Orals: Tue, 29 Apr | Room 3.29/30
Changes of discharge (Q) and sediment yield (SSY) during flood events provide critical insights for flood disaster prevention and control. However, our understanding of the long-term variations and driving factors of Q-SSY relationships during flood events remains limited. This study examined the variations in Q, SSY and sediment rating curves (SSY = aQb) during maximum flood events (one, three, and five) across fifteen catchments in the China’s Loess Plateau during 1956-2019. The partial least squares-structural equation modeling (PLS-SEM) was used to quantitatively decouple the effects of driving factors (precipitation, soil, vegetation, topography, and soil and water conservation measures (SWCMs)). There was a significant declining trend in both Q and SSY during flood events across catchments, but the contribution of these events to annual SSY significantly increased by 41.48% during 1956-2019, underscoring the critical role of floods in sediment transport. The Q-SSY relationship during flood events weakened over time, with coefficient a decreased and index b increased. In addition, 44 - 49% and 36 - 51% of the changes in a and b can be attributed to the comprehensive effects of the five factors, respectively. The direct effects of vegetation (-0.921) and precipitation (0.616) on coefficient a were significant. Index b was principally dominated by SWCMs and vegetation, and the effects diminished from one to five flood events. These findings highlight the importance of increased vegetation cover and effective SWCMs in mitigating sediment transportation processes, and informs the development of tailored sediment management strategies for the Loess Plateau and similar regions.
How to cite: Gao, G.: Quantitatively decoupling the relationships between discharge and sediment yield during flood events in China's Loess Plateau, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19415, https://doi.org/10.5194/egusphere-egu25-19415, 2025.
Fine sediment transported in suspension is an important part of the total sediment yield in most rivers with erodible upland sediment sources. Fine sediment has positive effects on the stabilization of riverbanks, the accretion of floodplains, nutrient transport, and carbon sequestration. However, when fine sediment load is excessive, it can also clog the streambed, reduce invertebrate and fish habitat, prevent river-aquifer exchange and hyporheic flows, and damage hydropower infrastructure.
To effectively design sediment management policies in rivers, it is fundamental to understand the fine sediment dynamics at the catchment scale. This study focuses on the washload, the fine sediment fraction that, once entrained, remains in suspension until its deposition.
Washload dynamics are typically quantified by concurrently measuring stage or discharge (Q) and turbidity, from which suspended sediment concentration (SSC) is derived. Q-SSC pairs often create a hysteretic relationship, allowing us to infer the distance of fine sediment sources upstream of the station.
This contribution adopts a reach-scale perspective on Q-SSC analysis, moving beyond single-station hysteresis loops and leveraging Q-SSC data from two stations, one upstream and one downstream. The core idea is that we can study washload as a passive tracer to gain further information about the hydraulic variables of roughness and water velocity, for each event separately. We can then integrate this information to further describe the fine sediment sources dynamics and the washload regime of the studied reach. Combining the subsequent reach-scale information we can completely reconstruct the washload production timing and yields across the whole catchment.
For this purpose, we developed new tools which ought to become the new standard for Q-SSC analysis. First, we identify in the discharge timeseries the flood and sediment pulse events through a new algorithm based on Empirical Mode Decomposition. Second, we study the virtual velocity of the flood and sediment signal by a new definition of cross correlation, analysing the Hilber transforms of the signal. Third, we study the presence and the nature (e.g. intensity and seasonality) of suspended sediment sources and tributaries through a time dependant boundary condition analytical solution of the advection-diffusion equation, both for discharge and washload concentration.
The development of these three new tools and their application to the Arc-Isere (France) with six stations and four reaches, allowed us to identify the fine sediment sources and sinks in the river network. We also gained insights into seasonal fine sediment yields, the deposition and re-suspension dynamics of riverbed sediment stocks, and their progressive depletion during the spring-summer season. These methods are generalizable and applicable wherever discharge (Q) or stage and SSC data are available at two or more locations.
How to cite: Agostini, L. and Molnar, P.: New methods for the identification of fine sediment sources: from the discharge-turbidity relation to a reach scale understanding, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8969, https://doi.org/10.5194/egusphere-egu25-8969, 2025.
Understanding soil erosion history in ecologically fragile karst regions is essential for sustainable land management. The potential use of border polje (BP) soil profiles as reliable records of erosion deposition remains uncertain. This study investigated the geochemical characteristics of limestone and siltstone weathering profiles on both sides of the BP, using geochemical fingerprints to quantify BP soil source proportions and erosion changes. Key findings include (1) The karst and non-karst soil profiles on the slopes on each side of BP exhibit distinct geochemical signatures, with weathering indices indicating chemical weathering processes originating from limestone and siltstone, respectively. (2) Discriminant analysis and conservative element testing achieved accurate differentiation between the limestone and siltstone weathered soil sources, with a model goodness-of-fit above 80%, confirming the effectiveness of geochemical fingerprinting for determining soil provenance. (3) Siltstone-weathered soils dominate the bulk of BP soils, with small amounts of weathering products from limestone near the karst hills. (4) A marked increase in weathered material from both karst and non-karst sources at depths of 1.2–1.4 m, along with charcoal presence, suggests intensified erosion following historical fire events in the area. These results affirm the feasibility of the use of BP soil profiles as records of historical erosion, with geochemical fingerprints capturing shifts between karst and non-karst hill contributions. This study highlights the potential of BP soil profiles as archives of environmental changes, providing a framework for reconstructing historical landscape dynamics in complex terrains.
How to cite: Zhang, C., Jiang, Z., Zhang, C., Chen, Z., Sun, P., and Zhu, T.: Historical soil erosion events in border polje revealed by geochemical fingerprint analysis of soil profiles, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5010, https://doi.org/10.5194/egusphere-egu25-5010, 2025.
To mitigate erosion, soil and water conservation measures have been widely implemented to reduce on-site erosion rates and catchment sediment yield. However, the effectiveness of these measures has often been questioned, particularly in Ethiopia, where gullying has intensified due to conservation programs that primarily target sheet and rill erosion on cropland. This study aimed to identify erosion hotspots and sediment source areas using an integrated approach. The study was conducted in the 211 km² Fota-Gumara catchment, a highly erosion-prone area in Northwest Ethiopia. First, erosion hotspot areas were identified through field observation, farmer’s interview and modelling. Then, sediment sources areas were identified using sediment fingerprinting by employing fallout radionuclide tracers (210-Pbex and 37-Cs). Local communities identified communal grazing lands and croplands as particularly vulnerable to erosion. Field observations corroborated these findings, highlighting steep slope cropland and grazing land as erosion hotspots. The Analytical Hierarchical Process (AHP) model indicated that 23.5% of the area experiences severe erosion, predominantly on steep slopes under cropland, shrubland, and valley bottoms where saturation excess runoff drives gullying. Sediment fingerprinting further revealed that subsoil is the dominant source of sediment. Bayesian models (MixSIAR and BMM) consistently showed that subsoil contributes approximately three-quarters of the sediment, with median contributions of 73% and 81%, respectively. We conclude that prioritizing gully rehabilitation and managing steep slope croplands should be central to land management strategies in Ethiopia.
Keywords: Sediment fingerprinting, Lake Tana Basin, Land Degradation Surveillance Framework, Analytical Hierarchical Process Model, Gully erosion
How to cite: Abere, T., Evrard, O., Chalaux-Clergue, T., Adgo, E., Lemma, H., Verleyen, E., and Frankl, A.: Identifying hotspots of erosion from local knowledge and sediment fingerprinting (Lake Tana Basin, Ethiopia), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7219, https://doi.org/10.5194/egusphere-egu25-7219, 2025.
Human activities have profoundly influenced sediment dynamics in tropical regions, altering the functionality of critical water infrastructure. This study focuses on the Ruiru Reservoir, a key water supply source for Nairobi, Kenya, constructed in 1949. Using a novel "source-to-sink" approach, we begin by integrating sediment core analysis, geochemical and stratigraphic profiling, and historical land-use reconstructions to examine sedimentation dynamics over the past seven decades (1949 - 2017).
