This session aims to bring together interdisciplinary researchers working across field, experimental, and numerical modelling approaches who are advancing methods and providing new insights into: (i) sediment transport and morphodynamic functioning of fluvial systems, (ii) evaluating morphological change at variable spatial and temporal scales, such as at event vs. seasonal scales, and (iii) investigating the sedimentology of these river systems. We particularly welcome applications which investigate the morphodynamic response of fluvial systems in all types and sizes and we would specifically like to encourage submissions from early career researchers and students.
Andean foreland rivers are preferential sites for ongoing and planned hydroelectric dam construction in the Amazon Basin. These rivers are characterized by high sediment fluxes that drive rapid rates of channel migration, large river-floodplain sediment exchanges, and creatediverse floodplain morphologies. Dams alter water and sediment supply to these dynamic rivers with expected morphodynamic and environmental impacts over decades to centuries. However, current observations and models of river response to dam construction do not fully incorporate the processes related to lateral channel migration and focus on short-term morphodynamic change.
Here, we use an innovative hydro-morphodynamic model that accounts for flow, sediment transport, and channel-floodplain morphodynamics, including bend migration, dynamic vegetation, and channel abandonment. We demonstrate that Amazonian foreland rivers will undergo significant vertical and lateral erosion within less than 100 years following dam construction, with persistent or irreversible effects lasting for centuries. While downstream scour may partially offset the sediments trapped by dams, widespread erosion leads to formation of an entrenched inner secondary floodplain, which diminishes the extent and frequency of primary floodplain inundation. This entrenchment disconnects abandoned cutoff channels from the active river and potentially transforms floodplain ecosystems. Net erosion volume, and associated hydrologic changes, depend on pre-dam river characteristics: pre-dam rivers with high sediment loads and lateral migration rates experience the largest changes. Our simulations underscore the significant role of channel-floodplain interactions in driving fluvial reorganization and ecological adaptation downstream of dams. New dams could thus trigger a rapid and irreversible system reconfiguration, with critical impact on riparian ecosystems and the livelihoods of local communities.
How to cite: Brückner, M., Nicholas, A., Aalto, R., Almeida, R., Ashworth, P., Best, J., and Dunne, T.: Dams trigger long-term river-floodplain decoupling in dynamic Andean foreland rivers , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13952, https://doi.org/10.5194/egusphere-egu26-13952, 2026.
Fluvial geomorphology has often relied on case studies to deepen our knowledge of landscape processes. Through detailed terrain mapping, historic photo analysis, field measurements, sedimentology and geochronology, we have investigated how rivers respond to the processes that act on them, and how rivers in turn act on the landscape. This site-specific approach is crucial to the foundation and future of our discipline, but recent work across geomorphology and hydrology has highlighted the insights that can be gained from comparing a wide range of sites spanning one or more environmental gradients. In this talk, we advocate for this large-sample approach to fluvial geomorphology, which we term "Global River Science". We present a review of Global River Science research spanning a range of time scales in geomorphology, from landscape evolution through to event scale morphologic change. Finally, we identify challenges to Global River Science and priorities for its future direction.
How to cite: Leenman, A., Clubb, F., and Slater, L.: Global River Science: a call for “large-sample” fluvial geomorphology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8299, https://doi.org/10.5194/egusphere-egu26-8299, 2026.
Despite significant advances in the study of meandering rivers, the precise mechanisms by which erosion and sedimentation interact to drive meander migration remain poorly understood. Two longstanding competing theories attempt to explain this interaction: one suggests that inner-bank sediment deposition precedes outer-bank erosion (bar push), while the other posits that outer-bank erosion initiates inner-bank sedimentation (bank pull). To date, research addressing which of these mechanisms dominates in real environments has predominantly focused on a small number of bends and at limited temporal scales, leading to inconclusive results. In this paper, we analyse the occurrence of bank pull versus bar push across 4,923 river bends worldwide. This was done by estimating outerbank erosion and inner-bank sedimentation rates using a 38-year time series of Landsat data, from which classifications of bank pull and bar push were derived through Dynamic Cross-Correlation analysis. We found that both bank pull and bar push occur frequently in a wide range of natural environments, but with a slight dominance (55.7% of bends) of bank pull over bar push (47.3%). Nevertheless, we also identify subtle patterns in the relative frequency of push versus pull migrating bends based on river characteristics. Vegetated rivers with slower, less variable, flow and finer boundary materials are more likely to exhibit migration via bar push, where sediment deposition along the inner bank plays a dominant role. In contrast, less densely vegetated rivers with faster, more variable flows and with coarser boundary materials, show a higher occurrence of bends migrating via bank pull. This means that most bar-push migrating bends are located in densely-vegetated tropical environments, with bar pull tending to dominate in other regions. This study represents the first largescale analysis of bank pull and bar push in real rivers, providing valuable insights that could be used to improve river dynamics modelling and inform more effective river management strategies.
How to cite: Nagel, G., Darby, S., and Leyland, J.: Bank pull or bar push: Who leads the dance ofmeander migration?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8381, https://doi.org/10.5194/egusphere-egu26-8381, 2026.
Longstanding efforts to explain the origin of river planforms are typically based on a simplified dichotomy (or spectrum) between single-thread meandering planforms and multi-thread braided planforms. However, multi-thread planforms in nature are exceptionally diverse. They can be classified as braided, wandering, anastomosing, and more based on various metrics, with definitions across studies that are inconsistent, non-exclusive, and lacking a physical mechanism. To tackle this knowledge gap we investigated four decades of planform dynamics along 49 rivers around the world imaged by NASA Landsat, leveraging established proxies for floodplain development (e.g., NDVI) and a state-of-the-art automated migration-mapping technique based on particle image velocimetry (PIV). Results reveal multi-thread planform diversity originates from competition between migration and floodplain development on mid-channel bars, which we quantify in terms of a floodplain development timescale (Tfp) and a bar turnover timescale (Tbar). If bars migrate slowly relative to the pace of floodplain development (Tbar >> Tfp), bars are converted to floodplains by fine-sediment deposition and vegetation growth, resulting in an anastomosing planform. In contrast, if bars migrate quickly (Tbar << Tfp), they remain bars because migration reworks vegetation and fines before any floodplain develops (braided). And if bars migrate at intermediate speeds (Tbar ~ Tfp), they form a mosaic of partially converted bars and floodplains (wandering). Put to practice, these findings can advance our ability to predict future planform changes in response to climate change and human activities; and help decipher ancient planforms left behind in the sedimentary record.
How to cite: Chadwick, A. J., Greenberg, E., and Ganti, V.: Multi-thread planform diversity originates from competition between migration and floodplain development on mid-channel bars , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13623, https://doi.org/10.5194/egusphere-egu26-13623, 2026.
Empirical and theoretical studies of alluvial river meandering planforms have indicated that channel width is a first-order controller of lateral migration rates. There is even a rule of thumb in fluvial geomorphology that alluvial meandering rivers typically laterally migrate at a rate of 1-2% of their channel width per year. However, the process of lateral migration is driven by a combination of boundary shear stress in excess of the critical shear stress for erosion of the cut bank and a deficiency of shear stress that enables sediment deposition on the point bar. As boundary shear stress is a function of the velocity profile away from the channel boundary, often approximated as the product of channel depth and slope, it is counterintuitive that channel width should be a strong controller of lateral migration rate. To address this knowledge gap, we first combine multiple global datasets of bank erosion rates to confirm that channel width does indeed correlate with lateral migration rates. Additionally, we find a width scale-dependence in the proportion of channel widths migrated per year with narrower channels migrating a greater proportion of their width per year than wider channels. To understand the mechanistic influence of channel width on lateral migration rates, we utilize Delft3D to model flow down a meandering river reach. We manipulate bathymetric data of a reach of the Merced River to stretch and compress the channel’s width while preserving the channel’s vertical bathymetry and gradient to isolate the control of channel width on the flow structure. Utilizing a Ray Isovel Model, we extract boundary shear stresses along the channel’s wetted perimeter within meander bends. Results show that the magnitude of boundary shear stress remains largely unaffected by channel width scaling. Furthermore, flow in narrower channels appears to exert a relatively higher stress at the cutbank than in wider channels. Our findings, in combination with hydraulic scaling relationships, suggest that the apparent control of channel width on lateral migration rates, while a useful tool, is an artifact of width-depth scaling. In this light, we reanalyze our global datasets to demonstrate that channel depth exerts a first order control on lateral migration rates, with average migration rates clustering around approximately 20% of channel depth per year.
How to cite: Dunne, K., Baar, A., and Shimomura, R.: Untangling the Control of Channel Width on Lateral Migration Rates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18497, https://doi.org/10.5194/egusphere-egu26-18497, 2026.
Floodplains are integral components of dynamic biogeomorphic river systems, serving as significant storage reservoirs for water, sediment, and carbon across diverse temporal and spatial scales. Previous research suggests that floodplain carbon storage potential varies with river type and planform characteristics (e.g., meandering vs. braiding). Nevertheless, the fundamental mechanisms by which distinct geomorphic floodplain types govern carbon sequestration and downstream export remain poorly understood. This study integrates remote sensing and quantitative geomorphic analyses to evaluate how variations in river and floodplain planform configuration control spatio-temporal patterns of overbank inundation, sediment deposition, and channel migration across two contrasting East African river systems: (1) the braided Sabaki River and (2) the meandering Tana River. The insights gained are then used to discuss potential implications for floodplain carbon storage. We first estimate spatial patterns of flood extent and recurrence using a combination of Sentinel‑1 and Sentinel‑2 data and a simple inundation model. The inundation model delineates potential flooding extents by river stage, cross-referenced with observed spatial flooding patterns. This approach allows us to estimate the potential maximum flooded area per season and identify locations of riverine suspended sediment and associated carbon deposition. We subsequently link the predicted flooded areas with a multi-temporal analysis of river channel migration rates along longitudinal river profiles. Reach-averaged flooded areas and channel migration rates are further compared with measurements of sediment core organic carbon stocks, which are upscaled to the floodplain extent. Preliminary results indicate that floodplains in meandering reaches serve as more effective organic carbon sinks than those in braided reaches. This trend is attributed to the high lateral fluxes and chronic sediment reworking inherent to braided systems, which exhibit higher seasonal reach-averaged channel migration rates of approximately 50 m compared to 20 m in meandering systems, reflecting the lower migration and enhanced burial stability characteristic of meandering reaches. Finally, this integrated framework establishes a mechanistic link between geomorphic regimes, floodplain type, and carbon cycling, providing new constraints on the role of river geomorphology in regulating fluvial carbon pathways and long-term carbon sequestration potential.
