Solution to world water shortage

I've been thinking about this for awhile. I have been thinking about a giant flexible tube suspended in the sea full of fresh water from a large river mouth somewhere like the say the Indus river leading all the way to somewhere that has not much fresh water like across the Persian gulf to Oman.

When I say large I mean large like say 500 meters in diameter. After all the area of a circle is the square of the diameter so bigger is better.

The tube would be fabricated out of some very tough lightweight material that was also extremely inexpensive. <-humor.

Now I have always imagined the tube to act like a kind of intestine and push the water along the pipe in some way like peristalsis. But I have never had any ideas about how this would be achieved. Tonight I had an idea. My idea is that there should be valves made with be flaps of material spaced at say two or three diameters or some optimal distance. The tube would be tethered at these points. In between there would be lines leading to the surface attached to buoys. The action of tides lifting the buoys would tend to bend the tube forcing water through the valves along the tube.

Of course the number of problems to be solved is huge. Would the tidal gradient be sufficient over a kilometer or so? Would not currents destroy the tube? How is the tube primed to begin with? What happens at either end? What kind of material would be strong enough and cheap enough? I don't have the answers and I'm not likely to find them but someone might. I just like the basic idea of possible a way to move large amounts of fresh water a long way cheaply.