That's a terrible idea, unless I am missing something.
Why not cover the vast amount of uninhabitable land in solar panels, rather then what small amount of precious resource land that exists.
But I still cannot wrap my head around this being a good idea, destroy the ecosystem of rivers, provide next to zero power (compared to resources required to build and maintain), require a HUGE investment as it's fast moving water and everyone knows fast moving water destroys material, have to deal with overflowing from rain, drought, etc.
Way too many factors for this to be a good idea.
It could probably if it was a man made canal or something with a set amount of water, but that still destroys any chance of an ecosystem.