How to cite: Samarasinghe, S., Cherono, S., Tamooh, F., Bouillon, S., and Schwarz, C.: Geomorphic Controls on Floodplain Carbon Sequestration: Linking Flood Dynamics, Channel Migration, and Carbon Sequestration Across Meandering and Braided Rivers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5837, https://doi.org/10.5194/egusphere-egu26-5837, 2026.
Satellite remote sensing has gained significant relevance in the monitoring of riverine processes over the past years. Time series of satellite imagery, e.g. from the Landsat or Sentinel-1 and -2 constellations, are of particular interest as they allow us to assess not only distinct landcover classes but also dynamic processes such as inundation duration. Over the recent years, the rise of AI supports the analysis of these big earth observation archives. The increasing volume of earth observation data and computational burden of large AI models, however, lead to challenges in data processing. In the remote sensing community, the use of foundation models, large neural networks trained on massive amounts of data, promise to reduce the computational burden for end users. In addition, raw data encoded by these models, so-called earth embeddings, provide a ready-to-use dataset which transforms complex, multitemporal data of hundreds of satellite scenes from different sensors into annual images with abstract numerical representations of the original data. While in the remote sensing community, there is an increasing number of studies evaluating the application of geospatial foundation models and embeddings for various applications, there is to the best of our knowledge no comprehensive evaluation of the use of these recent developments for assessing dynamic hydro-geomorphic patterns and processes of river corridors.
In our study, we assess the potential of two openly available embedding databases for their potential to represent typical riverine habitat types and river dynamics such as the inundation duration or erosion/formation features related to channel shifting. Specifically, we evaluate the recently released AlphaEarth embeddings (available on Google Earth Engine) and University of Cambridges TESSERA embeddings database (retrievable from their online database through a dedicated python package). Primary case study is the Naryn River in Kyrgyzstan. This is still a near-natural river on a length of more than 600 km. Along with an average active channel width of 400 m and average river corridor width of 1200 m, this makes the Naryn an ideal example for remote sensing applications in river science. We use a total number of 1873 ground truth points representing different geomorphic features and typical riparian habitat types as reference to evaluate how well embeddings are capable to distinguish these classes. To test the predictive capability of embeddings, we train supervised classification models based on the embeddings. In addition, we use satellite derived time series of inundation duration and inter-annual change derived from Planet Scope images to evaluate the potential of embeddings to represent dynamic characteristics and enable change detection. To analyze how this approach generalizes to other river systems, we apply the trained models to selected European rivers and validate the outcomes. Our initial results show a high potential of embeddings for analyzing riverscapes and their dynamics. We discuss how geospatial foundation models and embeddings as novel, AI driven tools in earth observation can contribute to generalizing remote sensing models across different river systems and how this can path the way towards global monitoring of riverscapes and their dynamics.
How to cite: Betz, F., Arisoy, B., Lauermann, M., Egger, G., Belletti, B., Bizzi, S., and Piégay, H.: Analyzing the potential of geospatial foundation models and earth embeddings for assessing dynamic riverine processes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14002, https://doi.org/10.5194/egusphere-egu26-14002, 2026.
Distributive fluvial systems (fluvial fans) have been demonstrated to dominate the planform area of modern sedimentary basins. Due to their dominance in areas where sediments are actively aggrading, it has been argued that they form the bulk of the fluvial rock record. However, there are some key gaps in the documentation of DFS characteristics, particularly the quantification of channel characteristics. Meandering planforms are prevalent across DFS. In recent years, great advancements have been made in understanding processes associated with meandering rivers as well as increasing our understanding of their deposits. However, little work has been done on understanding how, and whether, meander characteristics vary across a fluvial system.
This study assesses geomorphic patterns across a suite of DFS from a variety of climates to; 1) understand how channel characteristics change downstream on DFS; and 2) assess whether meander characteristics (amplitude, wavelength, migration rate and deposit area) change from proximal to distal regions. Observations from modern systems will be compared to the Jurassic Morrison Formation for which channel width and meander deposit area can be measured.
Our studies show that the active channel width and channel belt widths broadly decrease downstream, except in instances where: 1) an axial system truncates the toe of a DFS; 2) a nearby fan contributes sediment laterally into the system; and 3) a significant spring line is present. Interestingly, the active channel and channel belt width do not concurrently decrease downstream. It is postulated that this is due to planforms playing a key role in the width of the channel belt opposed to the active channel width. Migration rates and meander deposit area generally decrease downstream on the measured systems, however, trends on the Wood River DFS are weak with axial truncation interpreted to be a reason for a weak downstream trend. The Jurassic Salt Wash system mirrors patterns observed on modern systems, in particular the Wood River DFS as a downstream decrease in active and channel belt width is observed, with weak to no changes observed in meander deposit area.
These findings contribute to our overall understanding of fluvial processes, which is essential to understand flood risk for large population centres that live on DFS. In addition, a greater understanding of DFS deposits is gained, contributing to our understanding of reservoir characterisation in fluvial deposits.
How to cite: Owen, A., Kerr, H., Kwetishe, D., Williams, R., and Hartley, A.: Geomorphic patterns on distributive fluvial systems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18767, https://doi.org/10.5194/egusphere-egu26-18767, 2026.
In recent decades, sand extraction from rivers has accelerated to meet the needs of economic development. Locally, this results in river bed and bank erosion, but it is unknown how these local disturbances affect the larger-scale morphodynamic feedback and whether sustainable sand-mining strategies can be designed to minimise impacts. Our objective is to test dredging strategies in a river-estuary Delft3D model and to quantify the resulting morphodynamic response of the system. We systematically varied the number and intensity of dredging sites along the river, relative to the sediment supply from upstream.
Results show that sand extraction produces system-wide effects, with severity increasing with both extraction frequency and volume relative to the upstream sediment supply. We found that when intensive sand mining occurs at a small number of sites, mined reaches accumulated sediment and were able to recover after mining ceased, whereas unmined zones continued to erode due to sediment-depleted flows. This results in a long-term destabilisation of the delta and indicates a sensitivity to upstream perturbations. In contrast, less intensive sand mining spread over a larger number of sites results in an overall lower riverbed that continues to erode and export sediment after sand mining ceases. System recovery occurs only when sediment supply exceeds removal. These findings highlight that localised sand extraction can induce long-lasting geomorphic change, emphasising the need to constrain extraction volumes to maintain morphological stability.
How to cite: Baar, A. and Hackney, C.: Thresholds in the morphodynamic resilience of river deltas to sand extraction, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19017, https://doi.org/10.5194/egusphere-egu26-19017, 2026.
Fluvial systems act as integrative components of landscapes, recording both long-term geomorphic conditions and rapid anthropogenic reorganization of land surfaces in their sedimentary archives. In tropical river basins, land-use intensification, urban expansion, and agricultural reconfiguration modify sediment sources, connectivity patterns, and energy regimes, producing measurable changes in sedimentation rates and grain-size composition. This study evaluates how recent anthropogenic landscape reorganization is recorded in fluvial sediments by quantifying changes in sedimentation rates and grain size over the last century in an anthropogenically modified tributary basin in southeastern Brazil.
The dataset integrates sediment core analysis, grain-size measurements, and multi-temporal land-use analysis. A sediment core with a total depth of 74 cm, collected from the fluvial bed, was dated using excess lead-210, with radionuclide activities measured by high-purity germanium (HPGe) gamma spectrometry. Sediment grain size was characterized by laser diffraction. Land-use and land-cover (LULC) changes were evaluated using multi-temporal MapBiomas classifications derived from Landsat satellite imagery (30 m spatial resolution), providing consistent annual land-use information since 1985 and complemented by transition matrices to assess land-use conversions through time.
The 210Pb age–depth relationship reveals a segmented depositional history, in which linear trends define three successive phases of quasi-constant sedimentation rates, consistent with a Constant Flux (CF) model appropriate for sustained 210Pb supply under variable sedimentation conditions. These phases indicate a progressive acceleration of sedimentation, from 5.0 mm yr⁻¹ between 1946 and 1968, to 7.4 mm yr⁻¹ during 1968–2004, and reaching 9.6 mm yr⁻¹ after 2004. Grain-size results show a pronounced temporal shift, representing a clear inversion from fine-grained (clay + silt-dominated) deposits in the older sections to predominantly sand-rich sediments in the most recent decades, occurring in parallel with the progressive increase in sedimentation rates. LULC analysis indicates a monotonic expansion of urban areas, intensification of agricultural land uses—particularly sugarcane cultivation—and a strong spatial reorganization of pasture and mosaic-of-uses classes. Transition matrices indicate that mosaic-of-use areas are a primary source of land-use conversions toward urban and agricultural classes.
Distinct depositional phases identified from the 210Pb age–depth model, together with grain-size variability and coherent land-use transitions, indicate that shifts in sedimentation regimes coincide with major phases of urban expansion and agricultural reconfiguration. These findings demonstrate that land-use change exerts first-order control on recent fluvial sedimentary records, allowing depositional regimes to be interpreted as stratigraphic expressions of anthropogenic landscape reorganization.
