The PLOS One study examined whether one pseudo-dipole survey could reduce the need to collect several standard electrode-array datasets separately. The analysis combined analytical solutions, finite-element forward modeling, inversion and controlled noise experiments. It was not a field trial, so the results describe performance under modeled homogeneous, vertical-contact, multi-anomaly and four-zone resistivity conditions rather than performance at a hydrogeological site.

Forward and inverse calculations were performed with GeoElectroLab, a finite-element program developed by the research team. The inversion module used a smoothness-constrained Gauss–Newton algorithm, an unstructured mesh and the PARDISO parallel solver. Numerical tests varied electrode numbers and spacings, background and target resistivities, random noise, anomaly depth and inversion settings. Monte Carlo simulations used 100 realizations to examine filtering behavior across homogeneous half-space, vertical-contact and multi-anomaly models under noise levels from 1% to 30%.

The pseudo-dipole configuration fixes a reference current electrode and a reference potential electrode at opposite ends of the survey line. A mobile current-potential pair is then moved along the line in an inverted-trapezoidal measurement pattern, with one additional series obtained by interchanging the mobile electrodes. The study used this arrangement to generate apparent-resistivity pseudosections and inverted models, and compared them with a conventional dipole array and with Wenner α, β and γ arrays.

Under a homogeneous half-space model with 128 electrodes at 2.5 m spacing, a background resistivity of 100 Ω·m and 10% random noise, the average relative error of the apparent-resistivity analytical solutions was 2.5% for both the dipole and pseudo-dipole arrays. The dipole array produced a cumulative error approximately half that of the pseudo-dipole array, but the pseudo-dipole dataset was about twice as large. In a separate vertical-contact model, both arrays closely followed the theoretical response, with slightly lower average relative errors for the pseudo-dipole configuration, although the numerical and analytical discrepancy was larger for that configuration.

Resolution was evaluated with a model containing 11 low-resistivity anomalies, each 10 m by 10 m in a 1,000 Ω·m background. In the deeper layer with anomaly tops at 25 m, the pseudo-dipole inversion had an average full width at half maximum of 14.3 m, compared with 22.7 m for the dipole array; the true anomaly width was 10 m. This corresponded to a reported 37% improvement in lateral resolution. Semi-quantitative anomaly-recognition scores declined with depth for both configurations, from 0.85 to 0.41 for the pseudo-dipole array and from 0.83 to 0.23 for the dipole array as targets were moved from 5 m to 35 m depth. At 25 m depth, the dipole inversion clearly resolved four of seven anomalies and also produced false anomalies, whereas the pseudo-dipole inversion retained central anomalies with greater shape and value accuracy.

The transformation method reconstructs a target array by selecting the relevant dipole measurements, applying the required linear-combination coefficients and calculating apparent resistivity with the target array’s geometric factor. Reciprocal pseudo-dipole measurements were used for quality control because their values are not expected to be equal. A relative-difference threshold of 0.2 retained more than 90% of reliable data and excluded more than 95% of severely contaminated measurements across the tested model and noise conditions. In a multi-anomaly model with 10% noise, tightening the threshold from 0.2 to 0.15 changed normalized root-mean-square error by less than 5%, whereas relaxing it to 0.25 increased the error by more than 15%. The authors cautioned that site-specific noise could still affect the appropriate threshold.

Transformation accuracy was tested with a four-zone model containing resistivities of 10, 100, 200 and 1,000 Ω·m. With 5% random noise, relative differences between standard and transformed Wenner datasets were 2.5% for Wenner α, 3.1% for β and 1.8% for γ. Direct and transformed inversions produced generally consistent spatial patterns, although the pseudo-dipole inversion was closest to the true model. Its final root-mean-square error was 1.04, compared with 1.95 for standard Wenner α, 2.32 for standard β and 5.44 for standard γ. The corresponding transformed-array errors were 2.29, 2.02 and 6.10, respectively.

The study also estimated acquisition requirements rather than recording field time. For a 64-electrode survey with 61 pseudosection layers, the estimated number of current injections was 1,953 for the Wenner dataset and 496 for a four-channel pseudo-dipole configuration. Transformation amplified errors by approximately 2.0 to 2.2 for noise levels up to 20%, and the linear relationship was not expected to hold above 30% noise. The analysis therefore supports the numerical feasibility and modeled resolution of the approach, but the authors emphasized that field validation across diverse geological settings is still required. The current implementation also assumes two-dimensional subsurface structure, and secure placement of two reference electrodes at the line ends may be impractical in some environments.

Subject of Research: Numerical evaluation of a pseudo-dipole high-density DC resistivity array and its transformation into standard Wenner array data

Article Title: A comparative study of pseudo-dipole arrays and standard arrays based on the high-density DC resistivity method

Article References: Jiang, X., Jiang, S., Chen, H., Gong, J., & Liu, S. (2026). A comparative study of pseudo-dipole arrays and standard arrays based on the high-density DC resistivity method. PLOS One, 21(10), e0360161. https://doi.org/10.1371/journal.pone.0360161

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360161

Keywords: high-density DC resistivity, pseudo-dipole array, electrical resistivity tomography, Wenner array, array transformation, numerical modeling, aquifer mapping, inversion, quality control, hydrogeophysics, comparative, pseudo-dipole

Urban soils are unlike any others. Excavation, backfilling, sealing, compaction, demolition, and the importation of exogenous materials create intricate mosaics of soil horizons and anthropogenic deposits over very short distances. Physical and chemical properties such as texture, bulk density, porosity, organic matter content, pH, nutrient availability, and contaminant concentrations can change abruptly both laterally and vertically. Trace metals and organic pollutants inherited from former industrial activities, traffic emissions, and construction materials are frequently distributed in localized hotspots, further increasing spatial complexity. This heterogeneity challenges conventional soil sampling strategies, which often fail to adequately represent the spatial organization of soil properties and associated environmental constraints, making accurate characterization essential for land-use planning and avoiding inappropriate uses.

Over the past two decades, near-surface geophysical methods have become valuable tools for investigating soil spatial variability because they provide rapid, non-invasive, and spatially continuous information at resolutions that cannot be achieved through conventional sampling alone. Techniques including electromagnetic induction, ground-penetrating radar, seismic methods, and gamma-ray spectrometry respond to different physical properties of the subsurface, such as electrical conductivity, dielectric permittivity, seismic velocity, or natural radioactivity, which are themselves controlled by soil texture, water content, porosity, bulk density, clay mineralogy, soil structure, and the presence of coarse fragments or anthropogenic materials. Among these approaches, ERT has received particular attention because it provides high-resolution two- and three-dimensional images of the spatial distribution of subsurface electrical resistivity. The method is based on injecting electrical current into the ground and measuring the resulting potential differences, from which the true resistivity distribution is estimated through inversion procedures.

Soil electrical resistivity is governed by several interacting factors, including water content, pore connectivity, texture, clay mineralogy, porosity, and the abundance of coarse fragments or anthropogenic materials. Because electrical current is transmitted predominantly through the pore water rather than the solid mineral phase, bulk resistivity is controlled by the amount and composition of the pore water, pore connectivity, and the geometry of the pore network, all of which are strongly influenced by soil texture, structure, coarse fragment content, compaction, and horizon development. Consequently, resistivity integrates the effects of several key soil attributes and provides a physically meaningful representation of subsurface heterogeneity rather than direct measurements of individual soil properties. This integrative nature is particularly advantageous in urban environments, where soil variability often results from multiple superimposed processes that cannot easily be disentangled using conventional point measurements alone.

The study site was a plot of approximately 1,000 square meters located on the IRD site in Bondy, within the Seine-Saint-Denis department of the Paris metropolitan area. According to the land-use plan of the city of Bondy, the site lies over a succession of alluvial deposits derived from the 1:50,000-scale geological map produced by the French Geological Survey. Historically, the area was known in the mid-18th century for its dense forest, as shown in the 1756 Cassini map, and later became a popular destination for Parisians seeking rural retreats. The site was significantly altered during the construction of the IRD research center in 1947, when many gardens, vegetable plots, and refuse areas were consolidated, and the topography was substantially modified through the import and leveling of various materials, subsequently covered with a layer of forest-origin topsoil that was initially uncontaminated.

The ERT survey was carried out along linear profiles using a SYSCAL Pro resistivity meter operating quadrupoles sequentially selected among seventy-two electrodes. Measurements were performed using two electrode arrays: a reciprocal Wenner-Schlumberger configuration, which is well adapted to detect vertical contrasts in electrical resistivity and offers a better signal-to-noise ratio and greater depth of investigation, and a Dipole-Dipole configuration, which better captures horizontal contrasts and yields more pronounced resistivity contrasts at shallow depths. Short transverse profiles of 26.25 meters were spaced every 6 meters, while long longitudinal profiles of 53.25 meters were spaced every 1.5 meters, with a unit electrode spacing of 0.75 meters for both sets. The total number of measurements collected was 1,870 for the Dipole-Dipole array and 2,282 for the Wenner-Schlumberger array. Data interpretation was performed using RES2DINV and RES3DINV software, and spatial variation maps of calculated resistivity as a function of depth were generated using Surfer software.

