No land within the areas of special flood hazard shall hereafter be subdivided, or have its lot lines adjusted; nor be improved, filled, graded or cleared; nor shall any structure, including a manufactured home, be constructed, reconstructed, substantially improved, relocated or erected; nor shall any other development, as defined above, be commenced upon such land unless the person responsible therefor shall first obtain a development permit for such action, as set forth in SMC 15.16.150, except that projects of the City of Sebastopol shall not be subject to the provisions of this chapter.