How to cite: Silva de Campos, R. A., Lupinacci, C. M., and Tomazini da Conceição, F.: Acceleration and grain-size inversion of riverbed sedimentation driven by anthropogenic landscape reorganization (SE Brazil), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12864, https://doi.org/10.5194/egusphere-egu26-12864, 2026.
The assessment of four-dimensional channel change through topographic differencing has evolved rapidly from a research frontier to an established tool to inform sediment and flood hazard management. This transition has been driven largely by the growing availability of broad-area, multitemporal lidar surveys that enable system-scale analysis of river adjustment across space and time.
Despite these advances, the application of lidar-based differencing in fluvial environments remains fundamentally constrained by the limited availability of bathymetric data to complement conventional infrared lidar terrain models. This data deficit is commonly managed through the prescription of spatially distributed elevation uncertainty models, or more crudely by assuming that compensating patterns of erosion and deposition across exposed channel areas are representative of areally averaged changes in mean bed level. Such assumptions are frequently applied in large braided rivers, where much of the channel bed is exposed at low flow and morphodynamics are dominated by lateral channel mobility.
These assumptions can rarely be tested quantitatively due to the scarcity of repeat, high-quality bathymetric datasets. Here, we address this limitation by comparing system-wide patterns of channel adjustment for a large piedmont braided river derived from conventional hydroflattened DEMs and from seamless topobathymetric lidar elevation models. The analysis uses three surveys of the Rees River, New Zealand, acquired between 2021 and 2025 using co-mounted Riegl VUX-240 (1550 nm) and VQ-840-G (532 nm) lidar systems on a helicopter platform.
Our results reveal a five-fold increase in net volumetric change when derived from topobathymetric terrain models compared to hydroflattened DEMs. This difference reflects substantial sedimentation within wetted channels between 2022 and 2025, a process that is poorly captured by hydroflattened models. Moreover, aggradation within wetted anabranches evident in the 2022 topobathymetric DEM is not balanced by subsequent channel incision by 2025. The net effect is a reversal in the inferred direction of bed-level change: topobathymetric analysis indicates a significant increase in mean bed elevation, whereas hydroflattened analyses imply marginal degradation.
These findings highlight the importance of sediment fluxes within the wetted network of braided channels and demonstrate that morphodynamic interpretations based on exposed-bed differencing alone may be fundamentally misleading without effective bathymetric correction.
How to cite: Brasington, J., Correia, F. M., Pingram, M., Rogers, J., and Stout, J.: What lies beneath: Revisiting braided river morphodynamics with topobathymetric lidar, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15873, https://doi.org/10.5194/egusphere-egu26-15873, 2026.
In the current climate, approximately 60% of rivers in the Northern Hemisphere freeze during winter, draining over a third of the planet's land area and forming a crucial part of the cryosphere. Climate change shortens these ice-cover durations, which significantly affects river hydrodynamics, water levels and flow velocities. However, understanding these dynamics is difficult due to the challenges in obtaining detailed field data about ice roughness, flow characteristics, and pressure conditions, resulting in limited knowledge across diverse ice-covered flow scenarios. Flume experiments have proven valuable in studying ice-covered flows, but they often utilize smooth or floating materials that fail to accurately represent the stable subsurface ice roughness observed during mid-winter in (sub)arctic rivers. This research investigates how subsurface ice roughness affects hydrodynamics in ice-covered rivers through flume experiments, using field observations from the subarctic Pulmankijoki River in northern Finland to inform the setup and experimental conditions. Conducted in a 16 m long, 0.6 m wide, and 0.8 m deep flume, the study employs a stable proxy ice material with subsurface ice roughness and bedforms derived from mid-winter measurements at Pulmankijoki. By systematically varying the combinations of smooth bed and bedforms, along with smooth ice and subsurface ice roughness, the experiments aim to evaluate the impact of subsurface roughness on river hydrodynamics. Flow velocity and pressure measurements are used to enhance our understanding of ice-covered river dynamics and their response to climate change.
How to cite: de Vet, M., Vaahtera, R., Jarvela, J., and Lotsari, E.: Assessing the Impact of Subsurface Ice Roughness on Hydrodynamics in Ice-Covered Rivers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9589, https://doi.org/10.5194/egusphere-egu26-9589, 2026.
Rivers in cold regions are integral to the global hydrological cycle, yet their flow and ice regimes are undergoing rapid transformation under anthropogenic climate warming. The Arctic has warmed nearly four times faster than the global average, intensifying hydroclimatic extremes and altering processes that regulate river discharge, ice formation, and seasonal flow dynamics. Earlier snowmelt, increasing winter rainfall, reduced snow storage, and more frequent freeze-thaw cycles are weakening flow seasonality and shifting runoff peaks toward winter and early spring. Concurrently, river ice cover is becoming thinner, shorter in duration, and reduced in extent, modifying freeze-up and breakup dynamics, sediment transport, and ecological conditions. Despite growing recognition of these large-scale changes, field-based understanding of under-ice hydraulics and sediment processes remains limited.
This study investigates how changing hydroclimatic conditions influence river flow regimes and sediment dynamics in cold-region rivers of Finland (60°–70°N). An integrated, multi-scale approach is applied, combining (1) statistical analyses of multi-decadal discharge records at the watershed scale, (2) in-situ winter measurements of under-ice flow and sediment transport, and (3) spatial analyses of flow structure and turbulence beneath ice cover across a meander bend. Together, these complementary methods provide new insights into how climate-driven hydrological shifts are reshaping discharge regimes and governing flow and sediment processes during the ice-covered season. The results contribute to improved understanding of winter river dynamics in rapidly warming cold regions.
How to cite: Lintunen, K., Kasvi, E., Lotsari, E., and Alho, P.: Changing cold-region rivers: Flow characteristics and sediment transport beneath ice cover and shifts in discharge regimes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9591, https://doi.org/10.5194/egusphere-egu26-9591, 2026.
The abundance of vegetation in natural and manmade streams has a substantial impact on flow dynamics, nutrient distribution, and aquatic habitat condition (Nepf, 2012; Richardson et al., 2007). To understand the impact of vegetation, laboratory experiments have been conducted in a flume with rigid, continuous submerged vegetation. The vegetation is arranged along both boundaries with a non-vegetated section along the centre of an open channel. The size of the experimental flume is 10 m (length) × 0.4 m (width) × 0.6 m (depth). To simulate continuous vegetation patches, hard cylindrical plastic rods are used and evenly spaced along the boundaries of the channel. A flow tracker, ADV Lab-II, was used to measure the velocity of the water at different depths in the upstream and downstream non-vegetated sections as well as inside the vegetated area. Data was collected at a sampling rate of 5 Hz. Velocity data were recorded at 24 vertical measurement points in each location. Approximately 6000 instantaneous velocity points were recorded at each vertical location over 20 minutes (Kashyap and Barman, 2025). Measurements were conducted under a constant flow discharge of 0.0153 m3/s, and the submergence ratio of the vegetation was 0.43.
The findings showed that the presence of vegetation caused considerable changes in the velocity profiles. The non-vegetated upstream segment showed a logarithmic velocity pattern, which is typical of open channel flow. The velocity profiles of the vegetated zone are compared to the non-vegetated conditions. Specifically, the presence of vegetation reduced near-bed velocities while increasing velocities in the upper water column. The presence of vegetation visibly increases the Reynolds shear stress both within and downstream of the vegetation patches. This suggests that stem flow interactions led to more momentum exchange and turbulence eddies (Ghisalberti and Nepf, 2006). These effects spread outside the vegetated zone and have a prolonged effect on the turbulent structures of the flow. These results indicate the need for consideration of vegetation structure at different patch scales for hydraulic modelling.
Keywords: ADV, Reynolds shear stress, Rigid vegetation, Vegetation patches
References:
Ghisalberti, M., & Nepf, H. (2006). The structure of the shear layer in flows over rigid and flexible canopies. Environmental Fluid Mechanics, 6(3), 277-301.
Kashyap, S.N., & Barman, B. (2025). Turbulent flow characteristics over gravel bed channel with submerged vegetation patches. Physics of Fluids, 37(3), 035123.
Nepf, H.M. (2012). Flow and transport in regions with aquatic vegetation. Annual Review of Fluid Mechanics, 44(1), 123-142.
Richardson, D.M., Holmes, P.M., Esler, K.J., Galatowitsch, S.M., Stromberg, J.C., Kirkman, S.P., Pysek, P., & Hobbs, R.J. (2007). Riparian vegetation: degradation, alien plant invasions, and restoration prospects. Diversity and Distributions, 13(1), 126-139.
How to cite: Kashyap, S. N., Barman, B., and Heller, V.: Velocity Distribution and Reynolds Shear Stress Characteristics in a Narrow Gravel-Bed Open Channel with Submerged Rigid Vegetation Patches, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16432, https://doi.org/10.5194/egusphere-egu26-16432, 2026.
Pools and riffles are alternating topographic lows and highs that are ubiquitous in gravel-bed rivers. They create a mosaic of aquatic habitats and have therefore been central to the design of many river restoration initiatives. Despite extensive research, there remains much uncertainty about the processes governing their long-term evolution, while field identification remains constrained by subjective, flow-dependent criteria.
We present an objective and reproducible framework for delineating pools directly from bed topography. The method was applied to a 45-year record of annual topographic surveys at Carnation Creek, British Columbia. Our results indicate that pools persist in channel narrowing sections and become increasingly transient where the channel widens. The most persistent pool exhibited four distinct morphological phases, marked by non-uniform adjustments in depth, area, width, and volume. Principal component analysis further reveals that these phases are embedded within broader, reach-scale elevation patterns, demonstrating how pools are dynamic yet resilient features capable of organizing reach-scale channel morphology. Their adjustment arises from recurrent cycles of aggradation and degradation driven by feedback among flow variability, sediment storage, and antecedent bed conditions.