The resistivity maps revealed significant variability both laterally and vertically. A linear anomaly observed at x = 5, extending down to approximately 90 centimeters depth, corresponded to a trench, with additional trench-like features visible near the center of the site radiating from a central manhole. At the surface, a first layer with resistivity around 50 ohm-meters corresponded to the topsoil layer distributed across the site. Below this, starting at approximately 25 centimeters depth, a second layer appeared with markedly lower resistivity values, indicative of coarse backfill material. In some areas, high-resistivity materials emerged with values reaching up to 315 ohm-meters, while at greater depths, intermediate resistivity zones of around 102 ohm-meters were detected in the southern and northeastern parts of the site, possibly corresponding to sandy pockets. The three-dimensional inversion enabled the generation of vertical resistivity profiles across the site with a spatial resolution of 37.5 by 37.5 square centimeters.

Two combined statistical analyses, Principal Component Analysis and Hierarchical Cluster Analysis, were used to classify all resistivity profiles by depth into four distinct groups, which served as the basis for the resulting classification map. While resistivity values were relatively similar across classes in the uppermost layer from 0 to 0.5 meters, they became highly discriminant between 0.5 and 2.5 meters depth. Class 1 showed both maximum and median resistivity values below 100 ohm-meters, whereas Class 4 reached a maximum resistivity exceeding 300 ohm-meters with median values around 220 ohm-meters. Classes 2 and 3 were intermediate, and Class 3 was notably distinct, characterized by a near-linear increase in resistivity with depth and high values beyond 2.5 meters. Following this typology, 30 auger surveys were distributed according to a proportionally stratified sampling design considering the surface area of each mapped resistivity unit, and soil samples were collected in each of the four soil categories at four different depths, totaling 120 samples.

The subsequent laboratory characterization showed that the ERT-derived classes corresponded to meaningful differences in measured soil characteristics. Soil texture was primarily controlled by depth, with only a weak effect of soil class, and the overall profiles exhibited a coarse texture with sand contents of 71 to 76 percent across layers. Classes C3 and C4 were relatively enriched in fine silt and clay, and significantly coarser textures occurred in layers B and C of soil class C4, which was also characterized by a relatively high sand content and low clay content in the surface layer. High concentrations of organic carbon and total nitrogen were observed in the surface layer corresponding to the added topsoil, with organic matter content decreasing markedly with depth to approximately tenfold lower organic carbon concentrations in the deepest layer. Both pH in water and pH in potassium chloride varied only with depth, showing an increase of approximately 0.5 pH units from the surface to the deepest layer, while cation exchange capacity, Olsen phosphorus, and most exchangeable cations were mainly driven by depth, positively correlated with soil organic carbon but negatively correlated with pH.

Mid-infrared spectroscopy revealed clear differences in organic matter composition among the ERT-derived classes, particularly for hydrophobic functional groups and polysaccharide-related compounds, suggesting that ERT may be more sensitive to qualitative differences in organic matter than to its total abundance. This interpretation is physically plausible because organic matter exerts a strong indirect control on soil electrical properties through its influence on aggregate stability, pore architecture, wettability, and water retention rather than through its intrinsic electrical conductivity. Hydrophobic organic compounds may reduce soil wettability and modify infiltration patterns, whereas microbial polysaccharides promote aggregate formation and enhance pore connectivity, thereby influencing the spatial distribution of soil water and the propagation of electrical current. Elemental composition determined by ICP-MS showed a strong and significant effect of depth for most elements, with significant differences among soil classes observed for several major elements including aluminum, iron, magnesium, and phosphorus, as well as for trace elements such as chromium and zinc. Trace elements, particularly lead, were detected at the site, but no significant differences among soil types were observed except in deeper layers, and variations in physico-chemical conditions, especially soil moisture, may influence trace element speciation and mobility, potentially affecting biota.

The findings carry broad implications for how cities understand the ground beneath them. Because the geoelectrical classes were established before soil sampling, the subsequent physicochemical measurements provided an independent assessment of whether the geophysical units corresponded to systematic differences in soil characteristics, and the significant differences observed when the physicochemical variables were considered jointly support the relevance of the spatial classification. ERT proved valuable not only for identifying spatial discontinuities but also for confirming the relative homogeneity of the site, thereby reducing uncertainty in soil characterization regardless of the degree of anthropogenic disturbance. The approach extends the use of ERT beyond conventional subsurface characterization by using continuous geophysical information as an operational decision-support tool for subsequent soil sampling, with broad potential applications including the optimization of soil quality and contamination monitoring programs, as well as the design of field experiments that account for pre-existing soil heterogeneity and thereby reduce experimental bias. Future studies should investigate the potential of time-lapse ERT, combined with complementary techniques such as electromagnetic induction, ground-penetrating radar, and digital soil mapping, to better characterize soil functioning, contaminant mobility, and temporal changes in urban environments, potentially opening new opportunities to investigate the links between soil structure, hydrological functioning, and carbon cycling in urban ecosystems.

Subject of Research: Urban soil science and geophysical characterization

Article Title: Exploring spatial variability in the physical and chemical properties of urban soils using electrical resistivity tomography

Article References: Ribler, C., Lerch, T. Z., & Robain, H. (2026). Exploring spatial variability in the physical and chemical properties of urban soils using electrical resistivity tomography. Frontiers in Soil Science, 6, Article 1924576. https://doi.org/10.3389/fsoil.2026.1924576

Image Credits: AI Generated

DOI: 10.3389/fsoil.2026.1924576

Keywords: electrical resistivity tomography, urban soils, soil sampling, organic matter, trace elements, geophysics, Exploring, spatial, variability, physical, chemical, properties

The study, published in the journal Plant and Soil, monitored three wheat genotypes with contrasting root architectures through a full season of terminal drought, the period during grain filling when water supply becomes progressively restricted and yield potential is sealed. Rather than relying on qualitative snapshots of soil wetness, the team converted time-lapse resistivity images into depth-resolved estimates of root water uptake, achieving a cross-validated accuracy of roughly 0.019 cubic metres of water per cubic metre of soil against independent sensor measurements. The result is a non-invasive phenotyping framework that can distinguish not just how much water a genotype extracts, but when, and from where in the profile.

The technical achievement rests on solving a long-standing calibration problem. ERT works by injecting electrical current into the soil through arrays of electrodes and measuring the resulting voltage differences; because soil electrical resistivity is strongly sensitive to water content, drying zones light up as resistivity hotspots. But translating resistivity into actual water content has traditionally required fixed petrophysical relationships, such as Archie-type models, which assume a single universal equation links the two quantities. In heterogeneous field soils, where texture and pore structure change with depth, that assumption breaks down. The Israeli team instead trained a Random Forest regression model that used both resistivity and measurement depth as predictors, allowing the data itself to define how the resistivity-moisture relationship shifts between soil layers.

The calibration dataset came from 278 paired observations between ERT-derived resistivity and Time-Domain Reflectometry sensors installed at depths from 0.2 to 1.5 metres. When the researchers compared five candidate models using cross-validation grouped by survey date, a strategy that prevents temporal data leakage, the Random Forest dramatically outperformed the analytical alternatives, which produced errors roughly three times larger. The machine learning model achieved a correlation of 0.974 with directly measured soil water content, with negligible bias, demonstrating that the geophysical signal could be trusted as a quantitative, not merely qualitative, record of soil drying.

The field experiment itself was a feat of logistical intensity. Under a mobile rain-out shelter at the university’s Rehovot experimental farm, 64 stainless steel electrodes lined a 32-metre transect divided into three 6-metre genotype zones. The team conducted 44 ERT surveys, at least three per week, from January through crop maturity, each requiring about 52 minutes. Terminal drought was imposed in mid-February by excluding all rainfall, leaving the plots with just 142 millimetres of total available water. Because rainfall was excluded and the coarse, sandy soil limited capillary rise and drainage, the researchers could attribute changes in soil water content almost entirely to root uptake, converting the calibrated moisture time series into cumulative extraction estimates for each 10-centimetre soil layer.

What the images revealed were three fundamentally different water-use strategies. The genotype WM-203, which combined a wide root angle with high root biomass, displayed what the authors describe as an aggressive extraction strategy: it engaged multiple soil layers early, simultaneously, and in a coordinated fashion, with correlation coefficients between daily uptake at different depths reaching 0.80 to 0.98. Its cumulative uptake climbed steeply from 11 millimetres in early February to roughly 85 millimetres by early April, the highest seasonal total, representing about 60 percent of the available water. This spatial redundancy, drawing from many depths at once, meant the plant never depended on a single moisture reservoir as the profile dried.

