To collect groundwater
To collect groundwater can be done in many different ways depending on the soil conditions at the site. It can be anything from collecting it in ponds to building ditches that meander over the site to decrease the water’s speed. Why not opt for a pond with fish, for example? The more ways you can use to slow the water from leaving your garden, the better the site can withstand drought. When you have a rainy period, it is also good to control the water flow.
Different sites have different conditions. On a steep site, it is about preventing gravity from transporting the water too fast. The preventing can be done by – instead of letting it run straight down – steering the flow of water along the slope and possibly making a smaller pond that halts the water on its way down. If there is a fair bit of water and a sufficient slope, the water’s energy can also be utilized.
On a flat site, however, it is a matter of finding ways to gain the water’s momentum. To gain momentum might even mean pumping the water to achieve a natural flow. For this, the water is pumped up into a raised tank of some type, from where it can be released down to the crops. This way may seem unnecessary; you should just be able to pump the water directly out to the crops, right? No, because the plants will be happier with room-temperature water, so it is better to have it sit in a tank first. Also, water that moves across and through the soil will pick up lots of nutrients that are not present when coming straight from a hose.
To collect groundwater the swale is perfect
A swale ditch is a combined cultivation and irrigation system that efficiently takes care of the groundwater and benefits the crops along its edges.
To collect groundwater with swales are most commonly used on larger sites. Still, the technology can also be used on a small scale with a single swale where the groundwater is captured to benefit bushes and trees.
A swale is easiest described as a ditch running along the site’s contour lines. Parallel to and on the lower side of the ditch is the raised cultivation beds. An example is found at the end of this chapter.
If the site has areas where it is impossible to dig ditches – like mountainous areas – a solution may be to transport the water past these parts via pipes.
Before starting work on a swale ditch, you need to review your specific conditions and decide where the waterline should run.
It may also be appropriate to make one or several ponds along the waterline. These might be ponds for irrigation, to water your animals, or just for pleasure’s sake.
The distance between each swale ditch depends on how much rain you get. A rule of thumb is that the distance should be 5–6 meters for rainfall of about 1200 millimetres per year and about 15 meters for rainfall of 380 millimetres per year. Similarly, the swale ditches themselves need to be fashioned according to how much water they will hold.
A smaller swale
To collect groundwater begins with planning where the ditch should be placed and if there is something that needs to be addressed before you start creating the swale ditch.
During the excavation, it is crucial to ensure that the ditch’s bottom has a slope so that the water flows in the right direction. At the same time, overflow drainages must be created, both at regular intervals along the entire ditch and the end of each ditch. These overflows are needed to protect the system from being destroyed by heavy rain or large amounts of water from melting snow.
You should avoid walking on the bottom of the ditch while working on it so that the soil there will retain its permeability.
⇾ Start by marking out the width of the ditch, which should be at least 30 centimetres.
⇾ Cover the surface of your future cultivation bed with a thick layer of cardboard. Feel free to let the card board stretch a little outside the dimensions of the finished bed. The bed should be twice as wide as the ditch.
⇾ Dig away the turf from where you marked out the swale ditch, and place this upside down on the card board. The digging can be done either by hand or with a small excavator.
⇾ Dig the ditch down to 30–40 centimetres deep and place the soil you remove on top of the turf. The swale ditch is now complete.
⇾ You can supplement your cultivation bed with topsoil or finely divided compost soil, if necessary.
⇾ Finish by raking through the bed and shaping it into a soft hill.
To collect groundwater with the best result it is good to let the construction of the ditches take some time so that you get to see that all parts of the system work as intended before you start planting.
With time, the underground water plume grows further down the ground. When it meets bedrock, the water can return to the surface in the shape of a pond or ditch.
The best plant combination in the cultivation beds is different types of trees, shrubs, and ground cover plants. With proper planning, you can potentially harvest at every level if you want to. When the beds are new, it may sometimes be advisable to temporarily place some smaller and more fast-growing trees or shrubs that will quickly help to bind the soil.