If you can't divert accumulating water, consider Plan B -- install plants that don't mind getting wet feet from time to time.
Q. We want to landscape an area that remains wet for a while after each rain. Which plants would be best?
A. If there's nothing that you can do to alter the soggy conditions, then you need plants that don't mind the muck.
Wet soil can mean the death of many landscape plants — due not only to excess water but also to lack of oxygen. Plants that can't tolerate such conditions usually die of suffocation.
Improving drainage in the area is always a plus; consider installing a French drain, a wet-weather bed or raised beds. If none of those possibilities, choose plants that handle varying degrees of wetness.
If you have an area in your landscape that's occasionally wet but dries reasonably well in a few days, you might consider these perennials, shrubs and trees: astilbe, cardinal flower, sedge, rose mallow, summersweet, hibiscus, European cranberrybush viburnum, leucothoe, fothergilla, inkberry, sweetspire, sweet and swamp azaleas, white spruce and black gum.
For more serious water issues, check the following pages for plants that can handle longer submersion.
Perennials That Can Handle Prolonged Submersion
Shrubs That Can Handle Prolonged Submersion
Trees That Can Handle Prolonged Submersion