The trouble is, there are just too many people. That puts pressure on the housing market and encourages developers to build more houses, and councils are under pressure to grant PP, so flood plains get built on. Farmers are under pressure to produce more food, and cheaper and more efficiently, so hedges get ripped out, ploughing and crop planting are done with maximum exposure to sunlight in mind rather than controlling run-off. The overall result is floods. Nothing to do with AGW.