20And Noah builded an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar.
21And the LORD smelled a sweet savour; and the LORD said in his heart, I will not again curse the ground any more for man's sake; for the imagination of man's heart is evil from his youth; neither will I again smite any more every thing living, as I have done.
22While the earth remaineth, seedtime and harvest, and cold and heat, and summer and winter, and day and night shall not cease.
i think the point is that God knows us as a race. if God did more floods, even localized ones, every time man got this bad,
then He'd have to wipe us ALL out completely.
I actually think this is a point in favor of a local flood...local to the adamic valley.