since the 1960's. Particularly between the Bayou Sorrel Locks & Belle River.
Severely aggraded and silted up areas of the Lower Grand River channel are holding back the water flow especially around the Bayou Pigeon Pontoon Swing bridge.
Dredging and channelization of Lower Grand River has not occurred since the 1920’s. In fact it may have not been dredged for over 100 years.
Note the dates and depths of the dredging.
Documentation of last dredging in Lower Grand river
Some local residents say that since the Grand River at Bayou Pigeon is no longer part of the Alternate route of the Intracoastal waterway, ie, since the Bayou Sorrel Lock. The lack of barge traffic does not help scour to keep channel open anymore.
Problem #2 - The Pontoon Swing Bridges On Lower Grand River
The Bayou Sorrel pontoon-style bridge, built in 1964, carries La. 75 over Upper Grand River and Bayou Sorrel in Iberville Parish.
When the Lower Grand River water level gets high, the bridge master pumps water into the Bridge barge to lower it into the water column so it is level enough for vehicular traffic to cross; otherwise the bridge would be too high above the ramps. As a result the sunken bridge restricts the water flow even more, and especially at a time when maximum drainage flow is needed to allow the floodwater to drain downstream.
It has been said that the water level elevation on the north side of the Bayou Sorrel Pontoon Bridge and the south side of the bayou Pigeon Pontoon Bridge is as much as 11”.
If that difference can be validated, it means they are an significant impediment to rapid drainage.
Which begs the question why the bridges can’t be in open position in the wee hours in the morning 11 PM to 4 AM except in cases of emergency. There is essentially no barge traffic in The lower Grand river below the Bayou Sorrel lock
Note: There are pontoon bridges at Belle River and Pierre Part.
Problem# 3 - Lock Structures
Bayou Sorrel Lock & Dam
Lock structures have guidelines by water stages on when they cannot allow Boat traffic or leave open the lock gates. Boat traffic is ceased at 6.5 ft at the Bayou Sorrel Lock gauge.
Even though boat traffic is stopped the lock gates remains closed. You would think opening the lock gates, that it would let some of the high water into the Atchafalaya Floodway, where there are no residents.
“Which brings to this point”
Will the Bayou Chene Automated Barge Flood Gate alleviate all, most or some of the extreme Rain Water over bank flooding below Jack Millers Landing , through Bayou Sorrel, Bayou Pigeon?
Without addressing Water / Sediment management and the pontoon bridges situation and not being able to move some of the high water out of Lower Grand River to the Atchafalaya Floodway.
I think the answer is at best some relief and most likely very little to none.
The water will still go out very slow. Even if the annual Atchafalaya Flood Pulse is average.
Just saying … We are still screwed !
Overbank Flooding Is An Economic Threat To Iberville Parish
Overbank flooding is a threat to the sustainability and growth of the entire Lower Grand River corridor. The Bayou Pigeon Heritage Association is a voice for our local community we are pushing for flood protection that is critical to our survival and that will help us continue to improve our community and the ‘Down the Bayou’ part of Iberville Parish.
Iberville Parish - The Eastern Gateway To The Atchafalaya
Bayou Pigeon is the center point in the between I 10 and HWY 90