A rain garden is a planted depression that is built into the landscape allowing rainwater runoff from a roof, driveway, sidewalk, street, or even compacted lawn areas to slow, collect, and be absorbed into the ground. When planted with perennials, grasses, and shrubs, they help conserve rainwater and filter out pollutants while reducing runoff from your property. Plus they can provide a beautiful spot for song birds, butterflies, and other critters searching for food, water, and shelter.
Whether you excavate your own rain garden site or use an existing depression or swale, several factors are important for success. First, choose plants depending on where in the rain garden they will be planted. There are 3 general zones: lowest/wettest, middle/transitional, and upper/driest. Second, it is very important to plant when there is sufficient time for roots to become well established BEFORE you expect regular rain events. Even the most expertly planted plants cannot hold on through regular gully washers!
You can get very elaborate and bring in big equipment to address your issue, or you can take advantage of natural features to handle large amounts of water. Either way, a rain garden is an effective way for you to beautify your property and provide food and shelter for wildlife while also minimizing runoff and improving water quality.
Here are some great links to help you with your project.
Rain Gardens for Tennessee
State College, PA, Borough Rain Gardens
What is a Rain Garden