PICO
This session focuses on the continuum from soil erosion on hillslopes and agricultural lands, through sediment transport within river networks, to deposition and transformation in floodplains, lakes, and reservoirs. Contributions addressing physical, chemical, and biological processes controlling erosion, sediment connectivity, transport, storage, and contaminant fate across spatial and temporal scales are particularly encouraged.
A key highlight of this session is the application of next generation tools to address these challenges. We particularly welcome contributions showcasing:
- Innovative Monitoring: Remote sensing using Sentinel and Landsat missions, high resolution field sensors, tracers, and novel low cost or open-source measurement techniques for erosion and sediment dynamics.
- Advanced Modelling: Process based and empirical models such as SWAT and InVEST, combined with artificial intelligence, machine learning, and cloud computing platforms including Google Earth Engine to improve prediction, scaling, and uncertainty assessment.
- System Dynamics: Sediment budgets, archive analysis, source attribution, and the influence of human interventions such as hydropower, river regulation, flood management, and soil conservation policies.
- Ecosystem Impacts: Responses of riparian, hyporheic, riverine, and lacustrine ecosystems to changing erosion rates, sediment fluxes, and contaminant loads.
This interdisciplinary session aims to bring together soil scientists, geomorphologists, hydrologists, ecologists, and data scientists to advance understanding and management of erosion driven sediment and contaminant dynamics in a changing environment.
PICO: Thu, 7 May, 08:30–12:30 | PICO spot A
Enhancing soil structure is essential for maintaining soil functions and overall soil health, and its development is strongly influenced by climate, land use, and soil type. This study evaluated near-saturation water retention—an indicator of structural condition—in soils from four climatic regions under long-term land use (>20 years) and compared these effects with a one-time application of anionic polyacrylamide (PAM). Soils from humid (USA: crop CT–conservation tillage, crop NT–no till, grass, forest), temperate (Ethiopia: crop CT, grass, bush, forest), semi-arid (Turkey: crop CT, grass, forest), and arid (Israel: crop CT, orchard, virgin) regions were analyzed (272 samples ranging from sandy loam to clay). In each region, three crop CT soils with contrasting textures were treated with PAM at 0, 25, 50, 100, and 200 mg L⁻¹ (60 samples).
Structural effects were assessed using the high-energy moisture characteristic (HEMC, 0–50 hPa). Water-retention curves were described using modified van Genuchten parameters (α and n), and structural stability was quantified as SI. Treatments produced distinct curve shapes (α = 0.036–0.099 hPa⁻¹; n = 7.1–20.6), reflecting changes in macropore domains (>250, 125–250, 60–125 μm) associated with large and small macroaggregate stability (SI = 0.002–0.060 hPa⁻¹).
Higher soil organic carbon (SOC) contents (crop CT < crop NT < grass/bush/orchard < forest/virgin) and increasing PAM rates improved α (0.054–0.096 hPa⁻¹) and SI (0.004–0.059 hPa⁻¹), while reducing n (16.0–6.3). However, the magnitude of these effects depended on soil type, texture, and climatic region. SI correlated strongly with SOC or SOC/Clay ratio in humid and temperate regions, and with SOC and clay content in arid and semi-arid regions.
Crop CT soils had the lowest SI, typically 2–4 times lower than other land-use types. Applying PAM at 25–50 mg L⁻¹ increased SI (0.007–0.033 hPa⁻¹) to levels comparable to crop NT, grass, bush, or orchard soils (0.009–0.032 hPa⁻¹). Higher PAM rates (100–200 mg L⁻¹) raised SI (0.014–0.042 hPa⁻¹) to values up to twice those of NT, grass, and orchard soils, and in some cases similar to forest or virgin soils (0.014–0.059 hPa⁻¹). PAM and SOC effects were strongest in medium- and clay-textured soils; notably, a single PAM application often improved SI more effectively than SOC, particularly in drier regions.
Across all climates, long-term NT or grass soils with SOC ≥ 2 g g⁻¹ and soils treated with 25 mg L⁻¹ PAM produced similar SI values, indicating a useful threshold for evaluating structural quality (SI ≥ 0.010–0.020 hPa⁻¹). Exponential relationships between SI and α or n (α: R² = 0.85; n: R² = 0.64, p < 0.001) can guide (I) the assessment of soil structural stability, macroporosity, and SOC; (II) the interpretation of land-use impacts on pore and aggregate-size distributions; and (III)the determination of optimal PAM rates within conservation agriculture. These relationships support the development of resilient soil structure, accelerated SOC accumulation, and site-specific management practices—particularly valuable for weakly structured, degraded soils.
How to cite: Mamedov, A. I., Levy, G. J., and Norton, D. L.: Structural stability and near-saturated water retention of soils from four climatic regions under long-term land use versus one-time polyacrylamide treatment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-473, https://doi.org/10.5194/egusphere-egu26-473, 2026.
The ever-evolving earth’s topography reflects the complex interaction of several geomorphic processes. These processes play a central role in how soil is detached, transported, and ultimately lost from a landscape. This raises a fundamental question: how does topography influence soil loss? To explore this, we introduced a geomorphic metric, ridge density (Rd), defined as the density of topographic ridges within a landscape. This metric provides a simple description of how rugged or smooth the terrain is. Our analysis shows a strong negative relationship between Rd and soil loss. Landscapes with high Rd experience lower soil loss. This is expected because highly dissected terrain contains steep but short slopes. Short slopes limit the distance over which runoff can gain energy and transport sediment, which reduces the overall erosion potential. The components of RUSLE further support this pattern. The LS-factor decreases as ridge density increases, suggesting that closely spaced ridges shorten the effective slope length, reducing the potential for runoff to accelerate and erode soil. In contrast, the K-factor increases with Rd, showing that areas with rugged terrain may contain soils that are more erodible. Even with a higher K-factor, the strong reduction in LS dominates, which explains why total soil loss still decreases in rugged terrain. Overall, the results show that Rd effectively captures the topographic influence on soil loss.
How to cite: Raina, S. S., Raj, R., and Biswal, B.: Topographic Signature of Soil Loss, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-476, https://doi.org/10.5194/egusphere-egu26-476, 2026.
Climate variability affects sediment dynamics; however, the relative contributions of individual climate parameters and the nature of these relationships (linear versus non-linear) remain unexplored. This knowledge gap hinders the development of effective, climate change-adaptive water quality management strategies. This study develops a multi-model framework to identify the complex relationships between climate parameters and sedimentary parameters (Turbidity and Total Dissolved Solids). Two modelling approaches, multivariate linear regression (MLR) as a baseline, and Random Forest (RF), were compared to capture both linear and nonlinear sediment dynamics. The SHAP (Shapley Additive exPlanations) method is used to quantify the contributions of climate parameters in variations of turbidity and total dissolved solids concentration. The model has developed a relationship between five climate variables (precipitation, average temperature, wind speed, solar radiation), reservoir operations (reservoir level), and sedimentary parameters. SHAP feature importance was quantified through an evidence-based evaluation for both models, providing a methodology and interpretation for both linear and non-linear pathways.
The results indicate that random forest substantially outperformed linear regression (R² = 0.65 versus 0.47, representing 38% improvement), with RMSE reduced by 19% and MAE by 36%, indicating significant non-linear climate-turbidity dynamics. Whereas the total dissolved solids model suggests an improved R² of 0.30 compared to 0.04 for linear regression. Furthermore, SHAP analysis revealed a divergence in precipitation importance between random forest and linear models, which attributed only 12.8% of the linear contribution. While non-linear models identified precipitation as the dominant driver, accounting for 50.8% of the contribution, a 38 percentage-point divergence was observed. SHAP dependence analysis identified a 10 mm/day as a critical precipitation threshold, below which the impacts of turbidity remain minimal. The precipitation contributions increase exponentially, reaching +10 to +13 SHAP units at precipitation levels exceeding 100 mm/day. The SHAP dependence result suggests that air temperature interactions amplify precipitation effects, with high-temperature periods generating 30-40% larger turbidity events to equivalent precipitation. In contrast, other climate parameters show consistent SHAP values across models (solar radiation: 28.8% MLR versus 16.1% RF), indicating predominantly linear relationships that were adequately explained by simple regression. Additionally, the reservoir level is a major contributor to total dissolved solids, with 35.7% non-linear contribution compared to 28.2% linear contribution, followed by precipitation and solar radiation. The reservoir level, ranging from 255 to 265 m, provides buffering capacity to absorb precipitation-driven sediment loads without significant fluctuations in turbidity and total dissolved solids.
The identified thresholds enable the development of climate-informed, tiered operational protocols: standard operations below 10 mm/day precipitation, enhanced operations at 10-100 mm, and advanced operations above 100 mm with different treatment dosages. Instead of the proportionate responses predicted by linear extrapolation. The non-linear dynamics for climate adaptation planning suggest that anticipated 20-30% increases in monsoon precipitation intensity could lead to 50-80% increases in peak turbidity events. This multi-model SHAP system provides a modelling approach for determining operational thresholds, measuring parameter contributions, and assessing the complexity of climate-water quality interactions to inform practical management strategies.
How to cite: Yelne, L. and Chandel, M.: Climate-Driven Linear and Non-Linear Sediment Dynamics: A Machine-Learning Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-513, https://doi.org/10.5194/egusphere-egu26-513, 2026.