Together, this study presents the first empirical record of the surprisingly decadal-scale persistence and adjustment of pools at an annual resolution that has not been previously reported by any field-based investigation. From a restoration perspective, these findings underscore the need to restore underlying channel processes that allow pools to self-organize, rather than imposing static, form-based designs.
How to cite: Ng, R. and Hassan, M.: Pool evolution in gravel-bed reaches: Insights from a 45-year record at Carnation Creek, British Columbia , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-233, https://doi.org/10.5194/egusphere-egu26-233, 2026.
The Eastern Himalayan Syntaxis (EHS) hosts some of Earth’s deepest gorges and rapid exhumation, yet the mechanisms sustaining its extreme relief remain an active area of geomorphic research. Classic interpretations invoke the tectonic aneurysm model, in which rapid fluvial incision feeds back with crustal deformation to concentrate uplift around the Namche Barwa massif. However, emerging evidence suggests that large-scale drainage reorganization may also set the stage for this focused topography. The well-documented diversion of the Lohit headwaters into the Siang system provides a natural experiment in how river capture can redistribute erosional power across the landscape. To assess this interaction, we combine geomorphic analysis of the Siang–Dibang–Lohit network with landscape evolution modeling to explore how capture-driven changes in drainage area and discharge propagate through the channel system. Our simulations show that the addition of Lohit drainage to the Siang following upstream reorganization of the Yarlung system enhances incision along the main valley and establishes long-lived disequilibrium at adjacent divides. This response persists under uniform uplift but becomes markedly subdued when localized uplift is introduced, aligning with expectations from tectonic aneurysm hypothesis and with patterns observed in the present landscape. Taken together, these results indicate that drainage capture acted not merely as an isolated geomorphic event but as a primary perturbation that initiated transient incision and set up conditions favourable for subsequent focused uplift. We argue that the interplay between channel reorganization, erosional feedbacks, and crustal flow offers a more flexible framework for understanding how the EHS evolved—and why it remains one of the most dynamically responsive mountain regions on the planet.
How to cite: Kashyap, A., Attal, M., Mudd, S. M., and Behera, M. D.: How Drainage Capture Restructures Incision and Uplift in the Eastern Himalayan Syntaxis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1129, https://doi.org/10.5194/egusphere-egu26-1129, 2026.
The hydraulic geometry of a river is defined by three quantities, width, depth and velocity, the product of which gives the discharge. While depth and velocity can be predicted from fluid flow physics, prediction of channel width remains a stubbornly difficult problem. In alluvial channels, the geometry of a river is set by persistent erosion and deposition of sediment on channel margins. It has been argued that some bedrock rivers have the same hydraulic geometry as alluvial rivers, but there are clear contrasting examples of rivers with high bedrock exposure that are narrower and deeper than alluvial channels. Here we explore how rock exposure on river banks impact channel width using observations from small drainage basins to the largest bedrock rivers on Earth. We find that bedrock-bound channels, where both banks are rock, are distinctly narrower and deeper than alluvial channels. Our results also suggest that even where there is substantial bedrock exposed in a channel, alluvial erosion and deposition processes may still dominate channel morphology. But when channels are bound by rock, they tend to adopt geometries that do not occur in alluvial channels and should be considered a distinct class of channels.
How to cite: Venditti, J., Tailor, R., Sklar, L., Li, T., and Lamb, M.: The width of bedrock-bound rivers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3624, https://doi.org/10.5194/egusphere-egu26-3624, 2026.
Tectonic uplift is the primary control on bedrock river incision; however, in places where uplift is absent, such as the Hawaiian Islands, other factors including climate, lithology, sediment flux, fluvial thresholds, baselevel history, and time become crucial to understanding the form and incision history of streams. Ferrier et al. (2013) argued that streams on Kauai show a linear relationship between unit stream power and incision rate with a negligible incision threshold. However, large boulders that choke Kauai’s streams suggest significant incision thresholds, and young lavas at river level suggest that incision has been negligible for ~2 Myr. We suggest that these channels are at a critical threshold set by climate, fluvial thresholds, and sediment flux that prevents them from further incising into bedrock. We present 7 new Ar-Ar ages of young lavas emplaced within Kauai’s canyons along with an extensive grain size dataset spanning 22 catchments, and 17 new catchment-averaged erosion rates (36Cl in magnetite) from catchments on Kauai and West Maui. Our results show that the young lavas were emplaced at 1-2 Ma, confirming negligible modern bedrock incision. The size of boulders in streams (D84 from gridded point counts and “area-by-area” analysis) covaries with normalized local channel gradient (ksnQ), suggesting that sediment size determines the threshold for motion and that these boulders can block bedrock incision. Finally, catchment-average erosion rates are weakly correlated with MAP, ksnQ and valley wall gradient, suggesting that both fluvial thresholds and sediment flux, modulated by local climate, play a role in setting channel steepness and slowing bedrock incision on the Hawaiian Islands.
How to cite: Lodes, E., Colaianne, N., Raming, W., Whipple, K., Yager, E., Granger, D., Strauch, A., Rosales Rivera, I., and Matthews, D.: Blocked by boulders: Examining the roles of climate, fluvial thresholds and sediment flux in slowing bedrock incision on the Hawaiian Islands , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15099, https://doi.org/10.5194/egusphere-egu26-15099, 2026.
Earth's rivers, especially in mountainous settings, carry sediment with a wide variety of properties, among which are size and lithology. Despite their critical influence on bedrock incision, transport/deposition patterns, and topographic forms, sediment properties are often overlooked in landscape evolution models. Here we present a new set of Landlab components centered on the Enhanced Gravel Bedrock Eroder (EGBE), which simultaneously describes the evolution of a gravel-sized alluvium layer and the underlying bedrock in a network of rivers. The component implements numerical solutions to fluvial sediment transport, deposition, attrition, and bedrock incision, taking into account sediment load heterogeneity in size or toughness. Additionally, EGBE allows the user to select between two assumptions regarding channel geometry: a fixed-width model (in which channel width scales with water discharge) and a dynamic-width model (in which channel width adjusts such that the bed shear stress is slightly above the transport threshold for the median-size sediment grain). EGBE relies on other Landlab components that handle flow routing and mass exchange among different sediment classes, and it can be coupled with hillslope sediment transport components. These components are integrated in a code called EGBE-LEM.
A set of 1D EGBE numerical experiments highlights the importance of sediment size for channel steepness. These experiments illustrate how an upstream source of coarse, resistant gravel leads to a steeper overall profile. Conversely, a downstream source steepens only the lower portion of the profile, leading to a break-in-slope that coincides with the lithologic transition. Several additional EGM-LEM experiments explored the impact of sediment toughness heterogeneity on landscape evolution. These demonstrate how upstream variations in toughness can influence the form and dynamics of channel networks downstream. For example, upstream variations in the toughness of source material can lead to asymmetric drainage divides and contrasts in the steepness index across adjacent drainage basins. In addition, we demonstrate how lithologic heterogeneity can influence river network concavity, planform geometry and steepness.
EGBE improves on previous modeling efforts by explicitly representing sediment attrition and size-dependent transport of heterogeneous sediment load: a useful addition given that size and lithology are two of the most commonly used and accessible measures of river systems. In addition, the EGBE-LEM code provides an advanced integrated modeling platform for understanding mechanisms and dynamics across a range of river types and geological settings.
How to cite: Shmilovitz, Y., Tucker, G. E., Morey, S. M., Gabel, V., Campforts, B., and Hutton, E.: Extended Gravel-Bedrock Eroder 1.0: a Landlab component for sediment and bedrock dynamics across a range of river systems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19265, https://doi.org/10.5194/egusphere-egu26-19265, 2026.
Base-level fall can trigger river incision, often creating discrete knickpoints. As these knickpoints migrate upstream through heterogeneous bedrock, they can be modified and transformed. We investigated the role of stepped base-level fall vs. bedrock heterogeneity on knickpoint evolution and river incision in a series of rivers on the North Shore of Lake Superior. The most recent period of base level fall is thought to have initiated around 10.8 to 10.6 ka (Breckenridge, 2013) as low eastward-draining outlets opened on what is now Lake Superior, initiating incision on local rivers. As incision migrated upstream and rivers downcut through glacial sediments and underlying bedrock, they created river terraces and discrete knickpoints.
Knickpoints were identified as reaches with high stream power along river long profiles. Terraces were mapped in the field and on aerial lidar data, with several dated using optically-stimulated luminescence in overlying alluvium. Base-level fall chronology relied upon detailed mapping of shorelines and outlets in published literature. Bedrock competency was quantified in situ through a combination of compressive strength (measured via Schmidt hammer), fracture intensity, and fracture density. Samples were run through an abrasion flume to measure attrition rates on different lithologies.
Results indicate that while the highest suite of terraces aligns with the elevation of the highest lake-level stand of glacial Lake Duluth, the predecessor to western Lake Superior, other terraces do not align with intermediate lake levels. Although lake-level fall initiated overall incision in the system, the stepped nature of the lake level fall was rapid enough that it did not form discrete sets of terraces and knickpoints. OSL ages indicate incision history is complicated, with some sites showing steady incision through the past 10.8 ka and others showing faster rates initially. The widest valleys and most abundant terraces are located in areas where rivers are primarily migrating and incising through surficial glacial deposits. Knickpoints are currently located on the most competent bedrock lithologies.
The most common lithology present, basalt, has variable competency characteristics depending on location within the lava flow (resistant and massive flow bases vs. weaker often vesicular flow tops) as measured by compressive strength, fracture intensity and density, and experimental attrition rates. Interestingly, the weakest and most fractured surfaces in otherwise high competency basal basalt flows, were found in and around knickpoints, potentially indicating that physical weathering occurs in high stream power reaches prior to erosion.
