I hear references to flood stages on the weather reports. The flood stages are stated as a number of feet above or below flood stage on various rivers in the area. It seems that a reported flood stage as a certain number of feet above flood stage would result in flooding. Can you please explain?
You make a good point! And the truth is ... "flood stage" does mean flooding for almost every river in south Louisiana, except for the Mississippi .. and possibly some sections of the Atchafalaya.
Here's why: flood stage does reflect the level at which a river/bayou has risen above its 'natural' banks, but flood stage does not include any additional containment resulting from the construction of levees and/or flood walls.
Since few if any of our smaller rivers (i.e., the Amite, the Tickfaw, the Tangipahoa, etc.) have any significant levees, reaching or exceeding flood stage does indeed mean that flooding will occur.
But along the Mississippi, flood stage is based on water levels that WOULD create flooding if the levees were not present. So the next obvious question might be: why not change the "flood stages" for the Mississippi (and Atchafalaya) to match the levees?
For most of us this makes perfect sense, but we often forget that there are businesses and river operations -- and numerous river camps -- INSIDE the levees. For these "inside" locations, the original, historical flood stages have meaning -- from operating tugs and barges, to managing the ferryboats, to deciding whether the camp-community on Raccourci Island (Pointe Coupee Parish, Mississippi River) should be vacated due to high water.
You can be sure, however, that whenever the Mississippi River gets EXTREMELY high, the WAFB Storm Team will let you know! As a for-instance, in March 1997, the Mississippi topped at at just under 44 feet, nearly nine feet above flood stage but still within the limits of the levee containment.