Accurate prediction of sediment yield and streamflow is essential for effective watershed management and climate change adaptation planning. This study develops and validates an innovative SWAT-ANN hybrid model that integrates the physically based Soil and Water Assessment Tool (SWAT) with Artificial Neural Networks (ANN) to improve hydrological predictions in the monsoon-dominated Manjira River Sub-Basin (MRSB), India.
The SWAT model was calibrated and validated using daily streamflow and sediment observations from three Central Water Commission gauging stations (1998-2019). Multi-site calibration achieved satisfactory performance with NSE = 0.75 and R² = 0.79 for streamflow, while sediment yield modeling yielded NSE = 0.56 and R² = 0.60. Building on these simulations, an ANN model was trained using SWAT-generated outputs combined with meteorological variables to capture nonlinear sediment transport relationships. The SWAT-ANN hybrid model demonstrated significant improvements, with streamflow predictions achieving NSE = 0.95 and R² = 0.98, compared to standalone SWAT. For sediment yield, the hybrid approach improved NSE from 0.56 to 0.72 and R² from 0.60 to 0.75, showcasing the complementary strengths of physics-based and data-driven modeling.
Climate change impact assessment was conducted using 13 CMIP6 models under SSP245 (moderate mitigation) and SSP585 (high emissions) scenarios. Under SSP245, ensemble mean streamflow increased by 47.5% (2015-2045), 68.5% (2046-2070), and 123.9% (2071-2100) relative to baseline (1998-2014). SSP585 projections were more severe, with streamflow increases of 41.3%, 137.4%, and 269.4% for the respective periods. Sediment yield responses were equally dramatic: SSP245 scenarios projected increases of 61.3% (near-future), 81.9% (mid-future), and 146.6% (far-future), while SSP585 showed 48.3%, 166.4%, and 331.9% increases. The most aggressive model (CanESM5) projected sediment yield increases exceeding 1,900% by 2100 under SSP585, while conservative models (INM-CM5-0) showed minimal changes.
The SWAT-ANN model successfully captured temporal variability in both streamflow and sediment responses across all climate scenarios. These projections indicate that the basin will experience unprecedented hydrological changes, with sediment yields rising 2.5-4.3 times baseline by 2100 depending on emission pathways. The developed hybrid methodology provides a powerful tool for water resource managers to quantify climate-driven changes in streamflow and sediment dynamics, enabling adaptive management strategies and sustainable planning in data-limited monsoon-dominated basins. The transferable methodology addresses critical gaps in sediment yield prediction for similar South Asian river systems.
How to cite: Kumar, S., Choudhary, M. K., and Thomas, T.: Hybrid SWAT-ANN Modeling of Climate-Driven Changes in Streamflow and Sediment Yield: Manjira River Basin, India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-934, https://doi.org/10.5194/egusphere-egu26-934, 2026.
Most sediments in the Loess Plateau of Yellow River basin originate from the gullied-hilly loess terrain, with approximately 50% deriving from gully systems which is the dominant geomorphological features. Accurately simulating the water and sediment processes in this area remains challenging due to the intricate sediment generation mechanisms within the slope-gully-river cascading systems. This study presents an enhanced version of the physically-based distributed hydrological model WEP-SED to reflect the influence of topographic slope variations on sediment production and transport processes.
The WEP-SED employs a three-tiered hierarchical structure (slope-gully-river continuum) to simulate coupled water-sediment dynamics (Fig. 1), which includes splash erosion, runoff & overland flow erosion, conflux & erosion in slope-gully, gravity erosion, conflux & sediment transport, and conflux & sediment transport.In the new model, the contour band in the sub-watershed is changed to upper-middle-down slope band, which is designed to better resolve slope-dependent erosion dynamics. This spatial discretization methodology accounts for both hydrological flow paths and local slope gradients, enabling more precise representation of erosion processes across varying topographic conditions, especially the mechanism of seriously soil erosion in the steep slope terrain and sedimentation in the valley floor of the gully. The refined sediment transport mechanisms within each slope band are schematically depicted in Figure 2. The breakpoint for the three slope band is 10°, one is the first one from top to bottom, the other is the first one from bottom to top, where the slope is just change over 10°. In the upper gentle slope band, the splash erosion and runoff & overland flow erosion is considered; in the middle steep slope band, splash erosion, runoff & overland flow erosion, conflux & erosion in slope-gully, gravity erosion is considered; in the down gentle slope band, splash erosion, runoff & overland flow erosion, gravity erosion, conflux & sediment transport in gully and river is considered.
The enhanced model was implemented in the Nanxiaohe sub-watersheds to investigate erosion-sediment dynamics during seven flood events in August 2009. It indicates that the model performs a relatively good fitness in simulating the water and sediment processes, and reflects the erosion difference in seven flood events. According to the model simulation results, the middle steep slope band constituted the dominant sediment source (70%), followed sequentially by down gentle slope band (27%) and the Upper gentle slope band has the smallest contribution. Thus, the enhance model could reflect the slope impact on sediment erosion and transport in Loess Plateau, which could be used for the benefit evaluation of soil and water conservation engineering projects.
Fig 1. A schematic illustration of the model structs and principle of the WEP-SED model.
Fig.2 Schematic diagram of geomorphic unit division
How to cite: Liu, J., Wang, K., and Zhou, Z.: Study on water and sand simulation in Loess Plateau considering slope difference of land surface, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9370, https://doi.org/10.5194/egusphere-egu26-9370, 2026.
Soil erosion and sediment transport pose major challenges for river basin management in India, where
intense monsoon rainfall, diverse physiography, and rapid land-use change generate high and spatially
variable sediment fluxes causing significant challenges like reservoir siltation, soil degradation, and
downstream coastal impacts. However, sediment quantification through modeling at national and basin
scales in India is often constrained by data availability, input data selection and other uncertainties
associated with the choice of empirical options in the models. This study aims to explicitly quantify and
assess input data source–induced uncertainty in the InVEST Sediment Delivery Ratio (SDR) model driven
at 1km resolution for major Indian River basins (viz. Sabarmati, Narmada, Baitarani, and Tapi) for the
period 2005–2019. The adopted multi-input modeling framework utilized several datasets, including
topography from the HydroSHEDS digital elevation model, land use and land cover from HILDA+, rainfall
erosivity (R factor) derived from ERA5 hourly precipitation data using the EI60 formulation,
Furthermore, the rainfall erosivity was computed using five empirical kinetic energy relationships
(Wischmeier & Smith; Brown & Foster; McGregor et al.; Van Dijk et al.; Meshesha et al.) to capture
methodological uncertainty in rainfall intensity representation. Four soil erodibility (K factor)
combinations were generated based on two data sources and two estimation methods: (1) HWSD–EPIC,
(2) HWSD–Nomograph, (3) SoilGrids–EPIC, and (4) SoilGrids–Nomograph . In total, 20 rainfall
erosivity–soil erodibility input combinations were created by systematically varying the erosivity and
erodibility datasets and estimation methods within the InVEST SDR model, using its default
configuration settings. Results indicate strong basin-specific sensitivity to input data selection, with
rainfall erosivity emerging as the dominant control on sediment export, followed by soil erodibility and
then topographic controls (LS factor). Sediment export estimates showed comparatively lower
uncertainty for the Sabarmati and Narmada basins, followed by Baitarani and Tapi. The study highlights
that input data choice represents a major source of uncertainty in large-scale sediment modelling in
India river basins and underscores the need for transparent evaluation of data-driven variability prior to
calibration.
How to cite: Shah, M., Kumar, R., and Remesan, R.: Quantification and evaluation of input data source induced uncertainty in the InVEST sediment exportmodelling framework for major Indian River basins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17714, https://doi.org/10.5194/egusphere-egu26-17714, 2026.
Nutrient management and cropping system strategies are so different between natural and conventional agroecosystems that soil health generally follows very different trajectories, thereby affecting crop growth, functioning, and system sustainability. To examine these effects, a field experiment was conducted during the rainy season in the humid subtropical region of the north-western Himalayas, India, to evaluate seasonal soil physicochemical changes under natural farming inputs, conventional chemical fertilizer applications, and okra-cowpea intercropping, and to establish their relationships with crop growth and yield Soil samples were collected from the experimental field before sowing to establish baseline soil conditions. Write all measurements you did and what analyses you performed Two-way ANOVA indicated that soil pH was affected by treatment (p = 0.00011 < 0.05) and season (p = 2.05 × 10⁻²⁹<0.05) with a significant interaction of treatment x season (p = 0.0329 < 0.05). Soil EC was strongly affected by season (p=5.19× 10⁻⁶⁵<0.05), whereas treatment (p=0.502) and interaction effects (p = 0.204>0.05) were not significant. Organic matter content was significantly influenced by treatment (p= 1.37 × 10⁻⁵<0.05) and season (p = 3.34 × 10⁻¹⁵<0.05), while the interaction effect was marginally non-significant (p= 0.060>0.05). Dry density exhibited a strong seasonal effect (p=4.00 × 10⁻²⁶), with no significant treatment influence (p=0.298). Treatments with higher post-harvest organic matter (up to 3.12%) and reduced dry density as low as 1.31g cm⁻³ recorded greater plant growth, higher leaf area index (up to 1.58), and increased stem diameter. One-way ANOVA revealed that stem diameter (p=0.0306) and okra yield (p=1.50×10⁻⁵<0.05) were significantly affected by treatments, whereas plant height (p=0.176>0.05) and total biomass(p=0.396>0.05) were not. The correlation analysis using Pearson's correlation was strongly negative between post-harvest soil pH and Okra yield (r = -0.61), while organic matter was moderate in correlation (r = -0.31). Principal component analysis explained a cumulative percentage of 66.9% in total variance, in which soil pH, organic matter, and dry density were strongly associated in PC1. Soil Quality, derived from PCA, varied between 0.10 and 0.51, which was higher in natural farming practices and intercropping. Land equivalent ratio in intercropping was significantly improved in all cases, ranging between 1.24 and 1.73, which proved that it was significantly better compared to mono cropping in both natural farming practices and conventional inorganic nutrient management. The results demonstrate that natural nutrient management combined with intercropping offers a viable, low-input strategy for farmers to improve soil quality, reduce dependency on external fertilizers, and thereby strengthen farm-level economic and ecological resilience.
