It seems impossible to “garden” rain but the practice is not so far-fetched.
Rain gardening actually means planning your landscape so rain stays on your property to benefit your plants. If excess water occurs, rain is directed to an area where it can collect and soak into the soil.
Of course the plants in that area must be tolerant of wet soil….but there are many such plants from which to choose.
The Georgia Clean Water Campaign has published an excellent brochure explaining the concepts of rain gardening.