The governing body of any city having a population not in excess of 30,000 may, in lieu of the reassessment provided by general law, by ordinance provide for the annual assessment and reassessment and equalization of assessments of real estate therein, and to that end may appoint a professional real estate assessor certified by the Department, or a board of assessors, to assess and from time to time reassess for taxation in such city, and shall prescribe the duties and terms of office of the assessor or assessors.
Va. Code § 58.1-3251