SSS11.4

EDI
Field and laboratory experiments in Soil Science, Geomorphology and Hydrology research and teaching

A well-designed experiment is a crucial methodology in Soil Science, Geomorphology and Hydrology.
Depending on the specific research topic, a great variety of tempo-spatial scales is addressed.
From raindrop impact and single particle detachment to the shaping of landscapes: experiments are designed and conducted to illustrate problems, clarify research questions, develop and test hypotheses, generate data and deepen process understanding.
Every step involved in design, construction, conduction, processing and interpretation of experiments and experimental data might be a challenge on itself, and discussions within the community can be a substantial and fruitful component for both, researchers and teachers.
This PICO session offers a forum for experimentalists, teachers, students and enthusiasts.
We invite you to present your work, your questions, your results and your method, to meet, to discuss, to exchange ideas and to consider old and new approaches.
Join the experimentalists!

Co-organized by GM2/HS13
Convener: Miriam MarzenECSECS | Co-conveners: Thomas Iserloh, Jorge Isidoro, Anette EltnerECSECS, Petr Kavka
Presentations
| Wed, 25 May, 13:20–15:55 (CEST)
 
Room G1

Presentations: Wed, 25 May | Room G1

Chairpersons: Miriam Marzen, Jorge Isidoro
13:20–13:25
13:25–13:31
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EGU22-6627
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Virtual presentation
Hiroaki Izumiyama, Takao Yamakoshi, Yuya Takahashi, Yuki Nishiguchi, and Ryosuke Okuyama

Precise prediction of travel distance of debris flow is required to design countermeasure strategy against natural disaster. A lot of numerical simulation tools have been developed using a selected shear stress which has been modeled to express the characteristics of debris flow and a modeled entrainment ratio. However, the calculation results for past events often show underestimated travel distance. One of the possible causes of the fact may be that the effect of grain size distribution on the entrainment ratio. This is because most models have been modeled assuming debris flow is constituted by a single size particle. An entrainment ratio model involving the effect of particle size distribution may improve the calculation reproductivity. From an engineering point of view, it is desirable that the effect can be taken into account as simply as possible. In this study, we conducted an experiment to know the extent to which the entrainment ratio is affected by the grain size distribution. The experiments were undertaken in a rectangular flume the channel slope of which can be adjusted at two points in longitudinal direction. Two-size mixtures of spherical glass beads or gravels were set as debris flow material. For each mixture, travel distance of debris flow and fractions of each size of debris flow material deposited near the channel slope change point were measured using high-speed camera.

How to cite: Izumiyama, H., Yamakoshi, T., Takahashi, Y., Nishiguchi, Y., and Okuyama, R.: An experimental study on effects of grain size distribution on debris flow deposition characteristics, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6627, https://doi.org/10.5194/egusphere-egu22-6627, 2022.

13:31–13:37
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EGU22-6737
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Virtual presentation
Marino Hiraoka, Naoki Imamori, Takeshi Shimizu, and Koji Ishida

After pyroclastic materials are deposited in a watershed following a volcanic eruption, the risk of debris flow initiation may increase during subsequent rainfall events. Clarifying the rainfall-runoff process on tephra-covered slopes is essential to understand the mechanism of debris flow initiation after an eruption. Because the quality and quantity of pyroclastic materials vary from volcano to volcano, and from eruption to eruption of the same volcano, each rainfall-runoff process is expected to differ accordingly. Laboratory rainfall simulation is useful to highlight parameters (rainfall and sample conditions) that may affect the surface runoff process on slopes during and after a volcanic eruption. In this study, a laboratory experiment was conducted using a calibrated rainfall simulator to investigate how the occurrence of surface runoff during the first rainfall after an eruption depends on the fine particle content. Pyroclastic material was volcanic ash collected on Mount Sakurajima, Japan and the fine particle content Fc was adjusted using artificial silt: Sample A (Fc = 20%, control) and Sample B (Fc = 30%, adjusted). The experimental plots (1723.4 cm2 of the projection area) were prepared by filling each sample with a 5 cm thickness at a constant pressure on highly permeable silica sand, and placed at an inclination of 10°. The initial moisture condition of both samples was assumed to be dry (≈ 5% of water content ratio). The rainfall simulation was performed for 3 hours on each sample at an intensity of 30 mm h-1. Runoff water including sediment from the experimental plot during the simulation was captured at the lower end of the plot and the weight was recorded. Two soil moisture sensors were buried 2.5 cm below the surface of each sample to measure the change in volumetric water content (VWC) over time. Runoff water including sediment occurred and increased with time on Sample B though hardly occurred on Sample A. In both samples, the VWC increased with time and eventually approached a constant value. However, the maximum value of the VWC, and the time to reach the maximum value, were different; lower and slower in Sample B. The saturated hydraulic conductivity of Sample B was one order of magnitude lower than that of Sample A. These comparative results suggested that surface runoff may be greater during the first rainfall after an eruption because the infiltration is lower when the fine particle content, that is particle size distribution, in pyroclastic materials is high.

