Except for purposes which are to be financed by a method not requiring a budget appropriation, no money shall be drawn from the treasury of the city without an appropriation thereof, nor shall any obligation for the expenditure of money be incurred without an appropriation covering all payments which will be due under such obligation in the current fiscal year. The Council may transfer any unencumbered appropriation balance, or any portion thereof, from one department, fund or agency to another. In the case of emergency arising from fire, flood or other calamity, the Council may make additional appropriations to cover unanticipated expenditures required of the city because of such emergency. The balance in any appropriation which has not been encumbered at the end of the fiscal year shall revert to the general fund.
At the beginning of each quarterly period during the fiscal year, and more often if required by the Council, the officer responsible for the maintenance of the city accounting system shall submit to the Council data showing the relation between the estimated and actual revenues and expenditures to date; and if it shall appear that the revenues are less than anticipated, the Council may reduce appropriations, except amounts required for debt and interest charges, to such a degree as may be necessary to keep expenditures within the revenues.