scholarly journals Resolution capacity of geophysical monitoring regarding permafrost degradation induced by hydrological processes

2017 ◽  
Vol 11 (6) ◽  
pp. 2957-2974 ◽  
Author(s):  
Benjamin Mewes ◽  
Christin Hilbich ◽  
Reynald Delaloye ◽  
Christian Hauck
Keyword(s):  
Electrical Resistivity ◽  
Seismic Tomography ◽  
Field Data ◽  
Electrical Resistivity Tomography ◽  
Geophysical Methods ◽  
Phase Model ◽  
Permafrost Degradation ◽  
Resistivity Tomography ◽  
Refraction Seismic ◽  
Ice Content

Abstract. Geophysical methods are often used to characterize and monitor the subsurface composition of permafrost. The resolution capacity of standard methods, i.e. electrical resistivity tomography and refraction seismic tomography, depends not only on static parameters such as measurement geometry, but also on the temporal variability in the contrast of the geophysical target variables (electrical resistivity and P-wave velocity). Our study analyses the resolution capacity of electrical resistivity tomography and refraction seismic tomography for typical processes in the context of permafrost degradation using synthetic and field data sets of mountain permafrost terrain. In addition, we tested the resolution capacity of a petrophysically based quantitative combination of both methods, the so-called 4-phase model, and through this analysed the expected changes in water and ice content upon permafrost thaw. The results from the synthetic data experiments suggest a higher sensitivity regarding an increase in water content compared to a decrease in ice content. A potentially larger uncertainty originates from the individual geophysical methods than from the combined evaluation with the 4-phase model. In the latter, a loss of ground ice can be detected quite reliably, whereas artefacts occur in the case of increased horizontal or vertical water flow. Analysis of field data from a well-investigated rock glacier in the Swiss Alps successfully visualized the seasonal ice loss in summer and the complex spatially variable ice, water and air content changes in an interannual comparison.

scholarly journals Resolution capacity of geophysical monitoring regarding permafrost degradation induced by hydrological processes

2016 ◽  
Author(s):  
Benjamin Mewes ◽  
Christin Hilbich ◽  
Reynald Delaloye ◽  
Christian Hauck
Keyword(s):  
Electrical Resistivity ◽  
Seismic Tomography ◽  
Field Data ◽  
Electrical Resistivity Tomography ◽  
Geophysical Methods ◽  
Phase Model ◽  
Permafrost Degradation ◽  
Resistivity Tomography ◽  
Refraction Seismic ◽  
Ice Content

Abstract. Geophysical methods are often used to characterise and monitor the subsurface composition of permafrost. The resolution capacity of standard methods, i.e. Electrical Resistivity Tomography and Refraction Seismic Tomography, depends hereby not only on static parameters such as measurement geometry, but also on the temporal variability in the contrast of the geophysical variables (electrical resistivity and P-wave velocity). Our study analyses the resolution capacity of Electrical Resistivity Tomography and Refraction Seismic Tomography for typical processes in the context of permafrost degradation using synthetic and field data sets of mountain permafrost terrain. In addition, we tested especially the resolution capacity of a petrophysically-based quantitative combination of both methods, the so-called 4-phase model, and by this analysed the expected changes in water and ice content upon permafrost thaw. The results from the synthetic data experiments suggest a higher sensitivity regarding increasing water content compared to decreased ice content, and potentially larger uncertainty for the individual geophysical methods than for the combined evaluation with the 4-phase model. In the latter, ground ice loss can be detected quite reliably, whereas artefacts occur in the case of increased horizontal or vertical water flow. Analysis of field data from a well-investigated rock glacier in the Swiss Alps successfully visualised the seasonal ice loss in summer, and the complex spatially variable ice-, water- and air content changes in an interannual comparison.

Permafrost monitoring by reprocessing and repeating historical geoelectrical measurements

2020 ◽  
Author(s):  
Christian Hauck ◽  
Christin Hilbich ◽  
Coline Mollaret ◽  
Cécile Pellet
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Geophysical Methods ◽  
Swiss Alps ◽  
Permafrost Degradation ◽  
Resistivity Tomography ◽  
Climate Signal ◽  
Data Source ◽  
Ice Content