The findings highlight six major sedimentation periods corresponding to heavy rainfall events and extensive land-use changes. Peaks in sediment accumulation align with transitions from forested landscapes to agriculture and urbanization, coupled with episodic climatic events. Advanced geochemical fingerprinting methods would enable the identification of sediment source areas, linking elevated sediment loads to hotspots of erosion caused by deforestation, agricultural expansion, and infrastructural development.
This multi-proxy analysis underscores the reservoir’s role as an environmental archive, documenting the Anthropocene’s imprint on hydro systems. It provides actionable insights into managing erosion and sedimentation under intensifying anthropogenic and climatic pressures. The research emphasizes the importance of sustainable catchment management and highlights how retrospective sediment analyses can inform future policies to enhance the resilience of tropical water reservoirs.
How to cite: Githumbi, E., Kamamia, A., Kämpf, L., Mwangi, H., Sang, J., Karanja, J., Zech, M., Julich, S., and Feger, K.-H.: Tracing the Impacts of Land-Use Change on Reservoir Sedimentation: Insights from the Ruiru Basin, Kenya, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2774, https://doi.org/10.5194/egusphere-egu25-2774, 2025.
Human activities like deforestation intensify runoff and soil erosion, leading not only to local land degradation but also to off-site impacts such as excessive lake sediment deposition. Climate change may further exacerbate the erosion rate, particularly where human activity is highest. Hence, the sustainability of natural lakes is threatened by soil erosion and climate change. This is certainly the case for the tropical lakes of Abaya and Chamo in the southern Ethiopian Rift Valley. High rainfall intensities, steep slopes, and increasing population levels make these lakes susceptible to high rates of sedimentation, and rising water levels due to changing sediment and water budgets lead to coastal flooding of agricultural land and infrastructure. However, in order to properly assess the impact of human-induced land use change and climate on the lakes, quantitative assessments of the water and sediment delivery to the lakes are required. High-quality data are often missing for tropical lake environments, especially in developing countries.
Here, we established seven streamflow and suspended sediment concentration (SSC) monitoring stations across four selected rivers draining to Lake Abaya and Lake Chamo: Bilate (5480 km²), Elgo (298 km²), Kulfo (467.2 km²) and Shafe (191 km²). Together, these stations monitor 35% of the total area contributing to both lakes. Streamflow was measured at 10-minute intervals using a transducer, with atmospheric pressure corrections from a Baro diver. In total, 3501 samples were collected to measure SSC. Observed SSC ranges from 0.08 g/l to 107.75 g/l, whereas discharge varies between 0.01 and 410.65 m³/s. Sediment rating curves were developed using SSC and streamflow data to enable the estimation of total suspended sediment yield (SY) using continuous streamflow records. SY from the four gauged catchments was calculated at 11.3 Mt/year, with area-specific SY varying between 1083.43 and 10117.5 t/km²/year. Overall, Bilate River contributes 67% of the total sediment load, making it the most significant river in terms of the total SY. However, when normalized by catchment area, the Gamo highland catchments have higher net erosion rates. Strong temporal variability in SSC and SY is observed, which can be explained by seasonal changes in vegetation cover and rainfall intensity. Time series of SSC for each river can be correlated with NDVI-data in the corresponding catchments and rainfall erosivity calculated from high-resolution meteorological data. Catchments draining the Gamo highlands have their highest sediment transport rates at the start of the rainy season (May to June) when vegetation cover is low, contributing 60% of SY. In contrast, Bilate, which drains the rift valley itself, experiences a peak sediment yield in August-September, representing 61% of its annual SY.
The integration of satellite-derived NDVI, high-resolution rainfall erosivity data, and timeseries of SSC and discharge enables to identify periods and areas of enhanced erosion and sediment delivery to the lakes. Such spatio-temporal information will be used to calibrate and validate erosion models, which in turn can simulate the impact of management scenarios on lake water and sediment budgets.
How to cite: Ayana, M. T., Tilahun, A. K., Minda, T. T., and Verstraeten, G.: Monitoring water and sediment delivery to Lake Abaya and Lake Chamo in the Southern Rift Valley Basin, Ethiopia , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16326, https://doi.org/10.5194/egusphere-egu25-16326, 2025.
Sediment production is often intensified in peri-urban areas as landscapes transition from predominantly rural to urbanized conditions. This transformation alters hydrological and sediment dynamics, which are complex and remain poorly understood, particularly during the process of urbanization. There is a need to begin systematically monitoring the impacts of urbanization on sediment production and transport. This study focused on monitoring suspended solids concentrations and loads in stormwater drainage systems over six months in Officer, Melbourne – a peri-urban area experiencing rapid urban development. Using low-cost automatic monitoring stations developed by our research team, we collected data across sites with different stages of urbanization, ranging from early construction to fully developed areas.
We found that during storm events, mean concentrations of suspended sediments in early urbanization stages can reach up to 100 times those observed in mature urbanized areas. Most importantly, suspended sediment yields in early-stage urbanization areas were up to 10 times higher than in fully developed areas, despite lower runoff volumes. Sediments from early stages of development were also finer than sediments from later stages. These high loads of fine sediments present increased risks to receiving water bodies, such as streams, bays, and wetlands, due to their ability to transport pollutants over long distances and contribute to environmental degradation.
The findings highlight the value of combining innovative monitoring technologies with geospatial and time series analysis to better understand sediment dynamics in a complex and rapidly urbanizing landscape. Additionally, the findings underscore that erosion and sediment control measures are vital, particularly during the early stages of urbanization, requiring proactive management throughout this process to mitigate fine sediment impacts and protect downstream waterbodies, ensuring sustainable growth in peri-urban areas.
How to cite: R. M. da Silva, P. V., L. Russell, K., D. Fletcher, T., Cherqui, F., Navratil, O., and Cossart, E.: Early-stage urbanization drives critical sediment production, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3910, https://doi.org/10.5194/egusphere-egu25-3910, 2025.
Artificial fallout radionuclides (FRNs), such as 137Cs and 239+240Pu, released during nuclear weapon testing from the 1950s to 1980, have been widely used over the past three decades to quantify land degradation processes. The spatial distribution of global fallout generally aligns with latitudinal bands in areas with similar precipitation regimes. Despite nearly 80 years since these tests, no comprehensive reference map exists for FRN inventories across the Southern Hemisphere.
Therefore, this study aims to create the first complete reference maps for 137Cs and 239+240Pu along with their spatial uncertainties over the entire Southern Hemisphere and Equatorial band. To accomplish this objective, we employ the random forest algorithm to predict the concentrations of FRNs in soils of this part of the world. This is achieved by utilizing a compiled data set of soil 137Cs (n=429) and 239+240Pu (n=102) inventories (Bq/m2) (Dicen et al., 2024; under review) under the AVATAR Project (“A reVised dATing framework for quantifying geomorphological processes during the Anthropocene”). The training phase of modeling relied on environmental covariates, including monthly mean precipitation (following test months), elevation (m.), euclidean distance to test sites (km.), terrain wetness index, flow accumulation, and soil texture.
Preliminary results indicate that precipitation distribution strongly influences FRN inventories, with the highest values observed between 20°S to 30°S due to atmospheric circulation patterns driving fallout dispersion. Consistent with previous studies, southern America emerges as a major depositional region, while Australia exhibits the lowest inventories. These differences primarily reflect the proximity to nuclear test sites, such as French Polynesia, a significant source of fallout radionuclides. The euclidean distance and westerly wind patterns are key factors shaping FRN inventories.
In equatorial regions, recent land disturbances highlight the need for additional sampling, particularly for 239+240Pu, to enhance prediction accuracy and reduce spatial uncertainties. This study addresses critical gaps in the spatial distribution of FRN inventories, providing a robust foundation for geomorphological reconstructions in the Southern Hemisphere and Equatorial regions.
