I believe that it is useful to have a term as WHC that describes the
total amount of measurable water that we can expect to see retained
in a soil profile. This is useful for comparing against methods that
measure total water such as neutron meter, TDR, etc. In addition,
many old soil surveys contain soil water holding information that is
often equivalent to the above definition of WHC. Therefore, it is useful
to keep a term around that is compatible with the old data.