Doctoral defence: Raul Paat “Groundwater and surface water interactions in peatlands: Hydrogeological insights from Estonian mires“

On 3 October at 12.15 Raul Paat will defend his doctoral thesis “Groundwater and surface water interactions in peatlands: Hydrogeological insights from Estonian mires“ for obtaining the degree of Doctor of Philosophy (in Geology).

Supervisors:
Associate Professor Argo Jõeleht, University of Tartu
Research Fellow Marko Kohv, University of Tartu

Opponent:
Professor Jonathan S. Price, University of Waterloo (Canada)

Summary
Peatlands are important ecosystems in our landscapes. They serve as crucial habitats for plant and animal species, act as large soil carbon stores, and regulate the hydrology of landscapes. Their area has decreased over the past century both globally and in Estonia, primarily due to drainage that lowers water levels in peatlands. The drainage impacts from agriculture, forestry, and peat extraction are well-known and studied. However, less is known about how the drainage of underlying affects the water levels in peat. This dissertation investigates the impacts of underground drainage on a peatland using the example of Selisoo, located in northeastern Estonia, near an active oil shale underground mine. The water levels monitoring confirms that lowering of groundwater levels caused by mining, also affects the water regime of the bog, especially at bog margins where the peat layer is thinner. Consequently, this dissertation investigates the physical properties and hydraulic conductivity of peat in other bogs in northeastern Estonia. Based on the observed relationships, two statistical models are proposed to predict hydraulic conductivity using the peat properties discussed in the study. Additionally, the dissertation proposes a method for investigating the vertical hydraulic conductivity of peat. This methodology has not been previously used for peat, but the presented results indicate that it could be used to assess vertical conductivity. The obtained data and the proposed method and models are important for gaining a broader and more detailed understanding of the hydrology of bogs in the region. This is necessary for developing accurate hydrological and hydrogeological models to assess the impacts of drainage beneath the peat on these ecosystems.