<p>Geophysical methods and especially electrical techniques have been used for permafrost detection and monitoring since more than 50 years. In the beginning, the use of Vertical Electrical Soundings (VES) allowed the detection of ice-rich permafrost due to the clear contrast between the comparatively low-resistive active layer and the high-resistive permafrost layer below. Only after the development of 2-dimensional tomographic measurement and processing techniques (Electrical Resistivity Tomography, ERT), in the late 1990’s, electrical imaging was widely applied for a large range of different permafrost applications, including ice content quantification and permafrost monitoring over different spatial scales. Regarding ERT monitoring, the comparatively large efforts needed for continuous and long-term measurements implies that there are still only few continuous ERT monitoring installations in permafrost terrain worldwide. One of the exceptions is a network of six permafrost sites in the Swiss Alps that have been constantly monitored in the context of the Swiss Permafrost Monitoring Network (PERMOS) since 2005, enabling the analysis of the long-term change in the ground ice content and associated thawing and freezing processes (Mollaret et al. 2019).</p><p>On the contrary, a much larger number (estimated to be > 500) of permafrost sites exist worldwide, where singular ERT (or VES) measurements have been performed in the past - many of them published in the scientific literature. These data sets are neither included in a joint database nor have they been analysed in an integrated way. Within a newly GCOS Switzerland-funded project we address this important historical data source. Whereas singular ERT data from different permafrost occurrences are not easily comparable due to the local influence of the geologic material on the obtained electrical resistivities, their use as baseline for repeated measurements and subsequent processing and interpretation in a climatic context is highly promising and can be effectuated with low efforts.</p><p>In this presentation we will show evidence that singular ERT surveys in permafrost terrain can indeed be repeated and jointly processed after long time spans of up to 20 years, yielding a climate signal of permafrost change at various sites and on different landforms. Examples are given from various field sites in Europe and Antarctica, and the results are validated with borehole data, where available. We believe that a joint international data base of historical ERT surveys and their repetitions would add an important data source available for permafrost studies in the context of climate change.</p><p> </p><p>Mollaret, C., Hilbich, C., Pellet, C., Flores-Orozco, A., Delaloye, R. and Hauck, C. (2019): Mountain permafrost degradation documented through a network of permanent electrical resistivity tomography sites. The Cryosphere, 13 (10), 2557-2578.</p>

scholarly journals Characterization of a Shallow Coastal Aquifer in the Framework of a Subsurface Storage and Soil Aquifer Treatment Project Using Electrical Resistivity Tomography (Port de la Selva, Spain)

2021 ◽  
Vol 11 (6) ◽  
pp. 2448
Author(s):  
Alex Sendrós ◽  
Aritz Urruela ◽  
Mahjoub Himi ◽  
Carlos Alonso ◽  
Raúl Lovera ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Water Reuse ◽  
Electrical Resistivity Tomography ◽  
Groundwater Modeling ◽  
Geophysical Methods ◽  
Soil Aquifer Treatment ◽  
Modeling Tools ◽  
Resistivity Tomography ◽  
Implicit Modeling ◽  
The Difference

Water percolation through infiltration ponds is creating significant synergies for the broad adoption of water reuse as an additional non-conventional water supply. Despite the apparent simplicity of the soil aquifer treatment (SAT) approaches, the complexity of site-specific hydrogeological conditions and the processes occurring at various scales require an exhaustive understanding of the system’s response. The non-saturated zone and underlying aquifers cannot be considered as a black box, nor accept its characterization from few boreholes not well distributed over the area to be investigated. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological heterogeneities that has demonstrated useful to provide the detailed subsurface information required for groundwater modeling. The relationships between the electrical resistivity of the alluvial sediments and the bedrock and the difference in salinity of groundwater highlight the potential of geophysical methods over other more costly subsurface exploration techniques. The results of our research show that ERT coupled with implicit modeling tools provides information that can significantly help to identify aquifer geometry and characterize the saltwater intrusion of shallow alluvial aquifers. The proposed approaches could improve the reliability of groundwater models and the commitment of stakeholders to the benefits of SAT procedures.

