Yesterday Chip, Ike, and I took a morning walk up the shady west side of our mesa. Ike lasted about the first 1/4 of the walk before turning back to wait for us in the culvert by the truck, once the day grew hot...
The west side is cut deeply with big arroyos that must be wildly raging on the rare occasions that they run!
Nurturing Land
A large part of our research over the last two years has been centered on learning about how to live and grow on a desert mesa without destroying it. We explored sites on greening the desert, food forests, rainwater catchment, ancestral Pueblo land management & farming techniques, permaculture, and desert gardening.
Brad Lancaster's name kept coming up. We bought the first two volumes of his Rainwater Harvesting for Drylands and Beyond, and read the whole thing cover-to-cover — it is dense with information, packed with actionable steps exactly suited to our situation, and very accessible. Volume One should be read by anyone anywhere who has a yard and who drinks, or uses water in any way.
We broke his first principle in our initial attempts to support our land, so please don’t judge him by our blunders — please blame us for any mistakes we make!
Long and Thoughtful Observation
Brad’s Principle One (which is also the first principle in permaculture however worded) is “Begin with long and thoughtful observation.” We’ve long been thoughtful about our water situation, but have been 1000 miles away, so our observation has been too little and too vague (there’s only so much you can see from plat maps and Google Earth)!
Brad’s Principle Two is “Start at the top.” This resonated with us, because one of the most obvious water problems on our land (besides lack thereof) is that the shared road is washed out badly on the west side. There are three major ridges in that area, and two major arroyos that wreak havoc on the road (I am speaking very loosely — counting ridges and arroyos is a fool’s game, since they connect and split all over the face). Across the road, the worst of those arroyos becomes a canyon. Hopefully the road won’t join the canyon formation any time soon, although it is threatening to inch its way there…
We can’t (at least in the short term) go back and have the whole subdivision’s road redesigned with water management principles incorporated… but our land is “the top” of this problem area, and anything we can do to encourage the rare rains to infiltrate a little more and run off a little less would benefit our downstream neighbors (who own two downstream lots but live out of state) and everyone who uses the road (which at the moment means us and one other couple, plus a family who comes out some weekends, as well as the occasional curious or lost driver).
Baby Steps
Brad’s Principle Three is “Start Small and Simple.” Well, we started way earlier than recommended (meaning Day 6 on our land), but we were very careful to take the tiniest of baby steps. One of the techniques introduced to us by Brad’s book (and used by many others as well — here is one example explanation) is the one-rock dam. This is a small permeable barrier in a stream that slows, but does not stop, the water flow. Sediment builds up behind the dam, allowing vegetation to take hold. Water that overflows the dam follows the same downstream channel, so the dam does not create any new runoff problems.
On our walk yesterday, Chip zoomed off ahead (as usual), and I dawdled, taking pictures and fiddling around (as usual). I didn’t presume to create any one-rock dams in our arroyo… but I did aim to observe how nature had created one-rock dams. There were many beautiful examples of rock (and/or juniper root) obstructions with grasses or flowers growing in the resulting sediment.
Nudging Nature
In several places I found rocks blocking most of the width, but with a small opening that let a chute through. That’s when I’d look for a rock not already doing any work. That is a challenge, because almost every rock on the mesa face has sediment built up behind it — a sign that the rock is already working to slow the flow! I didn’t want to disturb any workers already engaged in a task, since I know that I’m too ignorant to know whether I was helping or hurting by moving the rock.
Sometimes I found rocks that were sitting on other rocks, up away from any water flow. I found other rocks sitting in the middle of a flat pool area, without sediment built up behind them. When I found a rock that seemed like it wasn’t working near an almost-one-rock-dam with a hole to fill, I moved the rock into the hole.
Time (and a few good rain storms) will tell if our efforts made any difference!
Thanks, Todd!
I agree with your thinking that these are not intended to block the flow of water, and do need a spillway (in this case, the spillway is still in the center of the arroyo channel, since the one-rock "dams" never block the flow beyond the width of the channel). I use Brad Lancaster's (and others') terminology; his perspective is focused on rainwater infiltration rather than flood control or road maintenance (although they are all interrelated), to encourage more water to soak in rather than run off. That's what we're hoping for our land, wherever possible, to slow the flow and encourage infiltration. He does go into great deal about spillways for all of his methods, so that …
I prefer to think of these as spillways rather than dams. Spillways slow, rather than block, the flow, and dissipate the energy over a broader area. Dams don't survive long without good spillways to dissipate the energy of the flowing water. Some of the big flood control spillways here in ABQ are very wide and have lots of cement blocks sticking up to slow the water down so it doesn't have enough energy left to erode away the base of the dam when it gets to the bottom. Notice that the blocks are staggered and have spaces between them, rather than being in a line. So wider channels with staggered rocks may work even better than lines of roc…
What a great narrative, full of new (to me) ideas!
Fascinating!