Often when I’m meeting with a landscape design client in the DC metro area, drainage comes up as a concern. Sometimes the client knows he or she has an existing problem while other times I can look at what they want to do and see that we’ll then have to move the water somewhere. Around here it’s tough, because our clay soils are quickly saturated. If we’re running water across a lawn area and there’s sufficient slope that water doesn’t pool, it’s easy to move that water. When moving a good volume of water through a planting bed – especially on a significant slope – we need to control and direct that flow. That’s where a dry streambed can be a useful feature that also looks good.
In the case above, we pulled back the sod and we could see a defined channel (swale) where the water was already flowing. It was a couple of feet closer to the wall than I had it on plan, but one thing I’ve learned is that if you’re fighting water, come heavily armed or be prepared to lose. Rather than fight nature, we shifted the streambed to follow the existing flow.
As with any part of the landscape, proper construction is key to a good result. We clear and shape the area under the dry streambed, lay down a heavyweight fabric barrier that prevents silts from migrating up from the soils, and install the river stone. I use a mix of sizes, from boulders all the way down to 1-3″ river stone, to give it a natural look. Designed and installed properly, a dry streambed can help alleviate water issues – and look great doing it.