How to cite: Avcioglu, A., Gupta, S., Dicen, G., Vandromme, R., Alewell, C., Cerdan, O., Evrard, O., Bernard--Coquard, R., Angot, H., Sabatier, P., and Meusburger, K.: Reconstruction of 137Cs and 239+240Pu baseline inventories in the Southern Hemisphere and Equatorial Soils, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9055, https://doi.org/10.5194/egusphere-egu25-9055, 2025.
Karst aquifers, supplying nearly 25% of the global population with drinking water, are critical yet vulnerable resources. While sediment transport modeling in karst systems has progressed, fluviokarst systems remain underexplored, particularly regarding multilayer sediment dynamics during diverse hydrologic events. This study introduces a novel framework integrating stable isotope analyses (δ¹³C, δ¹⁵N) with high-resolution sensor data to investigate sediment transport mechanisms in Kentucky’s mature fluviokarst systems, focusing on the Cane Run Watershed and Royal Spring Basin in central Kentucky, USA.
The multilayer framework hypothesizes that sediment stored at different depths within fluviokarst caves originates from distinct sources and undergoes unique transport processes. During large hydrologic events, a single active sediment layer forms, mobilizing material from sources in the fluvial system to the cave outlet via suspension. Smaller hydrologic events activate only the top sediment layer within the cave, with transport characterized by intermittent deposition and resuspension of surface sediments, fluctuating between suspension and saltation. Surface processes across the fluvial system exhibit a similar pattern: smaller hydrologic events mobilize loose surface material, while larger hydrologic events erode deeper soil layers through gully formation, transporting material into the karst cave systems.
Tracer-aided modeling, combining sediment fingerprinting and sediment continuity equations, revealed two primary transport types: (1) larger hydrologic events characterized by high sediment trap weights, lower soil organic carbon (SOC) and total nitrogen (TN) values, less negative δ¹³C, and more positive δ¹⁵N values; and (2) smaller hydrologic events dominated by surface-derived material with higher SOC and TN values, more negative δ¹³C, and less positive δ¹⁵N values. Isotopic trends highlighted interactions between cave-stored sediment and external sources, with high-discharge hydrologic events mixing bottom layers and low-discharge hydrologic events remobilizing deposited sediment.
Three temporal periods were identified, reflecting the stream’s response to in-stream reconstruction: (1) a pre-reconstruction period with low sediment loads, (2) a reconstruction period with elevated sediment loads from disturbances, and (3) a post-reconstruction recovery period with reduced sediment loads as the stream stabilized.
This research provides critical insights into sediment transport dynamics in fluviokarst systems, emphasizing the interplay between hydrologic variability, sediment sources, and anthropogenic impacts. It advances predictive capabilities for sediment behavior under future hydrologic and climatic conditions.
How to cite: Bettel, L., Fox, J., Riddle, B., Beckman, M., Zhu, J., and Al Aamery, N.: Multilayer Sediment Dynamics in Fluviokarst Systems: Insights from Stable Isotopes and Sensor Measurements, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13413, https://doi.org/10.5194/egusphere-egu25-13413, 2025.
Global population growth and economic growth lead to increasing energy demand. This propels the construction of river dams and artificial reservoirs to produce hydropower. Ecological effects of water impoundments, such as the fragmentation of free-flowing rivers, habitat changes, loss of habitats and biodiversity, and changes in biogeochemical cycles have been addressed by researchers for several decades. Also, the influence of flooding on the soils within reservoirs and shore erosion have been studied in a variety of environments and soil types. The development of soil carbon stocks in the submerged soils and soil carbon mineralization upon flooding are of particular interest. Some studies observe a significant decrease of carbon stocks in submerged soil, whereas others report the opposite. Here, we present a study on the influence of 24 years of water impoundment on properties of organic and mineral constituents in submerged Andosols of the Blöndulón hydro-electric reservoir in the Icelandic highlands. Drowned soils are relatively enriched in carbon content, carbon densities and carbon stocks compared to the reference soils, while they are depleted in pedogenic minerals ferrihydrite and allophane. Depth patterns of carbon are rather uniform in the drowned soils in contrast to declining trends in the reference soils. Likely, movement of organic material from upper to lower horizons, and carbon additions from decaying vegetation in the years after the reservoir impoundment explain the carbon enrichment and altered depth distribution. While the drowned soils are enriched in carbon after a comparatively short inundation time of less than three decades, the stability of the soils carbon is uncertain. The apparent loss of mineral soil colloids will likely render the carbon more sensitive to oxidation in the coming decades, particularly during times of exposure of the inundated soils. Assessments of the consequences of water level fluctuations or potential future dam removal need to take the vulnerability of the exposed soils into account.
How to cite: Möckel, S. C., Bonatotzky, T., Mankasingh, U., Alvarez, I., Erlendsson, E., and Gísladóttir, G.: Carbon stocks in submerged soils of a hydro-electric reservoir after 24 years of flooding, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12254, https://doi.org/10.5194/egusphere-egu25-12254, 2025.
Small, shallow lakes are under severe stress from the combined impact of anthropogenic eutrophication and modern climate change. Therefore, such lacustrine sediments provide key information for understanding the lake’s eutrophication and the ongoing unprecedented climate change. The present work focuses on the saline Kallar Kahar Lake located in the Salt Range of Pakistan, to unravel the extend of anthropogenic impacts and climate change on sedimentation in lakes using a core section of 180 cm. Dark gray marly mud dominates with interlayered greenish-gray sandy/silty layers in the lower part. Geochemical results indicate that the SiO2 and Al2O3 contents drop to around one-third (from 54.6% to 16.4% and from 9.8% to 3.5% respectively) vertically upward in the cored interval, whereas the CaO content displays a three-fold upward increase (from 11% to around 30%). Similarly, the Total Organic Carbon (TOC) and Total Organic Sulphur (TOS) contents show a three-fold vertical upward increase (from 3% to > 15% and < 0.3% to 0.9%). The paleoredox proxies V/(V + Ni), V/Cr, and especially Th/U indicate an upward decrease in the oxygenation level and establishment of an anoxic setting in the lake. Paleoclimate proxies including Mg/Ca, Rb/Sr, and Sr/V indicate a progressive upward increase in the aridity. Paleosalinity proxies Sr/Ba and Rb/K suggest an upward increase in the salinity of the lake. The anthropogenic impact proxy elements Mo and Hg indicate enrichment and display strong negative correlations with detrital supply. Similarly, As, Pb, Zn, and P neither correlate with the detrital influx proxies nor with in situ sedimentation proxies thereby pointing to their anthropogenic source. These results indicate that urbanization and anthropogenic activities have blocked the natural drainage of the Kallar Kahar Lake, reducing the detrital influx to around one-third. The increasing aridity of the area due to modern climate change has transformed the lake into a closed-water body where evaporation has increased the salinity forcing a nearly three-fold increase in the in-situ organic carbonate production in the sampled interval. Thus the Kallar Kahar Lake provides an ideal case study site to understand the eutrophication of shallow lakes due to anthropogenic drainage blockage, pollutants inputs and impacts of modern climate change that is observed in many small shallow lakes globally.
How to cite: Iqbal, S., Bibi, M., and Wagreich, M.: Geochemical signals for anthropogenic eutrophication and climate change from the Kallar Kahar Lake, Salt Range, Pakistan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19498, https://doi.org/10.5194/egusphere-egu25-19498, 2025.
The growth of a territory is usually linked to the increase of contamination with Potentially Toxic Elements (PTE), which show stable, persistent, and non-biodegradable characteristics. PTEs became of great interest because they threaten humans and ecosystems through their bioaccumulation capacity and mobility in water systems. The main source of high levels of PTE is human activities such as mining, industries, and factory emissions. The erosion of soils contaminated by emissions and deposits of these activities can lead to great contamination levels in sediments, which greatly concerns environmental quality.
