To mitigate riverbed erosion both longitudinally and transversely, control water flow, and stabilize riverbanks, the use of groundsills has become a widely adopted engineering method. For large conservation areas, using a series of groundsills is standard practice. However, the sediment transport in rivers is a dynamic process, and the implementation of series groundsills can cause discontinuities in the longitudinal corridor of the river, leading to damage to the ecological environment and landscape. Although there is considerable consensus on various aspects of series of groundsills, current research primarily focuses on the influence of the configuration of groundsills (such as height and width) on sediment downstream. Therefore, this project aims to estimate the trends in sediment transport through scaled experiments and numerical simulations. Results shown that according to the analysis results, neither the Q5 nor Q95 criteria are met in the proposed plan for the complete removal of the groundsills. This project believes that the complete removal of the groundsills may have a drastic impact on the environment, potentially leading to unstable conditions, and thus requires careful evaluation. The design of openings in the groundsills is an effective ecological adjustment project. Regarding the design of the opening height, this project suggests considering two factors: one is to reduce the similar damming effect caused by lowering the elevation, and the other is the gathering of water flow. It is a trade-off between these two factors. Increasing the depth of the opening may benefit the ecology but could lead to unintended erosion due to concentrated water flow, and vice versa.According to the analysis results, neither the Q5 nor Q95 criteria are met in the proposed plan for the complete removal of the fixed-bed structure. This project believes that the complete removal of the fixed-bed structure may have a drastic impact on the environment, potentially leading to unstable conditions, and thus requires careful evaluation. The design of openings in the fixed-bed structure is an effective ecological adjustment project. Regarding the design of the opening height, this project suggests considering two factors: one is to reduce the similar damming effect caused by lowering the elevation, and the other is the gathering of water flow. It is a trade-off between these two factors. Increasing the depth of the opening may benefit the ecology but could lead to unintended erosion due to concentrated water flow, and vice versa. he proposed plans can optimize benefits for both upstream and downstream water conservation, and protect downstream objectives by managing sediment transport.

Keywords: series groundsill, ecology, sustainable management, sediment transport

How to cite: Lin, P., Hsieh, T., Liao, K., Wei, K., and Lin, G.: Impact Analysis of Series of Groundsills on the Fluvial Stability and Geomorpholog, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7560, https://doi.org/10.5194/egusphere-egu24-7560, 2024.

In this study, the variations of rainfall, river discharges and suspended sediment discharges were analyzed in the Chenyulan watershed in Nantou County, central Taiwan. The hydrological data, such as rainfall, daily discharges and daily suspended sediment discharges, was collected based on Neimaopu hydrology station during the period from 1972 to 2020. The yearly costs of structure conservation to prevent sediment disasters and slope hazard events were implemented in the watershed between 1999 and 2020 as well. The Rating Curve Method with the formula Q_s=aQ^b is adopted to estimate sediment discharges with the corresponding discharge events. The impact factors that caused the variation of discharges and suspended sediment discharges were also analyzed to provide the references for the influence of geological and hydrological changes on sediment yielded on slope and following suspended sediment discharges in the rivers in the watershed. The analyzed results show that the suspended sediment discharges in 1972-1989 are less than the average value in 1990-2009 at the same discharges. The suspended sediment discharges in 2010-2020 are gradually reverted to that in 1972-1989. The causes of decreasing the suspended sediment discharges in last decade are analyzed, including: 1. The variations of rainfall were gradually calmed in last decade; 2. the loose soil on slopes in the watershed caused by Chi-Chi earthquake became concreted with time; 3. the landslide and debris flow disasters obviously decreased in last decade and the soil yield from slopes has slowed down; 4. the local government involved a lot of money to build the conservation structures in upstream creeks to trap the loose soil and control the volume of sediments from flowing into rivers.

How to cite: Huang, W.-S., Chen, J.-C., Chien, K.-H., Lia, Y.-T., and Wu, F.: Impacts of rainfall variability on river discharges and suspended discharges : A Case Study in Chenyulan Watershed, Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5507, https://doi.org/10.5194/egusphere-egu24-5507, 2024.

The measurement of river bed grain size has become an integral aspect of fieldwork in river geomorphology and regional ecology. Over the past years, various authors have proposed remote sensing methodologies to assess grain size based on ground and aerial images. With the burgeoning applications of small unmanned aerial systems (SUAS) in geomorphology, there is a burgeoning interest in leveraging these remote sensing granulometry methods for SUAS imagery. However, a dearth of studies exists that systematically investigate spatially consecutive images yielding grading curves or specifications over extensive areas within mountainous watersheds.

