Last month, we discussed how this would likely be a La Nina winter and the challenge of heavy rains compressed over several days at a time. The good news is that water reservoirs are filling up and the Sierra snowpack is running way above historical averages. The downside is that these surpluses are only "to date." There has been a huge deficit of rain, and despite the good start, if precipitation is low for the remainder of the year, California will still be in a status of drought. Short, intense rainfalls also prevent topsoil from being able to absorb water all at once, and we don’t have enough reservoirs to store and save large downfalls for later. Plus, we can’t utilize the subsequent runoff in the spring, when the snowpack melts, so when the drought kicks in later, we don’t have the water we need. Gardeners in Contra Costa County may also be familiar with our local, clay-like soil, which may be high in minerals but doesn’t readily or efficiently absorb excessive water from dramatic bursts of rain.
What can we do on the home front?
We can use principles of permaculture at home to manage and conserve rainfall. Permaculture is a sustainable, organic agriculture system that maximizes what nature does naturally in order to meet human goals while using less energy. The following permaculture techniques manage rainfalls effectively with this mantra: “Slow it, spread it, sink it.”
The Power of Permeable Paving
Permeable paving systems enable storm water to flow through surfaces that are porous or flow in between surfaces that are nonporous. This mimics the way soil naturally reacts to rainwater compared with conventional and impervious surfaces such as concrete, asphalt, or compacted gravel, which give rainwater nowhere to go; it either puddles and sits on top or runs off and floods. Permeable pavements aid in storm water management, reduce runoff, decrease flooding risks, and prevent landscape erosion. Our drought stricken neighbors down south have been given an interesting incentive. Voters in Los Angeles approved Measure W, a tax of 2.5 cents per square foot of impermeable surface on their parcels of land. Landowners can either pay the parcel tax or replace their impermeable land with permeable surfaces.
A Swale Idea
Swales are ditches, sunken channels, and marshy areas in commercial and residential landscapes that are usually accompanied by man-made mounds, ridges, or barriers called berms, which are made of compacted materials such as soil, gravel, or stones. These swale systems of slopes and ditches enable rain to pour downhill and into crevices, thereby slowing and redirecting it so it can spread and sink into garden beds gradually instead of simply running off flat surfaces before it has a chance to absorb. For example, a swale around a tree is a circular ditch around the trunk that manages rainwater like a coffee filter so it can soak down into the root system over time. If your yard doesn’t have natural slopes, you can create them along contour lines yourself. Visit this link for pictures of swales and directions on how to build them.
It is no secret to gardeners that mulching is extremely useful for water retention. In addition to conserving soil moisture during droughts and dry seasons, mulch controls soil erosion, suppresses weeds, regulates soil temperature, feeds soil organisms, and enhances the visual appeal of your yard. There are many different types of mulch, including wood chips, recycled glass, leaves, burlap, landscape cloth, and compost. You can use mulch when creating swales. Sheet mulching is a technique that people often use to reduce or eliminate thirsty, unsustainable lawns and replace them with drought tolerant garden beds. Here's an article on the what, why, and how of sheet mulching.
Optimizing Through Ollas!
Ollas (pronounced oh-yahs) are unglazed terracotta clay pots that use an ancient method of drip irrigation for container gardening and ground applications. Burying these porous pots down in the soil next to plants allows water to slowly release directly onto underground roots. This prevents surface evaporation and the need to water plants as frequently. Check out this article for making your own ollas, either in greenhouses or outdoors.