How to cite: Gran, K., Bugno, B., Jacobson, L., Marggraf, J., Wickert, A., Braunagel, M., Larson, P., Lavé, J., and Rittenour, T.: Controls on river evolution in incising post-glacial bedrock rivers along the North Shore of Lake Superior, Minnesota, USA, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16878, https://doi.org/10.5194/egusphere-egu26-16878, 2026.
Posters on site: Mon, 4 May, 14:00–15:45 | Hall X3
The interplay of rock weathering and erosion processes controls rock erodibility throughout a bedrock channel cross-section. Existing models of these processes in bedrock river channels have been developed using observations largely from silicate lithologies, with rock erodibility increasing with height above the channel. The effects of the dissolution of soluble minerals in carbonate lithologies has been understudied. Here, we present a study of rock erodibility in two limestone bedrock channels in the North Pennines, UK. Patterns in rock erodibility were assessed using Schmidt hammer surveys conducted in 12 cross-sections and were analysed alongside calculations of bedrock inundation interval, observations of sediment transport from bedload impact plates and long-term estimates of limestone dissolution rates from environmental data and in-situ field observations. Results show that erosion via dissolution can result in similar patterns of rock erodibility observed in silicate channels where erosion outpaces weathering. Bedrock inundation interval is a key control on bedrock erodibility; where the channel margin is not regularly inundated by flow, weathering processes which weaken the rock are still present but may be locally offset by dissolution driven by soil seepage of low pH runoff which erodes weathered material. Long-term estimates of abrasion and dissolution rate are broadly equivalent at our study site further demonstrating the effectiveness of dissolution at eroding carbonate lithologies. Future studies of bedrock incision processes in carbonate landscapes should re-evaluate how mechanical erosion and dissolution are represented, and how sensitive the balance of these processes is to potential changes in inundation frequency and climate.
How to cite: Baynes, E., Dingle, E., and Warburton, J.: Carbonate bedrock channel erosion dynamics inhibit weathering effect on bedrock erodibility, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4890, https://doi.org/10.5194/egusphere-egu26-4890, 2026.
Existing mechanistic models of bedrock erosion by particle impacts describe the competing effects of sediment supply in terms of erosional ‘tools’ or alluvial ‘cover’ which incise or protect bedrock river beds, respectively (Sklar & Dietrich, 2001). An oversight of this dynamic model is that bedrock channels episodically receive inputs of very coarse sediment from hillslopes (e.g., Dini et al., 2021; Shobe et al., 2016, 2021) and from bedrock detachment (plucking) and transport associated with extreme discharges (e.g., Cook et al., 2018). These coarse, often meter scale blocks or boulders, can persist on channel beds where they may remain immobile for hundreds to thousands of years (e.g., Nativ et al., 2022) and can exceed the maximum grain size that can be transported by typical flow conditions. Our ability to predict erosion rates and patterns are currently limited by complex feedbacks between relatively immobile bed cover, bed topography and bedload transport. Here, we present initial results from a series of experiments in a 2% tilting flume (10 m x 0.4 m) with a polyurethane foam board as an erodible bedrock proxy, 60-100 mm diameter particles as immobile sediment cover, and a constant feed of 5-8 mm angular gravel to drive erosion. Experiments were conducted using variable initial bed states (e.g., smooth/rough topography) and immobile sediment coverages for a duration of 25 hours. Observations suggest that rates and patterns of bedrock erosion are remarkably sensitive to the presence of immobile sediment cover. Erosion often appears locally enhanced around immobile elements, although this is offset to some degree by the cover effect produced by bedload deposited in association with hydraulic heterogeneity generated by the immobile sediment. Self-formed and imposed bed topographies also yield different patterns of erosion, suggesting initial boundary conditions may produce distinct patterns of sediment cover and erosion.
How to cite: Dingle, E., Rice, S., Hodge, R., and Johnson, J.: Exploring the effects of immobile sediment cover on patterns and rates of bedrock erosion, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9726, https://doi.org/10.5194/egusphere-egu26-9726, 2026.
Sediment transported by large rivers is a critical component of the global sediment cycle and is central to a broad range of fundamental processes of the Earth system, including river flooding and floodplain sediment dynamics, nutrient and adsorbed contaminant transport, and coastal sediment supply and coastal land loss. Yet, monitoring of bed sediment and sediment transport in large rivers occurs only rarely, if ever. The Surface Water and Ocean Topography (SWOT) satellite mission offers a novel ability to coincidentally measure river water surface elevation, extent, and slope and therefore can provide many, but not all, of the variables used to estimate sediment transport capacity in large rivers. In addition, the SWOT mission provides estimates of remotely-sensed river discharge using algorithms but these algorithms do not account for sediment transport related effects on hydraulic resistance.
For this initial effort, we build on previous work by making use of field measurement data collected routinely by water agencies at in situ gaging stations, including bed sediment data. Using discharge field measurements and SWOT data, we empirically solve for three critical variables that SWOT does not measure directly: depth to the bed, hydraulic resistance, and grain size. We use gaging station data where discharge is already known, combined with SWOT data, to solve hydraulic resistance equations for both Manning's n and the coefficient of friction, Cf. We also solve for the total depth to the bed and channel cross-sectional area. From these inversions, we derive an expression for hydraulic resistance, area and depth, directly from SWOT data for unmeasured sites. These relationships are used to estimate bed shear stress and bedload sediment transport capacity when combined with SWOT water surface elevations, extent and slope data. Through these initial models for hydraulic resistance and sediment transport, formulated from SWOT data, we improve SWOT river discharge products and can estimate bed sediment transport in large rivers.
How to cite: Minear, J. T., Johnson, J., Lamb, M., and Rowley, T.: Using SWOT Satellite Data to Estimate Hydraulic Resistance and Sediment Transport Capacity, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22321, https://doi.org/10.5194/egusphere-egu26-22321, 2026.
Rapids are a channel morphology common to bedrock-bound rivers that have been primarily identified by their characteristic chaotic flow. These complex flow structures develop due to reductions in channel cross sectional area through vertical steps in the bed or lateral constrictions. Flow features that develop include a tongue of convergent accelerated flow, followed by standing or breaking waves downstream, and horizontal recirculation eddies that may form sediment deposits where space permits. Rapids enforced by debris fans encroaching on the channel are relatively well studied in major canyons of the American Southwest, but rapids also occur in bedrock-bound channels without debris flow deposits.
We explore the distribution, controls, and characteristics of rapids in bedrock-bound rivers using satellite imagery and rafting guidebooks. We delve deeper in the dynamics of rapids in the 375 km long Fraser Canyon, British Columbia, Canada where diverse rapid morphologies are observed. Here we use high resolution observations of flow and topography to categorize rapid types and their causes. We find that there are two broad categories of rapids: sediment-controlled and bedrock-controlled. Those rapids can be further divided into two types based on the nature of the channel cross-sectional area reduction: constriction-type and step-type. Sediment-controlled rapids are created and maintained by mass movement processes where rapid characteristics are dependent on particle size, magnitude, frequency of sediment supply, and location of sediment input. Bedrock-controlled rapids have their morphology imposed by the structure of the rock that creates lateral constrictions or bedrock steps. Although we have defined broad categories, many rapids in the Fraser Canyon are the result of mixed controls and types.
Our observations indicate that rapid dynamics are discharge dependent and changes in discharge affect rapid subcategories differently. As discharge changes, rapids may wash out or become larger and more severe. Preliminary results show that sediment-controlled rapids tend to wash out as discharge increases due to the submergence of boulders and/or overtopping of the debris fan which reduces the constriction ratio. At bedrock-controlled rapids, complex channel geometry results in varied responses to changes in discharge. Rising water levels may lead to both overtopping of obstacles or new obstacles. Bedrock-controlled rapids become more severe where new obstacles are inundated as discharge increases.
How to cite: Ross, C., Venditti, J., Carr, J., Sklar, L., Kusack, K., and Wright, M.: Rapids in bedrock rivers: morphological characteristic, distribution, and flow dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15284, https://doi.org/10.5194/egusphere-egu26-15284, 2026.
In fluvial environments, knickpoints are key geomorphological landscapes exerting a disproportionate control on landscape evolution. Their influence extends both along the fluvial network and into adjacent hillslopes through coupled channel–hillslope processes. Despite this, previous studies focus on individual elements of knickpoint retreat (retreat rate, height, occurrence rate) with little focus on how they come together to wholly govern knickpoint retreat and the impact this has on wider channel evolution. We present a geometric model to illustrate the ways in which a channel can respond to changing forcing conditions – by changing knickpoint retreat rate, knickpoint spacing or knickpoint height. To evaluate our model, we conducted 22 analogue experiments in the Bedrock River Experimental Incision Tank at the Université de Rennes. To emulate bedrock, we use a silica paste of 45 μm silica, glass beads, and 18% water, with the ratio of silica to glass beads controlling substrate strength. Sediment was fed into the channel (±2% tolerance) via an infinite screw feeder, and base-level fall was simulated by a constant speed motor lowering a movable outlet gate. Conditions were constant throughout each of the experiments with sediment flux ranging from 0 g min-1 to 30 g min-1, base-level fall rate from 2.5 cm hr-1 to 5.0 cm hr-1 and silica to beads ratio from 2.5:1 (weakest) to 4:1 (strongest). A terrestrial laser scanner with a green water-penetrating laser scanned the bathymetry of the channel every 2 minutes, and the 2mm resolution digital elevation models (gridded point cloud data) used as input topography for the FLOODOS hydrodynamic model. Using Z-score normalised multi-variate regression we find knickpoint spacing is set primarily by base-level fall rate where base-level fall rate has 2.41x the impact of sediment flux and 3.61x the impact of bedrock strength. This results from the rate the channel can go through the cycle of initiating knickpoints. We find knickpoint retreat rate is set almost exclusively by bedrock strength explained by the impact of excess shear stress, with bedrock strength having 2.15x the impact of base-level fall rate and 3.61x the impact of sediment flux. Finally, knickpoint height is found to be set by base-level fall rate with base-level fall rate having 3.92x the impact of sediment flux and 4.59x the impact of bedrock strength. Next, the study looks at the impact of knickpoint dynamics on reach scale width and slope and find that these factors are governed by knickpoint morphology, with implications for channel-hillslope interactions. We find that vertical, steep knickpoints impact channel width and slope on a local scale, compared to long, elongated steepened reaches where knickpoint impacts extend beyond the local scale, reducing both overall channel width and slope. Overall, this study enhances the of understanding holistic knickpoint dynamics by assessing the interplay between multiple factors. This is important due to the broader implications for hillslope processes and landscape evolution resulting from knickpoint migration.
