The boreal peatlands of the northern Canadian Shield in Ontario, Canada, serve as headwater systems for the Hudson Bay Lowlands (HBL), the third-largest peatland complex globally and a critical carbon reservoir. This landscape—shaped by a heterogeneous mix of exposed bedrock outcrops and low-conductivity glacio-marine sediments—comprises a mosaic of treed peatlands, post-glacial lakes, and river systems, which play a key role in regulating water and carbon fluxes to downstream ecosystems. Despite their importance, the hydrological connectivity of these peatlands and their role in dissolved organic carbon (DOC) transport remain poorly understood, especially in the context of changing hydrological conditions.

This study investigates the hydrological and DOC dynamics along two 400 m flowpaths that originate in peatlands and terminate at Tomorrow Lake (49°55'2"N, 80°41'59"W), a 2.5 km² post-glacial lake draining into the North French River watershed. In June 2024, five monitoring nests were installed along each transect, equipped with porewater sippers (30 and 50 cm below ground surface) and screened pipes at depths of 75, 100, 150, and 200 cm. Continuous water table data were logged, and DOC concentrations were measured during June, August, and September 2024. A meteorological station, installed in August, captured local hydrological inputs and outputs, providing a detailed view of seasonal variability.

Results reveal a complex “fill-and-spill” hydrological connectivity at the flowpath outlets, driven by variations in topography. In the steeper transect, water tables dropped sharply from <30 cm below ground surface (bgs) at the peatland center to >150 cm bgs at the lake interface, entering the underlying low-conductivity mineral soil. This suggests slow, diffuse subsurface flow as the dominant transport mechanism. Average DOC concentrations correspondingly declined from 33 mg/L in the peatland center to 19 mg/L at the lake edge, aligning closely with average lake outflow concentrations (16 mg/L) and indicating potential carbon filtration through the mineral soil. By contrast, in the flatter transect, water tables remained elevated near the lake interface (<30 cm bgs), and a pipe-like surficial flow point was observed at the outlet in June transporting disproportionately large volumes of water—up to five orders of magnitude greater than subsurface flow—while maintaining elevated DOC concentrations (35–40 mg/L). DOC concentrations at the outflow remained high throughout the summer. However, the discharge rate progressively declined as the water table levels receded, almost ceasing entirely by September.

DOC concentrations in Tomorrow Lake are comparable the median annual concentration in downgradient North French River (~19 mg/L) the larger Moose River that this watershed supports (~16 mg/L), suggesting high connectivity within this landscape. These findings underscore the need to evaluate hydrological and biogeochemical processes holistically, integrating headwater and downstream dynamics, while considering seasonal and interannual variability to better understand contemporary carbon transport, transformation, and the anticipated responses of these systems to climate warming.

How to cite: Balliston, N., Cullinane, G., Finkelstein, S., Guzzi, A., Hathaway, J., Kuzyk, Z. Z., Ledger, K., Papakyriakou, T., Strack, M., Vogel, M., and Litvinov, A.: From Peatlands to Boreal Lakes: Fill-and-Spill Hydrology and Dissolved Organic Carbon (DOC) Transport in the Headwaters of the Hudson Bay Lowlands, Canada, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12415, https://doi.org/10.5194/egusphere-egu25-12415, 2025.

The importance of rivers and streams to the global carbon cycle is well established, and increasingly. research has emphasized the role of in-stream metabolism on carbon transformation within aquatic environments. However, while stream metabolism studies are abundant in northern latitudes, research on tropical streams remains notably scarce. In this study, we characterized carbon fluxes into and out of a small stream in a tropical, peatland-rich ecosystem of the Andes mountains. We measured dissolved oxygen, carbon dioxide, and discharge every 15 minutes at 4 locations downstream of a large peatland. Measurements were collected semi-continuously for a period of 12 months. CO₂evasion was both measured directly and estimated indirectly for comparison. We used continuous dissolved oxygen to estimate daily ecosystem respiration (ER) and gross primary production (GPP) throughout the study period using a Bayesian-based metabolism model. Our results unveiled both seasonal and event-driven patterns in carbon dynamics throughout the year. At the peatland outlet, the stream channel was strongly heterotrophic throughout the study period (GPP << ER), GPP averaged 0.1896 g O₂ m^-2 d^-1, and ER averaged -1.862 g O₂ m^-2 d^-1. ER and GPP were suppressed directly following high flow events, but ER rates rebounded to higher than pre-storm levels in the following days. Seasonally, rates of ER were highest during dry months of the year, but rates of GPP were lowest during the dry season. Aquatic CO₂ concentrations were also elevated during the dry season, but discharge was much lower. As a result, we found the majority of CO₂ was exported from the peatland during the wet season when hydrologic connectivity was highest. Taking together, our results provide much needed process understanding of carbon dynamics in understudied, high-elevation tropical catchments.

