Saltwater-intrusion due to drought

SeanKroll

Treehouser
Joined
Oct 13, 2016
Messages
12,252
Location
Olympia, WA
Anyone know about this?

We have lots of shoreline on the Puget Sound in Olympia. Olympia is a bunch of peninsulas on the Sound side of things.

Have heard it mentioned, but only briefly.

Going to do some research.
 
  • Thread Starter Thread Starter
  • #3
I'm concerned in relation to tree mortality along tidal shorelines. We've had 4 years of drought.

I have a customer to see who has a lot of mortality in a stand of doug-fir next to the Puget Sound. They live in a low-bank area, so the trunks are just above the tide line, by a matter of feet.


I wonder if a dropping freshwater table will cause saltwater intrusion that can kill the trees.
 
Here, in the Florida Keys, our Agricultural Extension Office will test soil for free. That might be an option for you up there. Even if they don't do it, they probably know a company that will do it for a nominal cost.

Again, here, we have trees that are very salt tolerant and others that are not. Any idea if Douglas Fir is salt tolerant? We have had a few storms that have pushed salt water over our islands and it is always interesting to see which trees it affects and when. After "Wilma", which pushed up to 10 feet of salt water over Marathon, we had Gumbo Limbo trees that looked good for about 3 years, then boom, on the ground they went. The root damage was obvious and then assumed it was from the 4 hours of salt water intrusion. (the water left the island in 4 hours) However, some Gumbos never have failed.

This past year, we had Irma which pushed a wall of salt water 12' over certain islands. Some trees went down with the 130 mile per hr winds lol, but it will be interesting to see, in a couple of years, which trees that were left standing were affected by the salt water.

Not sure if you have lived in that area long enough to know the answer to this, but are you seeing sea levels rising there? In my 20 years down here, I have seen it here. If I had not seen it with my own two eyes, you would not have been able to convince me that the sea level is rising.
 
Sea level rise is most apparent to those who live at sea level!
I see it in Bermuda.

We get weird effects off the Gulf Stream sometimes. If there is a 'warm eddy' the ocean will hump up and our tides will be high and super high, no real low tides until the eddy moves on. As the salt water table permeates the entire island from side to side and end to end, any freshwater from rain that percolates down 'floats' on top of the salt water in the bedrock.
With the super high tides this pushes the water table UP. You can see it in low lying marshy areas, puddles on the surface. In our biggest freshwater marsh a few years ago, some really old cedars that had survived the blight of the 40's and 50's, died due to waterlogging. Whether it was prolonges freshwater, or the salt water came up high enough to impact their roots, I don't know exactly, but they died.

In the opposite, if there is a 'cold eddy' the surrounding ocean sinks...again tides are low and super low. You can see the tops of soft corals and reefs sticking out of the water...they don't get enough or any water over them at 'high tide', and they bleach and die. There was a super cold eddy a few years ago too, the reef platform which stretches out 10 miles from land was visible!

Throw a cold or warm eddy on top of a spring full moon and wow! even more dramatic.
These effects have been happening for millennia, but lately they seem to be happening with more frequency.
 
Fiona, that is so interesting. We do, of course, see those extreme tides here as well but I feel like the water level in our canal is higher on a consistent basis. Miami is seeing the same.
 
Yes, very interesting info and perspectives.

In Southern California they are pumping so much water out of the ground that not only does it cause the valley floor to sink (30 inches ? since measurements began) but it also causes salt water incursion. (Up to 60 miles in some aquafers and places?)
 
Yes, very interesting info and perspectives.

In Southern California they are pumping so much water out of the ground that not only does it cause the valley floor to sink (30 inches ? since measurements began) but it also causes salt water incursion. (Up to 60 miles in some aquafers and places?)
I wonder how much of the lower central valley cannot grow crops anymore since salt contamination?
 
Our coast line is so rocky-rugged, and the tides vary 8 feet at extremes, it's difficult to see any actual difference in mean sea-level. But all what Bermy said about back eddies is very interesting. Never before had I heard anything about that phenomena.
 
Back
Top