Peat soils above groundwater level are exposed to the air and decompose. This causes a subsidence of 8-12 mm.y-1 and a CO2 emission of 18-27 tons.ha-1.y-1. Subsidence is also causing damage to infrastructure and buildings and is making water management ever more complex and expensive. In time, with rising sea levels in a nation largely under sea level, it is not wise to allow continued subsidence rates of 1 cm.y-1, particularly as climate change is likely to double subsidence rates by the end of this century. Raising ditchwater levels to 20 cm below the surface in summer are needed to halve subsidence and GHG emissions. This makes a viable dairy farming impossible and dairy farmers very strongly oppose this kind of solution. A potential alternative solution is the use of submerged drains to raise groundwater levels in summer which initial research has shown to halve subsidence and the resulting CO2 emissions. Whilst first results are promising, more proof in praxis is needed before this technique can be promoted and introduced on a larger-scale.
The RECARE project will work with an active network group of farmers in the area dealing with submerged drains and an existing stakeholders group on submerged drains to explore the technical and economic feasibility of using submerged drains to combat subsidence.
More information about the RECARE project in Dutch can be found here