Peatland–Aquifer Connectivity: Insights from a Raised Bog Resilience to Mining-Induced Drainage

Peatlands are groundwater-dependent ecosystems, even when they overlie less conductive glacial sediments. Their resilience relies on stable groundwater regimes, yet deep drainage from underground mining can disrupt these systems and amplify the changes in the climate. Selisoo bog (NE Estonia), a Natura 2000 raised bog, has been monitored since 2010 to track hydrological responses to adjacent underground oil-shale mining. The monitoring network spans from the bog margins to its centre and includes measurements of piezometric heads in peat, the underlying glacial sediments, and bedrock beneath the peatland. Analyses have revealed statistically significant declines in piezometric heads in peat at the bog margins and in surrounding drained peatland forests, driven by increased vertical hydraulic gradients and seasonal fluctuations, while the central part of the bog remained largely unaffected.

In 2021, restoration measures were introduced by damming forestry ditches along the eastern side of the bog to reduce lateral outflow. The second phase of the restoration was carried out in 2024. Here, we present data from the start of monitoring through the end of 2025, including the restoration works carried out and an “unusually” humid summer in 2025.

Our findings underline the need for an integrated monitoring of peatland–aquifer connectivity when issuing mining permits and designing restoration strategies for peatlands adjacent to mining areas. They also highlight how growing climatic variability interacts with human-induced drainage, affecting the hydrological regime of a raised bog in such hydrogeological settings. The continued long-term monitoring also enables us to assess the effectiveness of restoration and evaluate whether these measures can mitigate the effects of declining groundwater levels and rising vertical gradients.