Why can draining peat and muck soils cause the land surface to sink?

When peat and muck soils are drained for land reclamation, the land surface sinks primarily due to the loss of the soil material itself.

These soils are composed of high levels of organic matter that typically remain waterlogged, creating anaerobic conditions that prevent complete decomposition. When drainage systems are installed to remove excess water, the soil becomes aerated. This improved aeration increases the rate of oxidation, causing the organic material to decompose and break down. As this organic matter is lost, the physical volume of the soil decreases, leading to a subsidence of the land surface. In some instances, this process can cause the ground to sink by several feet.12

Beyond this loss of material, the drainage of such areas also contributes to the release of stored carbon into the atmosphere as carbon dioxide, which has significant environmental implications. Because peatlands are vital carbon sinks, their degradation is increasingly viewed as an unsustainable practice that undermines efforts to mitigate climate change.324