WM-140, a narrow-angled, high-biomass genotype, played a waiting game. Its uptake was dominated early by a single deep layer at 0.8 metres, which contributed a remarkable 47 percent of total uptake in February, the highest single-depth proportion observed anywhere in the experiment. As the season progressed, extraction broadened across mid- and deep layers, and cumulative uptake surged in mid-March, precisely when atmospheric vapour pressure deficit climbed toward its seasonal peak of 2.8 kilopascals. The third genotype, IPLR-760, with wide roots but low biomass, showed the most fragmented behaviour: erratic switching between shallow and deep extraction zones, with peak depths shifting by more than 0.6 metres between consecutive sampling dates, and weak hydraulic coupling in the mid-profile, where depth-pair correlations fell as low as 0.52.

The physiological consequences tracked the underground patterns with striking fidelity. WM-203 sustained photosynthetic capacity through grain filling and produced the highest grain yield at 7.0 tonnes per hectare, with remarkably low variability, translating to a water productivity of about 8.2 kilograms of grain per cubic metre of extracted water. WM-140 reached 6.3 tonnes per hectare, though with high replicate-to-replicate variability that hints at the risk inherent in its dependence on late-season deep moisture. IPLR-760, despite extracting a comparable total volume of water to WM-140, roughly 75 millimetres, collapsed physiologically: its chlorophyll fluorescence plunged to the lowest value recorded in the entire dataset during the critical grain-filling window, and its yield crashed to just 1.5 tonnes per hectare, with water productivity of a mere 1.9 kilograms per cubic metre.

That last comparison may be the study’s most consequential finding. Two genotypes extracted nearly identical volumes of water over the season, yet one produced four times more grain than the other. Total water uptake, in other words, is not the story; the timing, depth distribution, and coordination of uptake are. The authors argue that drought adaptation hinges on synchronising root hydraulic activity with canopy demand during grain filling, and that structural traits such as rooting depth and root biomass, while useful, are insufficient predictors of field performance on their own. A sparse root network, they suggest, may simply lack the density of active uptake sites needed to sustain water supply under the steep hydraulic gradients of a drying profile, a hypothesis consistent with broader soil-plant-atmosphere theory in which root conductance becomes the bottleneck under deficit.

The implications for breeding are considerable. Wheat production currently stands near 799 million tonnes annually, and meeting demand projected for 2050 will require at least a 60 percent increase, much of it from water-limited environments where every millimetre of extracted soil water counts. If ERT-based phenotyping can be scaled to larger breeding populations, breeders could select directly for functional water-use coordination rather than proxy traits measured in pots. The framework is not without limitations: the genotype zones along the transect were not replicated across independent plots, inversion smoothing and petrophysical model choice influence the depth resolution of the estimates, and the absence of direct root measurements leaves some structural interpretations open. The authors themselves call for integration with root imaging, isotopic water-source partitioning, and replicated transects in future work. But the core demonstration stands: a technique borrowed from hydrogeology, married to machine learning, has made the hidden half of the wheat plant visible, quantitative, and breedable, at exactly the moment a warming climate is making every root’s strategy a matter of global food security.

Subject of Research: Non-invasive quantification of root water uptake in field-grown wheat under terminal drought using electrical resistivity tomography and machine learning calibration

Article Title: ERT-based root water uptake quantification in field-grown wheat under terminal drought

Article References: Akaerue, E., Kashi, O., Sadeh, R., Peleg, Z., & Schwartz, N. (2026). ERT-based root water uptake quantification in field-grown wheat under terminal drought. Plant and Soil. https://doi.org/10.1007/s11104-026-09078-2

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09078-2

Keywords: Electrical Resistivity Tomography, root water uptake, wheat, terminal drought, Random Forest, soil water content, root system architecture, drought phenotyping, water productivity, grain yield, hydrogeophysics, plant and soil

The lake was no natural accident. Historical documents record that the Burgrave of Starkenburg had already constructed a lake for fish farming before 1463, and a charter from 1474 officially marks the beginning of Lake Lorsch as an artificial fish pond. Its fish were destined for the tables of Friedrichsburg, later called Neuschloss, a hunting lodge in the Lorsch Forest, and for the electoral court in Heidelberg. The lake sat in a landscape already rich in water: the area south of Lorsch Abbey, founded in 763 to 764 CE and now a UNESCO World Heritage Site, had been a marshy wetland for centuries, mentioned in a 1265 document that describes a planned drainage of the so-called Palus Laurissensis, the Lorsch marsh. Fish farming in the floodplain may even predate the abbey itself, with early medieval sources hinting at ponds in the Weschnitz lowlands.

Because nothing of the lake survives at the surface, the researchers turned to a combination of high-resolution remote sensing and subsurface investigation. Using a LiDAR-based digital elevation model with one-meter resolution, they computed a relative elevation model that detrends the terrain along the courses of the old and new Weschnitz channels, revealing subtle height differences invisible to the naked eye. The lake’s maximum extent, confirmed by boundary stones mapped after a 1721 legal dispute, occupies a basin lying between 94.5 and 95.5 meters above sea level, wedged between two belts of late-glacial sand dunes, one rising up to 10 meters in the west and a smaller belt of up to 6 meters in the east. Crucially, the model shows the lake area sits as much as 1.8 meters below the water level of the old Weschnitz channel, while the Landgraben canal lies even lower.

That topographic relationship solved a centuries-old engineering puzzle. Because the lake basin lies below the old Weschnitz but above the Landgraben, water could only flow into the lake by gravity from the old Weschnitz, which historical maps confirm was the source. A 1700 map shows an artificial supply channel, the Renngraben, carrying water from the old Weschnitz into the lake and even crossing the Landgraben, built between 1535 and 1544, on a small water bridge. Since the lake predates the Landgraben by roughly sixty years, the crossing must have been added later, a striking example of layered infrastructure accumulating in a single floodplain. The researchers emphasize that such quantitative elevation relationships simply cannot be extracted from historical documents alone, just as the sediments cannot be interpreted without the historical record.

Groundwater emerged as the second protagonist of the story. Records from a Hessian observation well spanning 1974 to 2024 show modern water tables averaging 2.2 meters below the surface, but a hydrological map from April 1957, before large-scale water abstraction began, shows groundwater within half a meter of the ground surface across the lake area, with occasional flooding in the north. The team argues that these pre-extraction levels offer the best available analogue for historical conditions. Medieval western Europe, other research suggests, experienced generally higher groundwater tables during warm periods. A groundwater-fed wetland would explain the persistent marsh, the repeated but apparently unsuccessful drainage attempt of 1265, and the fish farming practiced by Lampertheim farmers in the Krähenbruch area in the fourteenth and fifteenth centuries.

To test whether lake deposits actually survive, the researchers drilled four sediment cores along a transect through the central lake area, guided by the 1700 map showing the Renngraben. They supported the coring with electrical resistivity tomography along an 80-meter profile and with direct-push hydraulic profiling, which logs electrical conductivity and injection pressure at two-centimeter vertical resolution. Laboratory analyses included grain-size determination, loss-on-ignition measurements of organic content, magnetic susceptibility scanning, and portable X-ray fluorescence geochemistry, with element ratios such as log Ca/Ti, log K/Ti and log Rb/Sr used to track grain size, weathering and groundwater fluctuations through the profiles.

The cores delivered a clear verdict. Core LOR 21A contains a 26-centimeter-thick unit of silt and clay-rich sediment with a fining-upward trend, hydromorphic features, strong reducing conditions and a distinctive carbonate lens. The team interprets this unit as a genuine lake deposit. The thickness matches expectations remarkably well: natural lakes typically accumulate about one millimeter of sediment per year, and Lake Lorsch existed for roughly 250 years, predicting a deposit on the order of 25 centimeters. The carbonate lens, a feature known in the Upper Rhine Graben as Rheinweiss, marks a historical boundary of elevated groundwater, and secondary carbonate precipitation may also have been driven by aquatic plants such as stoneworts removing carbon dioxide from bicarbonate-rich water. Short cores LOSE 4 and LOSE 5 show a comparable clayey, organic-enriched unit, confirming the deposit’s lateral extent.

Core LOR 20A, drilled just 27 meters away, tells a different story. Its fine-grained, organic-rich unit sits at a lower absolute elevation than the lake deposits and is capped by a sharply bounded, mixed sandy layer. The electrical resistivity profile shows a high-resistivity anomaly exactly at this location, consistent with sand-filled sediments rather than clay-rich lake muds. The researchers interpret this core as the infill of the Renngraben itself, the anthropogenic supply channel, its high organic content reflecting dense vegetation along the waterway. The sharp overlying boundary likely records later leveling and backfilling associated with the drainage campaigns of the nineteenth and twentieth centuries. Without radiocarbon ages, a post-lake drainage channel cannot be entirely excluded, but the scale of the anomaly favors the Renngraben of the lake phase.

The lake’s biography was turbulent even in its working life. Historical sources record that it was not continuously filled: it was drained completely at intervals, variously reported as every three years or from time to time, both to maintain water quality and to convert the bed to pasture. It stood dry from 1595 to 1609 and was repeatedly drained in the following decades. From 1623, the electors of Mainz and the Palatinate fought a decades-long dispute over ownership and the lake’s exact size, and boundary stones from that conflict still dot the area. After the final drainage around 1718 to 1721, the land became the hamlet of Seehof, whose impoverished inhabitants emigrated to America between 1852 and 1855 before the Scipio family completed the modern drainage system in 1862.

