An idea to mitigate the coming Delta collapse

First of all, I do not agree with your assumption that sea levels WILL rise for sure, as there is evidence that either there is no real rise in global temperatures, as measured using sea water and not air temps, and that if there really has been global air warming, that trend has abated.

Second, I doubt commercial shippers will allow this. Also, how would you appease the very strong enviromental lobby in that this barrier, if it can mitigate sea water migration, will also stop animal (and silt) migration.

I do not see this as necessary or practical. Would it work to cure the ill in your proposed scenario? Maybe, for a short period of time - short enough to be insignificant.

"First of all, I do not agree with your assumption that sea levels WILL rise for sure, as there is evidence that either there is no real rise in global temperatures, as measured using sea water and not air temps, and that if there really has been global air warming, that trend has abated."

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??? I would be delighted if you were correct. Unfortunately, the evidence runs totally against you: as witnessed by (1) ice shelf calving (2) glaciar melting (3) temperature charts, and the correllation between temp charts and CO2 in the atmosphere.

I)AVI),

You address one of the related problems facing this unique area. I appreciate your post because it asked a question I hadn't considered. Currently, the land level on the various islands in the delta is dropping due to the farming's converting the incredibly rich peat soil into food crops which are harvested (three crops per year). The dikes at the edges of the islands are already stressed by the wakes of passing ships. In addition, high water levels during flood events have caused catastrophic failure of some of the dikes, with at least one large former island being permanently flooded. In a geological time-frame this is a normal process, but in a human time-frame it is a big problem.

The problem of salinity levels in the waters of the delta has been the subject of law suits and agreements for many years. I am not familiar with the details of any of these (having moved from SF over 30 years ago, and being busy in other fields).

I suggest two avenues to pursue: First, ask this question to the Army Corps of Engineers, who maintain and use the scaled hydraulic SF Bay and Delta model. They may have run this scenario some time already. If they have not, they might find it a good one to study. Second, check the approaches the Dutch are taking with the rivers near their below-sea-level farm lands. They would have more-informed opinions than I. Anything that is done could be quite expensive.

The other post mentioned a problem with silt being blocked, as well as marine animals. These are significant also.

--JMM

superb suggestion about the Army Corps..

I'm cognizant of potential probs with wildlife migration,

but if the barrier is dropped when the tide runs out, there should be an amelioration of that issue. Similarly, the slit mostly runs "out" ..

Also, I woudl not see a perfect seal, but one which allows some salt water upstream,

to maintain "historical" saline levels.