How to cite: Thakur, R., Jha, R. K., and Thakur, R.: Comparative soil health dynamics and crop morphological responses in natural and conventional agroecosystems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20152, https://doi.org/10.5194/egusphere-egu26-20152, 2026.
Recurring monsoon floods in the Kosi River Basin pose a critical threat to agricultural productivity, sediment deposition, and disruption of cultivable flood plains in Bihar, India. Severe seasonal rainfall combined with steep Himalayan topography generates high runoff and sediment fluxes in the Kosi River system. These hydrological conditions drive frequent channel instability, abrupt shifts in the river course, and widespread flood inundation leading to extensive deposition of sandy soil over fertile agricultural lands. Such recurring flood-driven erosion and sedimentation processes necessitate a quantitative assessment of their impacts on crop productivity, land-use dynamics, and sediment redistribution. Therefore, this study aims to provide a basin-scale quantification of flood-induced soil erosion and crop productivity losses in the Kosi River Basin using integrated remote sensing and hydrological modeling approaches. The Soil and Water Assessment Tool Plus (SWAT+) was employed to simulate basin-scale hydrological processes, sediment transport, and nutrient dynamics. Model parameterization utilized high-resolution topographic data derived from the Shuttle Radar Topography Mission (SRTM) digital elevation model and land use/land cover maps generated from Sentinel-2 satellite imagery. Climatic inputs, including rainfall and temperature, were obtained from the NASA POWER climate data archive, supplemented with observed rainfall records from the Indian Meteorological Department (IMD). Observed streamflow data from the Central Water Commission (CWC), India, were used for model calibration and validation. Spatial data processing and analyses were performed using Python-based workflows within QGIS and ArcGIS environments. We also examine the historical LULC trend from satellite data to understand the spatio-temporal changes in agricultural land and floodplain. We then run future climate scenarios: bias-corrected CMIP6 projections (SSP2-4.5, SSP5-8.5) are used to drive SWAT+ simulations of future flood extent, sediment yield, and land productivity. The final results of this research activity will be presented at the Conference.
Keywords: SWAT+, soil erosion, flood modeling, Kosi River, CMIP6, LULC, sedimentation.
How to cite: Kumar, A. and Jha, R. K.: Assessment of Flood-Induced Soil Erosion and Agricultural Yield Loss in the Kosi Basin Integrating Remote Sensing and Hydrological Modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20242, https://doi.org/10.5194/egusphere-egu26-20242, 2026.
Soil erosion and sediment connectivity play a crucial role in shaping river basin health, especially in monsoon-dominated regions where both natural processes and human interventions strongly influence sediment dynamics. This study investigates soil erosion patterns and sediment connectivity across two contrasting sub-basins of the Godavari River—Sabari, representing a near-natural system, and Manjira, a highly human-modified basin. Using multi-temporal land-use and land-cover data from 1985 to 2022, along with probabilistic indices such as sediment transport potential (STP) and the soil erosion and transport index (SETI), the study evaluates how geomorphic conditions, hydrological processes, and anthropogenic activities jointly control sediment generation and delivery. Six land-use classes were analysed to capture long-term landscape transformations, revealing rapid agricultural expansion and urban growth in Manjira, while Sabari remained largely forest-dominated. The combined STP–SETI analysis highlights distinct sediment hotspots, particularly in north–northwestern Manjira and central–southeastern Sabari, where steep slopes, reduced vegetation cover, and altered connectivity increase erosion risk. Major reservoirs, including Nizamsagar, Donkarayi, Singur, and Balimela, emerge as key regulators by disrupting sediment pathways and creating upstream sediment storage zones. The novelty of this work lies in integrating static erosion indicators with dynamic land-use changes using a probabilistic framework to identify spatially explicit sediment regimes. The findings emphasize the need for basin-specific management strategies, advocating vegetation restoration in Sabari and integrated sediment–reservoir management in Manjira to promote sustainable sediment governance.
How to cite: Singh, A. and Swarnkar, S.: Integrating Soil Erosion and Sediment Connectivity Indices to Identify Sediment Hotspots in the Godavari River Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20519, https://doi.org/10.5194/egusphere-egu26-20519, 2026.
Sedimentary archives preserved in fluvial and wetland environments offer valuable insights into how watershed systems respond to hydrological variability and human disturbance. Here, we reconstruct centennial-scale changes in sedimentation rates along the Sijeon Stream, which traverses the Sajapyeong wetlands in Korea, using 210Pb dating of sediment cores obtained from slackwater deposits. The resulting chronology spans the period from 1912 to 2019 and enables an assessment of the principal watershed controls on sediment accumulation. The reconstructed record reveals three successive intervals that are statistically distinguishable in terms of sedimentation rates: Period 1 (1912–1963), Period 2 (1964–2000), and Period 3 (2001–2019). These intervals correspond closely with distinct phases of land-use history identified from aerial photographs and satellite imagery, including a quasi-natural phase until the early 1960s, a phase of intensive agricultural activity from the mid-1960s to the mid-1990s, and a period marked by multiple forms of anthropogenic intervention beginning in the early 2000s. Across all periods, sedimentation rates exhibit clear associations with precipitation variability. A particularly pronounced and sustained rise in sediment accumulation after 2015, during the late part of Period 3, coincides with the implementation of artificial channel modifications and the occurrence of earthquakes. This pattern indicates that land-use change governs long-term trends in sedimentation, whereas precipitation extremes, channel alterations, and seismic events primarily exert short-lived influences. Furthermore, when these drivers act concurrently, their combined effects can substantially amplify sedimentation rates. The findings improve the understanding of the temporal effects of interacting watershed factors on sediment transport and emphasize the importance of considering these interactions in developing strategies for sustainable reservoir and wetland management.
How to cite: Kim, Y., Kim, M., Ki, S., Lim, Y. S., Lee, C., and Kim, J. K.: Centennial-scale sedimentation dynamics and their controlling factors in a human-modified mountainous catchment, Korea, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2711, https://doi.org/10.5194/egusphere-egu26-2711, 2026.
Phosphorus is an essential nutrient in aquatic ecosystems. Its concentration in surface waters regulates primary productivity, whereas excessive loading promotes eutrophication and associated water-quality degradation. Rivers are major conduits for phosphorus transport from land to downstream lakes, reservoirs, estuaries and coastal waters, with both water and sediment acting as primary carriers of phosphorus in river systems. Human activities and climate change have substantially altered water and sediment regimes in rivers worldwide. However, the resulting changes in the patterns and statistical characteristics of riverine phosphorus transport remain insufficiently quantified, despite their importance for managing aquatic ecosystem health.
Using the Mississippi River basin as a case study, we compiled long-term observations of river discharge, suspended sediment concentration and total phosphorus concentration from 1970 to 2020, and statistically analysed the patterns of riverine phosphorus transport and its relationships with water and sediment. To account for changes in water-quality and environmental policies within the basin, we further divided the record into two sub-periods (1971–1990 and 2001–2020) and considered the full period 1970–2020 for comparison. We developed a multiple linear regression framework to quantify interactions between phosphorus export, discharge and suspended sediment concentration, and to assess how watershed characteristics influence phosphorus transport under different flow conditions. This framework was used to characterise the temporal and spatial variability of phosphorus transport across the Mississippi River basin and to disentangle the effects of human activities and climate variability.
We find that phosphorus transport is source limited and negatively correlated with basin area under low-flow conditions. Human activities are strongly associated with phosphorus transport, with population density influencing total phosphorus concentrations both directly and indirectly through the TP–discharge and TP–suspended sediment concentration relationships. The interception effect of reservoirs on total phosphorus export increases with their regulation capacity, while trends in total phosphorus concentration are positively related to changes in precipitation and predominantly negatively related to vegetation cover. Our study provides a basin-scale perspective on source-to-sink fluvial phosphorus transport, offering critical insights for sustainable phosphorus management and for the integrated management of riverine and coastal ecosystems.
How to cite: Xu, J.: Riverine phosphorus transport and its statistical coupling with discharge and suspended sediment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16285, https://doi.org/10.5194/egusphere-egu26-16285, 2026.
The Mekong–Tonle Sap Lake–Delta system supports highly productive floodplain ecosystems and regional food security, in part through the delivery of nutrient-rich suspended sediment. However, this sediment pathway is strongly modulated by the flood-pulse–driven “reverse flow” at the Mekong–Tonle Sap confluence: during the wet season, high Mekong stages drive net inflow from the mainstream into Tonle Sap Lake, whereas during the dry season the lake releases stored water back to the mainstream and onward to the delta. How this bidirectional exchange reshapes sediment delivery—specifically whether Tonle Sap acts as a net sink or a net source of suspended sediment for the downstream Mekong—remains poorly quantified. Most existing assessments approximate delta sediment supply using upstream stations and do not resolve the river–lake exchange, largely because near-confluence discharge and continuous sediment observations are limited.
