After the budget has been adopted, no money shall be drawn from the Treasury of the City, nor shall any obligation for the expenditure of such money be incurred, except pursuant to the budget appropriation. The Council may transfer any unencumbered appropriation balance or any portion thereof from one department fund or agency to another. The balance in any appropriation which has not been encumbered at the end of the fiscal year shall revert to the General Fund and be reappropriated during the next fiscal year. In the case of emergency arising from a pressing need other than a regular or recurring requirement and necessary to protect the public health, welfare or safety, the Council may make additional appropriations to cover unanticipated expenditures required of the City because of such emergency.