How to cite: Riveros-Iregui, D., Whitmore, K., Jaramillo, R., DelVecchia, A., and Suarez, E.: Carbon fluxes and In-Stream Metabolism in a High-Altitude Tropical Peatland Ecosystem of The Andes Mountains, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4497, https://doi.org/10.5194/egusphere-egu25-4497, 2025.

Flooding events following periods of drought can export large quantities of sulfate (SO₄^2-) from headwater wetlands to surface waters, however the source and mechanism of SO₄^2- release have rarely been studied.  Due to the projected increases in severity and frequency of summer droughts and episodic flooding events as a result of climate change, there is a need to better understand the nature of episodic pulses of sulfate from wetlands and their downstream impacts on water quality. In this study, we monitored the evolution of the concentration and isotopic composition of surface and groundwater SO₄^2- in Beverly Swamp, a peat marsh area in southern Ontario, Canada, during a controlled field-scale flooding event. The event was created by the rapid drawdown of the upstream located Valens Reservoir at the end of a drought period. Up to seven-fold increases in SO₄^2- concentrations, relative to the pre-flood background levels, were observed during the flooding of the marsh. Stable S and O isotope ratios were analysed in stream and groundwaters to investigate the sources of SO₄^2-.

Following the flooding event, SO₄^2- concentrations in the outflow from the marsh increased significantly, while δ³⁴S-SO₄^2- values decreased. The latter is interpreted as indicative of SO₄^2- generated by sulphide oxidation (Schiff et al. 2005). Sulphide is likely produced by dissimilatory SO₄^2- reduction occurring during wet conditions, with storage of the resulting sulfide minerals in the upper peat layers. During the dry summer, the sulfides are re-oxidised to SO₄^2- and flushed from the wetland during flooding. Stable ¹⁸O-H₂O isotope signatures identified water released from Valens Reservoir as the initial driver of the SO₄^2- export across the wetland, followed by groundwater seepage from the deeper peat layers. Acidity increased shortly after the SO₄^2- pulse, but quickly dropped down to background levels due to buffering capacity of the wetland.

How to cite: O'Connell, D., Coulson, P., Rezanezhad, F., Mills, A., Lima, A., Durr, H., Macrae, M., Parsons, C., Shiff, S., and Van Cappellen, P.: Multi-stable isotope tracing of elevated sulfate export from a forested headwater wetland following an induced flood pulse event, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20214, https://doi.org/10.5194/egusphere-egu25-20214, 2025.

Riparian wetlands are strongly connected to water bodies and their capacity to provide hydrological services varies greatly over time. A better understanding of the temporal variability of this connectivity is necessary to improve our knowledge of how and when wetlands can influence floods. This work aims to empirically quantify the influence of a riparian wetland on floods in a small watershed located in the Montmorency Forest, Québec, Canada. To this end, 15-minute hydrometric data were retrieved from three Quebec government stations: one located upstream of a riparian wetland, one located downstream, and one located nearby in a control watershed with similar physical characteristics to the other two. With these data, a total of 229 flood events were identified between 1996 and 2022. The maximum flows for each event and the timing of each flood peak were isolated. Peak flow reductions and delays between the arrival of the flood peak for each flood event and between all catchments were calculated. Pre-flood flow, flood volume, total precipitation causing the flood, average water temperature during the flood and water level within the riparian wetland were used to explain the peak flow reduction patterns. The results show that the wetland reduces peak flow by a median of 27 % with a maximum reduction of 66 %. However, for some events there is an increase in peak flow after passing through the wetland. Delays in the arrival of the flood peak show a median of 135 minutes with a maximum value of 1300 minutes. Hysteresis patterns were observed between the river flow measured downstream of the riparian wetland and the water level measured in the wetland, indicating that the previous wetness of the riparian wetland influences the peak flow reduction capacity of the riparian wetland. Further hydrological and biogeochemical monitoring will be carried out at this site and will be used to improve our understanding of hydrological and biogeochemical processes in riparian wetlands, which are still poorly understood. Any future results will be compared with results from several sites in the Saint-Lawrence Lowlands, Québec, Canada, where an integrated wetland water and carbon cycle monitoring program is currently underway.

