mskeggs said
How do narrowboaters handle flood waters? What is best practice (assuming stay away is impossible)?

With caution!

Having been stuck by flood waters some 4 or 5 times this year you handle it as best you can. The biggest worry is that if the water rises high enough the boat will float over the towpath and then when the levels drop, you are left high and dry. 

If you can, as soon as it looks as if the level is rising then make for an alternative mooring with higher banks quickly. If not possible, make sure your mooring lines are tied to something solid and secure, not pins in the ground, that they are slack enough to allow for the boat to rise without tipping you over and keep checking. You can jam your boat poles down between the boat and bank to ensure you stay on the river side of the bank. If you are on a floating pontoon just stay put.

If you are stuck for any length of time then getting supplies can be a problem which is why we fill our water tanks every day. If you have cassette toilets then they can be emptied in the river in an emergency.

Remember, canals can flood too.

Regards

Pete