The flooding referenced in the article (that of dams and their ability to pass flow) is not affected by wetlands.

Yes, impervious surfaces have increased but on a large scale, that's only really affecting cities with their storm water runoff. Flooding on the large scale we are seeing in Australia is not really exacerbated by the surface impermeability. River erosion and river roughness reduction due to vegetation clearing has had some impact, but the big change is the climate.