"Major flooding" refers to a severe and extensive overflow of water from rivers, lakes, or other bodies of water onto land, causing significant damage and posing a major threat to people and their properties. Full definition
About six weeks after the vacation / breakup, I had what was, I believe, the eighth major flood in my apartment. (refinery29.com)
But in recent years, the frequency of major flooding events has been on the rise — and sometimes at unexpected times of year. (scientificamerican.com)
The frequency of major flooding events, in part due to climate change but greatly due to bad river management, are increasing. (dotearth.blogs.nytimes.com)