Here we develop an integrated modelling framework that couples a physically based, spatially distributed hydrological model with Delft3D-Flow hydrodynamics to reconstruct daily discharge and river–lake exchange over the last ~35 years, including the reversal period. We then estimate suspended sediment fluxes using seasonally stratified, hysteresis-aware rating curves that account for distinct sediment–discharge relationships on rising versus falling limbs of the hydrograph. Combining daily exchange discharge with the corresponding rating-curve sediment concentrations enables a bidirectional suspended-sediment budget across the Tonle Sap River, separating wet-season import to the lake from dry-season export back to the mainstream.
During the historical baseline (1980–2000), we estimate that the Mekong mainstream delivers ~4 Mt yr⁻¹ of suspended sediment into the lake on average, and a comparable magnitude is returned to the mainstream during the dry season, indicating that Tonle Sap primarily acts as a transient store rather than a sustained additional sediment source to the downstream system. In the mega-dam period (2010–2025), despite substantially reduced upstream sediment supply, the river–lake exchange continues to route similar volumes of water into the lake, but the suspended-sediment contribution released from the lake does not compensate for the mainstream deficit. These results suggest that reverse-flow dynamics alone do not sustain suspended-sediment delivery to the Mekong Delta under contemporary sediment scarcity, with implications for nutrient replenishment, recession agriculture, and floodplain productivity.
How to cite: Morovati, K. and Tian, F.: Reverse flow control on suspended-sediment exchange between Tonle Sap Lake and the Mekong River under historical and mega-dam regimes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16157, https://doi.org/10.5194/egusphere-egu26-16157, 2026.
Suspended sediment concentration (SSC) in rivers is commonly measured using depth-integrated sampling with a D-74 sampler. Although this method provides reliable reference data, it requires manual operation from bridges using winches, which involves considerable manpower and cost and poses significant safety risks, particularly during flood events. Due to these operational constraints, SSC measurements in Korea are conducted at only a limited number of stations each year despite the existence of a nationwide sediment monitoring network. To address this limitation, recent studies have actively explored indirect SSC estimation techniques based on acoustic backscatter intensity measured by horizontal acoustic Doppler current profilers (H-ADCPs). However, the application of such techniques critically depends on the availability of in situ SSC samples for calibration and validation. In this study, a pumping-based automatic and remote suspended sediment sampling system was developed to overcome the limitations of conventional manual sampling methods and to enable continuous and safe sampling during flood events and night time conditions.
The developed system consists of a sampling unit, a pumping unit, a control unit based on a remote terminal unit (RTU), and power supply and communication units. The sampling unit was designed with a multi-channel structure to sequentially fill multiple sample bottles in a single operation, and a strain-gauge-based load cell was applied to control the sampled mass with a resolution of 10 g. The pumping unit was designed to ensure stable water intake under high-turbidity and high-flow conditions. The control unit was configured based on a remote terminal unit (RTU) to integrate pump operation, sampling sequence control, sampled mass monitoring, and system status diagnostics. The control program supports both manual operation and automatic scheduling, and implements time-based and event-triggered sampling control schemes to enable unattended operation.
The system was deployed at a natural river site and operated under various flow conditions. Field application results showed that SSC samples collected by the automatic system exhibited similar concentration trends compared to those obtained by conventional manual sampling. Furthermore, continuous and unattended sampling was successfully achieved during flood conditions without on-site human intervention. The results indicate that the proposed system effectively improves operational safety and efficiency in suspended sediment sampling and can serve as a practical infrastructure for enhancing sediment monitoring networks.
How to cite: Lee, C., Lee, J., Choi, K., Chung, H., Woo, S., and Roh, Y.: Development and Field Application of a Pumping-Based Automatic and Remote Suspended Sediment Sampling System, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8899, https://doi.org/10.5194/egusphere-egu26-8899, 2026.
This study employed large-eddy simulations (LES) to investigate how local bed coarsening influence near-bed vertical velocity perturbations and scalar transport. Six cases were configured with varying degrees of sediment coarsening at a fixed Reynolds number of 10,000. Coarsening was quantified by the coverage ratio (Ac/At) of coarse particles (Ac) on the bed surface (At), ranging from 0% to 100%. To isolate the effects of heterogeneous permeability, the crest elevations of both non-coarsened (d) and coarsened particles (D, where d = 0.5D) were kept equal, effectively eliminating variations in bed elevation.
Results show that Ac/At = 64% induced the strongest perturbations: (i) Sediment coarsening enhances near-bed vertical velocity and turbulence, with increases of 10.0 and 3.0 times at 64%, and 3.5 and 1.5 times under full coarsening, relative to the non‑coarsened case. (ii) Bed coarsening strengthens downward advective and turbulent fluxes, peaking at 14.1 and 1.7 times the non‑coarsened values at 64%, and remaining elevated at 11.6 and 1.4 times under full coarsening; (iii) Coarsening increases scalar penetration, shortens residence time (RT), and enhances transfer coefficients on both water and sediment sides. Under non- and fully coarsened beds, penetration depths are limited to d and D, respectively, while partial coarsening (Ac/At = 16–64%) allows penetration to the bed bottom. RT drops from 4.49 s at 0% to 4.21 s at 64%, then slightly rises to 4.24 s under full coarsening. At Ac/At = 64%, transfer coefficients rise to 2.4 times (water side) and 1.8 times (sediment side) those of the non-coarsened case, and to 1.6 and 1.4 times under full coarsening.
The primary mechanism driving the intensification of vertical scalar transport is the enhancement of vertical instantaneous velocities, which subsequently leads to increased advective and turbulent fluxes. Consequently, near-bed scalar concentrations increased by 37.1% at Ac/At = 64% and by 65.4% under full coarsening compared to the non-coarsened case. The results offer new insights into how bed heterogeneity influences hyporheic exchange, biogeochemical coupling, and solute retention in permeable sediments.
How to cite: Liu, J., Zhu, Y., Jiang, Y., Geng, Z., and Liu, Y.: Structure-Induced Enhancement of Oxygen Penetration in Coarsened Sediment Beds: Insights from Large-Eddy Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5234, https://doi.org/10.5194/egusphere-egu26-5234, 2026.
A major concern of the scientific community working on deep lakes is the progressive isolation and consequent de-oxygenation that have been observed in the last decades. The distribution of the dissolved substances in a deep lake, such as oxygen and nutrients, is controlled by the action of wind-induced stresses, penetrative convection by surface cooling and density-driven plumes. The extent of deep circulation is thus the outcome of the competition between density stratification and the drivers of mixing, acting at the surface and at the boundary of the lakes.
Lake Iseo is a large (61 km²) and deep (256m) Italian subalpine lake, fed by two main tributaries with an overall average annual inflow of 55 m3/s. The first detailed scientific analysis documents a monomictic lake, characterized by deep water with 70% oxygen saturation. However, since the second half of the 1980ies the deep-water recirculation has been insufficient. The monimolimnion has become depleted of oxygen, has become enriched with solutes and had gradually warmed with rates that could be estimated approximately ~0.05°C/year.
In this contribution, we discuss the role of the chemical stratification of lake Iseo, induced by a gradient in calcium, bicarbonate and sulphate ions, in reducing the deep-water oxygenation. At this purpose, we computed the stability of the lake, by coupling a site–specific density equation to the high-resolution time series of lake’s ware temperature and conductivity data, and we quantified the external forcings from high-resolution wind, discharge and tributaries’ temperature data. We thus estimated the time series of the resistance by the chemical stability to wind upwelling and to rivers’ underflows. We finally showed that the progressive deep-water warming that followed the isolation of the monimolimnion has strongly decreased the lake’s thermal stability, counteracting the chemical stratification in the last 8 years. We finally concluded that it does not seem that chemically stratified deep lakes are necessarily doomed to anoxia, but on the contrary to periods of longer isolation alternated by sporadic deep oxygenation triggered by deep warming.
How to cite: Valerio, G. and Pilotti, M.: Reduced effectiveness of wind and tributaries in the deep oxygenation of a chemically stratified lake. , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9682, https://doi.org/10.5194/egusphere-egu26-9682, 2026.
Dissolved oxygen (DO) is crucial for aquatic ecological and biogeochemical processes in lakes, yet under-ice thermo- and DO dynamics, particularly in saline alpine lakes, remain poorly understood. This study examines DO, temperature, and salinity in three brackish lakes (Selin Co, Nam Co, Bamu Co) on the central Tibetan Plateau. The results reveal that solutes redistribution after ice-on strongly shaped under-ice thermal structures and DO regimes. Early ice-on period, all lakes exhibited unusual hypolimnetic DO ventilation, which was triggered by benthic solutes accumulation in snowy winter and penetrative heating in snow-free conditions. In more salt lakes (Selin Co and Bamu Co with average salinity of 11.42 ± 0.04 and 12.16 ± 0.05 g L-1, respectively), as high salinity lowered the temperature of maximum density (Tmax, 1.20 and 1.35 °C for Bamu Co and Selin Co) and enhanced solute gradients, the atypical under-ice warm stratification formed approximately two weeks before ice-off. In Bamu Co, along with the warm stratification, the dissolved oxygen showed a abrupt increased to supersaturated from the surface to ~23.2 m below the surface, suggesting abundant biological productions. Subsequently, combined warm thermal and chemical stratification inhibited DO ventilation after ice break-up, except during some instantaneous mixing events. These findings highlight the critical role of salinity gradients in shaping thermal dynamics and oxygen transport in ice-covered saline lakes, offering mechanistic insights into global limnological responses to warming and brine rejection.