Beyond its local interest, the study carries a broader message about the fluvial anthroposphere, the concept at the heart of a German priority program on how medieval and early modern societies transformed river landscapes. The creation of Lake Lorsch generated a new anthropogenic carbon sink within the floodplain, altered sediment routing, and left a palimpsest of channels, dikes and embankments whose path dependencies still constrain modern river restoration. Shallow, warm waters proved ideal for carp farming, and the engineered inflows allowed managers to regulate the lake despite natural groundwater variability, all without sealing the bottom. The authors caution that the relative weight of natural hydrological variability versus human intervention remains quantitatively unknown and call for future paleohydrological modeling. But the verdict on the past is firm: long before the industrial reshaping of Europe’s rivers around 1800, the people of the Weschnitz floodplain were already engineers of their waterscape, and the ground beneath the fields of Seehof still remembers it.

Subject of Research: Geomorphological and sedimentological reconstruction of the historical artificial Lake Lorsch in the Weschnitz floodplain, Upper Rhine Graben, Germany

Article Title: The geomorphological and sedimentological legacy of the historical Lake Lorsch within the Weschnitz floodplain (northeastern Upper Rhine Graben, Germany)

Article References: Henselowsky, F., Fischer, P., Appel, E., Jäger, B., Hillmus, N., Sandbrink, H., Becker, T., Prien, R., Schenk, G. J., Mächtle, B., Recker, U., Bubenzer, O., & Vött, A. (2026). The geomorphological and sedimentological legacy of the historical Lake Lorsch within the Weschnitz floodplain (northeastern Upper Rhine Graben, Germany). E&G Quaternary Science Journal, 75(1), 1-18. https://doi.org/10.5194/egqsj-75-1-2026

Image Credits: AI Generated

DOI: 10.5194/egqsj-75-1-2026

Keywords: Lake Lorsch, Weschnitz floodplain, Upper Rhine Graben, fluvial anthroposphere, medieval fish farming, groundwater, sediment cores, digital elevation model, electrical resistivity tomography, historical maps, floodplain geomorphology, water management

The stripes run across a parcel of land known as the Rindlache, part of the former course of the Bergstraßenneckar, a now-inactive channel of the lower Neckar River. During the late glacial period, beginning roughly 14,500 years ago, the Neckar did not take its modern direct route to the Rhine near Mannheim. Instead, it flowed northward across its alluvial fan, parallel to the forested flank of the Odenwald mountains, and joined the Rhine about fifty kilometers further upstream at Trebur. When the river abandoned this course at the transition to the Holocene, it left behind a chain of crescent-shaped paleo-meanders, some up to 150 meters wide and four meters deep, which can still be traced in the terrain and even in modern property boundaries and roads. Over thousands of years, the abandoned channels slowly filled with carbonate-rich mud, peat, and clay, becoming waterlogged swamps that persisted into historical times.

It was precisely this waterlogging that made the Rindlache such an unlikely place for mining. The name itself is a clue: “Lache” refers to the standing water that pooled in the depression, while “Rind” recalls its use as cattle pasture. In a landscape dominated by the sands and gravels of the Rhine and Neckar, the fine-grained organic-rich clays of the silted-up channel were a rare and valuable resource. But for most of history, the high groundwater table made digging into them practically impossible. The new study demonstrates that the excavation only became feasible after the great river regulation campaigns of the nineteenth century, initiated by the engineer Johann Gottfried Tulla between 1817 and 1882, which straightened and shortened the Rhine, caused the river to incise by up to ten meters, and dragged the regional groundwater table down with it. That distant, landscape-scale intervention quietly drained the swamps of the old meanders and unlocked their buried clay.

The investigation began with vegetation. Comparing multi-temporal satellite images from 2000, 2015, 2018, and 2019, the researchers noticed a consistent pattern of pale-green and yellowish stripes running south-southwest to north-northeast across an area of roughly 100 by 50 meters. The stripes reflect differences in moisture: the fine-grained natural floodplain sediments hold water differently than the medium sand that fills the buried trenches, and crops growing over the sand-filled features show reduced vitality in dry periods. A high-resolution digital elevation model added another clue, showing that the striped surface sits about forty centimeters above the neighboring channel floor. To peer beneath the surface, the team deployed electrical resistivity tomography, running a transect perpendicular to the anomalies. The profile revealed nine circular high-resistivity anomalies, one beneath each stripe, embedded in the low-resistivity clayey and organic layers of the channel fill, reaching down about seven meters.

Two hand-dug pits, each up to 1.7 meters deep, then exposed the stratigraphy directly. The undisturbed sequence reads like a condensed history of the Holocene. At the base lies a nearly white, carbonate-rich sandy silt interpreted as gyttja, the limnic ooze that accumulated on the floor of the abandoned channel during the Preboreal and Boreal periods. Above it sits a black peat, extraordinarily rich in organic matter at around seventy percent loss on ignition, marking the final silting-up of the meander. Higher still, organic-rich black clays record a distal floodplain phase fed by floods of the still-active Neckar, with the researchers suggesting that soil erosion triggered by early Neolithic forest clearing, and later by the Michelsberg and Corded Ware cultures, may have supplied the dark sediment. Gastropod shells scattered through these layers point to an open, amphibious floodplain environment, while a zone of secondary carbonate precipitation, locally known as “Rheinweiß,” preserves the memory of a once-fluctuating groundwater table.

Cutting violently through this natural sequence are the trenches themselves: massive, unstratified bodies of medium sand containing angular clasts of the surrounding mud, sharp boundaries, and even drapes of clay scraped from the trench walls during backfilling. Microscopic analysis of the sand grains provided the key to their origin. The quartz grains are well-rounded to very well-rounded and frosted, identical to sand from the Bettenberg dune, a parabolic dune of Last Glacial Maximum to late-glacial age lying only about two hundred meters away. In contrast, sand from the active Neckar channel contains shiny, coated grains and calcite fragments from the river’s catchment. The conclusion was clear: the miners had hauled dune sand from the nearby Bettenberg, which even has a documented historical sand quarry at its southern edge, to refill their excavation pits immediately after digging out the clay.

Dating the backfill proved to be an elegant challenge. The team extracted quartz grains from six samples and applied optically stimulated luminescence dating, which measures how long mineral grains have been hidden from sunlight. The results were wildly scattered: depending on the aliquot and the statistical age model applied, apparent ages ranged from the Last Glacial Maximum to a mere three hundred years before present. Rather than ruining the study, this scatter became evidence in itself. When sand is shoveled quickly into a trench in lumps, many grains never see the light and retain their ancient latent signal, producing exactly the kind of dose distribution the researchers observed. The youngest apparent ages, around three hundred to four hundred years, set a maximum bound on the filling event, while the true age of the operation had to be far more recent.

The decisive answer came from the Hesse State Archive in Darmstadt. Among files on Viernheim’s brickyards, the researchers found a license dated 1 June 1865, granted for a brickworks site belonging to Peter Minnig, with an attached plan whose parcels could be matched to the modern cadastral map. The former parcel number 33, registered to Minnig, covers precisely the striped anomalies of today’s parcel 153. The license conditions state that the clay substrate would be excavated in the center of the plot and the pits refilled immediately, with bricks stacked and fired with stone coal nearby. Every line of the archival document matches the physical evidence: the manual trenching, the immediate backfill with dune sand, and the depth of excavation reaching the black clay and peat layers. A hollow brick pushed into the sand infill during a 1970s land consolidation survey, and the absence of any trenching record in the 1930s soil appraisal, bracket the operation neatly between the mid-nineteenth century and the twentieth.

The broader significance of the finding lies in what it reveals about cascading human impacts. Clay mining for mud bricks is ancient in western Europe, introduced by the Romans and revived from the twelfth century onward, and the Viernheim area hosted brickworks from at least the Middle Ages, including a drowned clay pit documented in 1482. Yet the Rindlache operation stands apart because it was only made possible by a remote consequence of river engineering dozens of kilometers away. The Tulla-era regulation of the Rhine lowered groundwater across the entire Upper Rhine Graben, and without that drop below roughly one and a half meters, the sand-filled trenches would have flooded. The researchers even suggest that the narrow, sometimes discontinuous trenches, dug by workers starting at different points along a line, may have been kept slender deliberately to resist groundwater inflow. The silted-up meanders of the Bergstraßenneckar, the authors argue, are not just a natural landscape archive but a cultural one, and similar striped anomalies spotted in satellite images elsewhere in the Hessisches Ried hint that many more forgotten clay mines may still be waiting to be read from above.