How to cite: Bourgault, M.-A., Strach, Y., and Anctil, F.: Empirical analyses of the hydrological influence of a riparian wetland in the Montmorency Forest, Quebec, Canada, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7035, https://doi.org/10.5194/egusphere-egu25-7035, 2025.

The artificial drainage of carbon-rich peat soils is a common practice to increase agronomic production on waterlogged lands but may lead to the release of carbon dioxide to the atmosphere. In Ireland, there are an estimated 300-350,000 ha of permanent grassland on peat soils, with varying degrees of drainage. 80,000 ha of these grassland peat soils are targeted in the Irish National Climate Action Plan for reduced management intensity which involves manipulating the water table by removing and blocking existing artificial drainage features. This process is often referred to as ‘active water table management’ or ‘rewetting’.

Actively managing the water table in grassland peat soils is an important tool to reach EU climate neutrality goals by 2050 because the water table position dictates the carbon storage dynamics of the soils. Research shows that raising the water table in these grassland peat soils by 10 cm can reduce overall greenhouse gas emissions from them. However, to achieve this, the impact that peat soil formation and subsequent anthropogenic activities (e.g., drainage and peat extraction) has had on the hydrology of these lands must be better understood.

The Irish Department of Agriculture, Food and the Marine-funded project, ReWET, aims to provide a deeper understanding of the hydrologic impacts of active water table management on grassland peat soils. An objective of this project is to investigate rainfall and water table relationships at agricultural grassland sites on peat soils to: (1) compare these relationships within and across peat classification types, and (2) determine field scale hydrological patterns that can be used to aid in the classification of these and other sites into fen or raised bog peat types to establish future restoration potential. For this study, six field sites on grassland farms were selected and classified into peatland type based on their soil characteristics. The sites were instrumented with rainfall gauges and dipwells with pressure sensors to record the water table position every 15 minutes and were monitored from September 2023 through August 2024.

Results from this study show that hydrologic differences between and within peat classification types exist. For each site the annual average water table depth demonstrated that peat soil type has an impact on the drainage depth and that fen peat sites were more deeply drained than raised bog sites despite similar surface drain design. Rainfall event-based analysis allowed the sites to be compared based on total rainfall depth, water table rise, lag time from the start of an event to the highest water table position and calculated specific yield. The event-based analysis was also used to correlate water table rise with rainfall at each site and for each peat classification type. It was found that, overall, the fen sites exhibited a stronger correlation between water table rise and rainfall than the raised bog sites. The fen sites also had larger average water table fluctuations, longer average lag times and smaller average calculated specific yields during events than the raised bog sites.

How to cite: Pierce, H., O'Leary, D., Daly, E., Fenton, O., Shnel, A., Healy, M., and Tuohy, P.: Examining the relationship between rainfall and water table position in grassland peat soils, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9312, https://doi.org/10.5194/egusphere-egu25-9312, 2025.

The slow recovery of trees in peatlands disturbed by linear clearings that arise from geologic exploration, also known as seismic lines, has spurred scholarly investigation into the underlying factors. The effect of tree canopy removal on the line on local water balance is one of the unanswered questions in past studies. Hence, this study aimed to provide insights into the impact of seismic lines on water balance components using CoupModel. Simulated values were compared with field measurements from a seismic line located in Fort McMurray, Alberta, Canada. The simulations indicated an increase in precipitation, soil moisture and temperature, and snow depth on the seismic line compared to undisturbed conditions with results aligned with the field measurements. Simulations also showed that the snow density on the seismic line was 4.6 % higher than the adjacent natural area (herein referred to as offline). Furthermore, the predicted shallower groundwater depth on the line was consistent with the observations. Although simulated net radiation off the line was higher than on the line, the actual evapotranspiration (AET) on the line was 8.3% higher than off the line. It was also found that evaporation from moss is the dominant component of the AET from the seismic line and adjacent natural area. However, greater precipitation inputs due to reduced interception outweighed the high AET on the seismic line, so that the seismic line had higher water storage than off the line by 38%. Sensitivity indicated the importance of site location (i.e., latitude), soil physical properties, and leaf area index parameters in simulations.  As a consequence, the initial model of water balance necessitates future researchers to explore the impact of different seismic lines, particularly at the catchment scale, to better understand the cumulative impact of these disturbances on water balance in boreal ecosystems. 