How to cite: Kai, J., Wang, J., Ju, J., Wang, H., and Zhu, L.: Under-ice Thermal and Oxygen Dynamics in Saline Lakes from the Tibetan Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15619, https://doi.org/10.5194/egusphere-egu26-15619, 2026.
In many regions worldwide, dam removal is being considered as a means to restore rivers and to remove hazards and liabilities associated with aging infrastructure. The pace and scale of dam removals has increased exponentially in the past two decades, providing a rapidly growing knowledge base with which to evaluate the consequences and effectiveness of breaching and removing dams. The largest dam removal in U.S. history on the mainstem Klamath River in Oregon and California, USA, has presented novel suspended-sediment transport conditions by giving the river access to sediment accumulating in the reservoirs since 1918. Three large dams were removed simultaneously in 2024, and one low-head dam was removed in 2023. Turbidity monitoring and suspended-sediment concentration (SSC) sampling were conducted before, during, and after the dam removals as part of an inter-agency collaborative effort that included the dam removal entity (Klamath River Renewal Corporation), private consultants, the Karuk and Yurok indigenous tribes in California, and the U.S. Geological Survey (USGS). These data were used to generate ordinary-least-squares regression models to compute time series of SSC and suspended-sediment loads at six mainstem USGS streamgages spanning 300 river kilometers downstream of the former dam sites. The reservoir drawdowns prior to dam removal introduced large amounts of fine-grained sediment into the coarse-grained river corridor causing elevated turbidity and peak SSC of approximately 30,000 mg/L. Multiple stages of the dam removal process, including reservoir drawdown, geomorphic flows for sediment mobilization, and the breach of historic cofferdams, resulted in dynamic sediment-transport conditions. This work provides insight into differences between fine-sediment transport related to dam removal and natural sediment transport events in this large 40,000 km2 basin.
How to cite: Schenk, L., Wright, S., Haluska, P., Johnson, G., Cahill, J., Curtis, J., and East, A.: Sediment transport assessment and dynamics during and after the largest dam removal in U.S. history on the Klamath River, Oregon and California, USA, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13389, https://doi.org/10.5194/egusphere-egu26-13389, 2026.
The Magdalena River, Colombia, has the highest sediment yield of any major South American river. This high natural level and recent land cover change in the watershed have exacerbated the sediment load and deposition in the river's lowland floodplains. Excess sediment delivery has led to concerns regarding the ecological integrity of its floodplains and lakes, coral reef burial at the river mouth, and increased dredging needs. The largest floodplain system of the river, the Momposina Depression–a vast wetlandscape formed by > 100 interconnected wetlands, lakes, and floodplains where the Magdalena and Cauca rivers meet, including two Ramsar-designated sites–is accumulating and potentially buffering a large portion of this excess sediment load. However, mechanistic descriptions and seasonal-to-decadal variability of these processes are poorly understood. To fill this gap, we use MODIS and Sentinel-1 imagery at monthly timescales to investigate the spread of turbid water across the system and build a conceptual model for how sediment is captured and remobilized. We find that flooding in the early wet season can have turbidities as large as the highest-discharge periods, but turbidity can vary +/- 40% and flow is generally constrained to the main channels, thus leading to lower consistent floodplain sedimentation delivery. Later in the seasonal flood pulse, overbanking river water inundates areas up to 146% area more than typical dry seasons and, and the highest average sediment loads (>20,000 mg/L) in September–often more than twice that in the dry season–suggest that this late-season pulse drives most wetland sedimentation, before water levels recede for the incoming dry season. This seasonal-scale sediment capture also depends on ENSO cycles, local precipitation, and modifications to the hydrology by hydropower infrastructure, but despite higher in-channel turbidities during wet La Niña cycles, it is not clear if sediment associated with these cycles reaches off-channel wetlands. Our findings suggest the wetlandscape provides critical sediment retention, an overlooked ecosystem service with implications across the lower river reaches and estuary, but with high degrees of spatial and temporal variability. To reduce excessive sedimentation in this wetlandscape and downstream–including a degraded Ramsar-designated wetland and coral reefs at risk of burial–management and research initiatives should recognize the role of floodplain wetlands in sediment capture and flux buffering.
How to cite: WinklerPrins, L., Salgado, J., and Jaramillo, F.: Suspended Sediment Capture and Buffering by a Tropical Wetland Complex from Satellite Observations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12430, https://doi.org/10.5194/egusphere-egu26-12430, 2026.
Since the 1980s, South America has emerged as one of the world’s leading agricultural producers, resulting in significant environmental pressures, including land and water degradation.
The consequences of this agricultural development, both past and present, are still poorly documented in this region, particularly in the Pampa biome. Retrospective analysis using sediment archive can provide valuable insights for the characterisation of the long-term environmental degradation.
In this study, we analysed a sediment core collected in the Salto Grande dam constructed in 1982 on the Uruguay river, draining a 266,000 km2 catchment. We established an age model and characterised the sediment properties, using gamma spectrometry, high-resolution geochemical content analysis (XRF), pesticides, magnetic susceptibility measurements over time (1982-2022). This multi-proxy analysis of a sediment archive from the Salto Grande reservoir enabled the first long-term reconstruction of land degradation and pesticide fluxes in the very large Uruguay river transnational basin (comprising Brazil, Argentina and Uruguay) since 1982.
The results indicate that sediment fluxes have decreased significantly since 2000 and sediment provenance has shifted toward the southern part of the basin after this period. These changes coincide with the construction of dams in the upstream part of the catchment, the expansion of agriculture in the south and the widespread adoption of no-tillage practices. This change in farming practices induced an increase in pesticide fluxes, thereby posing potential ecological risks.
In this context, trade deals such as those between the European Union and the European Free Trade Association and Mercosur, combined with the anticipated increase in the area dedicated to soybean and cellulose production, should be considered in light of the potential consequences in terms of agriculture expansion and related environmental threats.
How to cite: Bardelle, A., Gastineau, R., Tiecher, T., Chalar, G., Cabrera, M., Tassano, M., Paolo Gomes Minella, J., Vasconcellos Inda, A., Cottin, N., Sabatier, P., Foucher, A., Cerdan, O., Alewell, C., and Evrard, O.: Dynamics of sediment and associated pesticide transfers in cultivated southernmost Brazil since 1982, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6446, https://doi.org/10.5194/egusphere-egu26-6446, 2026.
The extensive use of pesticides has resulted in their persistence in several environmental compartments, including soil, water, and air. The majority of pesticides remain confined inside soil and sediment, limiting their dispersion to other parts of the ecosystem. In Himachal Pradesh, an agriculturally and horticulturally rich state of the Indian Himalayas, the regular usage of chemical pesticides poses significant risks to the pristine Himalayan ecosystem. Pesticides applied to crops cultivated on the valley slopes, such as apples, are thought to accumulate in the soil and are then transported to adjacent rivers during the monsoon season by surface runoff. The behaviour and movement of these pesticides mostly depend on their adsorption on soils and river sediments. Therefore, this study aims to examine the adsorption capacities of sediment fractions (coarse, medium, and fine sand and silt-clay) collected from the Beas riverbed, one of the major rivers in the Kullu valley of Himachal Pradesh. Fungicides like carbendazim and thiophanate methyl that are commonly used in this region were selected for adsorption experiments along with coarse, medium and fine sands, and silt-clay fractions separated from the Beas River sediments. One gram of each sediment type was spiked with the pesticide mixture containing 100 mg/L of each fungicide and allowed to adsorb for 24 hours. Following that, the spiked sediments were eluted with deionized water to simulate rainwater flushing in the real conditions. The extracts were analysed using HPLC-DAD to measure the concentration of fungicides eluted with water. The findings indicated that sediment type significantly influenced the desorption of carbendazim and thiophanate-methyl. Approximately 6.2% of thiophanate-methyl and 90.2% of carbendazim were eluted from coarse sand. The elution percentages for carbendazim and thiophanate-methyl using medium sand were 87.21% and 4.5%, respectively. Fine sand exhibited increased elution, with 26.4% thiophanate-methyl and 92.2% carbendazim released. Silt-clay sediments released 37.7% of thiophanate-methyl and 89.7% of carbendazim. The findings indicate that sediment retention of pesticides is contingent upon particle size, affecting the quantity of pesticide that may be released into the water. Additional work on adsorption and desorption of captan (organochloride) along with these two pesticides using the batch equilibrium procedures is underway.
How to cite: Kumari, D., Kulkarni, H., and Giri, A.: Sorption characteristics of the selected pesticides on the river sediments in the Mid-Himalayan region. , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-732, https://doi.org/10.5194/egusphere-egu26-732, 2026.
River sediments play a crucial role in controlling the adsorption of contaminants in aquatic environments and act as major sinks for a wide range of organic pollutants, thereby significantly influencing the environmental fate of contaminants. In natural river systems, contaminant-sediment interactions occur under dynamic hydrodynamic conditions, which can alter mass transfer and adsorption processes. However, most existing studies rely on static batch experiments and therefore fail to capture flow-induced effects on contaminant adsorption by sediments. This limitation restricts the understanding of adsorption behavior under realistic flow conditions. In this study, sulfamethoxazole (SMX) is selected as a representative emerging contaminant to investigate how sediment properties and flow regimes jointly regulate adsorption behavior by integrating bench-scale tests with flume experiments.