This study aims to identify the impact of intensive past mining and smelting industries on the metal and metalloid contents in actual alluvial surface sediments. To assess the associated environmental risks, index calculations, and statistical treatments have been carried out on 78 sediment samples in both natural and urban streams. The two main studied areas are the Furan River watershed and the Ondaine River watershed (close to the city of Saint-Etienne, France), with about 10 samples on each river in addition to the tributaries samples (around 20 by river).
The study outcomes mainly show values above TEC values for As, Cu, Ni, Pb, and Zn, indicating that the contamination poses a potential threat to natural ecosystems. Moreover, the enrichment factor of PTEs, calculated along the length of rivers, indicates moderate pollution (> 2), after the biggest cities, which decreases with the distance downstream for Cr, Ni, Pb, and Cu for both rivers. The Furan River has even higher enrichment for Cu and Mo, as significant pollution (> 5) can be observed before decreasing to no pollution levels. On the other hand, Zn values stay at a limited pollution level over the entire rivers length. The overall moderate contamination of PTEs shown by the enrichment factor indicates high risks for the environment linked to human activities. To quantify the danger, a hazard index was determined, for all the PTEs of interest, on each sample. The results show that the PTEs levels are not of any harm for the environment, except for four samples that indicate high risks compared to the local geochemical background (SIGMINES database). This index puts the real risk for the environment into perspective since only 4 samples out of 48 show actual hazards.
In light of these observations, statistics (Principal Component Analysis and Correlation Matrix), and previous studies on similar areas, some links could be built with metalworking (Furan River) and dyes and paints industries (Ondaine River). However, in the absence of further evidence, it is not certain how this conclusion can be associated with past activities.
How to cite: Seillier, R., Riquier, J., Paran, F., Peuble, S., Faure, O., and Bouillot, B.: Alluvial surface sediments as a tool for Heavy Metal Pollutants determination of areas with strong industrial heritage , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5607, https://doi.org/10.5194/egusphere-egu25-5607, 2025.
Urban deposits pose many challenges compared to natural archives. Due do anthropogenic influence they often have only limited lateral continuity, highly variable deposition rates, are prone to (anthropogenic) erosion, reworking and resedimentation, and show omission surfaces. In Vienna (Austria) we investigated sediments from an archaeological excavation site near the city centre as part of a transdisciplinary project involving geosciences, isotope physics and urban archaeology. The study area at Karlsplatz is situated near the Wien River and records the change in land use of the expanding city. The site covers a section from natural flood sediments (17th century) and anthropogenic fill (before 1900) of the Wien River to the latest levelling period of the park area in the 1950s. Archaeological stratigraphy and historic data sets provide age constraints for the multiple deposition phases, with the oldest road structures dating from the 18th century and the youngest deposits dating around 1922, post-1945 and the park opening in 1959 (Mosser et al., 2022). Atmospheric bomb-testing fallout plutonium was used for further Anthropocene age constraints (Wagreich et al., 2023) dating the upper layer as deposited between 1952 and 1959.
The fine-grained matrix (< 2 mm grain size) of the deposits was used for X-Ray fluorescence (XRF) analysis of trace elements such as lead, copper and zinc. The highest levels of trace metals (Cu 330 ppm, Pb 633 ppm, Zn 852 ppm) are present in sediments of a 19th century deposit rich in charcoal and metal slags associated with nearby metal-working industry. The second highest peak occurs in a layer of WW2 rubble rich in technofossils of that era (Cu 71 ppm, Pb 208 ppm, 296 ppm). Overlying deposits of the 1950s show again much lower values (Cu 24 ppm, Pb 28 ppm, Zn 61 ppm) similar to the range of low contamination background and infill materials, although the uppermost topsoil layer shows a slight recent enrichment (Cu 35 ppm, Pb 56 ppm, Zn 99 ppm) compared to the 1950s. Spheroidal carbonaceous fly-ash particles (SCPs), the product of industrial coal and oil combustion, were found in elevated concentrations in the post-1945 levels. These results indicate both a local (iron industry of the 19th century, WW2 pollution) and a regional-global (e.g. lead from leaded gasoline, fly ash particles) control on trace metal and fly ash contamination and a correlation with technofossil findings. In conclusion, additional stratigraphic markers for the Anthropocene were identified and quantified in the urban anthropogenic sediments of the Karlsplatz site. Therefore, the site may be used as a correlative stratigraphic reference section for the Anthropocene.
References:
Mosser et al. 2022. Fundort Wien, 25, 2022, 4-53.
Wagreich et al., 2023. The Anthropocene Review, 2023, 10/1, 316-329. doi 10.1177/20530196221136427
How to cite: Meszar, M., Wagreich, M., Mosser, M., Rose, N., Nagl, P., and Hain, K.: Additional stratigraphic marker for an Anthropocene at the Karlsplatz reference site (Vienna, Austria), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19703, https://doi.org/10.5194/egusphere-egu25-19703, 2025.
Mountain catchments are highly sensitive to the impacts of global warming, which affects seasonal weather patterns, glacier retreat, permafrost thawing, and snow cover duration. These changes drive rapid transformations in their ecosystems and alter their hydrological and sedimentological regime, exacerbating their susceptibility to various hazards, including floods, shallow landslides, and debris flows, all closely tied to sediment dynamics. Consequently, sediment management plays a key role in developing watershed management strategies that lead to programme interventions for mitigating potential losses for the mountain communities.
In this context, an integrated approach combining field surveys and aerial imagery analysis is essential for evaluating the effectiveness of existing countermeasures (mainly torrent control structures) and for finding innovative solutions, especially in absence of sediment transport monitoring systems. This approach enables the collection of observations on lithology, geology, channel cross-section shape, longitudinal profiles, land use, active soil movements, and grain size distribution within sediment source areas and along the channel network. The field inspections of torrent control structures further provide a detailed assessment of their condition and functionality.
All these observations are essential for geomorphological approaches, statistical formulae, and hybrid methods to estimate potential debris flow volumes at both reach and catchment scales. Additionally, simplified rainfall-runoff modelling, such as the SCS-CN method, is employed to assess critical runoff thresholds that could trigger water-sediment flows. The outputs include the spatially distributed assessments of in-channel and hillslope sediment storage volumes, and the delineation of sediment source areas. Aerial imagery complements this process by verifying the spatial distribution and extent of sediment source areas and tracking land cover changes over time.
The proposed methodology was developed and applied to the Rovina Torrent basin, located in the Central Alps (Lombardy, North Italy). The basin is characterized by coniferous forest cover (37.2%) and extensive debris accumulations and lithoid outcrops (36.7%). In the study case, the results provide the typologies in terms of driving the triggering event mode within the catchment, the minimum critical rainfall for designing an early warning system, and the potential debris flow volume for adjusting the sediment trapping basin.
The outcome significantly enhances the accuracy of hazard mitigation strategies and supports the adaptation or redesign of the torrent control structures to better address evolving sediment dynamics. The combination of the scientific experience in similar mountain context and the additional field observations can quantitatively provide a robust diagnosis of the current scenario for planning maintenance operations, for proposing and designing alternative solutions to reduce the natural hazard and for effectively supporting the decision-making process including the strategic allocation of human and financial resources.
How to cite: Cislaghi, A., Morlotti, E., and Bischetti, G. B.: Combining field and aerial imagery monitoring for planning maintenance operations and strategies in an ungauged mountain catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4443, https://doi.org/10.5194/egusphere-egu25-4443, 2025.
In recent decades, watershed management has assumed a pivotal role in the face of the progressive anthropization of land use and the increasing frequency of extreme hydro-geomorphic events caused by climate change. Indeed, the reduction of hydro-geological risk in mountain basins is contingent on the effective and sustainable design of torrent control structures, including check dams and bed sills.
The up-to-date knowledge of basin morphology and the comprehension of the interaction between torrent control works and hydro-geomorphological phenomena represent fundamental elements for designing, managing and maintaining mountain watersheds. Nowadays, the interpretation of basin processes is significantly enhanced using accurate, high-resolution remote sensing (RS) data, in conjunction with analyses employing GIS software. However, the use of such techniques is not yet widespread and there is a need for user-friendly tools to facilitate the effective processing of RS data to support planning and management activities.