How to cite: Hiraoka, M., Imamori, N., Shimizu, T., and Ishida, K.: Laboratory rainfall simulation for surface runoff generation on tephra-covered slopes with different fine particle content, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6737, https://doi.org/10.5194/egusphere-egu22-6737, 2022.

13:37–13:43
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EGU22-1148
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ECS
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Virtual presentation
Tung-Yang Lai, Yu-Chao Hsu, Ji-Shang Wang, Yu-Wen Su, Guei-Lin Fu, and Cheng-Yi Hung

Sedimentation has been a crucial problem in the management of storage in farm ponds, which cuts down the capability of ponds in aspects of irrigation, flood detention, and water retention. The Hydrosuction sediment removal system features low energy consumption and reduction of structural modifications to the existing shaft, which is an economically feasible method to remove siltation in storage areas. However, the effect of desilting might be limited due to the position of inflow orifice of siphon-type pipe which controls the scope of desilting affected area. This study aims to enhance the desilting effect of a fixed siphon system through connected a designed drainage tube.

The experiments were conducted in a cubic tank with a volume of 1.0 m3. Inside the tank, a vertical square shaft with the height of 80cm connected to an outlet channel was placed, and the siphon-type pipe was arranged from the inner of the tank to the outlet channel along with the shaft with a 3.0 cm inner diameter. The tests were performed in two kinds of inflow conditions in three water heights (60, 70, 80 cm), one is constant head inflow condition for continuous inflow provided, the other is falling head inflow condition with limited inflow supply. The initially deposited depths of sediment varied from 30 or 40cm. The designed 24cm long tube which has three added upward orifices with two types of diameters (1.0, 2.0 cm) could be connected to the inflow orifice of the siphon pipe to compare the desilting effect with the original arrangement in the above flow conditions.

The experimental results revealed that the effect of desilting was promoted by the connection of the designed tube to the siphon system. Besides, the efficiency of desilting was affected by the sizes of discharge orifices on the designed tube in different inflow conditions. In the constant head inflow condition, the arrangement of the connected 2cm discharge orifice tube performed better results due to the larger amount of outflow induced by the larger orifice. On the contrary, the arrangement of the connected 1cm discharge orifice tube had better desilting effect in falling head inflow condition induced by the longer time of disturbance between flow and sediment in smaller discharge. The results indicate that the capability and efficiency of sediment removal in the siphon system might be promoted by connecting an extended drainage tube with an appropriate size of upward discharge orifices.

How to cite: Lai, T.-Y., Hsu, Y.-C., Wang, J.-S., Su, Y.-W., Fu, G.-L., and Hung, C.-Y.: Experimental Study on the Efficiency of a Hydrosuction System for Desilting Sediment from a Farm Pond, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1148, https://doi.org/10.5194/egusphere-egu22-1148, 2022.