Subject of Research: Historical clay mining in the silted-up paleo-channel of the late-glacial Bergstraßenneckar in the Upper Rhine Graben, Germany

Article Title: Historical clay extraction from paleo-channel deposits of the late-glacial Bergstraßenneckar in the Upper Rhine Graben, southwestern Germany

Article References: Henselowsky, F., Kadereit, A., Herzog, M., Tuczek, B., Thiemeyer, H., Bubenzer, O., & Engel, M. (2026). Historical clay extraction from paleo-channel deposits of the late-glacial Bergstraßenneckar in the Upper Rhine Graben, southwestern Germany. E&G Quaternary Science Journal, 75(1), 33-47. https://doi.org/10.5194/egqsj-75-33-2026

Image Credits: AI Generated

DOI: 10.5194/egqsj-75-33-2026

Keywords: Bergstraßenneckar, paleo-channel, clay mining, Upper Rhine Graben, OSL dating, electrical resistivity tomography, river regulation, groundwater lowering, brickworks, satellite imagery, geoarchaeology, fluvial anthroposphere

The scientific stakes are considerable. Rockfall and rock slope failures in periglacial environments are projected to increase as climate warms, threatening mountaineers, high-alpine infrastructure such as cable cars and huts, and even downstream valleys through large cascading events with long run-out distances. While the role of permafrost thaw in weakening rock has been studied intensively, the mechanical role of water and ice within fractures has often been neglected, even though hydrostatic and cryostatic pressures are increasingly recognised as key drivers in the conditioning and initiation of instabilities. Field evidence for these pressures has been scarce, largely because observing hydrological and cryogenic processes in steep, frozen rock is inherently difficult.

The Kitzsteinhorn site offered an ideal natural laboratory. The rockwall consists of fractured calcareous mica schist with well-developed schistosity dipping parallel to the slope, creating open pathways for water flow. Optical borehole scans revealed open fractures with apertures of up to 71 millimetres in the upper metres of the rock mass. The site is accessible year-round by cable car and hosts a dense array of complementary instruments, including a 30-metre-deep borehole recording rock temperature since 2015, fifteen nearly horizontal 25-metre-long rock anchors instrumented with hydraulic load cells, and a vertical borehole with a piezometer installed at 16.85 metres depth, exactly at the boundary between the mica schist and an underlying serpentinite band.

The electrical resistivity tomography setup itself is an engineering achievement. Thirty stainless-steel expansion anchors bolted into the rock at 2-metre intervals served as electrodes along a 58-metre profile beginning near the cable car station at 3,016 metres. A terrameter housed inside the summit station collected up to 135 data points per day using the Wenner configuration, chosen to maximise signal strength in the high-resistance conditions typical of frozen bedrock. Reciprocal measurements allowed the team to quantify errors precisely, and only about half a percent of data points exceeded even the strictest outlier thresholds, confirming the exceptional quality of the dataset, which totalled more than 20,000 measurements over the year.

Converting resistivity into meaningful physical information required careful calibration. The researchers used a resistivity-temperature relation calibrated with in situ borehole temperatures and laboratory experiments on saturated core samples from the site, whose pore water conductivity closely matched local snowmelt water. Inversions were performed with a time-lapse difference algorithm that suppressed systematic errors while preserving the rapid spatial resistivity changes caused by water infiltration along fractures, which conventional filtering approaches would have smoothed away. The result was a daily-resolution, quantitatively interpretable image of the subsurface through an entire seasonal cycle, something previous monthly surveys could only hint at.

The analysis revealed five characteristic phases of seasonal forcing. Phase I, stable freezing from April to May, kept rock temperatures below minus 0.5 degrees Celsius with fractures predominantly ice-filled and hydraulic heads gradually rising from 0.78 to 0.88 bar. Phase II, snowmelt and subsurface warming from May to July, proved dramatic: resistivity plummeted from around 140 to as low as 9 kilo-ohm metres as meltwater flooded the fracture network, while piezometric levels reached pressures equivalent to water columns of up to 12 metres, or about 1.2 bar. Simultaneously, anchor loads declined from 576 to 519 kilonewtons, signalling stress redistribution within the jointed rock mass as the active layer developed and ice in deep fractures began to melt.

Phase III, from July to September, saw the active layer reach its maximum thickness of 4.5 metres, with resistivity and anchor loads falling to their seasonal minima of 2.5 kilo-ohm metres and 493 kilonewtons respectively. Phase IV, superficial cooling from September to November, brought subzero temperatures through the entire rock mass by mid-October, yet resistivity and anchor loads at depth remained stable, indicating that the transition from water-filled to ice-filled discontinuities had not yet begun, likely due to freezing-point depression from rock properties, salinity or pore pressure. Phase V, deep freezing from November to April, then delivered the second critical window: resistivity in deeper layers rose and anchor loads climbed to a seasonal peak of 574 kilonewtons as the freezing front propagated downward, suggesting the onset of ice formation and rising cryostatic pressures within the fractures.

The mechanical interpretation of these two critical phases draws on well-established physics. During snowmelt, water perches above ice-sealed fissures, which are far less permeable than unfrozen ones, building hydrostatic pressure that can mechanically widen fractures; because flow through a planar fracture scales with the cube of its aperture, such widening feeds back into even greater water flux. Pressurised water also transports heat into the rock far more efficiently than conduction alone, potentially carving thaw corridors that accelerate permafrost degradation. In winter, the roughly 9 percent volumetric expansion as water freezes can theoretically generate pressures up to 207 megapascals, though fully confined, water-saturated freezing is unlikely on an open rockwall face. More plausible is ice segregation, in which slow freezing rates and sustained subzero temperatures draw water toward the freezing front, growing ice lenses whose crystallisation pressures are captured by the rising anchor loads. The team notes that cryostatic shear forces may rise faster than the cooling-strengthened shear resistance of the rock, preparing the ground for instability.

The broader implications reach well beyond one mountainside. Recent collapses at the Matterhorn, Bliggspitze, Piz Scerscen and Fluchthorn underscore how permafrost rock slopes are failing across the Alps, and the seasonal windows of high hydrostatic and cryostatic pressure identified here offer a framework for understanding when such failures are most likely to be preconditioned. The study also demonstrates that automated, temperature-calibrated resistivity monitoring can work reliably in one of the harshest monitoring environments on Earth, provided cables are protected from rockfall and avalanches and equipment is disconnected during lightning storms. As permafrost continues to warm, continuous daily imaging of the water, ice and stress hidden inside fractured rockwalls may become an essential early-warning tool for the infrastructure and communities that cling to high-alpine terrain.

Subject of Research: Seasonal hydrostatic and cryostatic forcing of permafrost rockwalls monitored with automated electrical resistivity tomography

Article Title: Seasonal thermo-hydro-mechanical dynamics of permafrost rockwalls revealed by automated electrical resistivity monitoring

Article References: Offer, M., Hartmeyer, I., Weber, S., Keuschnig, M., & Krautblatter, M. (2026). Seasonal thermo-hydro-mechanical dynamics of permafrost rockwalls revealed by automated electrical resistivity monitoring. Earth Surface Dynamics, 14(5), 661-683. https://doi.org/10.5194/esurf-14-661-2026

Image Credits: AI Generated

DOI: 10.5194/esurf-14-661-2026

Keywords: permafrost, rockwalls, electrical resistivity tomography, cryostatic pressure, hydrostatic pressure, rockfall, Kitzsteinhorn, snowmelt, ice segregation, alpine hazards, active layer, frost weathering

The stakes extend far beyond a single hillside. Landslides are the deadliest natural hazard in Nepal, concentrated in the middle Himalayan districts where steep terrain, fragile geology, and intense monsoon rainfall converge. The Himalayan belt as a whole, a tectonically active arc stretching 2,400 kilometers, suffers landslide damages exceeding one billion US dollars annually and claims hundreds of lives each year. Nepal occupies roughly 800 kilometers of this arc, and approximately 83 percent of its territory is steeply sloping. The Kali Gandaki corridor, which follows the river of the same name toward the Chinese border, is a lifeline for about seven million people across 24 hilly districts, connecting them to markets and economic opportunity. When a slope like Sirubari’s repeatedly collapses, entire communities lose their connection to the outside world.

The Sirubari site sits at a geologically telling location: the boundary between the Lesser Himalayan Sequence and the Higher Himalayan Sequence. The Lesser Himalayan rocks here are low-grade metamorphic units, chiefly quartzite, phyllite, schist, and gneiss, and phyllite in particular has a well-documented susceptibility to landsliding. These rocks dip generally northward, sub-parallel to the regional fabric associated with the Main Central Thrust, making the rock mass anisotropic and prone to weakness under saturated conditions. Earthquakes readily fracture these relatively weak formations, and the fractured rock then accumulates loose debris that heavy rainfall can mobilize. In other words, the site combines a structurally weakened bedrock foundation with a thick blanket of loose, water-hungry debris, a combination that forensic studies elsewhere in the Himalayas have repeatedly flagged as dangerous.

