This report on the aftermath of Hurricane Sandy refers to the process of removing water as unwatering. However, I always thought that this process was called dewatering. What, if any, is the difference between these terms?
The dictionary does not give an entry for unwatering. But a quick google search suggests the term seems to be widely used. If unwatering is not a valid term, why is dewatering not used instead?
The Corps of Engineers uses the term unwatering to describe removing water from locations where it is not supposed to be (subway tunnels, house basements). Dewatering describes removing water from locations where it is usually located (inside locks, river beds).