That’s not how it works. After it fills up you have to let water out of the dammed reservoir at the same rate it flows in (on average) or else it overflows. The issues created are related to sediments and flow consistency. More info in the top response here: https://earthscience.stackexchange.com/questions/18287/do-da...
I don't appreciate the downvote because you aren't listening to what I'm saying.
When it rains, it floods. They (stupidly) build dams for rate of flow during low season (cause it isn't raining)... then the wet season comes and the dams all overflow. Poor construction practices doesn't help either. They also build dam after dam along the same river... I've see 10+ of these things... ends up being a chain of mess when the first one fails.
Before the dam they'd have around the same amount of water, actually slightly less than that, as the reservoir loses water through evaporation.
Dams don't create water that wasn't there before.
It sounds like they're upset that the dam wasn't oversized to handle flood control in addition to hydropower.
That's a legitimate gripe with public investment and shortsightedness, but the damn aren't going to be making it worse (unless they're managed by morons).