How to cite: Norriss, W., Baynes, E., Hillier, J., Lague, D., and Steer, P.: Modelling and understanding knickpoint dynamics in homogenous substrates., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17457, https://doi.org/10.5194/egusphere-egu26-17457, 2026.
Step-pool structures are natural features common in steep streams and often used in channel restoration projects. Proposed mechanisms for how step-pools form, however, make contrasting step spacing predictions, which hinders specific restoration targets from being established. In order to clarify how regular or random step-pool spacing should be, we create a generalized framework that allows comparison across mechanisms and applies to field, flume, and model observations. By comparing observed measures of spacing variability to reference values, we define a spectrum for step-pool spacing and observe limits on the maximum regularity or randomness natural sequences achieve. Within these limits, step-pools occupy a continuum rather than dividing into distinct random or regular clusters, although few mechanisms result in sequences with regularity comparable to antidunes. For the few cases where step-pool spacing exceeds the bounds of the continuum, external factors seem to prevent full equilibration. These exceptions mean that, in addition to enabling comparison across diverse settings, our framework makes testable predictions about the trajectory of step-evolution in disturbed streams.
How to cite: Erikson, C. and Turowski, J.: A unified framework for evaluating step-pool spacing, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2777, https://doi.org/10.5194/egusphere-egu26-2777, 2026.
Understanding how hydraulic and geomorphic variables co-evolve along river corridors remains a central challenge in fluvial geomorphology, particularly in systems where multiple process domains and structural controls coexist. In this study, a network-based framework is applied to quantify geomorphic covariance structures across alluvial and bedrock reaches, valley confinement classes, and contrasting lithologic substrates. Using correlation-derived Geomorphic Covariance Networks (GCNs), this study moved beyond pairwise relationships to examine how channel geometry, flow hydraulics, and sediment-related metrics interact as integrated systems. In-phase and out-of-phase relationships among key variables are first identified, and the analysis is then extended spatially using rolling correlations and spatial cross-correlation functions to assess how the strength and sign of covariance vary along the river corridor. Network metrics (density, mean degree, and edge weight), together with centrality measures, reveal systematic differences in network organization between process domains. Alluvial reaches exhibit fewer but stronger connections, with shear stress, flow velocity, and total stream power acting as dominant hubs, indicating tightly coupled, process-driven feedbacks. In contrast, bedrock reaches show broader but weaker connectivity, with specific stream power, bank geometry, and coarse-grain-scale metrics emerging as central controls, reflecting structural and lithologic constraints on channel adjustment. Valley confinement and lithology further modulate network coherence, with partly confined reaches and mechanically uniform substrates producing the most densely connected and strongly coupled networks. Spectral properties and low clustering indicate that these systems do not conform to small-world network behavior but are instead hub-dominated and physically constrained. Overall, the results demonstrate that GCNs provide a powerful quantitative framework for diagnosing hierarchical controls, feedback strength, and spatial variability in fluvial systems, offering new insights into channel sensitivity and morphodynamic organization across contrasting geomorphic settings.
How to cite: Olusola, A.: Hierarchical Controls on Fluvial Connectivity: Insights from Geomorphic Covariance Structures, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2841, https://doi.org/10.5194/egusphere-egu26-2841, 2026.
Fluvial systems are repositories of past climatic and hydrological conditions, being sensitive to climatic, tectonic and environmental perturbations. Changes in these conditions trigger cascading effects within the system, altering the channel behaviour/morphology, geomorphic form and hydrological regime. Such perturbations often get preserved in sedimentary sequences and provide important links for understanding palaeo-environmental conditions. These links aid in reconstructing the evolutionary history of the fluvial system and their response to climatic and hydrological changes. The present work investigates the chronological evolution of the Subarnarekha River basin in eastern India. Situated within one of the world’s oldest cratons, this river’s corridor contains several remnant incised meander cutoffs on its upper terrace surface, steep successive terrace flanks, lateral meander migration signatures and well-defined scroll bar sequences on the adjacent floodplain. These topographic signatures denote possible alterations in the Subarnarekha River’s palaeo-hydrological regime, and its concomitant response. In thus study, such terrace deposits and palaeo-meander scroll bars have been investigated using high resolution DTM (2.5 m), geophysical imaging (GPR), sediment textural analysis and optically stimulated luminescence (OSL) dating techniques, along with historical maps, to reconstruct the evolutionary trajectory of this river and its possible causative factors behind the discerned channel alterations. The obtained geochronological results reveal traces of sequential floodplain reworking during the Late Holocene. The Subarnarekha’s paleo-meander hydraulic parameters were ascertained to be much higher compared to the present-day active channel parameters, and contains multiple sinuous scrolls along the adjacent floodplain. Bankfull paleo-discharge was estimated using channel dimensions of remnant cutoff meander bends, which was found to be lower than present day discharges and then related with changing monsoonal regimes during the Holocene, as discerned from various climate proxies. Meander migration started at around 1.9 Ka, and the most recent transition to the current low-sinuous course of this river occurred at around 300 years before present, with lateral migration rates ranging between 2.4 – 4.5 m/yr. While the lower terrace surface still experiences frequent inundation impacted by higher monsoonal discharges and can be considered to be of Recent origin, deposition and abandonment of the middle terrace surfaces had occurred around the Mid-Holocene Era, indicating high incision rates by the river. This timeline corresponds to previously reported alternate strengthening and weakening phases of the Indian Summer Monsson (ISM) during the entire Holocene Period, which had caused higher monsoonal precipitation and enhanced river discharge. The sequential phases of multiple meander migration in the region also corresponds to the variability of ISM during this period. The discerned chronological sequence of the Subarnarekha River’s evolution thus suggests a close coupling between regional precipitation/climatic patterns and its induced hydrological regime, thereby highlighting the importance of palaeoclimatic studies in ascertaining river behavior.
How to cite: Mondal, S. and Jaiswal, M. K.: Late Quaternary Geomorphic Evolution of the Lower Subarnarekha River Basin: Palaeoclimatic and Hydrologic Implications, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-786, https://doi.org/10.5194/egusphere-egu26-786, 2026.
The Amazon River is the largest fluvial system on Earth, and its present configuration reflects long-term interactions among climate, tectonics, and fluvial processes. Hydroclimatic variability during the Quaternary period played a fundamental role in shaping the spatial organization of the Amazon River Basin, influencing sediment transport, deposition, and landscape evolution. Variations in precipitation patterns and river dynamics contributed to the development of the modern mosaic of upland areas and seasonally flooded lowlands.
This study investigates geological records from the proximal sector of the Amazon River Basin, focusing on sedimentary deposits and fluvial terraces along the Amazon River and its major tributaries, including the Marañón and Ucayali rivers, in the Iquitos region of northeastern Peru. Previous studies have interpreted this area as the remnant of an ancient topographic high, the Iquitos forebulge depozone, which acted as a structural boundary influencing the evolution of the Marañón River Basin.
Regional geomorphology was mapped using high-resolution digital elevation models derived from 10 m TanDEM-X data. Sedimentological characteristics were documented through field observations, and the stratigraphic units were chronologically constrained using quartz optically stimulated luminescence (OSL) dating. One active floodplain and three distinct fluvial terrace levels were identified based on elevation, sedimentary features, and age.
The floodplain deposits, located between 88 and 96 m above sea level, represent the youngest unit and consist of very fine- to fine-grained sands with planar-parallel and trough cross-stratification, interbedded with silt- and clay-rich layers. Their mineralogical composition includes quartz, feldspar, and heavy minerals, with OSL ages ranging from 12.66 ± 0.15 ka to 3.14 ± 0.34 ka. The first fluvial terrace (T1), occurring at approximately 125 m elevation, is composed of sands with variable grain sizes capped by silt- and clay-rich horizons and displays mineralogical variability expressed by color changes from yellow to yellowish red. OSL ages range from 112.4 ± 0.16 ka to 42.44 ± 0.11 ka. The second terrace level (T2), located at about 133 m above sea level, consists of well-sorted, medium- to coarse-grained sands with subrounded grains and a high degree of sedimentary maturity, yielding ages between 354.69 ± 0.10 ka and 228.58 ± 0.09 ka. The uppermost terrace (T3), found at 139 m elevation, is dominated by silt- and clay-sized sediments, overlain by ferruginous and sandy facies, with ages ranging from 172.6 ± 0.12 ka to 133.66 ± 0.08 ka.
Some of these units have been previously described in the literature, notably the T2 deposits, formerly referred to as the “White Sands” formation (Roddaz et al., 2006) and assigned Miocene ages (~7 Ma). The new OSL data indicate substantially younger ages, requiring a reassessment of the regional stratigraphic framework. Overall, this study refines the spatial and temporal characterization of fluvial terraces in the Peruvian Amazon and provides new insights into the Quaternary landscape evolution of the Amazon River Basin.
How to cite: Simões, A., Pupim, F., Bookhagen, B., Souza, P., Cruz, C., Campos, G., Breda, C., Brito, R., and Sawakuchi, A.: OSL chronology of fluvial deposits in the Peruvian Amazon: implications for landscape evolution during the Quaternary., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20298, https://doi.org/10.5194/egusphere-egu26-20298, 2026.