This study focuses on the granulometry of the mountainous watershed in Val Camonica, located in northern Italy, employing a drone for initial photographic documentation. The study incorporates the BaseGrain software for importing drone spatially consecutive images and extracting granulation curves from the photographed areas. Additionally, the study encompasses the utilization of Structure-from-Motion (SfM) photogrammetry within a Ground Control Points (GCP) workflow to scale the drone-acquired photos. The precision of this scaling is systematically validated by comparing photos with scaling images including meter using BaseGrain software. The precision of AGISOFT software, employed in the SfM-photogrammetry process, is also critically evaluated by itself with different numbers of benchmarks.

Results indicate that, despite the non-professional nature of the instrumentation, the acquisition of high-resolution images is feasible. These images enable the generation of Digital Elevation Models (DEMs) with accuracies ranging between 2 and 3 cm, contingent upon the number of ground control points. The granulation curve, extracted through BaseGrain, exhibits acceptable accuracy within meter-scale resolution. This research contributes valuable insights into the potential of SUAS-based remote sensing granulometry for mountainous watersheds and underscores the importance of methodological precision for reliable results in river geomorphology studies.

How to cite: Benetti, M., Heidarian, P., Bonomelli, R., and Pilotti, M.: Exploring Remote Sensing Methodologies for River Bed Grain Size: Insights from a Mountainous Watershed Study in Val Camonica, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5752, https://doi.org/10.5194/egusphere-egu24-5752, 2024.

Debris flows are fast-moving masses of rock, soil, and water, which occur in mountain areas all over the world. Debris flows achieve maximum discharges that are many times greater than those associated with floods and are therefore often hazardous to people and infrastructure. Contrary to the general expectations that climate change will increase the magnitude and frequency of the debris flows, recent assessments have shown that under certain conditions future climate may increase the sediment transport capacity, but could also favor a reduction of the sediment supply and, therefore, reduce debris-flow activity.  The impact of glacier retreat together with future climate conditions on debris-flow catchments is not yet fully understood, but it is expected to increase due to uncovered glacial till, increased hillslope instabilities and an increase in peak rainfall intensities. We aim to quantify the effect of the changes in water availability (changes in precipitation regime, but also glacier meltwater) together with the subsequent landscape changes in climatically contrasting catchments in High Mountain Asia (HMA) on the frequency and magnitude of debris flows. We address it by further extending the sediment cascade model (SedCas), expanding the available hydrological response units to bedrock, vegetated and glaciated parts of the catchment. We further investigate (1) how sediment yield and debris flow magnitude-frequency change over time, and (2) how deglaciation and catchment greening (changes of land cover) affect debris flow activity for different climate regions across High Mountain Asia. We find that in the case study of sediment-unlimited catchments, from 1950 to 2022, glacier retreat increases the water supply. That, in combination with the warming temperatures (and therefore the change in the partitioning of the solid and liquid precipitation) and the decrease in number of extreme precipitation events, results in a decrease in the debris-flow activity. These preliminary results show that changes are not consistent across HMA and highly depend on the climatic regime and elevation. Our findings shed light on the debris flow and flood hazard in the data-scarce areas of HMA and highlight the importance of considering regional climate conditions for hazard assessment in addition to region-wide estimation of glacier retreat. The future development will investigate the sediment-limited conditions. 

How to cite: Bazilova, V., Duurkoop, L., Hirschberg, J., de Haas, T., and Immerzeel, W.: Deglaciation and debris flow dynamics: how does the glacier retreat affect debris flow activity in High Mountain Asia? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20102, https://doi.org/10.5194/egusphere-egu24-20102, 2024.

Several innovative techniques have been developed recently opening up new avenues to establish the assessment of sediment flux in the critical zone. These innovative techniques include the tracing or “fingerprinting” methods to identify the sources and quantify the dynamics of sediment and particle-bound contaminants. However, the use of these techniques is often associated with several methodological and statistical limitations, that are often reported although rarely addressed in the framework of concerted actions taken at the level of the international scientific community.

This presentation will present the main outcomes of the Thematic School organised in 2024 and the Scientific Meeting Days organised in 2022 and 2023 as a follow-up of a first training week organised in 2021 to bring together international experts working on these topics together. Based on the publication of an opinion paper (https://link.springer.com/article/10.1007/s11368-022-03203-1), new strategies to publish and disseminate sediment tracing databases will be presented. An example of formatted dataset will be given, with the objective to test research hypotheses based on multiple datasets adopting the same format of data/meta-data. Other perspectives regarding improvements of the sediment fingerprinting method in terms of modelling, tracer options and selection will also be presented.