Decennial multi-approach monitoring of thermo-hydro-mechanical processes, Kammstollen outdoor laboratory, Zugspitze (Germany)

2021 ◽  
Author(s):  
Riccardo Scandroglio ◽  
Till Rehm ◽  
Jonas K. Limbrock ◽  
Andreas Kemna ◽  
Markus Heinze ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Environmental Research ◽  
Permafrost Degradation ◽  
Earth Surface ◽  
Data Set ◽  
Resistivity Tomography ◽  
Near Surface ◽  
Permafrost Rock ◽  
Austrian Alps

<p>The warming of alpine bedrock permafrost in the last three decades and consequent reduction of frozen areas has been well documented. Its consequences like slope stability reduction put humans and infrastructures at high risk. 2020 in particular was the warmest year on record at 3000m a.s.l. embedded in the warmest decade.</p><p>Recently, the development of electrical resistivity tomography (ERT) as standard technique for quantitative permafrost investigation allows extended monitoring of this hazard even allowing including quantitative 4D monitoring strategies (Scandroglio et al., in review). Nevertheless thermo-hydro-mechanical dynamics of steep bedrock slopes cannot be totally explained by a single measurement technique and therefore multi-approach setups are necessary in the field to record external forcing and improve the deciphering of internal responses.</p><p>The Zugspitze Kammstollen is a 850m long tunnel located between 2660 and 2780m a.s.l., a few decameters under the mountain ridge. First ERT monitoring was conducted in 2007 (Krautblatter et al., 2010) and has been followed by more than one decade of intensive field work. This has led to the collection of a unique multi-approach data set of still unpublished data. Continuous logging of environmental parameters such as rock/air temperatures and water infiltration through joints as well as a dedicated thermal model (Schröder and Krautblatter, in review) provide important additional knowledge on bedrock internal dynamics. Summer ERT and seismic refraction tomography surveys with manual and automated joints’ displacement measurements on the ridge offer information on external controls, complemented by three weather stations and a 44m long borehole within 1km from the tunnel.</p><p>Year-round access to the area enables uninterrupted monitoring and maintenance of instruments for reliable data collection. “Precisely controlled natural conditions”, restricted access for researchers only and logistical support by Environmental Research Station Schneefernerhaus, make this tunnel particularly attractive for developing benchmark experiments. Some examples are the design of induced polarization monitoring, the analysis of tunnel spring water for isotopes investigation, and the multi-annual mass monitoring by means of relative gravimetry.</p><p>Here, we present the recently modernized layout of the outdoor laboratory with the latest monitoring results, opening a discussion on further possible approaches of this extensive multi-approach data set, aiming at understanding not only permafrost thermal evolution but also the connected thermo-hydro-mechanical processes.</p><p> </p><p> </p><p>Krautblatter, M. et al. (2010) ‘Temperature-calibrated imaging of seasonal changes in permafrost rock walls by quantitative electrical resistivity tomography (Zugspitze, German/Austrian Alps)’, Journal of Geophysical Research: Earth Surface, 115(2), pp. 1–15. doi: 10.1029/2008JF001209.</p><p>Scandroglio, R. et al. (in review) ‘4D-Quantification of alpine permafrost degradation in steep rock walls using a laboratory-calibrated ERT approach (in review)’, Near Surface Geophysics.</p><p>Schröder, T. and Krautblatter, M. (in review) ‘A high-resolution multi-phase thermo-geophysical model to verify long-term electrical resistivity tomography monitoring in alpine permafrost rock walls (Zugspitze, German/Austrian Alps) (submitted)’, Earth Surface Processes and Landforms.</p>

scholarly journals Small-scale characterization of vine plant root water uptake via 3-D electrical resistivity tomography and mise-à-la-masse method

2018 ◽  
Vol 22 (10) ◽  
pp. 5427-5444 ◽  
Author(s):  
Benjamin Mary ◽  
Luca Peruzzo ◽  
Jacopo Boaga ◽  
Myriam Schmutz ◽  
Yuxin Wu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Root System ◽  
Field Data ◽  
Electrical Resistivity Tomography ◽  
Root Zone ◽  
Plant Root ◽  
Root Water Uptake ◽  
Small Scale ◽  
Noninvasive Methods ◽  
Resistivity Tomography

Abstract. The investigation of plant roots is inherently difficult and often neglected. Being out of sight, roots are often out of mind. Nevertheless, roots play a key role in the exchange of mass and energy between soil and the atmosphere, in addition to the many practical applications in agriculture. In this paper, we propose a method for roots imaging based on the joint use of two electrical noninvasive methods: electrical resistivity tomography (ERT) and mise-à-la-masse (MALM). The approach is based on the key assumption that the plant root system acts as an electrically conductive body, so that injecting electrical current into the plant stem will ultimately result in the injection of current into the subsoil through the root system, and particularly through the root terminations via hair roots. Evidence from field data, showing that voltage distribution is very different whether current is injected into the tree stem or in the ground, strongly supports this hypothesis. The proposed procedure involves a stepwise inversion of both ERT and MALM data that ultimately leads to the identification of electrical resistivity (ER) distribution and of the current injection root distribution in the three-dimensional soil space. This, in turn, is a proxy to the active (hair) root density in the ground. We tested the proposed procedure on synthetic data and, more importantly, on field data collected in a vineyard, where the estimated depth of the root zone proved to be in agreement with literature on similar crops. The proposed noninvasive approach is a step forward towards a better quantification of root structure and functioning.

