Hi Fergus,
Thank you for your questions.
I don’t believe there is specific data on the max flood height in Port Stewart. The Bureau of Meterology will have data related to rainfall histories and river heights. This may be a useful resource.
Yes, we can assume that flood waters will pick up lots of debris such as sediments, tree branches, rubbish etc.
I recommend researching areas close to Port Stewart if you are having trouble findign specific information regarding that specific area.
Kind regards,
Evelyn