To address these demands, this work proposes the development of a QGIS plugin (i-GIS4HydroPlan) to fully support the hydrological design of torrent control structures, implementing functions such as the automatic extraction of watershed boundaries from the Digital Terrain Model (DTM), the calculation of the flow directions, upslope contributing areas, routing, and, finally, the design hydrograph. This output is estimated through the Kinematic Local Excess Model (KLEM), an event-based model applicable to small mountain basins that combines the equations of the Soil Conservation Service for the calculation of the effective rainfall, the kinematic method for the flow propagation to the outlet and a linear reservoir for the simulation of base flow. Moreover, the plugin incorporates functionalities that facilitate the management of multi-temporal DTMs, thereby enabling a comprehensive analysis of sediment dynamics within the entire basin or single torrent reaches equipped with torrent control structures. The module encompasses algorithms for the co-registration of DTMs and the error analysis that affects the DTM of Difference (DoD).
The plugin will be distributed under an open-source license with the objective of enhancing its dissemination and facilitating the standardization of workflows. This will in turn allow a more efficient design of new torrent control works and the assessment of existing structures to determine their criticality and establish maintenance priorities.
Acknowledgement: This study was funded by the European Union - NextGenerationEU, in the framework of the consortium iNEST - Interconnected Nord-Est Innovation Ecosystem (PNRR, Missione 4, Componente 2, Investimento 1.5, D.D. 1058 23/06/2022, ECS00000043 – Spoke1, RT1B, CUP G23C22001130006). The views and opinions expressed are solely those of the authors and do not necessarily reflect those of the European Union, nor can the European Union be held responsible for them.
How to cite: Maset, E., Cucchiaro, S., De Luca, A., and Cazorzi, F.: An open-source QGIS plugin to support hydrological and watershed management planning in mountain basins, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9960, https://doi.org/10.5194/egusphere-egu25-9960, 2025.
Monitoring and maintenance are crucial for effective mountain catchments management, particularly in mitigating geo-hydrological risks. Torrent control structures, such as check dams and bed sills, play an important role in stabilising streambeds and reducing the impact of hydrological events such as floods and debris flows. However, their effectiveness depends on proper watershed management supported by systematic monitoring, which must consider sediment dynamic characterizing the catchment.
Nowadays, the use of High-Resolution Topography (HRT) data could support torrent control structures monitoring. Light Detection and Ranging (LiDAR) technology has become a standard approach for generating reliable Digital Terrain Models (DTMs) and conducting multi-temporal analyses. When morphometric data derived from DTM are combined with up-to-date inventories of torrent control structures, they offer valuable insights into the condition and functionality of these structures.
This study aims to develop and implement an index to identify torrent control structures in the most critical condition at a regional scale, with validation conducted at basin scale. The primary study areas are But (324 km²) and Fella (703 km²) catchments in the Friuli Venezia Giulia region (Italy) on the border with Slovenia and Austria. The methodology integrates HRT-derived data with information from the regional inventory of torrent control structures. The developed index considers characteristics of the structures, such as height and year of construction, alongside site-specific factors like geology and morphometric parameters derived from DTMs. The results show how this type of analysis can prioritize maintenance interventions and enhance the management of torrent control structures.
How to cite: Chiarel, G., Cucchiaro, S., Cavalli, M., and Cazorzi, F.: Torrent Control Structures Monitoring: a Regional Scale Index based on Inventory Analysis and Remote Sensing, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6376, https://doi.org/10.5194/egusphere-egu25-6376, 2025.
Hydrological forcings and erosion dynamics are influenced by natural factors and anthropogenic activities. Flooding events associated with climate change are attributed to heightened rainfall intensity and frequency, alterations in landscape patterns across various scales, and an elevated risk of flooding and water scarcity. This study combined landscape pattern indices with sediment connectivity to analyze changes in sediment connectivity during extreme rainfall events in various check dam-controlled hillslope-gully systems. Aerial and field surveys of four systems within the Caijiachuan watershed, conducted before and after the rainstorm event in October 2021, utilized unmanned aerial vehicles (UAVs) and remote sensing imagery. Landscape indices were applied to analyze the spatial pattern characteristics preceding and following the rainstorm event. The sediment connectivity index (IC) assessed sediment transport connections in the chosen systems. It was found that extreme precipitation led to increased landscape fragmentation, decreased biodiversity, and higher sediment connectivity, especially on steep slopes compared to gully channels. Soil erosion hotspots were found on slopes between 0-50°, with landslides occurring in areas of high sediment connectivity. This altered the landscape pattern and further boosted sediment connectivity. Various hillslope-gully systems reacted differently to rainstorms. This study highlights the value of using sediment connectivity to assess check dams' responses to extreme precipitation, improve watershed and land management strategies, and evaluate soil erosion control measures in fragile ecosystems.
How to cite: Yu, Y., Feng, J., Zhang, Z., Crema, S., and Cavalli, M.: Divergent responses of hillslope-gully systems controlled by check dams to rainstorm events in the Loess Plateau, China., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16498, https://doi.org/10.5194/egusphere-egu25-16498, 2025.
The Hindol block in Dhenkanal, Odisha, with an average annual rainfall exceeding 1200 mm, faces persistent challenges in managing runoff and sedimentation. This study evaluates the effectiveness of soil and water conservation (SWC) techniques in mitigating runoff across clusters of untreated micro-watersheds within this region.
A water balance analysis, focusing primarily on surface runoff, was conducted using the Soil and Water Assessment Tool (SWAT). The model incorporated high-resolution datasets, including digital elevation models, land use, recent Land Resource Inventory (LRI) data, and local weather records. Based on the hydrological assessment, a series of SWC interventions were designed, including contour bunding, trench cum bunds, staggered trenches, and Drainage Line Treatment (DLT) measures such as loose boulder check dams, brushwood check dams, and gabions.
These interventions were simulated in the SWAT model by adjusting critical hydrological parameters, such as Curve Number (CN2), Universal Soil Loss Equation Factor (USLE_K), Manning’s roughness coefficient (CH_N), and tributary slope (CH_S). Comparative analyses of pre and post implementation scenarios demonstrated significant reductions in runoff volumes. The extent of these reductions varied with the type and combination of conservation measures implemented.
The results underscore the potential of integrated conservation strategies to mitigate runoff and restore hydrological balance in sub-watersheds with similar agro-climatic and topographical conditions. This study provides practical insights for watershed management practitioners and policymakers, facilitating informed decisions on selecting and implementing conservation measures to address runoff and sedimentation challenges.
How to cite: Biswal, S. S., Dash, P., and Ramadas, M.: Evaluation of Conservation Treatment Measures for Runoff Reduction using A SWAT Model-Based Approach: A Case study in Hindol Sub-watershed, Dhenkanal, Odisha, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6778, https://doi.org/10.5194/egusphere-egu25-6778, 2025.
Posters on site: Tue, 29 Apr, 14:00–15:45 | Hall A
The Yellow River used to be known as the most sediment-laden river in the world, but its sediment load has decreased dramatically in recent decades largely due to anthropogenic changes in the Yellow River Basin (YRB). Despite the observed trends, the spatiotemporal changes in hillslope erosion and river sediment and their response to soil-water conservation (SWC) measures remain unclear. To address the knowledge gap, this study conducted a basin-wide simulation of sediment processes in the YRB for the first time using the Geomorphology-Based Ecohydrological Model and analyzed the impacts of various SWC measures on hillslope erosion and river sediment transport. Our results showed a 72.8% decrease in area-averaged erosion modulus and a 90.6% decline in sediment load at Huayuankou station during 2000-2019 compared with that of 1960-1979. An exponential decay relationship was found between hillslope SWC coverage ratio and soil erosion modulus, indicating diminishing marginal effectiveness of further interventions. The relative decrease in soil erosion modulus was the highest in the Wei River and lowest in the Toudaoguai-Longmen (TDG-LM) section for the same increase in hillslope SWC coverage ratio. Annual sediment amount trapped by check dams relative to hillslope erosion increased from 5.9% in 1960-1979 to 29.7% in 2000-2019. By 2019, the cumulative deposited storage of check dams reached 4.74 billion m³, accounting for 54.3% of the total storage capacity. Compared with other tributaries, the sediment deposition proportions in check dams were relatively lower in Wei River. This research offers a reliable tool for understanding the sediment regime change under intensive conservation measures, and provides important insights for sustainable management in the region.