How to cite: Evrard, O. and the TRACING Event organisers and participants: TRACING 2021-2024 – Feedback on international events to develop novel strategies of sediment tracing in catchments and river systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1817, https://doi.org/10.5194/egusphere-egu24-1817, 2024.

Most of the total sediment load transported in river systems is carried in suspension. Therefore, if we are to reduce soil erosion and sediment export, it is essential to determine suspended sediment sources and the drivers of its mobilisation into the river network. In this study, we combined the monitoring of suspended sediment fluxes and the sediment fingerprinting approach to test if pre-event conditions and rainfall-runoff characteristics drive suspended sediment source variability in catchments under a semi-oceanic climate. The sedimentological response to storm runoff events was studied in seven nested sub-catchments of the Attert River basin (0.4 - 245 km²), which have contrasting geological bedrock (sandstone, marls and shale) and land uses (forest, cropland and grassland). We collected stream water samples during storm runoff events (~30 events per catchment) using automatic water samplers to measure suspended sediment fluxes. In parallel, time-integrated suspended sediment and sediment sources samples (i.e., from different land use types) were collected and analysed in the laboratory (geochemistry, colour and organic properties) to determine the sediment origin using the sediment fingerprinting approach. Each sampled event was parameterized to describe rainfall, runoff, sediment transport and the relative contribution of each land use type to the sampled suspended sediment. Next, we assessed the relationships between variables. We found higher significant correlations between suspended sediment loads and runoff parameters (i.e., peak discharge and event runoff) than between suspended sediment loads and rainfall parameters (i.e., event precipitation, antecedent rainfall, and maximum rainfall intensity). Peak discharge for single events was found to be the best predictor of sediment loads in the studied catchments. We show that most events exhibit clockwise hysteretic loops between discharge and suspended sediment concentration in all studied catchments. We attribute this finding to the erosion or remobilization of sediment previously deposited on the channel bed or an adjacent area. During most of these events with clockwise hysteretic loops, sediment source apportionment presented a consistent pattern.

How to cite: Martínez-Carreras, N., Iffly, J. F., and Pfister, L.: Pre-event conditions and rainfall–runoff characteristics drive suspended sediment source variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16692, https://doi.org/10.5194/egusphere-egu24-16692, 2024.

Sediment fingerprinting has become a key tool to identify and quantify sediment sources within a catchment. The technique involves statistical testing of a range of properties of source materials to identify a set of tracers that can effectively discriminate between different potential sources before estimating the source contributions with unmixing models. However, despite its increasing popularity among researchers, there is a lack of standardized procedures for tracer selection, which is crucial to estimating a reliable contribution of sediment sources. The most widespread methodology consisted of an initial mass conservation test, usually termed range test (RT), followed by the use of Kruskal-Wallis (KW) and discriminant function analysis (DFA) tests. However, KW and DFA even though identifies the best combination of tracers that provide the maximum discrimination between sources, do not incorporate the information of the sediment mixtures in the analysis. Novel methods highlight the importance of selecting the right tracers for each individual mixture and avoid the inclusion of tracers out of consensus or with non-conservative behavior by using consensus ranking (CR) and consistent tracer selection (CTS) methods. This contribution addresses the role of selecting appropriate tracers, demonstrating their impact on the results of the unmixing model. The main objectives are to emphasize the importance of considering the information provided by the sediment mixture in the selection of tracers and to pay attention to the impact of having sediment mixtures with values below the detection limit of the tracer being selected for source discrimination. A set of experimental and real sediment mixtures were selected to explore the different tracer selection methods, comparing the tracers selected and the contribution of sources obtained using the FingerPro unmixing model. We present the results of rigorously testing methodologies with the aim of understanding and assessing the suitability of each tracer selection method to select a combination of statistical and process-based criteria to select appropriate sediment properties for the unmixing models. Our findings highlight the importance of considering the information on the sediment mixture information for the selection of potential tracers, an aspect often neglected by conventional methods. This oversight can result in biased findings due to the use of tracers that are either not coherent or not conservative.

