Monday, January 14, 2013

Creating a Dry Creek Bed - with Tips for a Natural Look

Current State of the Creek. Two stone bridges, rough mounds, boulders not yet in place.
It took me three six-hour days to get this far, roughly.

I'm quite liking the look of the stones so far. As a rule of thumb, the middle sized stones go in the middle, smaller ones towards the banks. I don't have middle sized ones though. Large and small only. And it's a small creek, width wise.

I posted about how I backed into this hugely fun project here. In this post, I'll provide what advice I gleaned from the web, and show how I extended the dry creek across our south garden, to drain down into the chaparral slope.

I'm not done yet, but it's amazing how much you can do in a short time.  Friends gave me all the river rocks - Yesterday, local friends offered me 4 bags of small pebbles which really helps vary the look - a mixture of small and medium river rocks are really required.

So, to get back to the beginning of this project. After I put a short creek for drainage in the succulent bed that is next to the house, I decided to continue it, and break up the south garden layout a new way --  nibbling into Experimental Bed #1 on the left, and rerouting the cross-wise path towards the right.


First I did a rough layout with a hose, creek with three meanders. Meanders make for a natural look. 
I played around with the hose quite a bit - and when I was digging out I made more adjustments. I made the river widen on the outer curves of a meander.


Then I started digging out the channel. I recommend a wider channel than I used. It's easier to arrange the river rocks naturalistically in a wider channel. But - it also uses more rocks.
When I was putting the stones in, I made the outer curves even wider - mimicking erosion. I think I should have made them even wider perhaps. I like the changes in width - maybe it exaggerates reality a little.

I tried to create a little beach on the promontory of an inner curve (it's a small grey blob in the photo below, near the bird bath end) that is, on the "deposition" side of one meander - as shown in this fishing blog picture:



I'm going to work on that a bit more - I found some road gravel and used it, but I don't like the color or texture.

Here's how it looked yesterday. Today I started mucking about more with the mounds and moved one large rock roughly into place. I might put small pebbles into the succulent bed creek too. Not sure.

At the end - the swale end (I'm standing on the chaparral slope across from the house).
Not done here yet -- I'll probably extend it to distribute water more evenly down the slope and add small pebbles.

The rest of the post has some pointers I picked up from sites about dry creek beds, and some ideas based on how rivers flow, and deposit sediment, and erode banks.

Basic Advice

The best instructions I found for building a dry creek bed were on this Washington State University site. Here are the main points I used from their site (there is more info on their page):

  • A width to depth ratio of 2:1 should look about right. For example, if you want your dry stream bed to be about 4 feet wide, make it about 2 feet deep. 
  • Your dry stream bed should follow a meandering or curving path rather than a straight line. You may want to include a promontory or small beach to add further interest.
  • Line the channel with landscape fabric, to suppress weeds. (Note: I did not do this - I'll just weed.)
  • Choose rocks, stones, and gravel in a variety of shapes and sizes, combining smooth river rocks with sharper-edged rocks to make it look natural. 
  • Use rocks that are in scale with your setting and with each other-don't overwhelm a small stream bed with huge boulders.
  • Boulders that are too large for the current to move remain in the middle of the stream, while smaller ones are washed to the sides. 
  • Put large boulders at the bends in the stream and to disguise the headwaters. 
  • For a more natural appearance, put some rocks on top of each other or partially bury them. 
  • Avoid organizing the rocks in any pattern. 
  • Move the stones around to get the look you want, filling the spaces with more river rocks. 
  • Spread fine gravel at the lower end of the dry stream bed to create the appearance of naturally deposited sediment.

Advice About How Rivers Flow Round Meanders

I was particularly interested in how natural rivers meander and how it might affect rock placement. Here's basically how it works:
  • Deposition occurs along the inside bend where the water flows slower
  • Erosion occurs along the outer bend where the water flows faster
You can see it clearly in this small image I found on this watershed hydrology page:


And on this similar graphic from an The Encyclopedia of Earth page:


So I tried to follow that idea when I dug out the meanders of my dry creek bed. Not terribly successfully but I am still tweaking.

I'm not exactly sure how the rock sizes are distributed on the meanders. These graphics from a page about rivers on The Encyclopedia of Earth are helpful because they show where water runs fast and slow:

I'm figuring that the slower water areas have the larger rocks and, and the faster ones will have smaller rocks -- because the faster (stronger) flow can move the bigger rocks along and they'll get stuck in the slower areas. But I'm not sure. I'll have to go look at a real creek sometime soon!

I tried to put small rocks to indicate the areas of faster flow. A wider channel would make that more clear. My little creek is probably too small for these finer points to make much difference.




I don't think I'll get into riffles, but thought this was interesting. In a larger project you could add texture this way.

I hope all this inspires you to have a go yourself. Of course this is a real honeymoon period - before weeds grow!

I'll post again when I've tweaked and twiddled and put a couple groups of rocks in (reused from another part of the garden). Maybe I'll have a plan for plants, too.

For sure I'll want a couple mini gnomes - so my granddaughter and I can take them for little hikes along the creek, and go camping in the "mountains."

I'm just having too much fun with this project!

8 comments:

David Cristiani said...

That may be the nicest how-to I've seen for a dry creek bed / water harvesting swale. Thanks...worth studying, as you bring up so much people need to consider (too many bad uses of rock - don't get me started!) I'm imagining the plants softening it quickly, and further adding interest.

Jason said...

A really excellent post. Makes me so sad I have nowhere to put a dry stream bed.

Country Mouse said...

Thanks, David and Jason - I'm glad you found the post informational.

I just showed the dry creek bed to my brother who immediately also began peopling the "mountain" with villages and visualizing hotels on the "beach" - I guess there's a family resemblance there!

erika m. said...

Thanx a lot for this blog! You just helped me decide what to do in front of my block which I kind of claimed to be "my" piece of land and contribution to the environment to make it look nice and green(being considered weird to be an urban green thumb taking care of a piece of land which no one cares about). However, it suffers dryness most of the time and dry creek bed is an excellent idea! I will definitely use your advice, thank you :-)

Danielle said...

Thanks for sharing your method and knowledge about this. The pictures help a lot!

PattyMc said...

Are weeds a problem? How do you handle them? Thanks!

Country Mouse said...

Sorry for delay Patty. Weeds haven't been much of a problem for me - I guess I'm lucky. The dry creek area is so small that I can hand-pull weeds, and that's what I do.

Brie said...

Excellent post, lots of good pointers on placement of different sized rock. Will definately help in making my creek bed natural looking. Thanks!