The easiest way to replace a lawn with low water plants may be to plant on top of the lawn. Sheet mulching is a process for covering a lawn to do just that. It can be used to kill weeds as well. Sheet mulching is using cardboard or newspaper (2 or more layers are better) to smother the lawn/weeds.  Sheet mulching is effective because it blocks light so the plants can not photosynthesize. Helpful resources include: