The proceeds of bonds issued under authority of this chapter shall be paid into a special fund or funds in banks qualified to act as depositories for the city or county in which the port or harbor is located, allocated in such equitable manner as the board may determine and such depositories shall qualify as such by depositing bonds or other securities authorized by law to secure deposits in state depositories. The proceeds of such bonds shall be used solely for payment of the cost of the planned development and the redeeming of any outstanding bonds and shall be disbursed upon order of the board with such restrictions, if any, as the resolution authorizing the issuance of the bonds may provide. If the proceeds of such bonds, by error of calculation or otherwise, shall be less than the cost of the planned development, and the redeeming of any outstanding bonds, unless otherwise provided in the resolution authorizing the issuance of the bonds, additional bonds may in like manner be issued to provide the amount of such deficit which, unless otherwise provided in the resolution authorizing the issuance of bonds, shall be deemed to be of the same issue and shall be entitled to payment from the same fund without preference or priority of the bonds first issued for the same purpose. If the proceeds of the bonds of any issue shall exceed the amount required for the purpose for which the bonds were issued, the surplus shall be paid into the fund established for the payment of the principal of and the interest on such bonds.