????????? ??? ???? ??? ?? ??????? ?? ????? ?????? ???? ??? ??? ??????The southwestern part of the plains, formerly strewn with sand dunes, has largely been leveled off With all the expansion of irrigation projects.?????? ?????? ?? ????? ?? ??? ?? ?????????? ???? ??? ?? ???? ?? ????? ?? ?? ?????? ?? ?????? ??? ?? ????? ???? ???? ?? ???????? ???? ?