Bench-scale results revealed a discrepancy between predicted and observed adsorption effectiveness among four sediments (Rebolim, Figueira da Foz, Doñana, and Mira). Mineralogical assessments suggested superior performance of sediments rich in reactive minerals (e.g., smectites), particularly those from Figueira da Foz. However, experimental results identified the sediments from Rebolim as the most effective adsorbent. This discrepancy indicates that the presence and accessibility of organic matter (OM), rather than mineral abundance alone, can govern adsorption performance. Notably, the removal of OM significantly reduced adsorption capacity, confirming its dominant role in SMX uptake. Furthermore, the results highlight a distinction between adsorption kinetics and ultimate capacity, as some sediments exhibited rapid initial uptake but limited long-term adsorption potential.
Flume experiments further demonstrated that hydrodynamic conditions fundamentally reshape the spatiotemporal distribution of SMX. In low-flow regimes, transport follows a classical advective-dispersive model with clear longitudinal gradients. Conversely, high-flow regimes induce intense turbulence, leading to near-instantaneous vertical and longitudinal homogenization. Crucially, a non-monotonic relationship was observed between flow velocity and SMX attenuation: moderate turbulence enhances adsorption by increasing contact frequency at the sediment-water interface, whereas high velocities inhibit net adsorption due to hydrodynamic flushing and reduced residence time.
These findings provide a more comprehensive framework for understanding the transport and adsorption fate of emerging contaminants in riverine systems. Future work will extend the current steady-state flow conditions to unsteady flow regimes to better understand the adsorption behavior under dynamic hydraulic conditions.
How to cite: Wang, M., Morales-Hernández, M., Brufau, P., García-Navarro, P., Fernandes de Carvalho, R., Martins, R., Domingues, E., and Dinis, P.: Hydrodynamic effects on sulfamethoxazole adsorption on river sediments: Insights from bench-scale and flume experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13393, https://doi.org/10.5194/egusphere-egu26-13393, 2026.
This study analyzes the natural and induced mobilization of lead (Pb), cadmium (Cd), and arsenic (As) present in residues generated during zinc hydrometallurgy, aiming to evaluate their environmental impact and associated risks under uncontrolled conditions. Differential X-ray diffraction was employed to characterize mineralogical and amorphous phases under simulated environmental scenarios. Results indicate that all samples exhibit high susceptibility to releasing potentially toxic elements (PTEs) depending on environmental conditions.
Chemical characterization of residues and runoff waters from affected areas was performed, determining pH, electrical conductivity, salt content, and total and soluble concentrations of Zn, Pb, Cd, and As. Subsequently, toxicity bioassays (Microtox®, Ostracods, Gammarus, and Phytotest) were applied to leachates and contaminated waters. Mineralogical analysis identified previous industrial processes that influence physicochemical properties and PTE mobility.
The most critical scenarios correspond to: (i) natural mobilization of Cd and Zn due to rainfall, and (ii) changes in redox conditions in anoxic environments (flooding or incorporation of organic matter), that promote the reduction of As (V) to As (III) . High concentrations of soluble salts increase hazard potential, generating ecotoxicological risks and potential carcinogenic effects through oral ingestion
Results confirm elevated levels of heavy metals and significant toxic effects in residues and associated waters, highlighting the need to implement preventive measures and management strategies to minimize environmental and health impacts.
How to cite: Pérez-Sirvent, C., Martínez Sanchez, M. J., Hernandez Perez, C., Hernandez Cordoba, M., and Solano, A.: Assessment of Heavy Metal Mobilization in Zinc Hydrometallurgy Residues and Their Environmental Impact, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14865, https://doi.org/10.5194/egusphere-egu26-14865, 2026.
Pharmaceuticals and personal care products (PPCPs) from wastewater discharge are increasingly detected in urban river systems; however, their subsurface fate and transport remain poorly understood at the field scale. Here, we investigate the vertical migration and subsurface distribution of emerging organic contaminants (EOCs) at three anthropogenically impacted sites in the Yamuna River basin, Delhi, India: the Yamuna Riverbank, a major urban drain that discharges directly into the river, and an artificial lake that receives treated wastewater effluent. Target compounds included antibiotics, endocrine-disrupting compounds, prescription and over-the-counter pharmaceuticals, sewage-associated tracers, and an artificial sweetener.
Soil samples spanning the vadose and saturated zones were collected down to 30 m below ground level using standard penetration testing and the bailer (“Boki”) method. Nested piezometers enabled the spatiotemporal monitoring of surface water and groundwater in shallow, intermediate, and deep layers over a one-year period.
Deep penetration of PPCPs was observed at all three sites, with at least ten target compounds quantified in both soils and groundwater down to a depth of 30 m. Estrone exhibited the highest concentrations in soils, while non-steroidal anti-inflammatory drugs were the most frequently detected compound class across sites. Seven compounds showed detection frequencies exceeding 90% in soils at all three sites. Multivariate statistical analyses linked compound-specific distribution patterns to soil chemistry and subsurface hydrogeology. Stable isotope analysis (δ¹⁸O, δ²H) and fluorescence dissolved organic matter (fDOM) characterisation were applied to elucidate surface water–groundwater interactions. Soil mineralogy and elemental composition were characterised using X-ray diffraction (XRD) and X-ray fluorescence (XRF) to assess geochemical controls on contaminant retention and mobility.
In addition to targeted monitoring of 27 compounds, suspect and non-target screening was conducted on surface and groundwater samples to identify transformation products and to assess the influence of redox and geochemical conditions on subsurface transformation processes. Laboratory-scale batch sorption and biodegradation experiments conducted at environmentally relevant concentrations were used to support the interpretation of field-scale observations.
These results demonstrate that PPCPs can migrate vertically through soils and persist across both the vadose and saturated zones, with significant implications for groundwater quality, particularly in regions where rivers serve as both wastewater receivers and aquifer recharge zones.
How to cite: Gupta, S., Singh, D., Vellanki, B. P., and Boving, T.: From Surface Water to Deep Groundwater: Field Evidence of Fate and Transport of Pharmaceuticals and Personal Care Products (PPCPs) in Urban Alluvial Systems of Delhi, India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16820, https://doi.org/10.5194/egusphere-egu26-16820, 2026.
Acid mine drainage (AMD) poses a persistent threat to freshwater ecosystems by causing acidification and mobilizing heavy metals that have adverse effects on aquatic biota. Especially in Arctic regions, these impacts are amplified by the changing redox conditions due to the low temperatures and seasonal ice cover. Nature-based solutions (NBS), including constructed wetlands, offer an ecologically friendly option to remediate the water quality under various environmental conditions, including AMD. Before developing an NbS to mitigate AMD, we analyze sediment composition in the target area to understand heavy metal behavior, including water–sediment transfer and their potential (bio) availability. Langvatnet Lake, located in northern Norway, functions as the main receiving water body and the lowest point within the historic Sulitjelma mining district, where extensive metal mining activities (primarily copper and zinc extraction) occurred for more than a century (Davids, 2018). These long-standing operations have resulted in highly acidic inflows originating from abandoned mine workings that, despite being closed, continue to leak acidic water and generate small drainage streams that flow into the lake. This ongoing discharge transports elevated concentrations of dissolved metals, contaminating both the water column and lake sediments. While the overarching aim of this research is to develop and evaluate NbS strategies to improve the water quality of the inlet streams, our first step is to quantify how mine-derived contaminants accumulate, persist, and potentially remobilize within lake sediments. Therefore, we use the Community Bureau of Reference (BCR) sequential extraction procedure to quantify the heavy metal concentration in different geochemical fractions of the sediments (Rauret et al., 1999). The inlet samples are compared with a range of sediment samples from the lake’s surrounding areas. This approach enables us to assess their potential release under varying environmental conditions. By identifying the dominant binding fractions, this contributes to designing the best suitable NbS for the investigated area. Our findings provide a basis for understanding the local sediment geochemistry in relation to the targeted remediation strategy. In this context, improved understanding of sediment-water interactions supports the development of resilient, passive NBS to enhance water quality, promote ecosystem recovery, and ensure long-term sustainability in AMD-impacted Arctic Lake systems.
References:
Davids, C. (2018). Mapping of abandoned mine tailings and acid mine drainage using in situ hyperspectral measurements and WorldView-3 satellite imagery (Case Study Report No. 20/2018). Northern Research Institute.
Rauret, G., López-Sánchez, J. F., Sahuquillo, A., Rubio, R., Davidson, C., Ure, A., & Quevauviller, Ph. (1999). Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials. Journal of Environmental Monitoring, 1(1), 57–61. https://doi.org/10.1039/a807854h
How to cite: Cuida López, E. Y., Fajković, H., Rončević, S., Mun, Y., Palinka, S., and Stoica, A. I.: BCR fractionation of mine-affected sediments as a basis for NbS design and implementation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15891, https://doi.org/10.5194/egusphere-egu26-15891, 2026.
Nowadays, environmentally friendly agriculture contributed to a significant interest in the production of fertilizers based on water-soluble humic substances such as humates and lignohumate. These commercial products are dark brown powders and/or concentrated alkaline solutions, containing mixture of humic substances, lingo-humic acids, and smaller proportion of lightly hydrolyzing organic compounds. Their root and foliar application increase growth of roots and leaves, chlorophyll content, and activity of plant enzymes, etc. All of this has generated intense interest for an accurate and reliable method to quantify humic substances in caustobiolites and commercial products.