How to cite: Gaspar, L., Latorre, B., Lizaga, I., and Navas, A.: Advancing sediment fingerprinting techniques: The importance of considering sediment mixtures data in tracer selection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20482, https://doi.org/10.5194/egusphere-egu24-20482, 2024.

In this study, we quantify the spatial variation in sediment generation for the c. 12 km² large Gürbe catchment situated at the northern margin of the Swiss Alps. We particularly trace the sediment transfer from the hillslope to the channel network in the headwaters, and finally to the depositional fan at the downstream end of the catchment. Mapping shows that sediment production in the Gürbe catchment occurs through three primary mechanisms: (1) overland flow erosion generating sand and silt, contributing to the generation of suspension loads; (2) shallow and deep-seated landslides linked to the main channel, both supplying a mixture of gravel, boulders, and silt/sand during floods, thus generating sediment for both the bedload and suspension load of the Gürbe River; and (3) incision of the river into glacial till in the upper headwaters and into landslides farther downstream. The bedrock of the Gürbe catchment comprises Molasse, Flysch, and Quaternary deposits, posing challenges in tracing the origin of the material and estimating the relative importance of the various processes for sediment generation.  However, previous research has shown that the cosmogenic ¹⁰Be concentration can differ for various sediment sources (Cruz Nunes et al. 2015; e.g.). Therefore, we measured ¹⁰Be concentrations in the sand fraction (0.25 – 2 mm) in the main channel and in the tributaries, aiming to capture suspension load signals generated through overland flow erosion and landslides. As a novel approach, we also determined the bulk ¹⁰Be concentration of gravels (2 – 10 cm) collected from the same sampling locations in the Gürbe channel, in the three tributaries as well as from the landslide tongues reaching into the Gürbe. The results point to three different conclusions: First, there exists a clear difference between the signals measured in the sand fraction and the gravel samples. In particular, the ¹⁰Be concentrations in the sand fraction are two to four times higher than those measured in the gravel at the same sites. This grain size dependence aligns with previous findings by Puchol et al. (2014). Second, the sand samples in the main channel show a downstream decrease in ¹⁰Be concentration, thereby reflecting the supply of material from the tributaries and particularly from the landslides with low ¹⁰Be concentrations. Third, bulk gravel samples reveal a larger variability in ¹⁰Be concentrations than the sand samples at the same locations. This suggests that the supply and downstream transport of the coarse-grained bedload material occurs more episodic than the generation and transfer of the suspension load. 

REFERENCES 

Cruz Nunes, F., Delunel, R., Schlunegger, F., Akçar, N., & Kubik, P. (2015): Bedrock bedding, landsliding and erosional budgets in the Central European Alps. Terra Nova, 27(5), 370-378.

Puchol, Nicolas; Lavé, Jérôme; Lupker, Maarten; Blard, Pierre-Henri; Gallo, Florian; France-Lanord, Christian (2014): Grain-size dependent concentration of cosmogenic 10Be and erosion dynamics in a landslide-dominated Himalayan watershed. In: Geomorphology 224, S. 55–68.

How to cite: Schmidt, C., Mair, D., Schlunegger, F., McArdell, B., Christl, M., and Akçar, N.: Quantifying Sediment Dynamics in an Alpine River Catchment using a 10Be Tracing Method , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9807, https://doi.org/10.5194/egusphere-egu24-9807, 2024.

Monsoon-induced floods have played a pivotal role in shaping the fortunes of Asian civilizations and communities over the millennia, and their far-reaching consequences persist to this day. This study delves into the floodplain east of Nan ancient city, a city during Lan Na period in northern Thailand dating back to the 13^th century AD. Our primary objective was to unravel the source direction of a catastrophic flood event in 1818 AD, which ultimately led to the city's relocation. Our sedimentological analyses revealed a diverse range of deposition. An innovative provenance study using mid-infrared spectroscopy (MIRS), conducted for the first time in this region, indicated a significant contribution from eastern tributaries not from the Nan River. Only two of the nine sediment cores (WTR and HH2) presented evidence of Nan River sediment. Optically stimulated luminescence (OSL) dating revealed a striking pattern: modern floods dominated the shallow depths (ca. 0-1.10 m) of all cores, while deeper layers exhibited unexpectedly older ages, exceeding 11,000 years. This finding aligns with climate data from multiple proxies, suggesting that Nan ancient city, akin to neighboring e.g. Kingdom of Angkor, endured a dry period. Based on these comprehensive findings, we postulate that the 1818 AD flood catastrophe originated from the east. The deluge may have been triggered by rainfall during an extended dry spell, when the parched and compacted soil's permeability was severely diminished. This sudden surge of water swiftly transported the sediment, ultimately inundating and devastating the city. The insights gained from this study are a reminder of the profound impact of monsoon-related floods on human settlements in Asia. By understanding the conceptions between sedimentology, provenance, and climate, we can better comprehend the historical and ongoing challenges posed by these natural disasters and advance strategies for sustainable development in vulnerable regions.

