## 3 Literature Review
#### 3.1.2. Peatland Management and Restoration Strategies
Also, paludiculture methods have become more widely used in recent years [119]. Other restoration methods include, for example, restoring natural marsh vegetation or planting vegetation [40]. The existing emission mitigation strategies are shown in Figure 2.  
(1) Rewetting may cause nutrient leakage in peatlands  
One of the most often used methods to raise groundwater levels is peatland rewetting. Peatland rewetting is performed in degraded and drained peatlands to restore hydrological conditions [29]. According to estimations, peatland rewetting is effective if the water table is 20-30 cm [29] below the peat surface throughout the year [29]. Technological solutions such as drainage blocking allow for water retention in previously drained peatlands. It gradually raises the groundwater level, hence restoring a hydrological regime similar to that before the artificial drainage of the peatlands [120]. _Methods of peatland rewetting_  
The rewetting of peatlands using drainage blocking, small dam construction, and other methods is further described. Drain-blocking is a method used in rewetting peatlands, where the drainage areas of drained peatlands are blocked using technological structures, thus raising the water level. Ultimately, the drainage paths are blocked to prevent debris and trees from entering. Peat may settle within the dams and cause leakage. Therefore, the dams are recommended to be higher than the surrounding bog surface [12, 121]. Another rewetting method to prevent CO\({}_{2}\) emissions from degraded peatlands is drainage blocking with small dam constructions. It is estimated that an annual CO\({}_{2}\) emission reduction of 1.4-1.6 million tonnes yearly can be achieved by rewetting a peatland forest area of 590 km\({}^{2}\) using small dams [122]. _Pros and cons of peatland rewetting_  
Studies predict that by delaying or refusing to rewet, GHG emissions from degraded peatlands could reach 12 to 41% by the year 2100 [32, 42, 117]. Previous studies show that CO\({}_{2}\) emissions decrease after the rewetting of peatlands [123]. Peatland rewetting reduces emissions from peat mineralisation processes and reduces land subsidence [78, 124, 125]. The benefits of peat rewetting are not only related to the reduction of GHG emissions, but studies indicate that rewetting can also preserve and even increase biodiversity and restore ecosystem services because after rewetting, peatlands can be returned close to the state they were in before the drainage was performed and restore species' habitats. Also, studies show that peat rewetting can improve the nutrient balance regulation in peat [124]. Peat rewetting can gradually reduce the overall global warming potential, reducing the emissions of GHG from the soil in the long term (100 years) [124]. _Groundwater level_  
Although rewetting methods have several benefits, rewetting as a strategy for peatland restoration also has drawbacks [52]. During and after peat rewetting by drain-blocking or small dams, CO\({}_{2}\) emissions decrease, but the groundwater level rises, which can also change surface water levels, resulting in increased CH\({}_{4}\) emissions. Variability in the groundwater level and incomplete flooding may also affect the anticipated reduction of CO\({}_{2}\) emissions. For peatland rewetting to be successfully implemented and effective, the hydrological regime must be controlled, and no water level fluctuations are permitted; the water level must be sufficiently high and stable. Blocking runoff is considered the most economically  
Figure 2: The existing mitigation strategies for the reduction of emissions from peatlands. feasible solution for small areas of agricultural land. However, in this case, it is more difficult to control the groundwater level [14; 117]. Due to peat rewetting, the groundwater level must not be too low or too high. A low groundwater level will affect vegetation in the peatland, causing carbon emissions. A groundwater level that is too high will cause surface water to accumulate and form lakes.