The Phenomenon:

How can two seas not mix?

I think this is commonly known and the explanation everyone gives is "because they have different densities".

See more on:

http://physics.stackexchange.com/questions/51293/how-can-two-seas-not-mix

 And an explanation there on:

http://traveller24.news24.com/Explore/pics-14-of-natures-hypnotising-ocean-phenomena-only-mermaids-really-understand-20151222

" 7. Halocline Salinity separation phenomena - Halocline is a zone where there are extreme vertical changes in the salinity in the ocean.
In lower latitudes the halocline can represent a decrease in salinity with increased depth; high altitudes it represents the opposite.

The halocline normally develops in regions where there is a great amount of freshwater input from rivers producing surface waters of low salinity, a zone where salinity increases rapidly with depth (the halocline), and a deeper zone of greater saline, dense waters. "

And more images, from Google search for images:

https://www. google.com/ search?q=fresh+ and+saline+ waters+side+by+ side+on+the+ ocean.&espv= 2&biw=1164&bih= 645&source= lnms&tbm= isch&sa=X&ved= 0ahUKEwjU_ pjt4sTLAhUGORQKHbxSD4gQ _ AUIBygC#imgrc=_  

And one may go through:

http://www.britannica.com/science/density-current

Density current

 
PhysicsWritten by: Claudia Cenedese

And the Technology:

Harvesting Power When Freshwater Meets Salty

Renewable Energy: Researchers boost power output from osmosis method that generates electricity from salinity gradients. 

Although sunlight and wind are two popular sources of renewable energy, some researchers would like to tap saltwater to produce electricity. They have designed methods that harvest the energy released when fresh and saline water mix, such as when a river meets the sea. Now one team has created a prototype device that increases the power output of such methods by an order of magnitude ( Environ. Sci. Technol. Lett. 2013, DOI: 10.1021/ez400117d).

See more on:

http://cen.acs.org/articles/91/web/2013/11/Harvesting-Power-Freshwater-Meets-Salty.html

In this regards, one may visit the following link for ex-actual practice:

Regarding the osmotic generating station, one may visit the following link:
http://www.hydroquebec.com/sustainable-development/documentation-center/pdf/file-osmotic.pdf

In which one may read:
How an osmotic generating station works When fresh water is separated from seawater by a semipermeable membrane, the fresh water moves by osmosis through the membrane into the seawater, raising the pressure on the seawater side. This is referred to as “osmotic pressure” and is used to drive a turbine. Osmotic pressure is the cornerstone of the energy generating method conceived by American Sydney Loeb in the 1970s but developed and put into practice by Norway’s Statkraft Group between 1997 and 2013 . An osmotic generating station has a limited number of components: [ A semipermeable membrane contained in modules [ Freshwater and seawater filters that optimize membrane performance [ A turbine that generates a driving force based on the osmotic pressure and permeation flow rate [ A pressure exchanger that pressurizes the seawater feed required to maintain high salinity levels downstream from the membrane.

ÙŽ    Also on Wikipedia:

https://en.wikipedia.org/wiki/Osmotic_power

Osmotic power

    One more option, as well:

https://www.technologyreview.com/s/423903/salty-solution-for-energy-generation/

     The difference in salinity between freshwater and saltwater holds promise as a large source of renewable energy. Energy is required to desalinate water, and running the process in reverse can generate energy. Now a novel approach based on a conventional battery design that uses nano materials could provide a way to harvest that energy economically.  

Best regards,

Mashallah Ali-Ahyaie

Taxonomy

• Water
• Energy

2 Comments

1. Hello Pradip,
   Your example of the water and alcohol and water is quite evident, for vertical mixing. But here one is dealing with side by side mixing phenomenon, which is quite different. I had seen your link before, but couldn't reaching a good article thereon, with the diagrams, explaining the phenomenon.
   Could you kindly provide a link on that?
   Also, do you have any information on the locations of these merging seas?
   You may kindly also comment, on the following article of mine too:
   Searching for the Combined Application of Technologies with a Natural Phenomenon, Where Tow Seas Sections Meet Each Other
   
   https://www.linkedin.com/pulse/searching-combined-application-technologies-natural-where-ali-ahyaie?trk=prof-post
   
   Best regards,
   Mashallah

2. I would like to put forward my view and observation. We have two miscible liquids with slightly different specific gravity. Take an example of alcohol which has Sp Gr. around 0.8 and water is 1.0.
   Now pour water in a glass half full and then alcohol gradually. It will form three zones. Lower water, intermediate is mixed (dispersed) one and upper is alcohol.
   Now reverse the procedure. Put alcohol first and then water and we will get mixture and no zones.
   Coming back to fresh water and sea water interface. Flow direction of water is from river and it flows over sea water before it get churned. Calm water will show distinct difference.
   Thanks for raising the issue and food for thought.
   I am giving a link for a diagram which shows dispersion of fresh and saline water phenomenon.
   
   https://www.google.co.in/search?q=fresh-saltwater+interface&espv=2&biw=1366&bih=599&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi5ztSj3czLAhXSC44KHX7kCJ8Q_AUIBigB#imgrc=ofTEd-xMKG-goM%3A
   
   
   

   1 Comment reply

   1. Dear Mr. Pradip Pofali,

         Sorry for my late response and thank you for the link.

      Best regards,

      Mashallah