In her book Hydrate the Earth, Ananda Fitzsimmons talks about the role of water in climate change, and why and how we can regenerate water cycles in many different ways. There’s something for everyone!
We are publishing here a large extract from the “Green Infrastructure” chapter, which gives many examples of the positive role that man can play in restoring ecosystems, such as that of Neal Spackman at Al Baydha on the Red Sea.
“Our primary task is to maintain the small water cycle in order to rehydrate the earth. There is a finite amount of water on the planet and the issue is in how it is distributed. Modern management practices have focused on draining, which feeds the large water cycle, moving out to sea. Sea levels are rising, ostensibly because of glacier melt, but perhaps also because we are draining water from the land and letting it run rapidly towards rivers and streams. As temperatures warm, evaporation increases, rainfalls are more erratic and extreme. Heavy rains cause flooding and erosion as they run through drainage infrastructure, carrying topsoil, organic matter and contaminants.
Every day, massive quantities of water are pulled out of lakes, rivers and wells to be used for drinking water, household use, irrigation and industry. Our current thinking on sustainability is focused on water conservation. We have toilets that use less water, washing machines that use less water, irrigation systems that use less water, and we have attempted to recycle used industrial process water. More efficient water use is important, but it does not regenerate the water cycle: it merely slows the decline.
The above approach is similar to what we are doing with the carbon cycle. The full solution is not only to reduce emissions, but also to re-establish the carbon cycle. At present we are pulling carbon out of the earth and sending it into the atmosphere faster than the carbon can return to the earth. If we want to balance the cycle it means not only reducing emissions but also increasing drawdown with natural vegetation. The amount taken out of the bank has to be equal to or less than the amount deposited.
Similarly with the water cycle, we cannot continue to use massive amounts from the groundwater reserves if they are not being replenished at a rate equal to or greater than the withdrawals. We therefore need urgently to go beyond water conservation and think about how we can refill the aquifers and store water in the earth. It can be done, but everything needs to be re-designed according to regenerative principles.
Slow it, spread it, sink it
The regenerative principle at the core of restoring the small water cycle is: “Slow it, spread it, sink it.” The way that water gets from the sea back to the land is through rain. We have talked about rain cycles and the role of vegetation and trees to bring rain inland. Once rain falls, the way to recharge the small water cycle is to make sure it sinks into the ground instead of running off. The faster it runs off, the faster it leaves the land on which it fell. The principle of slow it, spread it, sink it, means the longer each drop of rain stays in the ground where it fell instead of moving on and going somewhere else, the better.
Think about a bathtub. Imagine it fills up to the brim. Then imagine how quickly it drains when you pull the plug and let the water run down the drain. Now imagine that instead of pulling the plug, you let the water run over the brim. The surface area to where the water spills is much wider than the drainpipe; the water will spill more slowly over a larger area. Then imagine if instead of landing on a hard bathroom floor, it was landing on a porous surface like fertile soil: most of the water would get absorbed instead of running away. This is exactly what we want to achieve.
As water flows down a slope, we want to put barriers in its pathway which will stop it from flowing immediately to the lowest point. These barriers allow the water to accumulate over a larger area. Think about the bathtub. As the water collects in a spot, it spreads over a wider area. It continues until there is too much to be contained there and then it starts to brim over. But if there is no one low point for the water to flow out of, it seeps out like water going out over the brim of the tub, over a wide area. In addition, the water sitting still in one spot or moving very slowly, is gradually seeping into the ground and evaporating into the air. So we are hydrating both the air and the land at the same time.
This is the principle of slow it, spread it, sink it. We slow down the flow by blocking the waters pathway. We give the water a wider surface area to spread into. And we allow the sitting water to infiltrate into the ground very gradually. It seems very simple but the effects of these techniques can make a powerful and significant change in the landscape.
In order to put the principle of slow it, spread it, sink it to work, we first have to understand how water flows over the landscape. It always flows to the lowest point. The greater the slope, the faster it flows. Where the ground is level the water sits still. On a gradual slope, it flows more slowly.
Percival Alfred Yeomans was an Australian inventor who developed what is known as the keyline design system. He wrote a book called Water for Every Farm, which was published in 1954 and influenced many thinkers around the world including many in the permaculture and soil conservation movements.
The essence of keyline design is to understand the shape of a piece of land in terms of how water will land and flow over the property, and to manage the flow in order to maximize its absorption into the land. Water will fall to either side of a ridge or high point.
There will be undulations in the shape of the land, water will accumulate in the valleys and flow off the ridges. If you want to slow the flow of the water, you need to determine a keypoint. A keypoint is the first spot near the top of the main ridge where water will naturally go to and accumulate. A keyline is the contour line which is exactly at the same elevation as the keypoint.
Water flows down from the highest ridge. The keypoints are the highest indentations where water would collect. Keylines are the contour lines where the land is at the same elevation. If we trap water at the keypoints and dig ditches along contour lines, water will travel more slowly down the slope and sink into the landscape.
There are two possible ways you could proceed, depending on the overall design of your land. You could dig a deeper hole at the keypoint and dam it, so that you have a pond uphill on your land. Water from an uphill dam would flow by gravity to lower points where it might be needed.
But if it’s not convenient to put a pond at that spot, you could dig a swale (a shallow ditch) or a trench along the keyline. The keyline is the contour line which is at the same level as your keypoint. If you dig a swale along that contour line with a slight berm (a raised bank) or mound on the downhill side of it, water will accumulate in that swale when it rains hard. If the swale is shallow, the water may not stay for very long. It will be absorbed into the land fairly quickly and the swale and berm can be shallow enough that you could mow right over it. It doesn’t have to significantly alter the use of that part of the land.
You could also make the swale with a gradual slope to deviate the water that it collects to another keypoint. There you have the same options. You could make a collector pond at the lower spot, or you could just make a shallow hollow spot and another swale to deviate the water in a zigzag pattern down the slope of your land.
Any one of those key points could be the site of a small or a large pond, depending on your needs. If you have large rainfalls at some points in the year, followed by dry periods at other times, there is an advantage to collecting a reserve of water when it falls in a pond or even a series of ponds. The swales which deviate the water across the landscape can be deeper or shallower. If they are deeper with a very low grade slope, or no slope, they may contain water for a longer time. Sitting water permeates slowly into the land, hydrating it and feeding the groundwater reserves. Even if you don’t make any ponds to collect rainwater for a longer storage time and your swales are just shallow undulations, you will still slow the flow of rainwater and make more of it sink on your property. The more carbon you have in your soil, the more of this rainwater will be stored just in the ground, even without ponds.
The core principle behind keyline design is really to be aware of the contour lines which define the structure of a piece of land and determine how water lands on and flows through the property. By making water soak in on the keylines, we can really decrease the speed at which water traverses. P. A. Yeomans also designed a special plow which rips a deep furrow along a keyline. Without needing to dig with an excavator, by keyline plowing, a farmer can make more water sink deeper into the field, because the water flow downhill will be slowed simply by having deeper penetration along the contour lines.
The addition of dams and ponds may not always be needed. But if you live in a place where water is scarce and often comes heavily at only a particular season, collecting reserves from the rain, rather than drawing it from groundwater can make all the difference to the sustainability of water use in that place.”