Water is a wonderful addition to just about any landscape, but too much of it can create havoc in your home or garden. The first defense is proper drainage, but rather than just digging and installing drain tile, you can create a natural-looking water feature that’s easier to build and looks beautiful. A dry streambed, or arroyo, can move water away from your home while creating a striking addition to your landscape.
Streambeds can be as small or large as you like, but moving water to another part of your yard — or to the street — may require permission from your local government. Contact your local public works department before you start. If you are unable to channel water to the street, consider creating a pond or a dry well to allow the water to seep into the ground.
A dry streambed (arroyo) is easy to build and can help control erosion
Form follows function
The first step in creating a streambed is to take a good look at your yard and determine where the starting point will be. It should begin at the highest point so gravity will move the water downhill. Use the natural slope of your location as much as possible. Mark the outside edges of the bed with landscaper’s paint or a garden hose. To achieve a natural look, try to undulate the flow of streambed as much as possible.
The size of your streambed depends on your landscape and type of soil. Sandy soils may require a deeper streambed than clay soils. A 3:1 ratio works well, meaning a 3-ft.-wide streambed should be about 1 ft. deep. Remember to vary the streambed’s width as it flows downhill to simulate a natural riverbed.
Dry streambeds can be large or small. Consider incorporating other design features such as steps and lighting
If you're lucky enough to have access to excavating equipment, digging will be easy. Otherwise, get out the shovels and invite a friend or two over to help you dig. Move the excavated soil to the outsides of the bed, filling in where needed to create a deeper channel. Rake the excavated soil smooth; then tamp to firm.
After determining your streambed's location, start digging and moving the soil to the outside of the bed.
To help keep weeds from growing, use landscape fabric to line your riverbed.
After excavation, install landscape fabric along the length of the bed, using garden staples or stones to hold the fabric down. Place gravel at the center and deepest part of the bed and work it down the length; then top it with a 1-in.-deep layer of sand or pea gravel.
After you have lined the center of the bed with drainage rock, add larger boulders at staggered intervals. Look to nature to guide you with placement. Don’t line up the stones evenly or use rocks that are all the same size. Place the larger boulders on the outside banks, wherever the stream changes direction and at areas where you want to hide the beginning of the bed. Stop occasionally and view your work from different angles, making alterations as needed.
Start with larger stones, then fill in areas with smaller rocks and gravel.
Once the boulders are in place, position the smaller rocks. Use a mix of river-washed stones and pebbles. Smoother rocks will help give your project the look of a true riverbed. As with the boulders, place larger stones toward the outside and smaller stones closer to the center of the bed. Once you’re satisfied with the look, scatter a thin layer of sand over the streambed and then lightly spray with water to fill in any cracks and crevices.
You could call the project done at this point, but you can enhance its beauty by adding plants that lend color and contrast to the ruggedness of the stone. Use a combination of small spreading and larger, taller plants. Incorporate naturally occurring plants such as ferns and grasses. Consult a local nursery to learn about appropriate plants for your climate. You may also want to add statuary, garden art or low-voltage lighting. Streambeds are generally low-maintenance, but you will occasionally need to clean up leaves, twigs or branches that become stuck within the stones. Additional sand may be needed to fill in any settled areas. When you’re finished, you may find yourself anticipating the next big rainstorm.