posted 15 years ago
berms swales puddles and ponds.
All I have gleaned abut swales
3 After these dents in the deserts and the blocking of the path of water with a bank, so it is held up and can’t run away, another permaculture practice seems to be swales, long wide or less wide channels that cross a piece of land that hold water so that it can permeate into the land slowly wetting it thoroughly so watering all the land that lies below them.
Swales are something mentioned in a paper by the group, “Harvest H2O.com” in a paper called, “Dikes berms and swales,” in google, as a practice that got lost when we started using concrete and getting the water to run off the concrete straight into drains. Channels or ditches that have an earth floor that carry runoff water or hold it, so, made to take the water were you want it or retain it. Swales unlike modern water channels don’t have concreted bottoms just lose earth ones. They are ditches.
They should be sown, seeded, with some plant that will stop them being eroded grass and such. They will not be wet all the year round just after a rain event. They are not necessarily an irrigation method they can also be a simple ditch used d to carry water to the place you deem best for it.
Permaculturists use swales as a irrigation method. They also have different techniques for collecting water for example they collect water from roofs and channel it to their swales. You can build a concreted area on the ground to catch water that works like a false roof.
The swales used for irrigation typically run from side to side of slopes cutting across water flowing down the slope, interrupting the downward flow. They are built on contour which is to say at the same level all the way round so as to hold water rather than carrying it. If they have been built to irrigate the land the water is held in them rather than running down them, stays level, so that as it is held there for a long time it can seep deep into the land to feed the plants on the lower side of the swales. The video that shows this is Youtubes’ “video of geoff lawtons that is called “permaculture water harvesting”.
The swale running across the slope can also reduce erosion, if the water flowing down possible carrying earth is held up, it flow stayed, its acceleration that gives it the impulse which helps it carry earth slowed, it will erode less soil. They also build their swales or ditches round hills. A swale humidifies and waters all the parts of your garden that are below it. At least for some yards.
The overflow from the far end of your swale, if there is enough water to overflow it, may be carried down to fill a swale at a lower level that waters the land below it and so on.
Swales bring about a much greater penetration of rain water than occurs with rarain that ltha tsimply falls on the surface of the earth. The soil will benefit from the first rains if there are swales to help the water penetrate the land, you wont have to wait till there have been enough rains to drench the soil through though the water they bring does not all lie on the surface but runs off the land or gets evaporated. Look at all the permaculture videos on you tube and read about permaculture water harvesting. After several heavy rains this autumn the soil on the slopes of my garden was still dry beneath the surface. The normal way rains wet the soil after a dry season is that the rain manages to wet a few inches of soil with the first rain event and a few more with the next and takes a good while to soak through.
More on swales
Another reason for using swales ditches as drains and channels instead of letting the water on your land flow in any old way is to hold the water on your own land not to lose it to a neighbors land or to the river.
Water that runs into the land will drip out slowly keeping rivers full for longer, while water that runs fast off peoples land, fills the river on the day of the rainfall and leave rivers empty the following days.
Swales on slopes.
Because the channel of the swale that you have cut across a slope, cuts through the first inches of land were the water normally runs down a slope, so that when the water in the slope gets to the channel that is crosses its path, it will find itself at the edge of a small drop to the bottom of the channel, the water flowing down the slope should drop into the channel, I imagine and help fill the channel. The permaculturists swale is sometimes also filled from water that has fallen off a roof or some such, maybe from a rainwater trap and directed into the swale.
Often in permaculture these channels are also fed with the runoff water from spaces that provide such, such as roofs and from yards. Bill Mollison creates sloped concrete floors in African villages that will work as roofs do catching the rain water which drains of the floor into an underground cistern that provides the village with water. You see this in his dryland strategies video. I have tried to buy his book and the shop got me a book with a preface by him, I will go on trying, I am going to try another shop.
Sometimes the overflow from the swale may be from all the length of the lip on the edge facing towards the bottom of the slope that will be a lot lower than the lip on the uphillside of the channel if you dig into a bank you always have to dig down a lot to where you are level with the down side edge of the hole you dig. You can build up a soft mound of absorbent organic material to receive the water that overflows from the lower lip of the channel on the down side of your channel a berm.The mound or berm of organic material built along the down side of the channel a will become saturated with water and will like the ditch also feed water slowly into the ground.
You also might provide the channel with a overflow at the end of the channel and carry the water that overflows down into another swale at a lower level in a channel or in a pipe. Vso as to assure that your slope is ell wetted at all levels.
Of course these are strategies for dry countries in wet areas most channels are built to drain the land not to irrigate it.
Swales are not meant to have compacted earth bottoms, much less plastic or concrete ones though they may have organic material in the bottom of the swale mulch to keep it damp when there is no rain fall or stones and rocks or broken bits of concrete. Ones that are made to carry water from one place to another may have rocks and walls in them to slow down the flow if they flow faster than you want them to.
Swales on pretty flat land,this is a description of Geoff Lawton “greening the desert” youtube .video of the swales he made to green the desert.
Swales are usually made on slopes but:--
Near the dead sea, the permaculturists Geoff Lawton made swales, on the pretty flat lands, though they are usually made where there is a slope. He was given ten acres of of pretty flat and salty land to green near the Dead Sea in Jordan in Jordan he built one and a half kilometers of swales in it ½ meters deep and two meters wide. He reckoned these swales would catch Jordan’s winter rains. His account is that they catch and feed into the soil when they are full a million liters of rain and they fill several times a winter. The swales, though they were on pretty flat land, in the most difficult place to green, a salty desert, worked! He greened an incredibly dry and salty place. Look up Geoff Lawton “greening the desert” on you tube.
He also used other permaculture techniques such as a lot of mulch, a half meter of it in the swale and on the banks of the swales to stop water loss from evaporation and planting the banks either side of the swales with specially chosen trees and other plants. Maybe he did other things like inoculating fungi the land with fungi. He put micro drip watering on top of the banks either side of the swales, he used a fraction of the water what surrounding farmers use in that area, I suppose this fraction of water he used refers to water from the mains, that he did not harvest. agri rose macaskie.