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•Remote sensing-based approach to indicate vertical displacement of the peat.•Annualpeatland subsidencein the BiebrzaValleypeatlands = 1.44 cm.•Verifying this approach vs. field ...observations (R2 = 0.7, RMSE = 0. 23 cm)•∼ 46 tones of peat per hectare lost per annum.•Subsidence due to artificial drainage and climate change at the regional scale.
Peatlands play a crucial role in carbon storage, but drainage and climate change-induced hydrological changes drivers degrade peat soils, followed by negative vertical displacement of the soil surface, referred to in the literature as peat subsidence. Assessing peatland subsidence is an important indicator of peatland status that allows the development of peatlands to be revealed over a given period. However, traditional methods are limited in their applicability to large and inaccessible peatlands. In this study, we introduce a remote sensing framework for easily indicating peat subsidence at a large scale. Our framework utilizes the Alaska Satellite Facility (ASF) Interferometry Synthetic Aperture Radar (InSAR) with on-demand cloud computing, employing an optimization process including a Small Baseline Set technique and seasonal-annual search approach. By implementing this approach in the Biebrza Valley, Poland, covering the period from April 2015 to April 2022, we unveiled a tragedy, an annual subsidence rate of 1.44 cm. It means a peat loss between 58.1 and 89.6 million cubic meters over seven years, an annual loss of 86.4 to 132.5 (average 109) m3, approximately 46 tons, of dry matter peat per hectare. This finding was verified through field surveys, with high accuracy. An R2 value of 0.7, and an RMSE value of 0.23 cm determine the reliability of this approach in estimating the vertical displacement. The potential of this tool as a robust method to assess large-scale peatlands would allow for the assessment of average water levels as well as greenhouse gas emissions over large areas of peatlands, even at the continental scale.
Currently, due to prolonged soil drought, dehydrated peat soils are particularly exposed to subsidence and, as a consequence, even to disappearance from the natural environment, in which they perform ...many important functions, e.g. storage of organic carbon and water retention. Therefore, predicting of settlement and disappearance processes of these soils is very important issue. This study was conducted to: (1) determine the degree and rate of subsidence of a drained peatland over 40 years, (2) establish the effect of subsidence on the depth of ditches and a watercourse, (3) verify empirical equations describing the subsidence based on field measurements. The work was carried out on fen in Central Poland which was managed as a grassland until around 2000, and then its use was discontinued. Subsidence rate was estimated from measurements of the peat deposit thickness taken in 11 locations in 1978 and 2018. Fourteen empirical equations used for estimating subsidence rate of drained peatlands were selected to verify the calculations against field data. The average subsidence rate of the studied peatland was relativity low (0.62 cm year
−1
), which may be associated with abandoning of agricultural use for the last 20 years. Loss of peat thickness varied from 5 to 41% and depended rather on drainage intensity than on its initial depth. In general, six from the verified empirical equations were useful in estimating average subsidence rate. Four equations seemed to be the most useful for deeply drained sites. Estimation of the subsidence solely on the basis of time since drainage may be biased.
Soil moisture monitoring is crucial for a variety of activities involving soil water regime estimation. Different phenomena such as drought, exhibit impacts of a variable extent in the soil profile, ...requiring moisture content monitoring as well as reliable analyses of the soil properties. In the village of Solec, located in central Poland, monitoring of the moisture content was attempted for a sandy soil in order to estimate soil moisture distributions for two dry years (2015, 2016) and a wet one (2017). Simple and easily obtainable drought indices, such as dry spells, climatic water balance, groundwater table depth, soil water content and potential were estimated and related with spatiotemporal evolution of soil water conditions. Soil layers subject to drought were found to be different either from a moisture (15–45 cm) or soil water potential (10–25 cm), showing diverse physical properties and relations with the ground water table. The coherence of the analysed drought indices was proven for a light, sandy soil, which has national significance for the state, drought monitoring network. Knowledge obtained during previous studies, which omitted soil water conditions for this type of the soil was supplemented. Based on its own water content, the profile of the analysed soil (Stagnic Folic Gleysols–Arenic) exhibits a negative climatic water balance and requires irrigation practices to mitigate drought effects.
