One of the key fundamentals of permaculture is "Design for Catastrophe". As our climate is changing, two things will be evident. Firstly, some areas of the world will become more wet and others drier. Secondly, there will be extremes of weather, so more flash floods, more droughts or extremes of temperature. We all need to become better designers to enable our properties to become resilient in the face of adversity. My permaculture 'specialty' is water - how to harvest it, use it, store it, recycle it, conserve it and move it. Having excess water can be a blessing if you can get into the ground or storage tanks or dams, or at least have provision to drain excess away. I don't have quick fix answers for a deluge from nature, but think about how you could mitigate these events should they occur.