The most efficient method for identifying drain-blocking locations is carrying out surface topography analysis using LIDAR. If LIDAR is not available, then traditional field survey methods are employed. When the traditional field survey methods cannot be employed then the manual method developed by the Irish peatland conservation council (IPCC) can be utilized. This method uses three sticks (each stick of 1m length) and spirit level for determining ground slope i.e. fall in the gradient (see figure above) or visit www.ipcc.ie for more information. This method involves inserting the first stick vertically on the edge of a drain/ditch and a second stick vertically on the other side of the bank. The third stick is held horizontally and levelled using a spirit level at the one-meter level at the downstream meter stick. The height difference between the two vertical sticks divided by 1m distance is the required slope.

Another method of drain blocking is using plastic sheets. The plastic sheets inserted firmly into a drain, so that it can withhold the pressure of water accumulated on its one side. However according to Mackin et al. (2017) document, the plastic sheet should be buried 50 cm or more into the peatland. Similar to peat dams, three plastic sheets inserted into the ground for every 10 cm drop in elevation. However, one can utilize more than three plastic sheets, but it can be expensive. Where the ditch/drain depth is larger and wider, water flow may be significantly higher, in this case combination of plastic sheets and peat dams required at same intervals as described above. According to NPWS, the drain blocking by plastic sheets and peat dams has proven to be effective, having minimal maintenance (Mackin et al., 2017). According to the NPWS experience, the drain blocking approach had produced positive results with evidence of sphagnum communities found on drained peatlands within 10 years of drain blocking (Fernandez et al., 2014).

Coillte, a commercial company managing Ireland’s forests are doing extensive work on rewetting formerly drained raised and blanket peatlands. The rewetting method employed by Coillte consists of clear-cutting commercial forestry, followed by brash removal and lastly drain-blocking using peat dams and plastic sheets. Coillte along with local organisations have restored a number of raised peatlands in Ireland, for example the Crosswood peatland (SAC), Lough Ree (SAC), Killyconny peatland (Cloghbally) (SAC), Girley peatland (NHA), Scohaboy peatland NHA and Wooddown.

The detailed procedure of clear-cutting is mentioned in Mackin et al. (2017). Essentially, trees are cut using a specialized machine which removes all branches, by cutting them into the specified lengths. However, the weight of the machine might compact the peatland surface and hinder growth of sphagnum mosses during the post-rewetting phase. To minimize this, cut branches and timber are placed underneath the machine to create a buffer, reducing the pressure on the peatland surface. The buffer i.e. the brash mat is later removed. There are other methods of tree felling such as halo thinning, ring barking, specialist track machines, chain saws or using cables and winches (Mackin et al., 2017). The selection of appropriate method depends on site characteristics such as the wetness of the surface or the number of trees.