It’s one of my favorite phrases, related to rainwater harvesting – induced meandering. The premise is simple. Whenever you can encourage rainwater runoff to slow down, to take a more circuitous route, to wind its way down a hill rather than rush full speed toward the gutter, storm drain, or gully below, you increase the likelihood that this runoff can become a resource rather than a nuisance.
When runoff slows down it’s able to sink in as it flows down slope. As the water sinks in, it irrigates plants on its way. This not only provides water for those particular plants, but, over time and given enough precipitation, refills the groundwater tables below – contributing to the overall health of the surrounding region.
Take, for example, the geraniums on the path in my garden. Granted, geraniums are fairly drought tolerant and hardy plants. That said, these geraniums never get watered, unless it is by the rain. In Baja the dry period is typically between about April and November. So, these geraniums live with basically no overt watering for 6- 7 months. Crazy, right?
Yes, but. When it does rain, those geraniums are fed by the stream that flows, winds, meanders past them. This runoff, from the road above, can be fairly strong. But as it makes it’s way downhill it is slowed down by both organic matter and loose granite along the path. At a certain point the stream encounters a ‘speed bump’ and makes its way into the garden, continuing to wind its way past an avocado tree, a plum, on toward an almond and from that down to an apple. Typically this is as far as it gets, but were the rain and the flow to be slightly stronger, it would continue on its way to the orange, down past the artichoke, and on to the guava.
The premise behind induced meandering is not just to slow the water down, to give it time to sink in, but also to ensure that, as much as possible, the rainwater doesn’t leave the property but is all used, absorbed, planted back into the ground.
So, how does one help to induce induced meandering? Easy.
- Observation – it is important to first watch how the water flows in a given area, or over your property. Where does it come from? Where does it go? Where does it run ‘fast’ and where does it slow down? Observe the path and pattern of the water.
- Action – once you have observed the patterns of the water it is time to experiment. How might the water be slowed in the fast areas? Typically this is done by either spreading it out, or by adding curves to its path. Perhaps it’s a dirt road that gets rutted from the rain – add a rock or other ‘block’ near the top of the rut and water will spread out rather than make a deeper rut. Perhaps it’s a downhill dirt path that, with each rain, gets cut deeper – add ‘speed bumps’ in the form of rocks or dirt to help slow the water down, to encourage it to spread out as it travels.