How to cite: Bayatvarkeshi, M., Strack, M., and Ketcheson, S.: Modelling hydrological responses of a peatland to disturbance by geologic exploration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10961, https://doi.org/10.5194/egusphere-egu25-10961, 2025.

We have shown that peatlands represent a cool humid island in their landscape context and that this cool humid island effect could be brought about by successful peatland restoration. However, it has been difficult to dis-entangle the controls on the direct climate impact of peatlands. Previous studies have been limited by a lack of pre-intervention data and the lack of significant target against which to test impact. The Onlanden, an area of peat south west of the city of Groningen, came under restoration management in 2012 when water tables were restored, but without active revegetation. The water table on the site was monitored before restoration and is ongoing and the area is . The direct climate impact of the restoration was assessed using remotely sensed land surface temperature, albedo and vegetation indices. Furthermore, the impact was modelled based upon a forced convection approach. The study can show that day time temperatures over the peatlands cooled relative to the surrounding land by up to 1.1 K (°C), but there was no significant change in night time temperatures. But there was a more dramatic change was observed for the peatlands the average amplitude of the diurnal temperature cycle decreased by upto 2.4 K (°C) over the period of the restoration.

The presence of an overall cooling effect means that a rising water table led to a lowering of the Bowen ratio. However, this result would suggest that open water would achieve an even greater cooling effect but would limit peatland development.

How to cite: Worrall, F., Borren, W., and Reinink, W.: Local climate impacts from ongoing restoration of a peatland – the Onlanden Experiment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6103, https://doi.org/10.5194/egusphere-egu25-6103, 2025.

Peatland ecosystems play a critical role in climate regulation by storing carbon and modulating energy fluxes. During evapotranspiration, radiative energy is converted into latent heat, which cools the atmosphere. Ecosystem energy fluxes which are strongly influenced by climate conditions can be tightly coupled to CO₂ fluxes through vegetation functioning. The relationship between carbon and energy fluxes in peatland ecosystems however remains relatively underexplored. Here we analyze eddy covariance measurements from a degraded raised bog in Amtsvenn-Hündfelder Moor (DE-Amv), located in North Rhine-Westphalia, Germany, to investigate the link between CO₂ uptake, canopy conductance and energy fluxes. DE-Amv has been part of the Natura 2000 network since 2004, with its flora dominated by Calluna vulgaris (L.) Hull and Molinia caerulea (L.) Moench. The dataset covers the entire year of 2023. We used the data to (1) examine the seasonal cycles of radiative and turbulent energy fluxes, and (2) evaluate the relationship between CO₂ uptake and energy fluxes. To investigate the ecophysiological drivers of latent heat flux (LE), we estimated canopy conductance (G_c) by inverting the Penman-Monteith equation and modelling a continuous time series of G_c over the study period.

Our results showed that the mean daily peaks of latent heat flux ranged from 8.5 W m⁻² to 215 W m⁻² in one year, with LE being strongly influenced by vegetation productivity (i.e., Gross Primary Productivity, GPP). Principal component analysis showed that GPP, vapor pressure deficit, and net radiation are the key drivers of LE dynamics (r > 0.85 for all variables). During the vegetation growing period (March to October) G_c ranged from a minimum daily value of 1.2 mm s^-1 in spring and autumn, to a maximum daily value of 15 mm s^-1 in August. While G_c was primarily driven by relative humidity during the colder months, it was mainly driven by net radiation from June to September, and it was not limited by VPD or soil moisture.

This study demonstrates how ecosystem eddy covariance flux measurements can quantify the stomatal regulation of energy fluxes in peatland ecosystems. By highlighting the strong coupling between energy and CO₂ fluxes, we emphasize the importance of understanding how environmental factors, particularly atmospheric vapor pressure deficit (VPD) and soil moisture, constrain G_c. Such insights are vital for predicting the effects of drier climatic conditions on the cooling capacity of drained peatlands, where vegetation type and management significantly influence their cooling potential.

