The board of county commissioners may provide covenants as it may deem necessary to secure the payment of the principal of and interest on such bonds and may, but shall not be required to, include covenants to create a reserve fund or account and to authorize the payment or deposit of certain moneys therein for the purpose of securing the payment of such principal and interest; to establish, maintain, and collect rates, charges, fees, rentals, and the like on the facilities and service the income of which is pledged for the payment of such bonds, sufficient to pay or secure the payment of such principal and interest and to maintain an adequate coverage over annual debt service; and to make any and all other covenants not inconsistent with the provisions of this chapter which will increase the marketability of such bonds. The board may also provide that revenue bonds payable out of the same source or sources may later be sold on a parity with any revenue bonds being issued and sold. The provisions of this chapter and any resolution or resolutions providing for the authorization, issuance, and sale of such bonds shall constitute a contract with the holder of such bonds, and the provisions thereof shall be enforceable by any owner or holder of such bonds by mandamus or any appropriate suit, action or proceeding at law or in equity in any court of competent jurisdiction.