Wonder how much water you'd actually have to drain to end a flood?
to reduce 10% the average volume of the 100th largest river in europe (Vjosa of Albania), you need to drain 1.680.000 m3 of water a day. An average work horse drink 50l of water a day, so this is equivalent to the consumption power of 33.6 million horses. The entire mongol empire had about 60 million horses.
To BOIL that much water, which's her initial plan, you need to provide 6.5 mWh over the duration. This is roughly the maximum output of the 17th power plant in the world, the bruce nuclear power plant in canada.
Oh yeah, and if you flash boil that much water (19.5m3 a second) you'd generate scalding vapour the size of a barn every seconds.