The fastest part of a river is the narrowest or shallowest. In broad, deep sections the water moves slowly, in narrow or shallow sections the river moves fastest. Of course the fastest flowing water is at a waterfall or rapid.
most narrow part
According to fluid theory, fluids tend to travel the slowest along the edges. Therefore the fastest current will be in the middle of the river.
The outer curve
the rite side
Usually it is the upper reaches (often termed as mountain streams) that flow the fastest. In the lower, flatter valleys, rivers tend to slow down (except in spate, when the river is in flood)).
A narrow waterway connecting two bodies of water is called a strait, like the Strait of Gibraltar. The deepest part of a river or waterway is known as the channel or the riverbed.
Amazon Actually the fastest flowing river in the world is one that no one would ever suspect. I claim the Passiac River at Paterson NJ is hands down the fastest flowing river in the world during flood stage. The Great Falls of the Passaic River at Paterson NJ falls 77 ft into an extreme narrow gorge which at the head of the gorge the river channel is no more than 25-30 ft wide. It is at this point in the falls into which the greatest volume of river water plummets. At flood stage when there is many billions of gallons per day going over the falls, the combination of the velocity of the descending water crushing down onto the channel squeezes or puts pressure onto the water in the channel from above. This combined with a very narrow cross section causes the velocity in that short and small section of the river to easily flow some 70 mph. There is nothing like it anywhere in the country maybe the world. This is not a man made channel, it is natural, so the flow velocity during floods is the fastest naturally occurring flow (if you can call it flow, it literally shoots laterally out of the narrow section of gorge)
Sicily is a large island off the coast of Italy and is part of Italy. The Strait of Messina is the narrow "river" that seperates Sicily.
the Missouri river
The source
the Missouri river
it is the fitzroy river in the southern part of Colorado