A Novel Method for Determining Vertical Hydraulic Properties of Peat Using Naturally Occurring Pressure Fluctuations

Peatlands are an invaluable part of our landscapes. To evaluate their interactions with underlying groundwater systems, the hydraulic properties of peat must be understood. Traditional methods for assessing vertical hydraulic conductivity in deep, compacted peat layers face challenges due to low permeability and sample collection difficulties. We introduce a field-based approach to determine vertical hydraulic diffusivity using naturally occurring hydraulic pressure fluctuations. Measurements were conducted at two peatlands in northeastern Estonia, using pressure transducers installed at various depths to capture fluctuations influenced by atmospheric pressure changes.

The vertical hydraulic diffusivity was calculated analytically from the recorded pressure data and combined with laboratory-measured specific storage values to estimate vertical hydraulic conductivity. Results indicate that deeper fen peat layers exhibit hydraulic conductivity values comparable to previous in-situ measurements, demonstrating the method’s viability for assessing the hydraulic properties of low-permeability peat. The method was also applied to calculate the hydraulic properties of the upper, less decomposed portions of the peatland. However, its applicability in more conductive peat layers requires further testing.

This observational method offers a practical solution for measuring the hydraulic properties of deeper peat layers, providing a way for a holistic understanding of their hydrological functioning. It addresses scale-dependent effects associated with conventional field methods, providing critical data for broader-scale hydraulic modeling and peatland management decisions. Furthermore, this method enhances understanding of peatland vulnerability to anthropogenic and climatic influences, supporting the development of strategies to mitigate hydrological disturbances in these vital ecosystems.