The paper presents the course of variability of the moisture content of the top layers in shallow (45 cm) and medium-deep (90 cm) peat-moorsh soil profiles in the years 2015–2019 against the ...background of the same meteorological conditions and a similar level of the groundwater table. The relative precipitation index ( RPI) classifies the years 2015 and 2016 as dry, 2017 as wet, and 2018 and 2019 as average. For periods of atmospheric droughts, the average daily climatic water balance ( CWB) ranged from –5.30 to –1.35 mm∙d –1. The water table did not fall below 90 cm b.g.l. during the entire study period, and the range of its fluctuations was 8 cm greater in the shallow than in the medium-deep profile. The range of moisture at different depths varied significantly and ranged from approx. 6% in periods of drought to about 80% in wet periods. Soil moisture throughout the measurement period was above the plant available water range (p F > 4.2). The occurrence of soil drought in the shallow peat-moorsh soil profile had a range of up to 40 cm, and in the medium-deep profile of up to 30 cm. The sequence of no-precipitation days and the maximum amount of daily evapotranspiration during them determine the possible timing of drought; however, it is the precipitation distribution in individual months, considered in the current CWB values, that ultimately determine the formation of soil water resources at the research site.
The consequences of organic soil subsidence gained considerable importance in a wide range of scientific literature. Since most of the works focused mainly on the subsidence of the land surface, less ...attention was paid to the effects on hydraulic structures, either to their malfunctioning or to the proper management of the subirrigation systems. For the reasons mentioned above, the paper considers the selected technical parameters (underground pipelines covering thickness and soil subsidence behind inlet and outlet protections) of 37 culverts (communication structures) and 42 culvert-gates (communication and water damming). All the structures were located within the area of a subirrigation system on the previously drained organic soils (Solec system, Mazovian Voivodship, 30 km south of Warsaw). They underwent field measurements of the pipelines covering subsidence and land surface lowering behind their protections on the left and right side of the inlet and outlet section. The achieved results were confronted with the adopted limit and admissible values. Due to the progressing congestion and subsidence of organic soil, the covering thickness of pipelines did not exceed the limit value for 38.5% of the culverts and 36% of culvert-gates. From a long-term perspective (1971-2014) the average subsidence rates in the vicinity of the structures and surrounding peatland surface were found as comparable, ranging from 0.63 to 0.83 cm/year. Particular attention was paid to the influence of water damming that was evident for the inlet sections of culvert-gates showing considerably lower subsidence and damage degree.
Observed changes in hydrological conditions indicate the need for economical use of water. This pertains to water management on a national scale, river basins and drainage systems. The outflow of ...water can be extensively regulated after various forms of retention in the catchment. The water level regulators presented herein enable the damming of water in drainage networks and the adjacent ground. Their advantages include their simple structure and operation principles and also the ability to adapt to currently existing devices in sub-irrigation systems. Laboratory tests were conducted to determine the hydraulic characteristics and operating conditions of three innovative regulator solutions. They focused on changing water damming heights by the closure of successively placed beams in order to obtain the required water level in the given hydrometeorological conditions. The structures of the regulators were made of plastics and rectilinear fillings for securing S-type excavations and elements of sheet piling with a developed shape in the plan of U and Z types, offering advantages compared to traditional materials (with respect to installation, operation and durability). All tested regulators were characterized by the effective flow Qe, caused by water leaks due to the lack of tightness of the regulator elements. The regulator with rectilinear beams of S-type closures offered the highest effective flow, which was 4 ÷ 5 times higher than in other regulators. U- and Z-type regulators were better at facilitating the regulation of the water table and the flow than the S rectilinear regulator. This led to both: the greater tightness of connections and the use of an overflow with a developed crest in the plan. The U and Z controllers had the highest hydraulic efficiency, expressed as the flow increase coefficient, at overflow layer heights of up to 5.0 cm. For tested fillings larger than 5.0 cm, U-type beams with a cylindrical corner shape had a lower flow increase coefficient (kq = 1.25) than Z-type beams with an angular corner shape, for which kq ∈ <1.35 ÷ 1.38>.