The fluvial network of the Júcar river around Cofrentes village (hinterland of the Valencia through, Eastern Iberian Peninsula) presents an overall trellis pattern controlled by a polygonal system of Neogene grabens and salt-walls, some of them showing clear evidence of Quaternary activity. The main rivers of this network are the Júcar itself flowing from the West, the Cabriel from North-West, and the Jarafuel – Cautabán from the South, all three merging around Cofrentes village and showing diverging quaternary evolutionary history. The Júcar and Cabriel rivers are deeply incised into Mesozoic and Cenozoic bedrock, forming striking canyons and wide terrace systems, while the Jarafuel - Cautabán shows a much less developed terrace system, with its upper reaches and main tributaries flowing along broad and non-dissected floors, with scattered badly-drained zones and desiccated lakes.
The quaternary fluvial dissection in the area has been described to be driven not only by base-level changes in the Mediterranean Sea, but also by other external factors such as diapirism, evaporite-dissolution subsidence, volcanism, and neotectonics that have played a singular role in the dissection process. One of the most outstanding differential features observed among these fluvial valleys is the headward erosion that in the Júcar and Cabriel rivers reach distances as far as 160 and 250 km respectively, but along the Jarafuel – Cautabán valley only propagated 22 km. Headward erosion is marked by prominent knickpoints along this valley and tributaries, depicting a relevant change in the landscape style, with staircase terraces downstream and undissected late Neogene tectonic landscape upstream. This remarkable difference in headward erosion, and hence in terrace system development cannot be only explained by differences in variable erodibility of bedrock, but another driver must be invoked such as different timing in the opening of the fluvial network to a closer and active base level, that in this case is the Mediterranean sea level. The Jarafuel – Cautabán valley can thus be considered an active example of the interplay between different actors such as sea-level (base level) changes, differential headward erosion, diapiric uplift, and neotectonics. This contribution presents the first geochronological data (OSL dating) in the Jarafuel – Cautabán system, indicating that, although headward erosion started during the last glacial cycle at c. 95-85 kyr (end of OIS 5), the most important drainage reorganization and incision took place around the Last Glacial Maximum at c. 22 kyr ago, in response to the significant coetaneous sea-level fall.
Contribution supported by the Spanish Research Project I+D+i PID2021-123510OB-I00 (QTECIBERIA-USAL) funded by the MICINAEI/10.13039/501100011033/
How to cite: Bardají, T., Élez, J., Martínez-Graña, A., and Silva, P. G.: Evolution of a fluvial terrace system in a base level-changing scenery within the Jucar Drainage Basin (Valencia, Spain): The Jarafuel-Cautabán case study, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18762, https://doi.org/10.5194/egusphere-egu26-18762, 2026.
Fluvial sediment transport plays a fundamental role in shaping fluvial and coastal systems in the central Mediterranean, contributing to the formation of floodplains and deltas and to the maintenance of sandy coastal equilibrium. Over recent decades, this balance has been progressively altered by climate change, which has significantly modified precipitation regimes, their seasonality, and the intensity of extreme events, with direct effects on hydrological and sedimentary dynamics along the entire fluvial–coastal continuum.
This study investigates a century of sediment dynamics in Italy by analysing historical fluvial sediment transport data using modern machine learning techniques. Analyses conducted on the Arno and Ombrone rivers (central Italy) reveal a marked decline in suspended sediment transport since the 1930s. Model results indicate that climate change represents the primary controlling factor of this trend, mainly through reduced precipitation, rising temperatures, and the reorganization of atmospheric circulation patterns. Anthropogenic pressures, such as dam construction and land-use changes, contribute to the observed signal but are overall less influential than climate-related factors.
In addition to the long-term analysis, the study also includes the sampling and analysis of recent fluvial sediment transport data. Although these results are still preliminary, they highlight a level of complexity in sediment transport dynamics that cannot be explained solely by the geographical or morphometric characteristics of river basins. The interaction between climatic forcing, antecedent hydrological conditions, and intense precipitation events emerges as a key control on sediment fluxes, pointing to the need for more integrated and dynamic interpretative approaches.
At the national scale, shoreline evolution was analysed along 3,624 km of sandy coasts (1984–2024) using Landsat imagery and the CoastSat algorithm. The results indicate that 66% of major Italian rivers are associated with eroding coastal sectors; this percentage increases further, exceeding 75% when considering river deltas, which exhibit erosion on at least one of the two delta flanks, and reaches 100% along coastal stretches lacking artificial defence structures.
Overall, Italian river deltas emerge as among the most vulnerable areas in the Mediterranean under ongoing climate change. These findings underscore that only integrated strategies linking continuous monitoring, data infrastructure, and spatial planning can ensure sustainable sediment management and enhance coastal system resilience in a changing climate.
How to cite: Luppichini, M. and Bini, M.: Climate change and sediment dynamics in the central Mediterranean: a multi-scale assessment of riverine transport decline and coastal erosion, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9763, https://doi.org/10.5194/egusphere-egu26-9763, 2026.
The knowledge of supercooling and related frazil ice phenomena in rivers is critical for purposes of flow control, operation of hydraulic works and estimation of the conveyance capacity of the channels, in particular, at rivers having long and severe winters. Frazil ice is occurring when air temperatures are varying above and below zero degrees, and there is a drop in temperature overnight. However, the spatial analyses of the frazil ice and where it is anchored in riverbed are rare, especially in meandering sandy river systems, as it has been difficult to measure them in detail, such as based on aerial image data sets, together with reference flow measurements during consecutive days. Our hypothesis is that the frazil ice will attach to the river bottom in low velocity areas around bends and across slope reductions and in areas where the channel constricts.
The aim of the study is to detect the development of the spatial distribution of anchored frazil ice in a sandy-gravelly, meandering sub-arctic river. The work is based on field measurements done in the autumn freezing season of mid-October 2021. The data includes UAV-based orthophotos from a four days period when frazil ice anchored in the riverbed of the meandering Pulmankijoki river, in northern Finland. The flow velocities, derived from close-range remote sensing and Acoustic Doppler Current Profiler data, are used for detecting the causes of the anchoring of the frazil ice. Hydrodynamic modelling is performed to further gain information about the hydraulic characteristics within the regions of the anchored ice. The preliminary results are presented and discussed. The results indicate that the anchored frazil ice varied day to day during the four days period, covering about 5 % to 9 % of the channel area. The frazil ice advanced downstream, and spread throughout the channel, even although during the first day it was denser in the straight reach when compared to the meandering sections. The surface flow velocities were reduced during the course of time along with the increasing rim ice development.
How to cite: Lotsari, E., Eltner, A., Ding, C., Saberi, O., and Takala, T.: Spatio-temporal development of frazil ice at a sub-arctic meandering river – a case study based on close range remote sensing and numerical modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6442, https://doi.org/10.5194/egusphere-egu26-6442, 2026.
How to cite: Guha, S., Galia, T., Kaushal, R. K., Singh, A., Jain, V., Picco, L., Pellegrini, G., and Rainato, R.: A MATLAB toolbox for the quantification of the discharge-sediment hysteresis process, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13493, https://doi.org/10.5194/egusphere-egu26-13493, 2026.
Autonomous survey platforms operating under river ice cover allow ice and bed morphology to be measured in-situ with minimal disturbance to the ice cover, and hence to the fluvial conditions affecting the morphodynamics of the ice and bed sediment. This enables less invasive investigation of rivers during the morphologically important and under-studied winter season, when access by other survey vessels is impractical. Remotely Operated Vehicles (ROVs) are currently used to measure a range of qualities of- and under marine ice sheets, but so far applications in rivers are rarer.
This methodological study aims to evaluate the effectiveness of using high resolution stereo-camera imagery processed with structure-from-motion photogrammetry, and of two acoustic positioning systems (Doppler Velocimeter Log, DVL, and Ultra Short Base Line, USBL) systems for use in ice-covered rivers for the creation of digital models of both riverbeds and ice.
A BlueROV2 ROV is tested in a high latitude, ice covered river in northern Finland. The ROV is equipped with a pair of stereo-cameras and a USBL system linked to a GPS to determine absolute position, as well as a DVL. The system is used to survey a short reach of the Pulmanki River (nr 69°55'13.3"N 28°01'58.1"E). A range of lighting configurations are also tested. The surfaces derived from the ROV survey are compared to known topographic points taken with sub-centimetre accuracy RTK dGPS to determine their accuracies, and so the potential of these methodologies in studies of the critical dynamics of seasonal ice cover and morphodynamics in ice covered rivers.
How to cite: Johnson, J., Lotsari, E., and Välimäki, J.-M.: Remotely Operated Vehicle Stereo-camera photogrammetry and positioning techniques for topographic measurements under river ice cover., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12362, https://doi.org/10.5194/egusphere-egu26-12362, 2026.
Rivers migrate across floodplains, which cover roughly 10% of Earth’s continental surface, through either catastrophic avulsions or gradual bank erosion. These modes of movement operate on markedly different timescales, ranging from days to weeks in the case of avulsion to decades or centuries for bank erosion-driven migration. Lateral river channel mobility poses significant socioeconomic risks, while also playing a key role in regulating global biogeochemical cycles through sediment deposition and re-mobilisation.
While river avulsions are comparatively well understood, the specific controls on lateral migration through gradual bank erosion are not yet fully resolved. Previous studies have explored individual factors influencing lateral migration rates, including the roles of water discharge, sediment supply, channel planform curvature, bank height, riverbank vegetation, and bank erodibility.
However, the combined and interacting effects of such factors on lateral migration rates have not yet been systematically evaluated. Furthermore, limited work has assessed how these controls may vary when migration rates are measured across multiple spatial scales (e.g., individual meander bends versus reach-length averages), observation periods, and river planform types (i.e., single-thread versus braided systems).