How to cite: Flemming, V. E., Behrens, N., and Gharun, M.: Vegetation in the shadow of radiation: disentangling the cooling mechanism in a drained peatland ecosystem, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6636, https://doi.org/10.5194/egusphere-egu25-6636, 2025.

Peatlands are globally important long-term sinks of carbon, however there is concern that climate change-mediated drought will weaken their carbon sink function due to enhanced decomposition and moss moisture stress. Furthermore, heightened drought will also increase peat combustion loss during wildfire leading to peatland degradation and a potential ecosystem regime shift. Despite research developments on ecohydrological tipping points in semi-arid ecosystems, research in peatlands on the wet end of the ecosystem continuum has been “bogged down” (pun fully intended) by the traditional conceptual models of peatland hydrology and ecology. The consequences of this thinking loom large, given that northern peatlands face increases in the severity, areal extent, and frequency of climate-mediated (e.g., wildfire, drought) and land-use (e.g., drainage, flooding, and mining) disturbances, placing the future integrity of these critical ecosystem services in jeopardy.

In this presentation we explore the need for “thinking outside the bog” to quantify the ecohydrological tipping points to drought and wildfire. We argue that peatland ecohydrological resilience is a non-linear function of water storage dynamics and that water table data or peat moisture data alone are insufficient to capture this hydrological complexity. Given that the ability of Sphagnum moss to resist drought is largely a function of the rate of water loss by evaporation, the rate of upward water supply from the water table, and the water storage properties of the peat matrix, we suggest that ecohydrological resilience can be quantified by the magnitude and duration of the disconnect between the water table and near-surface peat. We discuss ways to measure ecohydrological resilience and explore simple metrics that reveal when critical tipping points have been exceeded and the implications this has for carbon storage and fluxes.

How to cite: Waddington, J. M., Moore, P., Sutton, O., Furukawa, A., Moore, M., Verkaik, G., Van Huizen, B., and Wilkinson, S.: Quantifying Peatland Ecohydrological Resilience to Drought and Wildfire by Thinking Outside the Bog , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13948, https://doi.org/10.5194/egusphere-egu25-13948, 2025.

Drainage is the main cause of a lower water table in peatlands, resulting in high greenhouse gas emissions. To combat this issue, the water table in peatlands must be raised, one most obvious way is by elevating the water level on the ditches. This practice has been implemented in many countries with extensive peatlands, such as Germany, Finland, Indonesia, Malaysia, etc. One question arises: how much is the water table raised in the peatland body after ditch water table was elevated?

To estimate the impact of elevating the water table in ditches on the field water table, we developed a field-scale model using MODFLOW6 in Python with the FloPy package. A physically-based model was chosen to account for different physical properties of peat and the underlying sediment layer, as well as topography and climate settings. The model was tested on a fen grassland field underlain by a highly porous sand layer in Gnarrenburger Moor, Northwest Germany. We used nationally available datasets as input, including elevation (DEM with 5m resolution), precipitation, and evapotranspiration data. The field size is 550m x 55m, bordered by ditches on all sides, and was dammed on two sides. A daily transient simulation was performed for 1,023 days from November 2020 to August 2023, and the model was calibrated using observational data.

The calibrated model results show an RMSE of 10 cm and a bias of 3 cm compared to observed water levels. We assessed the impact of ditch blocking by creating scenarios with and without ditch blocking. We found that by raising the water table in the ditches by an average of 31 cm (November 2021 – August 2022) and 30 cm (November 2022 – August 2023), the water table at the observation point was raised by 7 cm and 11 cm, respectively. For the entire field, the model estimate average water table raise by 20 cm (from -50 cm to -30 cm) and 23 cm (from -46 cm to -23 cm). If we only consider water table to calculate CO₂ emission, this corresponds to CO2 emission reductions of 5.21 tCO₂ ha^-1yr^-1 and 12 tCO₂ ha^-1yr^-1. Sensitivity analysis, conducted by adjusting calibrated parameters by ±5%, shows that the ditch water table is the most important factor influencing the field water table.