This study analyzed design depths (to), post-subsidence depths (t), shallowing magnitudes (d = to − t) and ratio values (d/t) of 12 drainage ditches in a fragment of the drained Solec fen-peat ...(central Poland) over a period of 47 years between 1967 and 2014. A significant decrease of the designed depth of the ditches to was shown, from the average designed value of 0.97 m to their average depth after subsidence, t = 0.71 m. The ratio (d/t) of 0.41, which is associated with the degree of organic matter decomposition, indicated medium degree of peat decomposition. The average values of bank and bottom subsidence of the ditches during the analyzed period, 1967–2014, were 0.43 m and 0.17 m, respectively. The values of the average annual rate of land surface subsidence in the vicinity of the ditches were varied and within the range of 0.09 cm year−1 to 1.70 cm year−1, with an average of 0.92 cm year−1. Two linear empirical equations were proposed to calculate the amount of subsidence and the average annual rate of subsidence of peat soil surface near the drainage ditch route, based on the knowledge of the initial thickness of the peat deposit. The results of calculations using the equations proposed by the authors were compared with calculations of the same parameters using 10 equations published in the literature. The results obtained using the proposed equations were mostly larger than those calculated with literature-published equations.
The proper monitoring of soil moisture content is important to understand water-related processes in peatland ecosystems. Time domain reflectometry (TDR) is a popular method used for soil moisture ...content measurements, the applicability of which is still challenging in field studies due to requirements regarding the calibration curve which converts the dielectric constant into the soil moisture content. The main objective of this study was to develop a general calibration equation for the TDR method based on simultaneous field measurements of the dielectric constant and gravimetric water content in the surface layers of degraded peatlands. Data were collected during field campaigns conducted temporarily between the years 2006 and 2016 at the drained peatland Kuwasy located in the north-east area of Poland. Based on the data analysis, a two-slopes linear calibration equation was developed as a general broken-line model (GBLM). A site-specific calibration model (SSM-D) for the TDR method was obtained in the form of a two-slopes equation describing the relationship between the soil moisture content and the dielectric constant and introducing the bioindices as covariates relating to plant species biodiversity and the state of the habitats. The root mean squared error for the GBLM and SSM-D models were equal, respectively, at 0.04 and 0.035 cm3 cm−3.
The papers presents the soil surface subsidence rate of drained (1967–1971) peat deposit in 1978–2015 years. The very high differences of the rate was observed on relatively small area (15 ha). The ...subsidence rate was observed in the range from 0.06 to 1.56 cm·year–1. The percentage loss of the peat deposit thickness in the years 1978– –2015 in the analyzed area was varied and did not depend on the initial thickness of the peat deposit. It oscillated between 2 and approx. 44%. The obtained measured data were able to perform the verification of selected published in the literature empirical equations to predict the subsidence rate of soil surface of drained many years ago lowland peatlands.
The aim of the studies was the assessment of the usefulness of selected pedotransfer function for calculating the water retention of alluvial soils in Żuławy Wiślane. Żuławy Wiślane are an important ...area, both as far as agricultural production and environmental values are concerned. The analysis accounted for three models, i.e.: van Genuchten-Wösten, Varellyay and Mieronienko, Hewelke et al. Based on 122 dataset of alluvial soils from the Żuławy area, the statistical relationships between the measured values of total available water and values calculated for individual models were analysed. The studies carried out indicate that the analysed pedotransfer functions are characterized by different compatibilities with results obtained by means of direct measurement. The lowest average errors of fit were obtained for the Hewelke et al. and van Genuchten models.
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