Upscaling of geophysical measurements: A methodology for the estimation of the total ground ice content at two study sites in the dry Andes of Chile and Argentina

2020 ◽  
Author(s):  
Tamara Mathys ◽  
Christin Hilbich ◽  
Cassandra E.M. Koenig ◽  
Lukas Arenson ◽  
Christian Hauck
Keyword(s):  
Hydrological Cycle ◽  
Spatial Scales ◽  
Geophysical Methods ◽  
Central Andes ◽  
Permafrost Degradation ◽  
Rock Glacier ◽  
Ground Ice ◽  
Refraction Seismic ◽  
Geophysical Surveys ◽  
Ice Content

<p>With climate change and the associated continuing recession of glaciers, water security, especially in regions depending on the water supply from glaciers, is threatened. In this context, the understanding of permafrost distribution and its degradation is of increasing importance as it is currently debated whether ground ice can be considered as a significant water reservoir and as an alternative resource of fresh water that could potentially moderate water scarcity during dry seasons in the future. Thus, there is a pressing need to better understand how much water is stored as ground ice in areas with extensive permafrost occurrence and how meltwater from permafrost degradation may contribute to the hydrological cycle in the region.</p><p>Although permafrost and permafrost landforms in the Central Andes are considered to be abundant and well developed, the data is scarce and understanding of the Andean cryosphere lacking, especially in areas devoid of glaciers and rock glaciers.</p><p>In the absence of boreholes and test pits, geophysical investigations are a feasible and cost-effective technique to detect ground ice occurrences within a variety of landforms and substrates. In addition to the geophysical surveys themselves, upscaling techniques are needed to estimate ground ice content, and thereby future water resources, on larger spatial scales. To contribute to reducing the data scarcity regarding ground ice content in the Central Andes, this study focuses on the permafrost distribution and the ground ice content (and its water equivalent) of two catchments in the semi-arid Andes of Chile and Argentina. Geophysical methods (Electrical Resistivity Tomography, ERT and Refraction Seismic Tomography, RST) were used to detect and quantify ground ice in the study regions in the framework of environmental impact assessments in mining areas. Where available, ERT and RST measurements were quantitatively combined to estimate the volumetric ground ice content using the Four Phase Model (Hauck et al., 2011). Furthermore, we developed one of the first methodologies for the upscaling of these geophysical-based ground ice quantifications to an entire catchment in order to estimate the total ground ice volume in the study areas.</p><p>In this contribution we will present the geophysical data, the upscaling methodology used to estimate total ground ice content (and water equivalent) of permafrost areas, and some first estimates of total ground ice content in rock glacier and rock glacier free areas and compare them to conventional estimates using remotely sensed data.</p><p> </p><p>Hauck, C., Böttcher, M., and Maurer, H. (2011). A new model for estimating subsurface ice content based on combined electrical and seismic datasets, The Cryosphere, 5: 453-468.</p>

scholarly journals Mountain permafrost degradation documented through a network of permanent electrical resistivity tomography sites

2018 ◽  
Author(s):  
Coline Mollaret ◽  
Christin Hilbich ◽  
Cécile Pellet ◽  
Adrian Flores-Orozco ◽  
Reynald Delaloye ◽  
...  
Keyword(s):  
Time Series ◽  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Permafrost Degradation ◽  
Data Set ◽  
Resistivity Tomography ◽  
Wide Range ◽  
Mountain Permafrost ◽  
Ice Water

