This would be awsome, as a flood in ANY game would be my dream come true however I still fail to see any floods in games...
I am really not sure how you would do this with OFPs outdated engine, because water cannot be shaped in this game, the possiblity would be drop effects, however in order for this to look realistic it would be so CPU intensing it could barly run.
The only alternative would be an addon mixed with drop effects, you would have to make an object that changes shape to fit the terrain however I am not even sure if this is possible.