Keywords: flood sediment, monsoon, Southeast Asia,  provenance analysis, OSL dating, Lan Na, Nan, Thailand

How to cite: Srisunthon, P., Berger, A., Fuelling, A., Abdulkarim, M., Ertlen, D., Mueller, D., Wilk, J., Reubold, M., and Preusser, F.: Reconstructing the Flood History of Nan Ancient City: Insights from Sedimentary Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8164, https://doi.org/10.5194/egusphere-egu24-8164, 2024.

Usual works for the reduction of the sediment volume transported by debris flows are the retention basins. Retention basins are usually built on the intermediate and low-sloping reaches of the debris-flow channels or at their end, where the terrain slope is usually not high. When the space required for trapping all the sediment volume is not available or the upper part of the basin must be protected deposition areas can be used. The deposition area is a retention basin without the downstream berm, to be placed in the high-sloping reach of a debris-flow channel. Therefore, it is proposed an approach for the progressive reduction of the sediment volume transported by debris flow: an in-series combination of deposition areas in the high-sloping reaches of the channel, and retention basins in the intermediate low-sloping reaches of the flow path.

An application of such approach is shown for the design of the control works on Ru Secco Creek at the purpose of defending the resort area and the village of San Vito di Cadore (Northeast Italian Alps).

How to cite: Gregoretti, C., Barbini, M., Bernard, M., Boreggio, M., Lopez, S., and Schiavo, M.: An approach for the reduction of the sediment volume transported by debris flow from the high-sloping reach of a debris-flow channel, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4719, https://doi.org/10.5194/egusphere-egu24-4719, 2024.

Impact of dam construction on suspended sediment load alteration

Zahra Karimidastenaei ^a*, Hamid Darabi ^b, Ali Torabi Haghighi ^a

^a Water, Energy and Environmental Engineering Research Unit, University of Oulu, P.O. Box 4300, FIN-90014 Oulu, Finland.

^bDepartment of Geosciences and Geography, University of Helsinki, Helsinki, Finland

*Corresponding author: Email: zahra.karimidastenaei@gmail.com

Abstract

Climate change and human activities have always impacted the fluvial processes, encompassing floods, soil erosion, sedimentation, and sediment transport in rivers, resulting in huge environmental concerns. Dynamics analysis of suspended sediment concentration (SSC) is a determining factor in the sediment budgets, and it has an important role in water resources management. In the current research, the relationship of the suspended sediment (SS) with precipitation (R) and flow discharge (Q) has been analyzed to assess the impact of Saveh Dam on the SSC during 1971-1982 and 1983-1994 as pre and 1995-2006 and 2007-2018 as post-impact periods in the Ghareh-chay basin, Iran. To quantify the spatio-temporal variation of SSC (due to climate change and anthropogenic activities such as dam construction and land use changes), a new measure Δα-based approach was introduced. The newly developed approach, referred to as the Δα-based method, was formulated by calculating the angle between (or the change in the slope of) the optimal Precipitation-Sediment (P-S) and Flow-Sediment (F-S) fit lines. This calculation is conducted spatially, encompassing both upstream and downstream locations, and temporally, by comparing data from different periods. The findings showed that Δα for the Precipitation-Sediment (P-S) relationship between upstream and downstream increased significantly after the Saveh dam commissioning. Initially, Δα was measured at 2.69 degrees and 1.35 degrees for the two pre-impact periods upstream and downstream, respectively. However, these values rose to 5.65 degrees and 9.39 degrees in the corresponding post-impact periods. Based on these results, it is evident that the notable changes in Δα for the Precipitation-Sediment relationship between upstream and downstream indicate the dam's impact on the Suspended Sediment Concentration (SSC) patterns in the Ghareh-chay river. The relatively short distance between the upstream and downstream gauge stations further supports the conclusion that these observed changes in Δα are directly attributable to the dam's influence, significantly altering sediment dynamics in the river system.