We curate and analyse a global compilation of lateral migration rates comprising approximately 500 measurements from 300 rivers and streams reported across 88 published English-language studies. For each measurement site, we independently quantify the previously mentioned (potential) predictor variables and key morphometric parameters, including channel gradient, upstream drainage area, active channel width, multi-decadal lateral migration extent, and channel belt area.
We apply principal component analysis and multivariate regression to quantify the relative importance of these predictors, identify a minimal set of dominant controls, and derive a predictive relationship linking migration rates to their governing parameters.
Preliminary analyses show robust power law relationships between bank erosion rate and both active channel width and channel belt width (derived from Sentinel-2 optical imagery), indicating that channel-scale geometry exerts a first-order control on lateral migration rates. Normalizing bank erosion rates by channel width is, therefore, necessary to isolate and evaluate secondary controls and reveal additional trends in the data. In contrast, we find no significant relationship between bank erosion rate (either raw or normalized by channel width) and a vegetation metric, such as canopy height (derived from Sentinel-2 and GEDI spaceborne LiDAR data), across the compiled dataset. This lack of correlation is consistent across all river planform types. Despite the common assumption that bank erosion increases with planform curvature, reach-averaged sinuosity shows no systematic relationship with either raw or channel-width-normalized bank erosion rates. This suggests that bank erosion may be more closely linked to local curvature than to reach-scale planform geometry.
Further inferences would provide a basis for predicting lateral migration rates under changing climate conditions and can be integrated into existing numerical landscape evolution models. Because such models rarely incorporate lateral river migration and therefore often fail to reproduce the wide river valleys observed in nature, our results offer a means to enhance their ability to simulate realistic patterns of long-term (103-104 years) fluvial widening and floodplain development.
How to cite: Chatterjee, D., Tofelde, S., and Bernhardt, A.: What controls bank-erosion-driven lateral river migration? Insights from a global synthesis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4984, https://doi.org/10.5194/egusphere-egu26-4984, 2026.
The active floodplain of the Gyüre in the upper Tisza River on the Bereg Plain in Hungary has a lot of different landforms, like meanders and natural levees. To understand how the sedimentation deposits in the Tisza River changed over time, we need to know how sediment builds up in this area. The aim of this study is to assess the sedimentation rate and analyze the distribution of ¹³⁷Cs in two vertically oriented paleochannels (the second and third meanders of the active Gyüre floodplain). We also intended to assess the influence of diverse geomorphological sites on sediment deposition. Satellite images and a LiDAR-based digital terrain model of the study area were used to choose the sampling points in order to ensure that the description of floodplain morphology to depth is accurate
We excavated four profiles for this research to a depth of 100-130 cm. Two in meanders (GYM3, GYM2) and two on natural levees (GYFH3, GYF2). Soil samples were collected at every 2 cm interval for high resolution. We characterized sediment samples by laboratory measurements, including particle-size distribution (Köhn pipette method), pH, EC, CaCO₃, and humus content (Tyurin method). Sequential framework created by measuring ¹³⁷Cs by gamma spectrometry at the HUN-REN Institute for Nuclear Research.
The profiles' depth indicates different sedimentation processes between meanders and natural levees. The ¹³⁷Cs distribution in GYM3 and GYM2 (two meanders) indicates continuous vertical accumulation over the last approximately 70 years. We estimated the sedimentation rate for the third meander (GYM3) to be about 0.4 cm/year, and it is about 0.6 cm for the second meander (GYM2) annually. Conversely, the natural levee samples demonstrated minimal ¹³⁷Cs downward movement, and the peak concentration of ¹³⁷Cs was restricted to topsoil layers. There is no ¹³⁷Cs accumulation in the natural levee profile, and the maximum quantity in natural levee samples is probably driven by plant root activity and soil particles.
In conclusion, the results indicate that the processes of sedimentation in the floodplain vary greatly from one place to another. Meanders are active sediment reservoirs that hold sediment at a rate of 0.4 to 0.6 cm per year. Natural levees stay pretty stable even though they don't get a lot of new sediment. The different levels of ¹³⁷Cs in meanders and the high levels of ¹³⁷Cs on the surface of levees show how important it is to do high-resolution radio-tracer studies of the different ways sediment builds up in the upper Tisza River floodplain.
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Azin Rooien is funded by the Stipendium Hungaricum Scholarship under the joint executive program between Hungary and Iran.
How to cite: Rooien, A., Szabó, G., and Vass, R.: Comparative analysis of sedimentation rates in meanders and natural levees of the Tisza River floodplain (Bereg Plain, Hungary) utilizing Cesium-137 (¹³⁷Cs) as a tracer., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17985, https://doi.org/10.5194/egusphere-egu26-17985, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 3
EGU26-19944 | ECS | Posters virtual | VPS26
FROM CATCHMENT TO CHANNEL: HIGH-PERFORMANCE PARALLEL MODELING OF SEDIMENT TRANSPORT IN THE TEL RIVER BASIN USING ANUGA SedTue, 05 May, 14:15–14:18 (CEST) vPoster spot 3
The Tel River, a major tributary of the Mahanadi River in eastern India, exhibits strong spatial and temporal variability in flow and sediment dynamics due to its monsoon-driven hydrology, heterogeneous terrain, and increasing human interventions. Soil erosion and sediment transport, although naturally driven by rainfall and surface runoff, have been significantly altered by agriculture, urbanization, and water management structures, leading to changes in soil loss, sedimentation, and degradation of water resources. Therefore, in this study, the production of soil erosion in the Tel River Basin is estimated using the Revised Universal Soil Loss Equation (RUSLE), while riverine sediment transport is simulated using ANUGA-Sed, a two-dimensional shallow-water hydrodynamic and sediment transport model based on a finite-volume scheme. The ANUGA flow and sediment modules were calibrated and validated using observed discharge and suspended sediment data from multiple gauging stations along the Tel River. Parallel simulations performed on the Param Pravega high-performance computing systems significantly reduced computation time while maintaining numerical accuracy, enabling high-resolution modelling of the entire Tel River Basin. The model was further evaluated for elasticity, computational accuracy, and optimal grid distribution per node on the HPC system, demonstrating robust scalability and efficient utilization of computational resources.
The model results show strong agreement with observations, with errors in net erosion and deposition generally below 10%. The simulations successfully reproduce the spatial patterns of sediment generation, transport, and deposition along the river network. Importantly, the model provides new insights into sediment dynamics between gauging stations where direct measurements are unavailable and captures cross-sectional channel changes associated with sediment transport processes. These results were further validated using field-based suspended sediment data collected in October 2023 at intermediate river locations using portable sampling instruments. The simulations reveal distinct zones of high erosion and deposition that are critical for understanding flood conveyance and channel stability. Overall, the results confirm that ANUGA-Sed can reliably simulate suspended sediment transport and riverbed changes in monsoon-dominated river systems.
How to cite: Dahiwale, A. V., Dutta, U., Singh, Y. K., Yendargaye, G., Prabhu, T. S. M., and Muddu, S.: FROM CATCHMENT TO CHANNEL: HIGH-PERFORMANCE PARALLEL MODELING OF SEDIMENT TRANSPORT IN THE TEL RIVER BASIN USING ANUGA Sed, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19944, https://doi.org/10.5194/egusphere-egu26-19944, 2026.
EGU26-8742 | Posters virtual | VPS26
Holocene Evolution of the Palar River, Southern India: Evidence for Channel Migration, Provenance Shifts, Weathering Processes, and Tectonic ControlsTue, 05 May, 14:51–14:54 (CEST) vPoster spot 3
The present study examines the catchment and source morphodynamics of the Palar River, southern Peninsular India. A multidisciplinary approach—remote sensing techniques, lineament analysis, geochemistry, and ground-penetration radar (GPR)—was applied to better understand its evolution during the Holocene. The major lineaments in the Palar River basin predominantly show a NE–SW trend. Five major faults have been identified in the basin, including a transition zone where frequent low-magnitude earthquakes have occurred. The major fault F1, a strike-slip fault, occurs in the upper reaches of the Palar River and follows a NE–SW trend. Other major faults, F2 and F3, are also associated with a transition zone where frequent minor and major tremors have been documented. Fault F4 runs parallel to the Cheyyar River, and significant changes in the river course have resulted from movement along these strike-slip faults. Fault F5, located nearer to the east coast, indicates a passive tectonic activity regime. The after-effects of tectonic activity in the basin are further evident from the GPR profiles.
Sediments of the active Palar River are dominantly litharenite, arkose, and wacke, whereas the paleochannel sediments are predominantly shale. Weathering proxies such as the Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA), elemental ratios, and the A–CN–K plot indicate intense post-depositional weathering of the paleochannel sediments due to climatic variability. In contrast, due to ongoing tectonic activity in the source region along with subsequent aggradation and degradation in the fluvial regime, sediments of the active Palar River exhibit low to moderate weathering.
Geochemical data further reveal that sediments from the active Palar River and the paleochannels are predominantly derived from active continental margin and passive continental margin settings, respectively. Major oxides, trace elements, and rare earth element (REE) data indicate that the Palar River sediments are derived from felsic sources, whereas the paleochannel sediments originate from mafic sources. Overall, the study suggests that the catchment area of the Palar River shifted southward during the Holocene due to tectonic uplift. Subsequently, the paleochannel sediments underwent post-depositional weathering. Ongoing tectonic activity combined with monsoonal variability has enhanced rapid erosion in the catchment, resulting in the deposition of thick sediment sequences from the middle to lower reaches of the active Palar River.
How to cite: m r, R.: Holocene Evolution of the Palar River, Southern India: Evidence for Channel Migration, Provenance Shifts, Weathering Processes, and Tectonic Controls, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8742, https://doi.org/10.5194/egusphere-egu26-8742, 2026.
