There can be no such thing as a 'natural man made river bank', things are either natural or man made.
However, I think you are referring to what is called a 'Levee'.
The elevation or height above sea level is called altitude.
The height of a place above sea level is called elevation.
The height above or below sea level is "elevation". Altitude is used only for distance above sea level.
The height of a mountain peak above sea level is called its elevation.
The measure of how high a place is above sea level is called elevation.
A pipe extended above the roof level is a soil pipe.
Land above sea level is called "elevation" or "high ground." It can also be referred to as "terrain" or "upland."
elevation
elevation
Land above sea level could be anything from flat lands to a plateau. It depends on the location of the sea and land.
inflation.
The general elevation of Upland, California is around 1,250 feet above sea level.