The council shall have the power to determine that the whole or any part of the cost of any public improvement shall be defrayed by special assessment upon property in a special district and shall so declare by resolution or resolutions shall state that estimated cost of the improvement, what proportion of the cost thereof shall be paid by special assessment, and what part, if any, shall be a general obligation of the city, the number of installments in which assessments shall be levied and whether the assessments shall be based upon special benefits, frontage, area, valuation or other factors permitted by law, or a combination thereof. The council shall also have the power of reassessment with respect to any such public improvement.