To see inside the slope, the research team deployed electrical resistivity tomography using the classic Wenner electrode array, chosen for its depth of investigation, its precision in both horizontal and vertical detail, and its favorable signal-to-noise ratio. Three two-dimensional profiles, ERT-1, ERT-2, and ERT-3, were run across the landslide zone with a combined array length of 1,237 meters. The field data were inverted with the RES2DINV software, converging to root-mean-square misfits of 2.8 to 3.5 percent, comfortably below the 5 percent threshold generally accepted as evidence of reliable inversion quality. The resulting resistivity sections revealed a layered subsurface: organic colluvial topsoil a few meters thick, unsaturated boulder-dominated colluvium, saturated silty colluvium, and beneath it all, fractured phyllite bedrock grading from unsaturated to fully saturated with depth.

The most consequential finding was the sheer thickness of the colluvial mantle. In the central sections of the ERT profiles, the loose debris deposits exceed 21 meters, and locally may reach 30 meters, before the fractured phyllite bedrock is encountered. Multiple slip surfaces were identified within this mass, confirmed both in the field and in the resistivity inversions. Crucially, the geophysical interpretation was not left to stand alone. The team drilled two boreholes, BH-1 and BH-2, each to 15 meters, and extracted the resistivity values at the borehole locations to calibrate the ERT sections against the actual lithological logs. The sandy colluvium encountered in both holes corresponded to resistivity values of 80 to 300 ohm-meters, while the measured groundwater levels, 5.45 meters deep in BH-1 and just 1.13 meters in BH-2, aligned spatially with the boundary between high- and low-resistivity zones in the profiles.

The boreholes themselves told a consistent story. Neither intercepted bedrock within 15 meters, corroborating the ERT evidence of exceptionally deep colluvium. The material was overwhelmingly sand, between 73.45 and 96.50 percent, with gravel content of 0 to 7.51 percent and fines ranging from 2.86 to 24.39 percent. Natural moisture content ranged from 17.52 to 23.58 percent, indicating moderate to high moisture retention throughout the mass, exactly what one would expect from a slope sitting atop a shallow water table. Specific gravity values of 2.65 to 2.72 are typical of phyllite-derived material, confirming the debris’s provenance. Direct shear tests yielded friction angles between 24 and 32 degrees and cohesion between roughly 2 and 14 kilonewtons per square meter, with the weakest samples, those from 4 to 10 meters depth in BH-2, showing the highest fines content and the lowest strength.

With the subsurface architecture established, the team built a coupled numerical model in GEOSTUDIO. A SEEP/W finite element simulation computed steady-state pore water pressures through the saturated and unsaturated colluvial profile, using van Genuchten hydraulic conductivity functions estimated from the grain size distributions and hydraulic conductivities of 10 to the minus 4 to 10 to the minus 5 meters per second for the colluvium, against only 10 to the minus 8 meters per second for the phyllite. The pore pressure field was then passed to SIGMA/W for effective stress redistribution, and both were fed into SLOPE/W, which performed limit equilibrium analysis using the Morgenstern-Price method, satisfying both force and moment equilibrium. The critical slip surface emerged at 18 to 22 meters depth, a deep-seated failure plane buried within the colluvial mass, and the computed factors of safety of 0.857 to 0.858 confirmed that the slope is in active failure under monsoon conditions.

The mechanism that emerges from this convergence of evidence is groundwater-driven, not structurally driven. Monsoon rainfall infiltrates the thick, permeable sandy colluvium and then ponds above the low-permeability phyllite bedrock, building up pore water pressures at depth. Rising pore pressure reduces effective stress, and with it the shear strength available along potential failure surfaces, a mechanism long recognized in colluvial slopes in the Alps and the Himalayas alike. The authors note that because the baseline factor of safety is already well below unity with design parameters drawn from the middle of the measured strength range, the diagnosis of active failure holds even if the weakest measured values are used. Large tension cracks observed near the crown of the landslide provide independent field confirmation of the substantial stresses within the moving soil mass.

The forensic team is candid about the limits of the investigation. The boreholes stopped at 15 meters without reaching bedrock, so the deep-seated failure surface is inferred from converging indirect evidence rather than directly observed; no inclinometers were installed to measure shear zone movement; the seepage modeling assumed steady-state rather than transient monsoon conditions; and no systematic rock mass characterization of the phyllite was performed. As follow-up priorities, they recommend slope inclinometers, deeper boreholes of 30 to 35 meters to intercept the colluvium-bedrock contact, transient seepage modeling driven by daily rainfall records, and a formal probabilistic sensitivity analysis of the strength and groundwater parameters.

The mitigation prescription follows directly from the diagnosis. Because groundwater lowering is the dominant control on stability, the primary recommendation is subsurface drainage: horizontal drains installed at 10-meter spacing to depress the water table, complemented by concrete-lined surface drains along the slope crest to intercept runoff before it infiltrates. These are paired with soil nail reinforcement on a 1.5 by 1.5 meter grid, 8 meters long and inclined at 20 degrees, and bioengineering measures for surface protection, with a design target factor of safety of at least 1.3 for the permanent slope. The urgency is underscored by national trends: more than 800 rainfall-induced closures were documented across 41 Nepali highways during the 2024 monsoon alone. For the seven million people who depend on corridors like the Kali Gandaki road, the Sirubari study offers something rare in Himalayan landslide management, a site-specific, evidence-based account of exactly why a slope keeps failing, and a technically grounded path toward fixing it.

Subject of Research: Groundwater-driven recurrent slope failure along the Kali Gandaki Road corridor in the Lesser Himalayas of Nepal

Article Title: Forensic geotechnical–geophysical investigation of groundwater-driven recurrent slope failure along the Kali Gandaki Road corridor, Lesser Himalayas, Nepal

Article References: KC, R., Mahato, A. B., Acharya, A., Ojha, B., Subedi, M., Misra, J., & Acharya, I. P. (2026). Forensic geotechnical–geophysical investigation of groundwater-driven recurrent slope failure along the Kali Gandaki Road corridor, Lesser Himalayas, Nepal. Discover Geoscience, 4(1), Article 311. https://doi.org/10.1007/s44288-026-00680-6

Image Credits: AI Generated

DOI: 10.1007/s44288-026-00680-6

Keywords: landslides, Nepal, Himalayas, groundwater, slope stability, electrical resistivity tomography, geotechnical engineering, phyllite, colluvium, pore water pressure, Kali Gandaki corridor, monsoon

The idea of the fluvial anthroposphere differs from the better-known Anthropocene. Rather than defining a single stratigraphic moment when humanity began leaving its mark on the geological record, the fluvial anthroposphere describes a long, uneven, and locally variable transition from natural to human-dominated river landscapes. This transition unfolded at different times in different places, shaped by societal responses, technological innovations, and ecological feedbacks. In the humid lowlands of central Europe, the shift began remarkably early, sometimes as far back as the Neolithic period in the sixth millennium BCE, as documented in Belgian catchments such as the Dijle and Gete rivers and in eastern German lowlands. In low-mountain ranges, however, the transformation often came much later, frequently not before the Middle Ages between roughly 500 and 1500 CE.

The Wiesent River catchment offers an ideal natural laboratory for studying this delayed transformation. Covering 1040 square kilometers of the northern Franconian Alb, the catchment has been settled since the Neolithic yet has remained overwhelmingly rural, without major cities, monasteries, or industrial centers. This makes it possible to assess the cumulative effects of ordinary human activities, such as small-scale agriculture and village life, without the overwhelming signal of urbanization. The river itself runs 78 kilometers from its source near Steinfeld to its confluence with the Regnitz near Forchheim, cutting through a karstic plateau of Jurassic limestone and dolomite that rises to around 450 meters above sea level. Deeply incised valleys, typically only 50 to 70 meters wide, confine the floodplains and concentrate the sedimentary record.

To reconstruct the valley’s history, the team combined a comprehensive multidisciplinary review with the first geoscientific field investigations. The review synthesized environmental data, archaeological findings, medieval and early modern documents, administrative records, place-name analysis, and archival maps. The fieldwork included electrical resistivity tomography, a geophysical technique that maps subsurface resistivity variations to reveal buried sediment bodies and ancient channel fills, along with percussion drilling and laboratory analysis of sediment cores. At the Höfen site, roughly two kilometers south of Hollfeld, the researchers extracted cores up to four meters deep and analyzed grain size distributions and organic content using the sieve and pipette method and loss-on-ignition measurements.

The stratigraphy that emerged tells a striking story. At the base of the sequence lie dark, organic-rich silty clays and peat, locally more than 40 centimeters thick, deposited during the Early Holocene when the valley floor was a waterlogged, marsh-like environment with weakly defined, anastomosing channels. Comparable peat sequences in the neighboring Aufsess River catchment have been dated to around 7400 years ago. Above these organic deposits, thin layers of well-rounded limestone and dolomite gravel record short episodes of high-energy flooding during the Middle to Late Holocene. Capping everything is the most dramatic unit: up to three meters of homogeneous, brown-beige silty to loamy overbank deposits with low organic content, laid down by repeated flooding as fine sediment washed off eroding hillslopes.

