Wherever the regulations made under authority of this chapter require greater width or size of yards, courts or other open spaces, or require a lower height of building or less number of stories, or require a greater percentage of lot to be left unoccupied, or impose other higher standards than are required in any other statute or local ordinance or regulation, the provisions of the regulations made under authority of this chapter shall govern. Whenever the provisions of any other statute or local ordinance or regulation require a greater width or size of yards, courts or other open spaces, or require a lower height of building or less number of stories, or require a greater percentage of lot to be left unoccupied, or impose other higher standards than are required by the regulations made under authority of Chapter 414, the provisions of such statute or local ordinance or regulation shall govern. Wherever any regulation proposed or made under authority of Chapter 414 relates to any structure, building, dam obstruction, deposit or excavation in or on the flood plains of any river or stream, prior approval of the Iowa Department of Natural Resources shall be required to establish, amend, supplement, change, or modify such regulation or to grant any variation or exception therefrom. Should any section clause or provision of this chapter be declared invalid, such shall not affect the validity of the remaining portions of this chapter.