Abstract. Mountain permafrost is sensitive to climate change and is expected to gradually degrade in response to the ongoing atmospheric warming trend. Long-term monitoring the permafrost thermal state is a key task, but it is problematic where temperatures are close to 0 °C. The energy exchange is indeed often dominantly related to latent heat effects associated with phase change (ice/water), rather than ground warming or cooling. Consequently, it is difficult to detect significant spatio-temporal variations of ground properties (e.g. ice-water ratio) that occur during the freezing/thawing process with point scale temperature monitoring alone. Hence, electrical methods have become popular in permafrost investigations as the resistivities of ice and water differ by several orders of magnitude, theoretically allowing a clear distinction between frozen and unfrozen ground. In this study we present an assessment of mountain permafrost evolution using long-term electrical resistivity tomography monitoring (ERTM) from a network of permanent sites in the Central Alps. The time series consist of more than 1000 data sets from six sites, where resistivities have been measured on a regular basis for up to twenty years. We identify systematic sources of error and apply automatic filtering procedures during data processing. In order to constrain the interpretation of the results, we analyse inversion results and long-term resistivity changes in comparison with existing borehole temperature time series. Our results show that the resistivity data set provides the most valuable insights at the melting point. A prominent permafrost degradation trend is evident for the longest time series (19 years), but also detectable for shorter time series (about a decade) at most sites. In spite of the wide range of morphological, climatological and geological differences between the sites, the observed inter-annual resistivity changes and long-term tendencies are similar for all sites of the network.

scholarly journals Hydrogeophysical Assessment of the Critical Zone below a Golf Course Irrigated with Reclaimed Water close to Volcanic Caldera

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2400
Author(s):  
Alex Sendrós ◽  
Mahjoub Himi ◽  
Esmeralda Estévez ◽  
Raúl Lovera ◽  
M. Pino Palacios-Diaz ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Hydraulic Properties ◽  
Electrical Resistivity Tomography ◽  
Reclaimed Water ◽  
Geophysical Methods ◽  
Water Infiltration ◽  
Golf Course ◽  
Pyroclastic Deposits ◽  
Undisturbed Soil ◽  
Resistivity Tomography

The geometry and the hydraulic properties of the unsaturated zone is often difficult to evaluate from traditional soil sampling techniques. Soil samples typically provide only data of the upper layers and boreholes are expensive and only provide spotted information. Non-destructive geophysical methods and among them, electrical resistivity tomography can be applied in complex geological environments such as volcanic areas, where lavas and unconsolidated pyroclastic deposits dominate. They have a wide variability of hydraulic properties due to textural characteristics and modification processes suh as compaction, fracturation and weathering. To characterize the subsurface geology below the golf course of Bandama (Gran Canaria) a detailed electrical resistivity tomography survey has been conducted. This technique allowed us to define the geometry of the geological formations because of their high electrical resistivity contrasts. Subsequently, undisturbed soil and pyroclastic deposits samples were taken in representative outcrops for quantifying the hydraulic conductivity in the laboratory where the parametric electrical resistivity was measured in the field. A statistical correlation between the two variables has been obtained and a 3D model transit time of water infiltration through the vadose zone has been built to assess the vulnerability of the aquifers located below the golf course irrigated with reclaimed water.

scholarly journals Degrading Permafrost Mapped with Electrical Resistivity Tomography, Airborne Imagery and LiDAR, and Seasonal Thaw Measurements

2021 ◽  
Author(s):  
Thomas A. Douglas ◽  
Christopher A. Hiemstra ◽  
Stephanie P. Saari ◽  
Kevin L. Bjella ◽  
Seth W. Campbell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Landscape Patterns ◽  
Fire Disturbance ◽  
Permafrost Degradation ◽  
Accurate Identification ◽  
Resistivity Tomography ◽  
Elapsed Time ◽  
Time Since Fire ◽  
Discontinuous Permafrost

Accurate identification of the relationships between permafrost extent and landscape patterns helps develop airborne geophysical or remote sensing tools to map permafrost in remote locations or across large areas. These tools are particularly applicable in discontinuous permafrost where climate warming or disturbances such as human development or fire can lead to rapid permafrost degradation. We linked field-based geophysical, point-scale, and imagery surveying measurements to map permafrost at five fire scars on the Tanana Flats in central Alaska. Ground-based elevation surveys, seasonal thaw-depth profiles, and electrical resistivity tomography (ERT) measurements were combined with airborne imagery and light detection and ranging (LiDAR) to identify relationships between permafrost geomorphology and elapsed time since fire disturbance. ERT was a robust technique for mapping the presence or absence of permafrost because of the marked difference in resistivity values for frozen versus unfrozen material. There was no clear relationship between elapsed time since fire and permafrost extent at our sites. The transition zone boundaries between permafrost soils and unfrozen soils in the collapse-scar bogs at our sites had complex and unpredictable morphologies, suggesting attempts to quantify the presence or absence of permafrost using aerial measurements alone could lead to incomplete results. The results from our study indicated limitations in being able to apply airborne surveying measurements at the landscape scale toward accurately estimating permafrost extent.

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