This three-meter blanket of floodplain loam is the fingerprint of human land use. The review shows that deforestation began in the Neolithic through rotating slash-and-burn cultivation, but intensified dramatically in the Middle Ages, a process preserved in place names bearing the suffix -reuth, which denote large-scale forest clearances. From the eleventh and twelfth centuries onward, village formation, settlement nucleation around churches and manorial centers, and the spread of the open-field system accelerated soil erosion on slopes. Sheep grazing amplified the effect: by the 1850s, manorial sheep farms in the region kept as many as 177,000 animals in total, and their grazing on steep valley slopes stripped vegetation cover and delivered sediment directly to the river system. Previous work in the Aufsess catchment dated the onset of sustained overbank deposition to between 2400 and 3000 years ago, with sedimentation rates eventually reaching up to two millimeters per year.

Human intervention extended beyond the slopes to the river itself. Historical sources document mills with mill races, small weirs, water wheels, and irrigated water meadows throughout the catchment, all of which altered flow conditions, sediment trapping, and channel morphology. The demand for winter fodder for the growing sheep flocks likely drove the construction of water meadows, which in turn reshaped how sediment moved between slopes, floodplains, and channels. Archival records from the sixteenth century onward reveal frequent disputes over water use among farmers, millers, and timber rafters, and nineteenth-century petitions to repair eroded river banks describe the loss of hundreds of square meters of farmland. Even the famous juniper heaths of the Franconian Alb, often mistaken for pristine nature, are revealed as cultural landscapes created by centuries of continuous grazing pressure.

The study also highlights a crucial complication in reading sediment archives: the response of rivers to human pressure is neither immediate nor linear. Eroded soil is often stored temporarily as colluvium on slopes or at foot-slope positions before eventually reaching the floodplain, a phenomenon known as the sediment cascade. This temporal decoupling between erosion and deposition means that layers of floodplain sediment may lag centuries behind the land-use changes that triggered them. In the Wiesent catchment, gullies up to ten meters deep near the confluence of the Aufsess and Wiesent rivers testify to severe historical soil erosion, while the absence of subfossil oak trunks in Main River deposits after around 1200 BCE has been interpreted as evidence of widespread deforestation upstream.

Climate, the researchers emphasize, played a comparatively minor role in this particular story. While events such as the 8.2 ka cooling, the Löbben Oscillation around 1600 BCE, the Medieval Climate Optimum, and the flood-rich phases of the Little Ice Age certainly influenced discharge and flood frequency, the long-term morphology and sediment dynamics of the floodplain appear dominated by anthropogenic disturbance. The close correspondence between the historical review and the empirical field data, the authors argue, confirms the Wiesent floodplain as a high-resolution archive of human-induced fluvial change. With its rural character, well-preserved stratigraphy, and absence of industrial contamination, the catchment is now positioned as a key study area for future work within the German Research Foundation’s priority programme on the fluvial anthroposphere, offering a template for disentangling human impacts from natural background processes in river systems across Europe.

Subject of Research: Human-induced transformation of the Wiesent River floodplain in northern Bavaria from wetland to human-dominated fluvial landscape since the Holocene

Article Title: The fluvial anthroposphere of the Wiesent River catchment, northern Bavaria, Germany: review and first results

Article References: Grimm, B. E. W. W., Voigt, A., Dix, A., Schreg, R., & Fuchs, M. (2026). The fluvial anthroposphere of the Wiesent River catchment, northern Bavaria, Germany: review and first results. E&G Quaternary Science Journal, 75(1), 49-67. https://doi.org/10.5194/egqsj-75-49-2026

Image Credits: AI Generated

DOI: 10.5194/egqsj-75-49-2026

Keywords: fluvial anthroposphere, floodplain, Wiesent River, Franconian Alb, sediment cores, electrical resistivity tomography, soil erosion, medieval land use, deforestation, sheep grazing, Holocene, geoarchaeology

The research combines three complementary techniques, each filling in a different layer of the story. Sediment coring provided vertical slices through the landscape, revealing the sequence of natural and human-made deposits beneath the site. Electrical resistivity tomography and direct-current resistivity soundings mapped subsurface structures horizontally, tracing buried features without breaking the surface. Finally, phytolith analysis, the study of microscopic silica bodies formed within plant tissues, allowed the researchers to reconstruct which plants grew around the city and how vegetation changed as urbanization took hold. Together, these methods produced a picture of Bubastis that no single approach could deliver: a city whose growth, layout, and even its religious geography were dictated by the shape of the land beneath it.

The most consequential discovery concerns a set of Pleistocene sand mounds known as Geziras. These are relict landforms, remnants of ancient sandy deposits that rise subtly above the surrounding floodplain and, crucially, stay dry during the Nile’s annual inundation. Garbe’s surveys identified several of these mounds across the Bubastis area, and their positions are anything but random. The Temple of Pepi I in the western part of the city stands on one. The palace and the cemetery area in the north occupy others. Residential zones in eastern Bubastis cluster on still more. Even a lost monument may now have a location: an additional mound in the southeastern part of the site can plausibly be linked to the Temple of Hermes, a structure known from ancient writings whose whereabouts had been uncertain. The new evidence supports those textual clues about where the temple once stood.

This pattern reveals a deliberate urban logic. Rather than spreading indiscriminately across the floodplain, the builders of Bubastis selected flood-safe Geziras for their most important and most permanent structures, while leaving the low-lying ground between them for uses that could tolerate, or even benefit from, seasonal flooding. The geomorphology of the Delta was not an obstacle to be overcome but a framework to be exploited. In a landscape where the Nile’s branches shifted course and flood levels fluctuated over the centuries, choosing the right piece of ground was a matter of survival, and the people of Bubastis appear to have understood that from the city’s earliest days.

The coring program also quantified just how intensively different parts of the city were used. In settlement area S1, the researchers documented anthropogenic deposits reaching a thickness of up to 9.5 meters, an extraordinary accumulation of debris, building material, and occupation layers that identifies S1 as the primary living quarter of the city. The thickest deposits date particularly to the Ptolemaic period, from about 332 to 30 BCE, and the Roman period, from about 30 BCE to 200 CE, showing that these late phases of Bubastis’s history were also among its most densely built. By contrast, the surrounding low-lying floodplain areas, especially area S2, show only sparse settlement evidence. These marginal zones were likely given over to agriculture, and they had a distinct advantage for it: a nearby Nile branch, flowing to the north and northeast of the city, regularly deposited nutrient-rich sediments across the floodplain, keeping the fields naturally fertilized.

The phytolith record adds a biological dimension to this reconstruction, tracking vegetation from the end of the last ice age through the city’s decline. During the transition from the Late Pleistocene to the Early Holocene, long before Bubastis existed, the landscape was dominated by grasses, shrubs, and trees, a natural Delta environment shaped by river processes rather than human hands. That changed with the arrival of settlement. From the Old Kingdom onward, spanning roughly 2850 to 2180 BCE, the onset of occupation coincided with a marked increase in cereal-type phytoliths. Crucially, these cereal signatures appear in the nutrient-rich floodplain sediments, providing the earliest evidence for localized cereal cultivation at Bubastis during the Early Old Kingdom. The fields, in other words, were already feeding the city in its formative centuries.

Inside the settlement itself, the phytolith data tell a different story. Elevated proportions of cereal-type phytoliths in anthropogenic deposits across the urban area, and particularly in the main residential zone S1, point to intensive cereal processing and storage taking place within the city walls. Grain was not only grown nearby but handled, threshed, milled, and stockpiled in the residential quarters, a pattern that speaks to the scale of Bubastis’s population and the logistical sophistication required to sustain it. The city was, in a very real sense, an agricultural machine as much as a religious and administrative center, with its food economy woven directly into the fabric of its neighborhoods.

Over time, that arrangement shifted. From the Late Period, beginning around 664 BCE, through Roman times, cultivation practices increasingly moved toward the settlement periphery. As Bubastis expanded and its builders consumed more land, the natural vegetation around the city diminished, and farming was pushed outward to the edges of the urban footprint. This trajectory, from cultivation embedded within and immediately around the early settlement to agriculture relegated to the periphery of a sprawling city, mirrors patterns familiar from urban growth in other ancient and modern contexts, but here it is documented with unusual precision through a combination of sediment chemistry, landform mapping, and plant microfossils.

The broader significance of the work lies in what it says about human adaptability in unstable environments. The Holocene Nile Delta was shaped by a constant interplay of river avulsions, sedimentation, and seasonal flooding, conditions that created fertile opportunities for early civilization while simultaneously driving settlement instability and frequent relocation. Bubastis’s longevity was not an accident of geography but the product of choices: siting temples and palaces on high ground, farming the fertile lows, and adjusting land use as the city and its environment co-evolved. Different geomorphological settings were deliberately selected for specific functions and phases of occupation, a dynamic interplay between nature and human decision-making that unfolded over three thousand years.

