Coming from a meeting with a client in Scotts Valley today, I saw a really well designed dry creek bed. I didn’t get a picture today, but I’ll go back, it was that good. How will this year’s La Niña affect our rainfall? According to NOAA (National Oceanic and Atmospheric Administration) our chances of La Nina winter rains are average to slightly above.
So with winter fast approaching you may be wondering how to channel that extra rain that runs down your property and do it with style. Here are some tips.
A dry river bed can slow runoff, spread it out and sink it back into the soil. Connected to a downspout they keep even more rainfall on your own property. A dry river bed is a rock-lined swale that uses rounded river rock in addition to vegetation to allow runoff to soak into the ground. Make sure there is a 2% slope from beginning to end to ensure that water is conveyed away from your house to the desired location. Non-woven geotextile fabric is often used underneath the rock.
You can create a depression or rain garden at the end of your dry river bed and plant it with plants that tolerate wet feet in the winter. Both a dry river bed and a rain garden allow water to sink back into the ground. The plants remove pollutants from runoff from roofs or other impervious surfaces.
A rain garden might be a simple, shallow depression filled with plants that can flourish in both moist and dry conditions. The size and depth will depend on how much water you need to capture in a winter runoff.
Sometimes a dry river bed will receive so much runoff that a dry well or dispersal pit is installed at the end. If you have a high water table or clay soil the water may not always soak in fast enough and an overflow device like this is needed. The goal is to keep water on your own property and not in the street or the neighbors’ yard.
There are good looking dry river beds as well as bad looking ones. A quick Google image search will show you what I mean. Your goal is to create something that looks like it belongs right where it is. The plants, the accent rocks, the cobble, the location—all need to work together.
If your property has a natural slope, follow the natural terrain if possible. You can install a dry river bed on flat land also by creating a channel for the river bed to follow. Keep in mind that even a dry river bed is more interesting if it is not all visible at once. Soft, flowing curves and bends create a natural look.
Start with the rocks and cobble. Rounded river cobble looks most natural for the creek bed. In nature, water flowing down a river would round off sharp rock edges to produce cobble of different sizes. A river never has just one size of rocks and yours shouldn’t either.
Accent rocks can be any type that you like as long as you get a variety of rock sizes and shapes. Use the larger stones to direct and channel water. Placing rocks on the outside of a curve creates a more natural look.
As in all gardens there is always a bit of maintenance to keep things looking and working great. Weeding in the first couple of months while plants become established is important. Replenish mulch as needed until the plants grow in.
Periodically remove leaves that have landed in your river bed and reposition rocks moved by runoff to keep your dry creek bed working for you when you need it. Also don’t start your dry creek bed too close to the foundation of your home if that area is flat. You can direct the water through a drain pipe connected to a downspout to a lower starting spot in your garden.
So whether you are adding a dry river bed to add interest to your lawn-free landscape or to double as catchment for winter storm runoff, make yours look like it’s always been there.
Jan Nelson, a landscape designer and California-certified nursery professional, will answer questions about gardening in the Santa Cruz Mountains. Email her at ja******@ao*.com , or visit jannelsonlandscapedesign.com.