How to cite: Yang, H., Wang, T., and Yang, D.: Spatiotemporal changes in hillslope erosion and river sediment caused by extensive soil-water conservation in the Yellow River Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2039, https://doi.org/10.5194/egusphere-egu25-2039, 2025.
Sediment modeling is an essential tool for understanding and managing sediment transport in river basins. With increasing impacts caused by changes in land use and occupation, models such as MGB-SED AS have played a crucial role in analyzing these processes, particularly in environmentally diverse regions like South America. This study aimed to enhance the performance of the MGB-SED AS model through recalibration and revalidation, improving the accuracy of suspended sediment discharge (SSD) simulations in the region's river basins. This process involved updating two fundamental parameters: the K Factor, measuring soil erodibility, and the C Factor, representing land management and cover. Both factors are critical for accurately modeling sediment dynamics and assessing the impacts of land use changes. The recalibration replaced the previous values of the K and C Factors with updated values derived from recent studies and databases reflecting South America's specific soil and land use conditions. Subsequently, the model's calibration parameters were adjusted to align simulated results with observed conditions in the river basins. Following this step, rigorous revalidation evaluated the recalibrated model's performance in terms of SSD simulations. Recalibration results revealed substantial improvements in simulation quality. Although the MGB-SED AS had already reliably simulated sediment fluxes and concentrations, updating the K and C Factors further enhanced estimate accuracy. The analyses demonstrated improved performance metrics, strengthening the model's applicability in complex and diverse scenarios. To validate the improvements, the model's performance was tested in five major South American river basins: the Amazon, Madeira, Doce, Araguaia, and São Francisco. These basins, including some of Brazil's largest rivers, were chosen for their representativeness in terms of climatic, geological, and land use diversity. Results consistently showed improved SSD simulations, demonstrating the model's capability to simulate varying sediment transport regimes and environmental conditions. This update enables more robust integration with studies on environmental impact and large-scale water sustainability. The recalibrated MGB-SED AS offers a scalable and adaptable tool, empowering researchers and managers to use it for integrated watershed management. Combining high spatial resolution and precise estimates, the enhanced model is established as a reference for studies on water planning, soil conservation, and environmental impact mitigation. Thus, the recalibration of the MGB-SED AS represents a significant advancement in sediment modeling for South America. By incorporating updated parameters and validating its performance in major river basins, the model reaffirms its role as an essential tool for managing water and sediment resources.
How to cite: Ribeiro da Silva, G., Bugoni Riquetti, N., and de Oliveira Fagundes, H.: A new calibration of the continental sediment model MGB-SED AS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11781, https://doi.org/10.5194/egusphere-egu25-11781, 2025.
It is well known that hyper-concentrated flows (HCF) in the middle reach of the Yellow River can cause a severe channel siltation in the Lower Yellow River to develop a world-famous “Aboveground River”. However, there has long been debate about the relative importance of HCFs from the Loess regions versus from the desert regions in the middle basin in causing such a severe channel siltation. In this study, we used 188 HCFs’ events in the lower reach in response to extreme rainfall events (daily precipitation records in 107 stations) in the middle basin from 1965 to 1985, and showed that HCFs from the desert regions (Type-N) contributed to about 3.1×109 t of sediment deposition in the lower river channel, or about 58.1% of the total sediment deposition, and that only about 16.8% from HCFs from the Loess regions (Type-S). Our results also indicated that the HCF with the SSC value more than 92 kg/m3 furnished about 83% of the total sediment deposition in the lower reach of the Yellow River, which primarily originated from the desert regions, rather than the loess areas, as has been traditionally anticipated before. Because the desert region can be a major source of coarse sediment contributor to the channel siltation of the lower Yellow River, its control should be a priority in protecting the Yellow River and ensuring its stability.
How to cite: zhang, X., Ta, W., zhang, X., and Liu, X.: Contribution of extreme rainfall-induced hyper-concentrated flows to downstream channel siltation in the Yellow River, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5465, https://doi.org/10.5194/egusphere-egu25-5465, 2025.
Current health status of check dams and their flood control capacity amid frequent heavy rainfall remain unclear, partially due to lack of a comprehensive and efficient method for health assessment targeting potential heavy rainfall pressures. Thus, this study developed a health assessment framework for check dams under heavy rainfall scenarios, focusing on structural composition and integrity, siltation capacity, and flood control pressure. Indicators for these three aspects were calculated based on a real-scene 3D model and a high-precision DEM generated by unmanned aerial vehicle (UAV) tilt photography for a typical watershed on the Loess Plateau. Comprehensive health assessment of 138 check dams revealed that 14% were in excellent health, 16% in good health, 26% in fair health, and 44% in poor health. For those 44% check dams (61 in numbers) in poor health, corresponding actions were recommended based on the assessment results to reduce pressure from flooding, with 15 demanding prompt repairs, 12 requiring increased dam height, 16 needing spillway expansions, and the remaining 18 requiring multifaceted measures or the construction of new dams. At the sub-watersheds scale, more than 70% of the check dams in the Majiagou and Tianjiagou were destroyed or in poor health, which require special attention during flood seasons. In the framework developed in this study, indicators were easily accessible and highly accurate, making it suitable for practical application. This study provided a scientific basis and methodological support for decision-making regarding the reinforcement of existing and future planning of check dams in the Loess Plateau region.
How to cite: Li, B.: Health assessment of check dams in China's Loess Plateau at the watershed scale, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5679, https://doi.org/10.5194/egusphere-egu25-5679, 2025.
Accurate identification of sediment sources is crucial for reliable source apportionment in sediment fingerprinting studies. However, the sensitivity of unmixing models to incomplete source information remains underexplored. This study investigates the impact of missing sources on unmixing model results, assessing the effects of deliberately omitting one source, simulating the effect of oversight or incorrect fieldwork. In this contribution, experimental sediment mixtures with four known sources (S1: 23.3%, S2: 23.3%, S3: 23.3%, and S4: 30%) and 18 geochemical tracers were analysed and the FingerPro unmixing model was implemented to estimate the relative contribution of sediment sources in different scenarios. Initially, the model was tested with all four sources, and the estimated source contributions closely aligned with the theoretical values. Before unmixing, an analysis of the conservativeness index (CI), consensus ranking (CR), and mathematical consistency (CTS) of the tracers was conducted, showing good consistency for most tracers (CTS errors below 0.06) when all four sources were included. However, when one source (S4) was excluded, the predicted source contributions became inaccurate. Additionally, a significant decline in mathematical consistency for most tracers was observed. These results highlight the challenges in achieving accurate source apportionment when critical information is missing. The study emphasises the importance of considering all relevant sources, as the omission of a key source leads to significant errors in interpreting the contributions of the remaining sources, ultimately resulting in incorrect conclusions. Furthermore, the potential use of CI, CR, and CTS tools for evaluating model reliability is discussed, particularly in the presence of missing sources. There is limited understanding of how unmixing models behave when faced with contributions that cannot be explained by the initial sources provided for the unmixing process. Instead of attributing these unexplained contributions to a potential unknown source, the models appear to redistribute them across the initial sources. This research highlights the need for further developments in unmixing models to better handle these limitations, which complicate the accurate estimation and interpretation of results. Missing sources in sediment fingerprinting datasets can lead to multiple solutions, resulting in erroneous model outputs. Our results suggest that these situations can be detected through mathematical consistency analysis (CTS).
