I the beginning of this long series if the water in the forest garden I promised that there would be a post about the construction of dams forward end. Much of what I have written about in previous posts was about to give a basic understanding of hydrological, so that you can find the best location for your pond. In this post, I will focus on how to constructs natural ponds, ie those not requiring dust cloth or regular filling with water.
My experience of the construction of dams based on that we have so far dug five dams in Putt Myra forest garden. Everyone keeps water all season, despite the fact that we take out a lot of water for irrigation purposes, and we have not used dust cloth to any of them.
Why build dams?
There is much to be gained to construct one or more ponds. For us the main reason from the beginning that we needed access to irrigation water to even begin with the establishment of forest garden. By the spring of 2013, ten months after the first dam was finished we realized that a dam has many more positive qualities than being a water reservoir. Suddenly it started to get a lot more insects and birds to the forest garden than in previous years, there was a beautiful water mirror to look at and it created a very favorable microclimate around the pond's edge. Digging ponds have probably been the single most important measure to promote biodiversity in our forests garden.
Finding the right place
dust No. 1 was the first thing we did dig (see the map below). We found the place by both observe the vegetation, which differed from the surrounding grassland by containing more moisture-loving plants, and by walking around barefoot and feel the difference in soil moisture. Our feet are an underrated tool for site observation! Only later we measured the height differences on the intended place and realized that the damp spot was just at a point of inflection, which I described in a previous posts means that the water table is where the closest land surface. Then it does not matter if you have a stiff clay soil and a permeable sandy soil, the water is there regardless. With that realization, just dig out the earth, and let the gap slowly filled with water. How much water flowing into all depends on what time of year you dig and how local water conditions,. Our ponds filled by anything from a few days (dust 5) to several months (dust 4).
With the latter, the ponds, we have instead begun studying the contour lines on the site, and has since completed our chart analysis with more hands-on on-site observation. You wear the right glasses fairly quickly and with little experience, it becomes easier and easier to identify suitable sites for natural ponds.
What kind and how much?
Our dams are between 20 kvm (dust 2) and 180 kvm (dust 5) large. According SSNC's excellent book "Vacuum Handbook" from 1997 is 100 sqm the smallest size in order to create a working pond ecosystem. However, I think that even the smaller dams fulfill their function well and would not allow me to limit the number.
Important it is to invest in the right form. The largest biological activity occurs in the transition zone between land and deep water. The longer this zone, the more lives will be in the pond. At the same time, it is important that there are zones in the pond that can not be ground freezing. The illustration below shows how a dam in cross-section could look like. The shallow zone is pulled out and is on the sunlit north side of the pond. There are only a djuphål in our dams are 1,5 m deep at its deepest. An extra ingenious tricks are the large stone left in illustration. It is located on the northern edge of the pond, which means that it gets a lot of sunlight in the. Already in the early spring becomes heated and transfers its heat into the pond. The water starts circulating and ice releases earlier, while oxygen is supplied. If you are lucky enough to find a few large stones at the excavation, it is a good idea to place them in the pond shallow northern part.
What the law says?
I'm no expert on the law on dams, but there is a good Published by Huss Demeanor Society and funded by LRF going through what applies at the pond digging. The scale covered in the report is different from most forest horticulturists will work in, but there are still a lot of useful information to find in the text. There, you can read that the construction of dams are classified as water operations and that all water operations fundamentally requires permission. As usual, there are a lot of exceptions and terms such as "If it is clear that neither public nor private interests are damaged by water activities on the water conditions, No license or notification of 11 gets 12 § MB, the s. k. exception clause. ". In many counties, it can be right in so that there is refund money seeking to build ponds and wetlands. If you are unsure about what applies on your land, it may be a good idea to start by calling the municipal and / or provincial government where you live.
Once you know where your pond should be located and how it will look like there is much that can go wrong in the practical work, so here are some tips based on what we have learned from our construction projects:
- Backhoe first, plant ago. If you have the possibility, start by digging your ponds before you build the rest of the woodland garden. Digging ponds is a rather extensive surgery and it is best to do it first, Before you put your precious plants, which otherwise risk being run over or buried under excavated.
- Dig a test hole. Do not you trust neither your own review or maps, it's a good idea to dig a big pit sample. Dig on any one meter deep and one square meter. Cover it with a sheet, so that it can not rain directly. Observe how the water table moves during the year. Wiper pit completely out sometime there are probably better places to build a dam on.
- Dig in autumn. The best time to dig ponds is late summer or early fall, when the ground water level usually is lowest. As is also the risk of permanent damage to the ground at its lowest. We dug our first pond in the middle of the wet summer 2012 and still suffers from the extensive compaction damage caused when.
- Where the clear with your instructions. I assume that you do not want to dig your pond by hand, although it is quite possible, especially if you have some friends who want to help. If you hire an excavator you need to be too explicit with your instructions. Most digger operators have never dug ponds and are used to a completely different job. We noticed the outline of the ponds with clearly marked sticks and excavator were always got a map of where they should put topsoil and mineral soil. They were also given instructions to minimize the number of movements of the machine, to minimize compaction damage. It is important that you are actually in the excavation, for even the clear instructions can be easily misinterpreted.
- Do not sell land. If you dig a 100 sqm dust can easily become 30 cubic meters or more topsoil. It may happen that the excavator operator think you should sell it. Do not do it, even if you get a good price! It is precisely the topsoil from the pond excavation which enables the construction of raised culture beds.
- Make yourself finarbetet. One thing digger operators seem to think about is to clean up piles of excavation masses by running them back and forth with the excavator, something they call planning. Then, of course, the risk of irreversible compaction damage immense. A better way to deal with the excavated material is to let them out of the bucket at the place where they should be and then straighten them gently with backhoe. Finarbetet you can do with seized and some friends' help.
- Think about safety. Dams are dangerous for small children, just like any other water body (plaskpoolen included). Drowning is the cause of death among children aged 1 to 6 years and each year drown 10 Children in Sweden. The water does not need to be deep for it to be dangerous and it does not take many seconds before a child drowns. Do you expect that young children will be staying in the vicinity of the dam, there are various precautions you can take. The dust guide recommended the creation of an edge of sharp rocks where the pond deeper parts begin, so that the children do not want to go further out. Safer is to fence the entire pond, so that children can not get out on their own. And most importantly, (in addition to teaching the children to swim): do not let the children a single second eyes when playing the pond.
I hope these tips will help you along with your pond project and please write in the comment box below if you have experiences you want to share!