Your thoughts are so spread and non informative that is difficult to give you suggestions.
In many parts of the world ( Africa and South America) people are generating electrical power with in-river-hydro systems.
What is the speed of the water, the depth in the area of interest -- then with the information a calculation can be done to see how many watts per square meters can be produced.
Indeed, it is a practical system for generation of power levels of around 100 watts up .
Nando