Keywords: Saveh dam; dynamics analysis; pre- and post-impacted; quantitative approach, sediment rating curve

Fig. 1. Location of the study area

How to cite: Karimidastenaei, Z., Darabi, H., and Torabi Haghighi, A.: Impact of dam construction on suspended sediment load alteration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5559, https://doi.org/10.5194/egusphere-egu24-5559, 2024.

Austria has a wide variety of protection structures at different condition levels due to the long tradition of torrent control works in the Austrian Alps. This has resulted in a large stock of protection structures and load models. In order to standardise the design of technical structures based on the Eurocode, including torrential processes, snow avalanches and rock fall, an interdisciplinary working group (ON-K-256) was established. The standardisation for torrential processes covers the definition and classification, the impact on structures, the design of structures, and the operation, monitoring and maintenance. These parts are based on and interact with EN 1990 (the basis of structural design), EN 1992-1-1 (the design of concrete structures), EN 1997-7 (geotechnical design) and the related documents for the Austrian national specifications. For torrential mass wasting processes with high variability in the concentration of solids, modern protection concepts are scenario-oriented. To optimize the mitigation measures for a multi-stage system, a functional chain must be implemented. This chain should have different structures to perform various functions such as dosing, filtering, and energy dissipation. When designing these torrential mitigation structures, it is necessary to simplify the model parameters, stress model, and load distribution. For debris flows, a standardized stress model combines the static and dynamic loads of debris flow impact on structures. This model was calibrated using available impact measurements of real debris flows and is in good agreement with common engineering design methods in Austria for debris flow impact on torrential barriers. The proposed method enables practitioners to design debris flow countermeasures with limited data availability.

How to cite: Nagl, G., Hübl, J., and Suda, J.: The new Austrian standard ÖNORM B4800 for torrent control work, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8068, https://doi.org/10.5194/egusphere-egu24-8068, 2024.

This study examined the sediment characteristics of areas where landslides occurred due to heavy rains between 2014 and 2019. A total of 5 types of geology in two geographic regions in Japan were examined using LiDAR LP topography data before and after the disasters occurred to estimate the changes in elevation. In addition, the volume of sediment runoff for each case was estimated for watershed areas ranging from 0.01 up to 0.1 km². The influence of geological differences on the sediment runoff volume within the basin using indicators such as the density of landslide occurrence, landslide volume, and watershed erosion intensity was also assessed. The results showed that, for all geology types, as the watershed area increases, the relief ratio decreases and the sediment runoff volume increases; however, the magnitude of this increase in sediment runoff volume differs depending on the underlying geology. In addition, the density of landslide occurrence was high in plutonic and metamorphic rocks. The landslide volume and the total eroded sediment volume within a watershed can be regressed using the linear equation y=ax. Since the average total eroded sediment volume within a watershed is approximately twice that of the landslide volume, there is a proportional relationship of 1:2. The relationship between the relief ratio and watershed erosion intensity shows that the watershed erosion intensity increases gradually as the relief ratio increases, and the rate of increase is larger in plutonic rocks (granite and granodiorite) than in the other groups. Metamorphic rocks had a relatively low watershed erosion intensity; these geological differences are reflected in differences in the degree of erosion of stream beds and banks by flood flows.

How to cite: Akita, H.: Comparison and analysis of the influence of geological differences on sediment runoff volumes from watersheds -case study of plutonic and metamorphic rocks in two sediment disasters in Japan-, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1808, https://doi.org/10.5194/egusphere-egu24-1808, 2024.

Hydrological and sediment transport regime are important in water resource management. Aim of this study is to identify the flow regime and the suspended sediment transport in a Mediterranean River Basin. Precipitation, temperature, soil, land use, discharges and suspended sediment concentration are used to quantify runoff and sediment yields at daily scales. WASA-SED (Water Availability in Semi-Arid environments – SEDiments) a spatially semi distributed model it is developed to simulate the flow and sediment transport in Seman Basin. Sediment deposits in Seman Basin contribute to a significant annual loss in the water storage capacity of the dams. Runoff and suspended sediments in Mediterranean hill slopes are closely related to rainfall intensities and land surface cover. This study gives a valuable approach in improving the prediction of flow and sediment transport in Mediterranean River Basin.

Keywords:
Flow, Sediment transport, WASA-SED, Mediterranean River Basin

How to cite: Doko, A., Bronstert, A., and Francke, T.: Hydrological and Sediment Transport Regime on Rivers in the Balkans: The Case of the Seman River in Albania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16053, https://doi.org/10.5194/egusphere-egu24-16053, 2024.