MODFLOW only considers saturated flow, thus minimizing the requirement for parameters. This model requires only saturated hydraulic conductivity (vertical and horizontal), specific yield, riverbed conductivity, and initial head for transient simulation. In this study, all parameters were unknown and therefore optimized. Despite this simplification, the model successfully simulates the observed water table.

The model was developed solely in a Python environment, utilizing open-source software and nationally available data, making it transferable to other sites with minimal modification. The intention is to apply the model to more rewetted agricultural peatland sites in Germany, as raising the water table in peatland drainage has become a Federal Government program.

How to cite: Ar Rahiem, M. M., Tiemeyer, B., Minke, M., Dettmann, U., Höper, H., and Piayda, A.: A MODFLOW Field-scale Model to Estimate Ditch Blocking Impact on Peat Water Table, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10511, https://doi.org/10.5194/egusphere-egu25-10511, 2025.

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.

How to cite: Paat, R., Jõeleht, A., Sarap, G. S., and Kohv, M.: A Novel Method for Determining Vertical Hydraulic Properties of Peat Using Naturally Occurring Pressure Fluctuations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6329, https://doi.org/10.5194/egusphere-egu25-6329, 2025.

Abstract

The hydro-physical properties of peat play a pivotal role in regulating the water, nutrient, and carbon cycles of peatland ecosystems. Despite their importance and complexity, our understanding of peat hydraulic properties remains limited. In this study, we compiled a comprehensive global database of the peat physical, hydraulic, and chemical properties, including bulk density (BD), porosity, macroporosity, saturated hydraulic conductivity (K_s), carbon content, and carbon density, encompassing tropical peatlands, northern fens, northern bogs, and permafrost regions. Our primary objective was to examine how these properties vary along a BD gradient across different climate zones. The results revealed a robust linear relationship between carbon density and BD for peat types with carbon content exceeding 35% (R²> 0.92, p < 0.001), suggesting that these functions can serve as reliable tools for estimating the carbon stock of peatlands. However, the specific functions differed between peat types and climate zones. Total porosity was found to decrease linearly as BD increased, while macroporosity followed a power-law relationship with BD. These trends were consistent across all peat types, underscoring a strong and reliable association between BD and both total porosity and macroporosity. Additionally, K_s exhibited a general decline with increasing BD, with the relationship characterized by log-log functions that varied among peat types and climate zones. This indicates that K_s is significantly influenced by the peat-forming vegetation such as wood, sphagnum, sedge, and the prevailing climatic conditions of the peatland. This study demonstrated that the key peat hydro-physical-chemical parameters—including carbon density, porosity, macroporosity, and K_s can be reliably estimated using the BD, with relatively high coefficients of determination (R²> 0.4), highlighting the critical importance of determining BD as a proxy for estimating other hydro-physical properties of peat when direct measurements are unavailable.

Keywords: peat; physical and hydraulic properties; bulk density; carbon density; saturated hydraulic conductivity, permafrost peatlands

Corresponding author: Haojie Liu (haojie.liu@uni-rostock.de)

Phone: +49 (381) 498 3193; Fax:  +49 (381) 498 3122

How to cite: Qi, J., Weigt, S., Wang, M., Rezanezhad, F., Quinton, W., Zak, D., Ahmad, S., Wang, L., Zhao, Y., Lennartz, B., and Liu, H.: Hydraulic Functions of Peat Across Types and Climate Zones, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6587, https://doi.org/10.5194/egusphere-egu25-6587, 2025.

In previous studies we found that the vertical movement of solutes within water-saturated peat of Puergschachen bog is limited. Furthermore, it is evident from literature that the hydrophysical and chemical properties of peat are influenced by the parent material of peat (i.e. plant material and layering), land use and the decomposition of peat. The study site, Puergschachen bog (an Long Term Ecosystem Research (LTER) site located in the Enns Valley, Styria), exhibits different stages of degradation, ranging from slightly degraded peat (Center), intermediately degraded (Inter), and two more strongly influenced sites covered with Betula pubescens (Birch) and Pinus mugo (Edge), which allows investigations along a degradation transect.

The objective of this study is to address the following research questions: how do hydrophysical and chemical properties of peat vary along a degradation transect and to what extent does depth influence these properties? We hypothesized that the degradation of peat influences the hydrophysical (saturated hydraulic conductivity (kF), water retention (pF2.5), bulk density (BD)) and chemical properties of peat (dissolved organic carbon (DOC), aromaticity of DOC (SUVA₂₅₄) and total dissolved nitrogen (TDN)), and that these parameters vary with depth.

