I may be 100% wrong on this, but ...
I think it's French culture to bury people above ground in stone structures. Paris cemeteries are often built like this. New Orleans cemeteries are sometimes built like this. If a flood hits a cemetery it may not be difficult to damage the structure and push the contents out through a hole in the wall.
But I'm not sure that's the case.
I believe in new Orleans the water table is so high they can’t bury people underground.
No idea about the rest of Louisiana.
[[ I may be 100% wrong on this, but ...
I think it’s French culture to bury people above ground in stone structures. Paris cemeteries are often built like this. New Orleans cemeteries are sometimes built like this. If a flood hits a cemetery it may not be difficult to damage the structure and push the contents out through a hole in the wall.
But I’m not sure that’s the case. ]]
It’s done because in some areas you can’t dig there and not hit water .
I remember standing in New Orleans by the river as a little kid where the ships move in and out and it looks like you are sitting in a hole looking up at the ships .
Water tables.