The study also refines interpretations of Bubastis’s emergence as a center of religious and administrative power, a status reflected in its extensive temple and palace areas, including the famous Temple of Bastet with its man-made sacred canals identified in earlier geoarchaeological work. Until now, knowledge of the site’s environmental conditions rested on a handful of historical texts and preliminary studies. By delivering the first area-wide reconstruction, the new research demonstrates how strongly the development of an ancient Egyptian urban center depended on regional environmental conditions, and it showcases the value of geoarchaeological methods for reconstructing human-environment interactions across the Delta, where so many settlements rose and fell with the shifting waters of the Nile. For Bubastis, the ground beneath the city was never just a foundation. It was a partner in the city’s survival, and reading that partnership from the sediments is what finally explains how one Delta town outlasted them all.

Subject of Research: Holocene landscape evolution and long-term settlement development at the ancient Egyptian city of Bubastis in the southeastern Nile Delta

Article Title: Holocene landscape evolution and settlement development in the surroundings of the ancient Egyptian city of Bubastis (“Tell Basta”), southeastern Nile Delta

Article References: Garbe, P. (2026). Holocene landscape evolution and settlement development in the surroundings of the ancient Egyptian city of Bubastis (“Tell Basta”), southeastern Nile Delta. E&G Quaternary Science Journal, 75(2), 169-171. https://doi.org/10.5194/egqsj-75-169-2026

Image Credits: AI Generated

DOI: 10.5194/egqsj-75-169-2026

Keywords: Bubastis, Tell Basta, Nile Delta, geoarchaeology, Holocene, Geziras, phytoliths, sediment coring, electrical resistivity tomography, ancient Egypt, urban development, Nile flooding

The review, led by Temitayo Olamide Ale of Adekunle Ajasin University in Nigeria together with colleagues in Nigeria and Malaysia, screened an initial pool of 321 publications and retained 172 peer-reviewed studies published between 2013 and 2025. The team set out with four goals: to classify the techniques used to investigate soil and water contamination around dumpsites, to evaluate how well stabilizing agents immobilize potentially toxic elements, to examine the role of artificial intelligence in contamination assessment, and to review remediation strategies for polluted soils and groundwater. Groundwater supplies nearly half of all drinking water worldwide and supports the daily needs of more than 2.5 billion people, so the stakes of the exercise could hardly be higher.

The problem begins with the dumpsites themselves. Unlike engineered sanitary landfills, open dumps are typically unregulated, unlined, and poorly managed, allowing waste to interact directly with surface water, soil, and groundwater. Rainwater percolating through heterogeneous mixtures of food waste, plastics, metals, batteries, electronics, and even hospital refuse generates leachate—a concentrated liquid cocktail of dissolved salts, organic matter, and potentially toxic elements such as lead, chromium, arsenic, cadmium, mercury, and nickel. Several major Nigerian dumpsites, including Olusosun in Lagos and Awotan in Ibadan, have operated continuously for more than four decades and now cover roughly 42 and 20 hectares respectively, making them long-term contamination engines rather than temporary nuisances.

One of the review’s most striking technical findings concerns how leachate moves underground. Geophysical imaging combined with hydrogeochemical analyses consistently reveals that migration is not a simple downward seepage. Instead, subsurface structure—weathered zones, fracture networks, and lithological boundaries—acts as a network of preferential highways, driving both vertical and lateral transport. Electrical resistivity tomography and vertical electrical sounding, the workhorses of dumpsite investigation, detect leachate-saturated zones as low-resistivity anomalies, with many studies adopting thresholds below 40 ohm-meters as indicators of possible contamination. Depth estimates show leachate commonly penetrating 10 to 15 meters into shallow aquifers, and in fractured basement terrains the plumes can follow faults and lineaments far deeper than soil properties alone would predict.

But resistivity anomalies are notoriously non-unique: saline intrusion, clay-rich sediments, and shale layers can all mimic leachate signatures. That is why the review argues forcefully for integrated, multi-method frameworks. Induced polarization adds chargeability information that helps distinguish leachate from clay; self-potential surveys track the electrochemical signals of active fluid flow; electromagnetic methods provide rapid reconnaissance over large sites; and seismic refraction, ground-penetrating radar, magnetic, and gravity surveys constrain stratigraphy, buried waste, and structural pathways. When these geophysical images are cross-validated against borehole logs, geotechnical tests, and water chemistry, interpretational ambiguity drops sharply and the true geometry of a contamination plume comes into focus.

The hydrogeochemical evidence assembled in the review is sobering. Mean concentrations of lead, cadmium, nickel, arsenic, manganese, and iron frequently exceed guideline values set by the World Health Organization, the US Environmental Protection Agency, and national standards in groundwater surrounding dumpsites. At the Abule-Egba dumpsite in Lagos, elevated total dissolved solids, sodium, potassium, chloride, and nitrate appeared in both shallow wells and deeper boreholes, signaling migration into multiple aquifers. Around Olusosun, hardness, lead, nickel, manganese, iron, and chromium rose highest during the wet season, when enhanced recharge and runoff flush contaminants downward. Temporal studies show the problem is cumulative: concentrations of arsenic, zinc, lead, and copper increased over time at long-operating sites, and roughly 80 percent of polluted water in some developing regions is used for irrigation, carrying toxins into the food chain.

The human health risk calculations are where the review becomes genuinely alarming. Using standard exposure models—average daily dose, hazard quotient, hazard index, and cancer risk—the authors synthesized results across dozens of sites and found that hand-to-mouth ingestion of contaminated soil and drinking of polluted groundwater dominate the risk profile. Hazard indices for soil ingestion reached values orders of magnitude above the safety threshold of one, with manganese and arsenic the dominant contributors, and children bearing the heaviest burden because of their lower body weight and higher soil ingestion rates. Total carcinogenic risk from groundwater ingestion exceeded the acceptable range of one in a million to one in ten thousand by several orders of magnitude at the worst sites. By contrast, dermal exposure during bathing and inhalation of airborne dust remained largely within acceptable limits—a finding that sharply narrows where intervention money should be spent.

On the solutions side, the review documents a rapidly evolving toolkit. Biological remediation exploits fungi such as Aspergillus niger and Phanerochaete chrysosporium, whose ligninolytic enzymes and organic acids can cut cadmium levels by up to 90 percent in various environments. Stabilization and solidification using cement, lime, fly ash, and phosphate binders lock contaminants into insoluble matrices, and studies show that agricultural and industrial wastes—sugarcane straw, sawdust ash, hydrated lime—incorporated at 5 to 30 percent can significantly reduce contaminant mobility. More futuristic are nanotechnology approaches: nanoscale zero-valent iron and magnetite nanoparticles stabilize toxic elements and polycyclic aromatic hydrocarbons in soil, while green-synthesized composites such as bentonite–green tea extract–nZVI have immobilized chromium. The authors caution, however, that most nanoremediation remains at laboratory scale, with open questions about nanoparticle transport, toxicity to soil microbiota, and long-term stability.

Perhaps the most forward-looking section concerns artificial intelligence. Machine learning frameworks—Random Forest, Naive Bayes, and Bivariate Local Moran’s I among them—are proving remarkably good at predicting the distribution of potentially toxic elements and delineating high-risk zones from environmental covariates such as soil pH, organic matter, elevation, and population density. One cited study achieved R-squared scores of 0.76 to 0.86 predicting eight different metals. The review is careful to note the caveats: model reliability depends on data quality, feature selection, and physical interpretability, and predictions must be constrained by geological and hydrogeological knowledge to remain meaningful. Embedded within integrated, process-informed frameworks, however, these data-driven tools promise faster, cheaper, and more transferable contamination assessment than conventional methods alone.

The review closes with a clear-eyed prescription. Site-specific assessment, regular monitoring at bi-monthly or seasonal intervals, informed urban planning, and integrated remediation frameworks are essential to mitigate the long-term impacts of dumpsite leachate. Engineered sanitary landfills—with compacted clay and geomembrane liners, leachate collection systems, and low-permeability caps—must be sited away from flood zones and fracture-prone bedrock, and targeted financial support is needed to build them in developing countries. The authors also call for stronger public education, protective equipment for the informal scavengers who work the dumps without gloves or masks, and honest communication of research findings to the communities whose hand-dug wells sit downstream of decades of unmanaged waste. As urban populations grow and waste volumes climb, the review makes clear that the invisible plumes beneath the world’s dumpsites will only deepen unless science, governance, and investment converge on the problem now.

Subject of Research: Soil and groundwater contamination from dumpsite leachate and its assessment and remediation

Article Title: A systematic review of soil and water contamination in dumpsite leachate impacted environments

Article References: Ale, T. O., Ololade, I. A., Akingboye, A. S., Ogunribido, T. H. T., Ajidahun, J., & Faseki, O. E. (2026). A systematic review of soil and water contamination in dumpsite leachate impacted environments. Discover Soil, 3(1), Article 112. https://doi.org/10.1007/s44378-026-00265-2

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00265-2

Keywords: dumpsite leachate, groundwater contamination, soil pollution, potentially toxic elements, geophysical methods, electrical resistivity tomography, health risk assessment, machine learning, nanoremediation, bioremediation, sanitary landfill design, developing countries