By Joshua Thayer
A drought can last a long time. In some areas a week, a month or more can pass without a single drop of rain. In California, up to six months or more can pass without a rain storm. When the storm finally does arrive, it can bring a torrent of water in very little time. It is these stormy moments that can make or break our landscapes. By designing our land to have rain catchment by-way-of a series of small earthworks, we can harness the rain and let that valuable moisture stay a bit longer; long enough to be utilized by our cultivated plants. If you are wanting to drought proof your home to create edible abundance with earthworks, read on.
Rain sheets down driveways, runs down on-ramps and on downslope, eventually to the sea. As it gains momentum, it picks up particles of topsoil and erodes fertile areas along the way. Always finding the most efficient route downhill, water knows how to run away from our properties; that is if we don’t direct it. By creating on-contour earthworks, called “swales” we can create temporary repositories which can fill in large storms and slowly percolate into our hill slopes at a rate that fruit trees can drink.
Slow it, Spread it, Sink It
Once the rain has sheeted into a swale, its velocity is slowed and spreads to fill the trench which is on contour and roughly two feet deep. On-contour means that the rain will not run away the way a ditch is designed to do. As the swale fills to capacity, the water can overflow into a connector pipe that runs downhill to the next swale system. In this way, the water is intentionally worked through the landscape in broad arcing levels. At each level runoff is slowed down enough to begin to percolate the soil, thus rehydrating dry land. At twenty degrees slope or less, these swale systems will work effectively to check the sheeting storm water runoff without overloading the slope as small check dams can sometimes do.
Swales and Net and Pan Systems
On steep hills of more than twenty degrees slope, another earthworks approach will be better suited. Called “Net-and-Pan” This earthworks system funnels rain and directs it to each fruit tree basin. Upslope from each hillside fruit tree, we create a diagonal one foot by one foot french drain. Two of these French Drains direct rain water into the fruit tree basin. This now widens catchment area to perhaps ten feet that now directs to the trees. This creates more water harvest to upslope crops, while allowing less to streak downslope and cause erosion. By staggering these Net-and-Pan systems downslope, all parts of the hill can become catchments and directed into these basins. (See illustration).
Swales and Net-and-Pan are two Earthworks systems that are simple, human scale strategies to drought-proof our lands. By catching the water where it will be consumed by crops, we can reduce the cost of transporting water long distances and utilize what does fall in our areas. These systems will increase our capacity to utilize and irrigate up slope areas and make our homes more in-the-flow with mother nature by checking the flow and guiding water intentionally through the land. Start now to drought proof your home to create edible abundance.