Hydrophysical parameters were measured under laboratory conditions using undisturbed peat samples from sites along a degradation transect in two depths (10–20 cm and 20–30 cm). For each site and depth, 5 replicates in vertical and horizontal direction were taken. Chemical parameters were measured for bog water sampled seasonally in 4 depths (10–20, 35–45, 60–70 and 85–95 cm). A non-parametric Man-Whitney-Test was used to test for significant differences between groups.

Our results revealed that BD differed significantly between Center (0.053 ± 0.011 (mean ± SD)) and Birch (0.071 ± 0.023) and Edge (0.076 ± 0.014 g cm^-3) and were generally slightly higher in upper horizons (10–20 cm). kF measurements showed that horizontal and vertical flow directions differ between sites as an anisotropic behavior of peat with higher horizontal conductivities in the upper (10–20 cm) and lower (20–30 cm) horizons for Center and Birch and higher vertical conductivities (both depths) for Edge, was observed. Water retentions at pF2.5 differed between sites and depths and were generally higher for deeper horizons, indicating reduced pore sizes, binding water stronger in pores. Also, differences between horizons were highest for Edge peat. Birch showed the highest DOC concentrations together with the highest aromaticity. DOC concentrations decreased with depth at all sites, while TDN and SUVA₂₅₄ showed no constant depth-related pattern.

Our results indicate that water and solute transport through peat is linked with peat degradation, which inhibits or allows movement within the soil. As shown, hydraulic conductivities can develop highly heterogeneous and anisotropic patterns of directional movement. Further studies are needed to assess the extent to which these heterogeneous hydrophysical properties affect solute transport and how this might influence peat decomposition processes.

How to cite: Müller, R., Zhang, E., Glina, B., and Glatzel, S.: Hydrophysical properties of ombrotrophic peat show anisotropic patterns along a degradation transect, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18639, https://doi.org/10.5194/egusphere-egu25-18639, 2025.

Globally, there is an increasing focus on the rehabilitation of organic soils currently under agricultural management, particularly modified peatlands which are significant net emitters of greenhouse gases. These carbon-rich landscapes have been extensively modified through drainage and agricultural intervention, transforming natural ecosystems into agricultural production systems.

Traditional land use practices have involved drainage to lower water tables, enabling agricultural productivity but simultaneously triggering significant carbon emissions. A potential approach for rehabilitation of these soils is "rewetting" - a strategic intervention aimed at restoring hydrological conditions closer to the soil's natural state. Rewetting offers a potential nature-based solution to reduce greenhouse gas emissions while simultaneously preserving these ecologically rich landscapes.

The primary objective of rewetting is to manage the water table to be, on average, within 30 cm of the surface throughout the year. This is conventionally achieved by infilling or damming open drainage channels that historically surrounded agricultural fields. However, a critical knowledge gap exists regarding the precise spatial extent and effectiveness of such rewetting efforts.

In Ireland, the ReWET project aims to contribute critical knowledge to emerging global strategies for peatland restoration and climate change mitigation on agriculturally altered peat soils sites. This is achieved by partial rewetting of several agricultural sites under various management practices, primarily cattle grazing, and subsequent monitoring of the impact of rewetting on several key indicators, such as water table depth.

Geophysical techniques offer promising methodological approaches to address the understanding of spatial extend of rewetting efforts. Electrical geophysical methods, which measure soil electrical conductivity, are particularly sensitive to water content and can provide detailed insights into subsurface moisture dynamics. Specifically, Electro-Magnetic Induction (EMI) surveys provide non-invasive, high-resolution mapping of subsurface electrical properties, which can correlate with soil moisture conditions.

In this study, EMI using a CMD Mini-Explorer 6L instrument was deployed several times on one ReWET site in Ireland, classified as a fen peat, to assess the hydrological modifications induced by rewetting interventions. Combining EMI measurements with advanced machine learning clustering, in-situ water table depth and soil moisture data, this study was able to identify the hydrological influence and extent of the rewetting, allowing for a quantitative assessment as to the efficacy of the rewetting operation.

Methodologically, this study demonstrates the utility of geophysical techniques in monitoring and evaluating field-scale hydrological interventions. The approach developed could be readily translated to other peatland restoration projects, providing a robust, non-destructive monitoring framework.