The aim of this work was to determine the content of humic substances in raw caustobiolites (i.e. lignite, leonardite, and alginite) and commercial humate products. Humic substances (HA and FA) were isolated from following samples: South Moravian lignite (the northern part of the Vienna basin, Mír mine near Mikulčice in the Czech Republic); leonardite (Afşin, Kahramanmaraş, Turkey); alginite (Pinciná in the Slovakia Republic); lignohumate MAX (Amagro, Prague in Czech Republic); and HumiKey (Xi´an, TBio Crop Science Co., Ltd., China). The humic substances were extracted using a new standardized method for quantification of humic substances (Lamar et al., 2014) recommended by the International Humic Substances Society. The content of humic substances was obtained by gravimetric analysis. The wt.% HA and FA contents were corrected for moisture and ash content. Furthermore, the humic substances were used in solid powder form and characterized by thermal techniques (i.e. elemental and thermogravimetric analysis), UV/Vis spectroscopy, and FTIR spectroscopy.
The determining factor influencing the yield of humic substances from raw caustobiolites and commercial products is their origin and method of extraction. The greatest content of HA (54.22 ± 1.76%) was obtained for sample isolated from Turkey leonardite. In contrast, the lowest contents were determined for HAs extracted from alginite and lignohumate MAX. It is obvious that these samples are characterized by significant content of FK and lightly hydrolyzing organic compounds. Extremely high ash content was determined for alginate. Caustobiolites (e.g. alginite) with high ash and low contents of humic substances appear to be less suitable as sources of HS for agricultural purposes.
All examined HAs isolated from caustobiolites were generally characterized by the complex and heterogeneous molecular structure with high average molecular weight and high degree of aromaticity. On the other hand, FAs, especially those isolated from commercial products, were predominantly aliphatic, with a smaller content of nitrogen and low degree of aromaticity and greater amount of oxygen-containing functional groups (e.g. carboxylic and phenolic).
This standardized method and studies on the physicochemical properties of HS can be helpful in predicting the behavior of such fertilizer components in the environment.
Reference
Lamar, R.T., Olk, D.C., Mayhew, L., Bloom, P.R., 2014. A New Standardized Method for Quantification of Humic and Fulvic Acids in Humic Ores and Commercial Products. J. AOAC Int. 97, 721-730. https://doi.org/10.5740/jaoacint.13-393.
Acknowledgement
This work was supported by The NATO Science for Peace and Security Programme, project Nr. G6296. https://land-security.org/.
How to cite: Enev, V., Mullerova, K., Kubikova, L., Ciz, J., Liskova, K., Klucakova, M., and Pekar, M.: Quantification of Humic Substances in Caustobiolites and Commercial Products Using a New Standardization Method, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5440, https://doi.org/10.5194/egusphere-egu26-5440, 2026.
The transfer of sediment‑bound contaminants from unstable hillslopes into fluvial and lacustrine environments is governed by the interaction between geomorphic processes, hydrological connectivity and sediment transport dynamics. This study develops a quantitative modelling framework to assess the mobilisation of arsenic (As) from a contaminated slope and its potential downstream propagation through an integrated slope–channel–lake system.
High‑resolution terrain data were used to parameterise slope geometry and derive section‑scale morphometric attributes relevant to sediment detachment and mass‑failure susceptibility (slope gradient, contributing area, profile curvature and cross-sectional geometry). Spatially distributed As concentration measurements were incorporated into a stochastic Monte Carlo model, which simulated 10,000 realisations of contaminant mass for each slope section using distribution-specific sampling to represent data variability. Mobilizable sediment volumes were estimated using geometrically constrained maximum‑failure envelopes, enabling derivation of event‑scale sediment yields.
Hydrological and sediment connectivity were conceptualised through a simplified source–pathway–receptor model. Collapse scenarios representing 10%, 20%, 30%, 50% and 100% slope mobilisation were propagated downstream assuming full sediment transfer efficiency and no attenuation processes such as channel storage, hyporheic exchange, settling velocity effects or precipitation–adsorption dynamics. This approach represents an upper-bound transfer model suitable for preliminary contaminant‑risk assessment.
Total As mass stored in the slope was estimated at approximately 458 kg. Model outputs indicate that even under complete slope failure, the resulting concentration in the receiving lake remains marginally below the commonly adopted 0.010 mg/L threshold for potable water, whereas partial‑failure scenarios yield concentrations an order of magnitude lower. Sensitivity analyses demonstrate that predictions are strongly influenced by bulk density assumptions, connectivity ratios and sediment pulse magnitudes, highlighting the importance of probabilistic approaches for representing parameter uncertainty.
These findings underscore the need to integrate hydro‑sedimentary modelling, geomorphic characterisation and stochastic uncertainty quantification when assessing contaminant transport in catchment‑scale systems. The methodology presented provides a transferable framework for evaluating contaminant propagation where legacy mining residues persist in erosion‑prone, hydrologically connected terrain.
How to cite: Sánchez-Canales, M., Barrio Parra, F., Berbel, I., Álvarez-Mejías, L., Serrano Garcia, H., Montalvo-Piñeiro, J., Izquierdo-Diaz, M., and De Miguel, E.: Stochastic hydro‑sedimentary modelling of arsenic mobilisation and downstream propagation in a coupled slope–channel–lake system, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17893, https://doi.org/10.5194/egusphere-egu26-17893, 2026.
Toxic trace elements preserved in lacustrine sediments provide valuable archives of long term environmental change yet their historical accumulation remains poorly constrained in rapidly developing regions. We investigate century scale trace metal variability using a well dated sediment core retrieved from the depocenter of Lake Maninjau, Indonesia. Sediment chronology was established using 210Pb dating and a high resolution multiproxy geochemical analysis of trace and major elements (ICP-MS, XRF) including total organic carbon (TOC). Cu, Zn, Pb, and Cd show a gradual increase from the early to mid-20th century followed by a pronounced enrichment in the early 2000s. This recent intensification is most evident for Cd which remains relatively stable earlier in the record before increasing sharply in the last two decades. In contrast Pb exhibits a decline in concentrations during the most recent period. These geochemical changes coincide with a marked increase in TOC beginning around the mid-20th century and a transition from detrital dominated sediments to diatom enriched facies indicating a shift in Lake Maninjau’s depositional regime. The pronounced metal enrichment in the last two decades temporally coincides with the period of intensified aquaculture activity in the lake. The co-variation between TOC and trace metal enrichment suggests that increased organic loading associated with aquaculture expansion enhanced trace metal accumulation under changing depositional conditions. This study demonstrates a clear intensification of trace metal accumulation and organic matter deposition in Lake Maninjau over the last century highlighting the value of sediment records for assessing long term pollution trajectories and environmental changes in tropical lake systems.
How to cite: Inyangala, S., Kiro, Y., and Waldmann, N.: A Century of Trace Metal Accumulation Recorded in Lake Maninjau Sediments, Indonesia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15314, https://doi.org/10.5194/egusphere-egu26-15314, 2026.
The August 2023 floods in Slovenia exposed how extreme hydrological events can transform industrial and mining legacies into acute public health and agricultural crises. Heavy rainfall triggered mass wasting and river overflows across 183 municipalities - an area of approximately 17,203 km² ‑ resulting in roughly €9.9 billion in losses.
Slovenia’s rich mineral deposits historically fueled industrial development but left enduring environmental burdens. Beyond the physical devastation, these floods remobilized toxic sediments from historical hotspots, including the Mežica Pb–Zn mine, the Celje zinc smelter, and the Idrija mercury mine. Our study uses field measurements, geochemical analyses, and a comprehensive GIS framework to examine how flood deposits contaminate farmland and influence human exposure pathways across the nation’s river basins.
We conducted a GIS-based analysis that integrated national geochemical surveys, environmental monitoring data, hydrological records, historical & modern land-use maps, and flood-hazard assessments. This enabled us to identify zones where contamination sources overlap with flood-prone areas across four major river basins: Sava, Drava, Mura, and Soča. By overlaying these layers with current land use, we delineated agricultural and urban parcels most at risk of metal contamination.
Analyses reveal pronounced contamination gradients and significant overlap between polluted zones and cultivated floodplains. In the Sava basin, multiple hotspots (Celje, Jesenice, and Litija) coincide with intensively farmed floodplain terraces. Overbank sediments here show metal concentrations tens to hundreds of times above background levels; specifically, Celje’s topsoils contain Zn up to 8,600 mg kg⁻¹ and Cd often exceeding critical thresholds. GIS overlays indicate that a substantial portion of this farmland lies within high-hazard flood zones. In the Drava basin, spatial analysis highlights a narrow corridor where the Meža plume passes through cropland; floodplain soils downstream remain laden with Pb, Zn, and Cd from legacy mining. By contrast, the Mura basin, while largely agricultural, shows minimal overlap between contaminated zones and flood-prone areas, reflecting its predominantly geogenic background and lower industrial impact. In the Soča basin, we observed moderate overlap: heavy Hg contamination from Idrija (sediment averages 603 mg kg⁻¹ and floodplain soils 157.7–294.8 mg kg⁻¹) is largely confined to specific terraces, yet downstream agricultural parcels remain at risk.