How to cite: Gaspar, L., Latorre, B., Lizaga, I., and Navas, A.: The impact of missing sources and the emergence of multiple solutions in sediment fingerprinting: When not all sources are included, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18633, https://doi.org/10.5194/egusphere-egu25-18633, 2025.
This study focuses on addressing soil erosion and phosphorus (P) runoff, critical issues for agricultural sustainability and water quality. Conducted in the Hydrological Open Air Laboratory (HOAL) in Petzenkirchen, Austria, the research aims to identify fields prone to erosion and predict future sediment and P loss under different scenarios. The 60-hectare HOAL catchment, typical of Austria’s Alpine foothills, offers diverse land use and extensive historical data, making it ideal for such investigations.Using data from 2010 to 2020, the study examines factors like soil management, fertilizer use, and erosive rainfall events. Advanced geospatial and statistical techniques, including GIS tools and regression models, will help map erosion-prone areas and identify key drivers of sediment and P loss.
The research aims to produce risk maps that inform land management decisions, helping to reduce sediment and P loss from high-risk fields. These findings will support sustainable agricultural practices and be useful for policymakers, farmers, and environmental scientists working to balance productivity with environmental protection.
Keywords: Soil Erosion, P loss, Water Quality, Sustainable Agriculture, Erosion Susceptibility
How to cite: Thoma, C., Schmaltz, E., Szeles, B., Bertola, M., Krammer, C., Strauss, P., and Blöschl, G.: Identification of critical source areas for sediment erosion (and phosphorus loss) in a small agricultural catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20861, https://doi.org/10.5194/egusphere-egu25-20861, 2025.
Over the last century, the anthropogenic impact on the landscape has increased significantly. In many regions, humans have become the most influential geomorphological factor. This has led to increased sediment fluxes, heavy metal contamination and plastic waste. As a result, humans are altering both the sediment budget and composition. Anthropogenic climate change is expected to further increase sediment fluxes. However, quantifying human-environment interactions remains a critical task.
To investigate such human influence on a central European landscape, reservoir sediments were analysed. The selected reservoir, built in 1905 and still in use, was completely drained in autumn 2020. This provided a rare opportunity to reconstruct the accumulated sediment volume and to analyse sediment deposition. High-resolution digital surface models were generated photogrammetrically and from historical topographic maps. In addition, 24 cores were retrieved and analysed for grain size, geochemical composition and microplastic content. Caesium-137 was used to date the sediments.
In contrast to many other regions, sediment accumulation in the reservoir has declined in recent decades. Similarly, the levels of heavy metals, particularly copper, lead and zinc, have decreased since the 1970s. These trends can be attributed to environmental legislation and the closure of a metal processing plant upstream. The Anthropocene imprint is thus highly spatially variable and influenced by effective government environmental protection.
How to cite: Stauch, G.: Human-environment interactions in the Anthropocene – a case study on reservoir sediments in Central Europe, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7166, https://doi.org/10.5194/egusphere-egu25-7166, 2025.
Human impact has become an external forcing control on Earth’s environmental and geological processes, reshaping entire landscapes and leaving traces in geological archives. Even though this anthropogenic influence can be seen on a global scale, regional studies characterizing the scope and growth of anthropogenic influence is scarce, especially for urban or peri-urban environments.
In this study, we investigate the anthropogenic impact of the metropolis Vienna on its peri-urban environment, and correlate and evaluate the main geological signals for a potential Holocene-Anthropocene transformation in the 1950s during the so-called “Great Acceleration” of Earth System Sciences by applying sedimentological and geochemical methods. The study area is located downstream of Vienna, in the National Park Donau-Auen, where direct human intervention into the archived Danube river sediments is currently nil and floodplain archives allow to trace and quantify the human stratigraphic fingerprint and test dating techniques using (artificial) radionuclides in an alluvial setting. Sedimentological, geochronological, and chemostratigraphic markers are applied to characterize date anthropogenic strata in the proximal floodplain sediments, i.e. erosional profiles, of the Danube. The age of flood deposits was evaluated by field sedimentological method and cross-validated by the radiogenic nuclides 137Cs and 239/240Pu, which give evidence of the atmospheric ‘bomb spike’ from nuclear weapon testing. First observations indicate three periods of distinct sedimentation patterns reflecting the river system’s response to human interventions in the upstream area. The first phase marks the first extensive river channelization between 1870 and 1900 resulting in rapid erosion of mid-channel bars and aggradation of dammed backwater areas. The second phase is characterized by laterally extensive and thick flood deposits indicating the fast and undamped sediment transport through the straightened river bed during extreme events. The last phase is marked by the onset of very thick, uniform, and seemingly structureless flood deposits. These silt-sized beds are interpreted remobilized sediment that has accumulated in barrier lakes since the construction of hydro-power stations between 1956 -1998.
The archive of natural Danube deposits is analysed for artificial radiogenic isotopes, trace metals, and (micro-)plastics with the aim (i) characterise the interplay between upstream human interventions and local river dynamics, (ii) to identify and evaluate the geological signal of the Great Acceleration of Earth System Sciences since the 1950s, and (iii) to evaluate global markers for a potential Holocene-Anthropocene transformation downstream of Vienna.
How to cite: Hatzenbühler, D., Weißl, M., Hain, K., Baumgartner, C., Hubmer, A., Lang, A., Pöppl, R., and Wagreich, M.: From Floodplains to Fallout: Anthropocene stratigraphic signals in Danube floodplain archives downstream Vienna, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10098, https://doi.org/10.5194/egusphere-egu25-10098, 2025.
Since Roman times, the Danube River has been an important traffic way. Along the banks of this stream, some of the oldest cities of Central and Eastern Europe were built. Many conflicts were fought out in the Danube floodplains for hundreds of years with the aim of getting control over navigation, commercial centres, strongholds, and the surrounding territories.
After a long period of wars and political crisis during the first half of the 19th century, the capital of the Habsburg Empire started a series of improvement measurements projected long before. Besides the drinking water supply and the demolition of the city's fortifications, the Danube River engineering was the most momentous building project in this period of industrialization. Thanks to new efficient machines and know-how developed by digging the Suez Canal, it was possible to corset the branched Danube River in a new and straightened bed, limited by bank reinforcements and dykes. A highly dynamic river system characterized by fast-changing flow rates, variable water levels, and migrating river branches was transformed in a well-defined channel.
Great effort was made to achieve three goals: good navigability along this part of the Upper Danube, flood protection sufficient for a growing metropolis, and channelized waterways near to the urban centres for the supply of foods and wood and for the wastewater draining as well. The requirements of river engineering had various effects on the resulting fluvial dynamics; some of them were premeditated, others were unfavourable but accepted, and several were entirely unexpected.
This study aims to analyse the evolving fluvial system and assess the role of human intervention by investigating sequences of flood events archived within levees in selected places downstream of Vienna. By combining sedimentological with historical methods, we seek to show the sedimentary evidence of a changing fluvial system responding to the increasing human impact during the last 200 years.
Primarily, the channelizing of the Danube River resulted in increased flow rates and accelerated bed load transportation. These changes significantly impacted the volume of moved gravel within the riverbed and contributed to fluctuating water levels. As a result of the river straightening process, water levels often deviate from desired conditions – occasionally rising higher but more frequently being lower than optimal levels. Bank reinforcements hinder lateral water flow and erosion as well, resulting in the aggradation within the floodplain and loss of habitats.
Since the 1950s, a chain of ten hydroelectric power plants has been built along the Austrian Danube blocking the transport of coarse bed load by barrages. The alternation of backwater areas upstream of the dams and fast-flowing stretches below results in a fractionated sedimentation of coarse bedload and fine sediment within different sections of the Danube. Extreme flood events can mobilize large amounts of such separate deposits, forming huge levees after the redeposition within the free-flowing section downstream of Vienna.
How to cite: Weissl, M., Hatzenbühler, D., Baumgartner, C., and Wagreich, M.: The Taming of the Blue: River engineering along the Danube and its impact on the sedimentary record downstream of Vienna., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18239, https://doi.org/10.5194/egusphere-egu25-18239, 2025.