By quantifying the spatial and temporal dynamics of rewetting efforts, this research supports more precise, evidence-based approaches to peatland management. The insights generated are crucial for environmental managers, climate policy makers, and agricultural stakeholders seeking to balance productive land use with ecological conservation and carbon sequestration objectives.

How to cite: O Leary, D., Tuohy, P., Fenton, O., Shnel, A., Pierce, H., Healy, M., and Daly, E.: Electromagnetic Induction as a means to assess the hydrological impact of rewetting agricultural fen peat sites, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1391, https://doi.org/10.5194/egusphere-egu25-1391, 2025.

Northern raised peat bogs are usually assumed to be entirely precipitation-fed, implying that they lack groundwater inputs from underlying sediments. The development and persistence of patterned pools in raised bogs have historically been attributed to both surficial flow filling depressions along the peat surface, and subtle differences in peat pore water chemistry. In contrast, we find hydrogeophysical evidence that patterned pools in three northern peat bogs of Maine (USA) are partially fed by localized upwelling of minerogenous groundwater from underlying glacial sediments imaged using ground-penetrating radar. Paired point measurements of temperature and specific conductance (SpC) around numerous pools across the three raised bogs showed statistically significant relationships diagnostic of focused groundwater upwelling, despite hydraulic heads measured using nests of piezometers generally suggesting downward flow around pools. Drone-based thermal infrared (TIR) mapping, augmented by handheld TIR imaging, further indicated groundwater inputs into pools during cold and warm seasons. Surface water samples from upwelling zones showed elevated iron and manganese concentrations indicative of glacial aquifer sources.   Vegetation samples taken around two pools with contrasting groundwater inputs indicate that the composition of plant communities is associated with contrasting water chemistry. This supports the hypothesis that these inputs influence the vegetation within the raised bog ecosystem. Visual observations and information from shallow geophysics suggest that macropore, ‘peat pipe’ features might enhance vertical connectivity between groundwater and pools, and horizontal connectivity by connecting pools across the landscape.

How to cite: Slater, L., Moore, H., Comas, X., Briggs, M., Holzapfel, C., Parag, H., Reeve, A., and Niedzinski, V.: Hydrogeophysics reveals evidence for groundwater inputs influencing the hydrology and ecology of northern raised bogs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5116, https://doi.org/10.5194/egusphere-egu25-5116, 2025.

The moisture status of peatlands is an important factor as it directly affects carbon dynamics. Therefore, it is critical to characterize and understand peatland moisture status and to monitor its spatial and temporal variations. This study aims to evaluate the potential of drone-borne ground-penetrating radar (GPR) in combination with full-wave inversion to investigate the spatial and temporal variability of peatland root-zone moisture. A secondary objective is to assess its benefits for restoration applications. This study was carried out on a 4.5 ha peatland in the Belgian Hautes Fagnes which was previously degraded by forestry activities. Ground-penetrating radar measurements were conducted every 2 to 4 weeks for 17 months, resulting in 19 peatland soil moisture maps with a 5-meter resolution. Reference soil moisture data were collected using ground-based probes to enable comparison.

The temporal variability showed an overall correlation of 0.71 between the GPR and the ground-based probes, indicating that this method effectively captures overall moisture dynamics across the entire study site throughout different seasons. In contrast, the spatial comparison of GPR with the ground-based probes showed a lower correlation, namely 0.23, which is attributed to the high micro-variability of soil moisture (on centimeter to meter scales) and the spatial mismatch between the measurements and their characterization areas and depths. However, we show that the spatial data contained high information content when applying a spatial clustering analysis to produce maps of homogeneous moisture classes. These clusters aligned well with other specific site characteristics, such as peat depth and vegetation composition, and can be used to support the planning of restoration efforts. This study introduces a new approach to studying peatland root-zone moisture and shows potential to guide and monitor peatland restoration strategies.

How to cite: Henrion, M., Li, Y., Wu, K., Jonard, F., Opfergelt, S., Vanacker, V., Van Oost, K., and Lambot, S.: Mapping and monitoring peatland soil moisture using drone-borne Ground-Penetrating Radar, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6425, https://doi.org/10.5194/egusphere-egu25-6425, 2025.