Hydro is definitely highly geography dependant, and certainly the environmental impact can be severe. Though there’s also been great advancements in smaller scale “low head” hydro where you don’t need to submerge half a valley or block migratory paths. Hence curiosity where hydro stacks up.
I suppose it’s so geography dependant you can’t make a meaningful global average to compare with other forms.
Then again in my particular neck of the woods solar is limited at best, for half the year. While the local landscape is nothing but mountains, valleys , lakes and rivers. So many lakes and rivers.
Another neat thing about hydro is that it’s a renewable base load. Geothermal is another, but that’s also highly geography dependant



“Pumped storage” is already a thing. Using excess grid electricity to pump water uphill.
Though excavating underground cavern for pumped storage sounds exceedingly expensive:O