The governing body of any county may, by ordinance, provide for the regulation of parking on county-owned or leased property and may prohibit parking within fifteen feet of any fire hydrant or in any way obstructing a fire hydrant. In any prosecution charging a violation of the ordinance or regulation, proof that the vehicle described in the complaint, summons, parking ticket citation, or warrant was parked in violation of the ordinance or regulation, together with proof that the defendant was at the time the registered owner of the vehicle, as required by Chapter 6 (§ 46.2-600 et seq.) of this title, shall constitute in evidence a prima facie presumption that the registered owner of the vehicle was the person who committed the violation.