TRANSIENT

(adjective)  Brief, transitory, temporary.

Transient is a word that describes the ephemeral state of something -- that is, it is not meant to last. The object described by the word exists only for a brief period of time, either in its physical form or in a certain time and place. More often than not, the "thing" being referred to is a person or group of people. The student population at a college is transient; they are only around for a few years. In its noun form, a transient is a person (a laborer or even the homeless) not expected to stay for too long in one place.

"Transient population leaves elderly alone: It's a symptom of the transient population. What we're seeing is family units are not staying together - a combination of the job market, the housing market. A whole number of factors come into play here. “

“For the purposes of this information sheet, a transient construction site is where short duration construction work is carried out by people working at one or many locations (typically short duration work covers work of up to a week’s duration). For example, emergency works, small-scale maintenance at fixed premises, maintenance work carried out by or on behalf of utilities, etc. Construction work of a longer duration carried out while moving over a continuous geographical area, eg major roadworks, cable laying contracts, etc, is also considered a transient construction site.
Source: YourDictionary