Rewetting

Rewetting refers to the restoration of hydrological conditions by returning water to a landscape that has been drained or dried. It is a key objective of wetland restoration and peatland rehabilitation, aimed at re-establishing a natural water table and surface water dynamics to support aquatic and semi-aquatic ecosystems. Rewetting can involve blocking drainage ditches, constructing levees, or creating natural or engineered water inputs to raise groundwater levels and surface inundation on the land.

Rewetting is often undertaken after drainage for agriculture, forestry, or development to recover ecosystem services such as biodiversity habitat, flood attenuation, groundwater recharge, and carbon storage in peat soils. The process can alter soil structure and microbial activity, with immediate releases of previously trapped greenhouse gases followed by longer-term stabilization; methane emissions often increase after waterlogging while oxidation of peat decreases, potentially providing a net climate benefit if peat is preserved.

Practitioners monitor hydrological indicators such as water-table depth, soil moisture, and surface inundation, along with ecological indicators like plant communities and wildlife presence. Potential challenges include salinization in coastal or estuarine areas, invasion by non-native species, and conflicts with land use such as agriculture or development. Rewetting projects are typically site-specific and require long-term management to maintain hydrological regimes and adapt to climate variability.

Examples include peatland restoration projects in Northern Europe and North America where drained bogs and fens are being re-flooded, as well as wetland creation schemes that mimic natural hydrology. Rewetting is distinct from simple irrigation because the goal is to reestablish a self-sustaining hydrological regime and associated ecological processes rather than introduce water for immediate crops.