Currently, research on the Anthropocene is advancing rapidly in China. Chinese scholars have investigated various indicators of human activity, such as artificial radionuclides (239,240Pu and 129I), microplastics, δ13C, δ15N, black carbon, soot, diatoms, and DNA, as recorded in different geological and biological archives. The variations in these indicators reveal environmental changes in China since the Great Acceleration, providing evidence for global comparative studies of the Anthropocene. The sediment profile of the Sihailongwan Maar Lake, located far from urban areas and human activity, is highly sensitive to global signals, making it an ideal site for Anthropocene research. The Institute of Earth Environment, Chinese Academy of Sciences, in collaboration with other institutions, has conducted integrated analyses of multiple indicators in sediment cores collected from Sihailongwan. The concentration of 239,240Pu increased rapidly in 1953, and systematic changes were observed in polycyclic aromatic hydrocarbons, 129I, soot 14C, carbon spherules, DNA, δ13C, heavy metals, and other indicators, all supporting the Anthropocene Working Group (AWG)’s proposal that the mid-20th century marks the onset of the Anthropocene. China has rich and diverse geological and biological records, a large population, and substantial human impact on the environment. Anthropocene research in China holds great potential, offering important insights into the effects of human activities on climate, the environment, and the Earth system. Furthermore, it provides scientific support for policymakers in formulating strategies to protect ecological environment.
How to cite: Zhou, W., Zhao, X., Chen, N., An, Z., Hou, X., Han, Y., Zhang, L., Yan, D., Tan, L., Lei, D., and Zhu, Y.: New developments in Anthropocene Science in China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10546, https://doi.org/10.5194/egusphere-egu25-10546, 2025.
Debris-flow hydrographs can have a wide variety of shapes. They either consist of just one surge or are made up of individual debris-flow surges. For design tasks, usually only the total volume is used and the peak discharge is calculated from this based on empirical relationships. This results in the problem that in a mostly triangular hydrograph, the geometric relations of total volume, temporal variations of the discharge and peak discharge do not match.
Therefore, hydrographs of 19 debris flows recorded at the monitoring stations Gadria (South Tyrol, Italy) and Lattenbach (Tyrol, Austria) run by the Institute of Mountain Risk Engineering of BOKU University, were analyzed. As far as possible, the debris flows were divided into individual debris-flow surges and typical patterns ()were determined. From these, dimensionless hydrographs were derived in order to allow determination of the hydrograph shapes using only a few parameters, analogous to the SCS dimensionless hydrograph. A quantile analysis was used to determine the peak discharges of 132 distinct debris-flow surges. The 9th decile was defined as the decisive value for the peak discharge.
For the duration to reach the peak discharge, a correlation with the discharge, which is given by a unit volume, could be determined. With the available data, it was also possible to assign the relative frequency of the total volumes of the individual surges to different volume classes. This makes it possible to divide the total volume into individual surges of different phenotypes and total volumes. The result is a proposal for seven design hydrographs of different total loads with the corresponding peak discharge and time-to-peaks. As the temporal sequence of these debris-flow surges is not known, the planner is free to arrange these design hydrographs according to time. With this simple method, more realistic debris-flow hydrographs can be derived for a given sediment volume to be used as an input for simulations and structural design calculations.
How to cite: Huebl, J.: Simple method for developing a debris flow hydrograph composed of various debris-flow surges for design purposes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6471, https://doi.org/10.5194/egusphere-egu25-6471, 2025.
Abstract
The increasing frequency of extreme weather events has amplified the need for effectivness management of torrent control structures to mitigate hydro-geomorphic risks. The TORRENT Interreg project (https://www.ita-slo.eu/en/torrent), a two-year cross-border initiative, focuses on improving the planning and management of catchments in vulnerable regions, specifically Italy and Slovenia, to address hydro-geomorphic risks. The project aims to enhance river basin management by establishing common guidelines for monitoring and assessing the status and functionality of torrent control structures, prioritizing maintenance, and improving risk planning strategies.
A key aspect of the project involves field surveys to inventory and assess the state and functionality of existing torrent control structures. In the coastal region near the village of Osp, 63 torrent control structures were surveyed, with their dimensions and condition carefully documented. This information will be used to calculate the Maintenance Priority Index (MPi), which ranks torrent control structures based on their maintenance needs (Cucchiaro et al. 2024). This index serves as a user-friendly tool to effectively guide resource allocation, ensuring that maintenance interventions target the most critical areas.
By creating an up-to-date database of torrent control structures, the project supports the development of long-term strategies for disaster resilience and climate change adaptation. It contributes valuable insights into the sustainability and performance of torrent control works, aiming to reduce flood risks, improve the management torrential hazards, and enhance the overall resilience of the region to extreme weather events.
Acknowledgments
We gratefully acknowledge the financial support of the TORRENT project, (ITA-SI0600150), funded by the Interreg VI-A Italy-Slovenija Program 2024-2026.
References
Cucchiaro S., Martini L., Maset E., Pellegrini G., Poli M.E., Beinat A., Cazorzi F., Picco L., 2024, Multi-temporal analysis to support the management of torrent control structures, Catena, 235, 107599, https://doi.org/10.1016/j.catena.2023.107599
How to cite: Žvokelj, L., Cucchiaro, S., Cazorzi, F., Bezak, N., Fabbro, M., and Zupanc, V.: Assessment and Prioritization of Torrent Control Structures in the Osp Area: Applying the Maintenance Priority Index (MPi) for Improved Resilience, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9939, https://doi.org/10.5194/egusphere-egu25-9939, 2025.
On April 23, 2024, this study conducted an experiment on the impact of dam-breach flood on spur dikes to explore the anti-erosion effect of soil-cement surface protection on spur dikes. The test site was located downstream of Landao creek in Huisun Forest in Nantou County, Taiwan where three spur dikes were constructed using soil from the riverbed. Soil-cement was applied to the upstream slope faces of the spur dikes to enhance their erosion resistance. This study monitored seismic and acoustic signals during the erosion process then used Hilbert-Huang Transform (HHT) for time-frequency analysis to investigate the signal characteristics of spur dikes under erosion. We used the iRIC Nays2DH program to simulate the erosion of spur dikes, inputting the digital elevation model (DEM) before the experiment for calculations. The simulation results were compared with the DEM after the experiment. We also conducted several scenario numerical simulations to explore the anti-erosion benefits of spur dikes with different angles and lengths.
How to cite: Feng, Z., Huang, C., Hsu, K., and Chen, S.: Field Experiment and Numerical Simulation Study on the Erosion Resistance Performance of Spur Dikes with Soil-Cement Protection, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4118, https://doi.org/10.5194/egusphere-egu25-4118, 2025.
The Loess Plateau region faces significant soil erosion challenges exacerbated by climate change and land use transformations. Check dams are critical soil and water conservation structures that reduce sediment transport, yet their long-term effectiveness under changing environmental conditions remains uncertain. This study evaluates the sediment retention benefits of check dams in the Yanhe River Basin, a highly erodible area in the Loess Plateau, under future climate and land use scenarios. We used the CMIP6 climate projections and the PLUS land use model to simulate future climate conditions and land use changes, integrated with the WaTEM/SEDEM model to predict soil erosion and sediment yield for the next 20 years under three scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). Results indicate that soil erosion and sediment yield will increase, particularly under high-emission scenarios (SSP5-8.5), where sediment yield may rise by 17.3% by 2040. However, check dams can effectively reduce sediment yield by 25.4%, mitigating the impact of future climatic and land use changes. These findings underscore the importance of maintaining and enhancing check dam networks for sustainable watershed management in erosion-prone regions. The study provides valuable insights for policymakers to implement long-term soil and water conservation strategies to mitigate the adverse effects of climate change on sediment dynamics.
How to cite: Sun, L.: Assessment of sediment retention benefits of check dams under changing environmental conditions in the Loess Hilly and Gully Region, China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11386, https://doi.org/10.5194/egusphere-egu25-11386, 2025.