Our findings show that Slovenian floodplains are disproportionately burdened by legacy pollutants that re-enter the environment during extreme events. As climate projections indicate more frequent and intense flooding in Alpine and Pannonian regions, it is urgent to integrate flood risk management with soil remediation, agricultural planning, and public health strategies to safeguard food security and human well-being.
How to cite: Golob, N., Gaberšek, M., Gosar, M., and Zupanc, V.: Flood‑Driven Remobilisation of Legacy Metal Contaminants in Sovenian River Basins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4427, https://doi.org/10.5194/egusphere-egu26-4427, 2026.
Headwater streams extend and retract both seasonally and in response to individual rainfall events. Stream network extension is typically accompanied by an increase in stream water velocity and water depth, which may overcome mobilization thresholds of particulate matter that may have accumulated in previously dried-out streams. Although this process is commonly conjectured, data documenting the pacing and mechanisms leading to the transfer of particulate matter from terrestrial to aquatic environments remains scarce. An improved mechanistic understanding of these processes in forested headwater streams is particularly needed because they are reportedly highly sensitive to the changes in timing, magnitude and duration of precipitation expected under a changing climate. In Luxembourg, the health of forest ecosystems has also declined severely over the past two decades. Together, these changes might ultimately affect flow persistence, alter the transport and transformation of water, energy, dissolved and suspended materials, and impact organisms throughout the river network. The potentially considerable consequences of these changes on our water resources, aquatic ecosystems and bio-geochemical cycles remain largely unknown. In this study, we investigate the relationship between catchment storage, water flow paths, stream network extension and particulate matter mobilization. During rainfall events, water might flow overland in previously dry streams if a shallow, perched, transient water table builds up and generates runoff, or if a deeper water table rises to the upper transmissive soil horizons. The former mechanism is more likely to occur when antecedent catchment storage is low, whereas the latter is expected when storage is high. Despite it has never been demonstrated with observations, these two processes leading to overland flow might be associated to different sediment mobilization mechanisms. To test these hypothesis, we designed a field study to gather unprecedented datasets on (i) stream network dynamics (i.e., network extension/retraction and intermittency) documented using time-lapse cameras, (ii) suspended sediment fluxes measured at the catchment outlet, and (iii) catchment storage estimated from an extensive, high-resolution hydrometric time series collected in the Weierbach Experimental Catchment (WEC; 0.45 km2; north-western Luxembourg). Our results show that stream extension during rainfall events drives particulate matter mobilization during single peak hydrographs in the WEC, when water rapidly reaches the stream network during precipitation pulses and catchment storage is low. In contrast, double peak hydrographs occur when catchment storage is high, resulting in limited stream network extension and low particulate matter mobilization. Building on these newly gained datasets, we aim to develop a novel conceptual framework linking particulate matter mobilization to its subsequent controlling factors, including rainfall characteristics, catchment storage, regolith structure, land cover and topography.
How to cite: Martínez-Carreras, N., Gourdol, L., and Iffly, J. F.: Mobilization of particulate matter in intermittent and forested headwater streams, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19124, https://doi.org/10.5194/egusphere-egu26-19124, 2026.
The establishment of standardized procedures for defining geochemical reference values is critical to ensure consistency, robustness, and reliability in environmental assessments, particularly in mining-affected regions where natural geochemical backgrounds commonly overlap with anthropogenic inputs. In these settings, the determination of reliable baseline values is essential for differentiating natural variability from contamination and for supporting informed environmental management and regulatory decisions. This study provides a detailed characterization of the geochemical composition of fluvial sediments from the upper and middle sectors of the Paraopeba River Basin (PRB), southeastern Brazil, with the aim of defining representative baseline values for potentially toxic elements (PTEs). The basin has been subject to prolonged environmental pressures associated with mining, culminating in the failure of the B1 tailings dam in Brumadinho. Notably, the sediment dataset used in this investigation was obtained prior to the dam collapse, allowing the characterization of pre-disturbance geochemical conditions. A total of 717 fluvial sediment samples were collected and analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Given the pronounced lithological diversity of the PRB, baseline were determined separately for each lithotype using multiple statistical techniques, including TIF, mMAD, and percentile-based approaches (75th and 98th percentiles). The results reveal a dominant geogenic control on the spatial distribution of several elements, particularly Ni, Cr, Co, Cu, and V, which are strongly linked to mafic and ultramafic lithologies of the Rio das Velhas Supergroup and the Santo Antônio do Pirapetinga Complex. Conversely, Fe and Mn show higher concentrations in areas associated with iron formations of the Minas Supergroup. Spatial mapping and multivariate analyses further indicate the combined effects of lithological controls and anthropogenic activities especially mining on sediment geochemistry. In some instances, the established baseline exceeds average upper continental crust concentrations and those reported for other mining-impacted river basins worldwide, underscoring the distinctive geochemical character of the Paraopeba River Basin. In summary, this study establishes the first regional geochemical reference framework for fluvial sediments in the Paraopeba River Basin, providing a robust scientific basis for environmental monitoring, contamination assessment, and the formulation of management and remediation strategies in watersheds influenced by mining activities.
How to cite: Leão, L., Pacheco, F., Fernandes, L. F., Vicq, R., Laureano, F., Marques, E., and Valente, T.: Establishment of baseline values for fluvial sediments in the Paraopeba river basin (Brazil), prior to the Brumadinho dam failure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7670, https://doi.org/10.5194/egusphere-egu26-7670, 2026.
Sediment surplus in rivers of the Bohemian Massif is a problem for habitats of freshwater pearl mussels (Margaritifera margaritifera). These relatively fine sediments get remobilized already at mean discharge conditions, leading to mechanical stress on the mussels. Further, this increases flood risk in certain river stretches. Thus, removal of the sediment is a necessity. Due to economic and ecological reasons, riverbed dredging should be avoided. In present work, a nature-based solution for self-dynamic desanding (SDD) was investigated with physical model experiments. Through SDD, sediment shall be deposited on the floodplain during high-flow conditions, where it can be removed cheaply without in-stream work.
The physical experiments were based on a stretch of the Malše River at the Austrian/Czech border in 1:20 scale and conducted in three stages. At first, in-stream measures were investigated to optimize the transport of sediment from the main channel onto a lowered floodplain. Secondly, measures on the lowered floodplain were developed to optimize deposition. Finally, these measures were tested in a quasi-unsteady flow scenario based on a one-year flood wave. Through these experiments, SDD was improved and the descending branch of the flood wave was established to be a decisive factor on the efficiency of the proposed measures, as deposited material was washed back into the main channel. Modifications of the developed measures mitigated this issue, leading to a slightly lower deposition than in the steady case. In the end, the model showed a capacity (in nature scale) of up to 14.6 m³ of deposited sand on an area of about 120 m² .
How to cite: Worf, D., Humenberger, S., Flödl, P., Sindelar, C., and Hauer, C.: Development of self-dynamic desanding measures through physical model experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7729, https://doi.org/10.5194/egusphere-egu26-7729, 2026.
Benthic fauna plays a critical role in mediating bed load sediment transport, an essential process influencing wetland restoration, water quality, coastal protection, and nutrient cycling. However, predictive models quantifying this biological mediation remain absent due to limited mechanistic understanding. Here, we develop a high-fidelity computational model coupling fluid flow, sediment dynamics, and benthic activity to quantify benthic fauna-mediated bed load transport. We show that benthic presence can reduce transport rates by up to 50%, primarily through two mechanisms: bioroughness-induced effective shear stress reduction and bioturbulence-driven wake zone expansion. Building on these insights, we propose two predictive formulas that align well with field data. These findings offer the first quantitative framework for bed load prediction in benthos-dominated environments and sheds light on sediment dynamics central to benthic morphodynamics.
How to cite: Chen, Z.: Benthic fauna-mediated bed load sediment transport dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19085, https://doi.org/10.5194/egusphere-egu26-19085, 2026.
Particulate bioavailable phosphorus (PBAP) plays a critical role in biogeochemical cycling and primary productivity in aquatic ecosystems, particularly in ecologically vulnerable alpine regions such as the Yarlung Tsangpo River. However, the understanding of PBAP dynamics remains limited due to the complex interaction and transport processes. To address this gap, we developed a mathematical model that integrated hydrodynamics, sediment transport, and the dynamics of dissolved and particulate phosphorus to investigate PBAP transport with sediment. PBAP bound to sediment was represented by coupling sediment mineral properties and environmental factors. Lateral inputs of water, sediment, and phosphorus from the watershed were incorporated using the Soil and Water Assessment Tool (SWAT). The model was applied to the Yarlung Tsangpo River and successfully reproduced PBAP distributions, with spatiotemporal concentrations ranging from 0.20 to 0.38 mg g−1, consistent with field measurements. The estimated annual PBAP flux was 2.77 Gg yr−1, partitioned as 46.0% Ex‑P, 37.7% Fe‑P, and 16.3% Al‑P, which exceeded the flux of dissolved phosphorus (~0.80 Gg yr−1). Furthermore, over 95% of annual PBAP flux occurred between June and September, indicating strong temporal variability in PBAP dynamics within monsoonal alpine basins. This model advances process-based quantifications of PBAP dynamics and has far-reaching implications for water resources research and management.
How to cite: Zhou, Y., Fang, H., and Huang, L.: Mathematical modeling for interactions and transport of particulate bioavailable phosphorus with sediment in the Yarlung Tsangpo River, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15671, https://doi.org/10.5194/egusphere-egu26-15671, 2026.
