Ben Bernanke

Among other objectives, liquidity guidelines must take into account the risks that inadequate liquidity planning by major financial firms pose for the broader financial system, and they must ensure that these firms do not become excessively reliant on liquidity support from the central bank.

You probably have to have redundant levee systems with canals in between them, like the Dutch have, to make sure that incoming water is channeled off to areas where you deal with it rather than have it drown you.