Traveling though the southwest, you can see dry streambeds everywhere. Their bottoms are covered with round river rock. Sometimes there is vegetation growing alongside the streambed.
Occasionally, during rains, or in monsoon seasons, rainwater will push its way from nearby mountains, or higher desert areas, and rush down through the streambed. For a short period, the dry streambed will become a creek or a river, depending on the amount of rainwater it receives. (That's what is called a flash flood. )Then, it will dry out again, leaving a streambed of rocks whitening in the sun.
But dry streambeds are far from dry. And they provide an enormous service to desert areas. First, the river rocks become a sort of mulch, which collects moisture during heavy rains, and keeps it in the soil beneath the rocks. This allows all sorts of organisms to grow and reproduce, provides food for animals (vertebrates, invertebrates and microbes alike), and stabilizes the desert soil.
You can reproduce this process in your desert garden, or on slopes that are in danger of erosion.
Simulated dry streambeds help reduce erosion, add beauty to your property, and create microclimates in which micro- and macro-organisms thrive.
If you’re going to build a dry streambed on a slope, outline its location first. You’ll want it to be at least three feet wide. It can be as long as the slope, reaching from top to bottom in a straight line, or it could meander down the slope. Of course, a meandering streambed is more attractive than a straight one, and looks more natural. But, a meandering streambed can be twice as long or more than a straight one, so cost and labor are also a factor.
For river stone, figure about $10 per square foot. In the west and southwest, cut river stone costs about $350 per ton, and a ton will cover about 35 square feet. That’s a little over 10 feet long by three feet wide. If your slope length is longer than that, use the $10 per square foot, or about $90 per square yard. These prices are just estimates and can very widely.
Once you’ve decided how long and how wide your dry streambed will be, you’ll need to follow the outline and dig a trench about six inches deep (or deeper), and as wide and as long as your outline.
Next, begin putting in the river stone, starting at the top. Lay the stone inside the trench. You may want to hire someone to help, or trade out some work with a neighbor or friend, because putting in river stone, especially on a slope, can be hard and tedious work.
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