Water is a precious resource. Some estimates put the number of people on Earth who already suffer from a shortage of water at 1 billion, and with climate change this number looks set to rise. On a global scale, we need to be doing all we can to avoid wasting it, and using what we have more efficiently and preserve it as much as we can. On the local scale, within our backyards, we also need to maximize the effectiveness of the water that comes onto our property. The rain that falls on our property is one of the essential elements of a successful garden, and the key to making the most of it, is to slow its exit. By slowing the flow of water, you allow it more time to seep into the soil, making it more available for plant roots to access it, and preventing drying of the soil, which can lead to erosion by wind. There are several things you can do to slow down the flow of water on your property.
You want to minimize the hard surfaces in your garden. Patio areas, paved paths and driveways are all liable to make water flow over them and either off the property or to pool in a single area, potentially saturating a single point in your garden. Breaking up the paving, either by using irregular pieces of material and leaving spaces in between, or by replacing with a more permeable material, such as gravel or mulch, not only minimizes runoff (allowing the water to sink into the soil) but also creates more edge in your permaculture garden.
Swales can be an important component in water preservation however big or small your permaculture property. These trenches can be used on even quite shallow slopes to catch and hold water. Remember to use the soil removed when digging a swale to build up the rim on the down-slope side (this is where you can plant, enabling the roots of trees of shrubs to access the water as it runs downhill under the surface of the soil). And, of course, mulch over the bare earth you have uncovered (mulch is something else that helps promote the absorption of water into the soil). For longer slopes you could consider creating a network of swales (sometimes called the ‘fish scale swale’ design) to divert water between trenches and so across a large swathe of the land.
The principle of the swale – creating a depression in the ground to vary the elevation and so contain water – can be used on a smaller scale as well. Consider digging a trench around individual trees, leaving the tree on its own earth island, so that water collets in the depression.
You can not only use plants that are suitable to the conditions of your plot, such as ‘water hungry’ plantings where water tends to collect, but simply having a good coverage of plants on the ground, whatever they may be, will help minimize runoff. The roots of plants also help bind the soil together so that if you do get unexpected flooding, they help prevent the soil eroding. This is especially important on sloped areas on your property. Plus, of course, the more plants you have in your garden, the more biodiversity and potential for harvest.
Increase Organic Matter
If you do have bare soil (and any permaculture garden is likely to have at least a little somewhere), you can help it absorb moisture by increasing the amount of organic matter within it. The earth is the largest, most efficient and easiest way to store water, so you want to increase its effectiveness at doing so as much as possible. Healthy topsoil promotes more robust root growth in the plants situated within it, which in turn will allow more water to percolate through than flat, bare earth, which can quickly become hardened and so increase runoff. (This root growth also benefits the soil by providing more aeration and space for earthworms and microorganisms.) Allowing more percolation of the water through the soil is also beneficial on a larger scale as it helps to replenish the water table and underground aquifers, creating a better distribution of water across the land. So composting and mulching are key parts of a permaculture garden for water retention as well as the other benefits they provide.
Plant Shade Trees
Planting trees is not only a great way of shading a property that gets a lot of direct sunlight, they can also help in wet conditions. Like their smaller plant cousins, trees contribute to the absorption of water through their roots, but their leafy canopies can also protect smaller plants from heavy rain, breaking up and dispersing the water across their width so it doesn’t all accumulate in one area.
Divert Runoff into Water Features
If you have problems with a lot of surface water, you could try using trenches and berms to divert the moisture to places you do want it, such as ponds and marshy areas. This not only takes the water where you want it to be, but also provides such features with a good supply of fresh water.
You can also slow water to a standstill by catching it and storing it for use. Installing a rainwater tank to catch runoff from the roof o your property (and other buildings you may have on the plot), gives you access to a regular supply of water that is not dependent upon the mains system. This could be used in the home, to flush toilets for instance, or in the garden to irrigate plants or feed ponds.
As a society, and as permaculture practitioners, we need to give water the importance it deserves. By using one, some or all of the techniques above gardeners can help improve the productivity and health of their own property while also contributing to the larger effort to preserve this essential resource and use it most effectively to minimize waste.