re: patience on morganza

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This is not true. Pressure varies linearly with depth.

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+1. What he said.^^^^ Hydrostatic, soil pore pressure, and effective soil stress are all defined by the their unit weights LINEARLY.

This thread is beginning to get on my nerves... If we're talking about silt deposition from the new water in the forebay, no, I'm not at all concerned about soil pressure on the river side. That's because water has only been there for a maybe a week, and no new water has come in, hence no opportunity to build up soil on that side. On the tail water side the initial water *might* deposit some residual sedimentation in some low spots. That will disappear quickly once the 300-400 kcfs comes roaring through the spillway. If anything scour should be a concern, not deposition.

Sediment deposition shouldn't be much of a concern in the spillway. A majority of the sediment in the river is carried as bed load, and will primarily be confined to the center of the main river channel. The spillway is essentially skimming water off the top, and the sediment in that part of the water column is primarily fine clays and silt. Most of that will take quite a while at low velocities to settle out.

Great topic, guys -

I don't have photos of '73 after gates were closed. All I have is a lot of memories.

After all gates were closed in '73 my buddies and I fished the Locks daily for several weeks (approx. May 1973). We worked at a plant in the BR area and would leave every day after work for the Morganza Locks. Parking on the side of the road on top of the Locks was not permitted then (posted signs). Probably not permitted now either. We would park our cars on the side of the road before the Morganza Locks structure and walk in with ice chests and rods/reels/tackle.

More later. Point is, we got up close and personal with those gates (about 30' wide x about 25' high) on a daily basis.

No scouring. None. Large (very large) rocks/boulders helped prevent that (IMO). I've said before I remembered that the Corps admitted to opening too many gates too quickly (12 gates or so within 1st several days). Still no scouring. In addition, no sediment deposition. Note this is my day to day observation(s) after the gates were closed and it was safe to walk down to large boulders (rip-rap) and the (about 1 foot wide) ledge that traversed the structure (approx. 4000') about 50' downstream of the closed gates.

The land (as far as I could see - maybe a mile) downstream of the Locks had neither silt buildup nor scouring once the water subsided - looked just like level land to me.

Over the course of 2 weeks the water level dropped (of course). At first it was only possible to walk on the ledge and rip-rap. At this point a "bayou" (only one) had been cut in the South side of the area downstream of the closed Locks. This 20 foot wide cut carried excess water to the West as far as the eye could see. One could argue this is scouring. I didn't think that at the time. We fished this high-velocity cut for several days. It eventually got too small to be of any significance after about a week.

Just adding my historical perspective.