13:43–13:49
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EGU22-7001
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ECS
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Virtual presentation
Yatirajulu Gurugubelli, Prafulkumar V Timbadiya, and Bandita Barman

Meandering rivers are one of the most complex earth-surface systems and have a significant impact on riverine ecosystem mechanics. Because of the fascinating intricacy of meander morphodynamics, scholars from various disciplines, from fluid mechanics, fluvial hydraulics, and geomorphology, have been fascinated by meandering rivers. In spite of many years of research still, many processes regarding meandering rivers are not answered. Recent decades of research are reviewed herein in this paper. Scholars and experts have studied about flow features and processes such as a distorted profile of longitudinal velocity, secondary flow, inner and outer banks flow separation, etc., and sedimentological processes such as point bars, bend scour, lateral bed slope, etc. Many of them studied time-mean flow, Reynolds stresses, turbulence intensities (TI), turbulent kinetic energy, quadrant analysis, and turbulence scales, etc. under the effect of meandering bends. Many laboratory experiments are carried out to understand the individual processes under different conditions. Due to the rapid enhancement of soft computational techniques, these experimental data sets can be validated. Some future recommendations are also suggested in the field, laboratory, and numerical modelling.

Keywords: Meandering rivers, secondary flow, Reynolds stresses, turbulent kinetic energy, turbulence scales

How to cite: Gurugubelli, Y., Timbadiya, P. V., and Barman, B.: Review on Morphology and Turbulence Characteristics in Meandering Rivers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7001, https://doi.org/10.5194/egusphere-egu22-7001, 2022.

13:49–13:55
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EGU22-6912
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Virtual presentation
Laxman V Rathod, Prafulkumar V Timbadiya, and Bandita Barman

Riverbank and floodplain vegetation substantially affects the fluvial processes and play a key role in river hydraulics and river management. Presence of vegetation influences the water levels, flow velocity profiles and resistance to flow. Therefore, better understanding of behavior of flow over vegetation is required in design of vegetative channels, construction of stage-discharge curves, determining horizontal flow structure around hydraulic structures, and to develop numerical models. A detailed review of flow resistance due to rigid and flexible vegetation has been done under both emergent and submerged conditions. Based on the flow conditions and vegetation features, the investigators made a transition between rigid, flexible, emergent, and submerged vegetation. The variation of the flow field in the vegetative open channel follows a two-layer approach, it is almost constant inside the vegetation layer and logarithmic one above the vegetation layer. Firstly, several theoretical approaches for determining the resistance due to rigid vegetation in emergent and submerged condition are discussed. For simplicity many investigators have considered a rigid cylinder without side branches and foliage, the vegetation having constant height, stem diameter, and uniform flow condition was considered as rigid. The resistance due to vegetation also depends on the uniform and staggered pattern arrangements, the latter has more impact on flow in comparison to the former. The analysis for flexible vegetation is complex due to the complex nature of vegetation, and it is difficult to take the heterogenous nature of field vegetation into the account. The resistance due to flexible vegetation is a function of the height of vegetation, vegetation density, foliage, plant form alignment of vegetation, submergence ratio, and type of vegetation. The flexible vegetation also assumes different configurations depending on the hydrodynamics of flow and bending stiffness. Furthermore, more recent approaches for describing the resistance due to flexible vegetation are presented.

Keywords: Rigid vegetation, Flexible vegetation, Resistance to flow, Rivers, Floodplains, Flow field

How to cite: Rathod, L. V., Timbadiya, P. V., and Barman, B.: Flow Resistance Due to Rigid and Flexible Vegetation: A Review, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6912, https://doi.org/10.5194/egusphere-egu22-6912, 2022.

13:55–14:01
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EGU22-6585
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Presentation form not yet defined
Petr Kavka, Martin Neumann, Tomas Laburda, Jan Devátý, and Tomas Dostal

Rainfall simulators are devices commonly used to study soil erosion in field and laboratory conditions. There is still an effort to develop equipment that will: not require a large number of workers, be easy to manipulate, have simple control systems, and automatically record data and parameters.

This paper shows a new variable rainfall simulator with many possibilities, it consists of four independent sections that can be joined into larger simulator. Each section can simulate rain on a 2x4m area. The rain is generated by swinging and pulse mechanisms. Soil sensors and rain gauges are integrated into the control unit.

The whole device is placed on a trailer that is moveable by car. On the trailer, there is also a 1m3 water reservoir, control unit based on WAGO control unit with electric switchboard, water pump, hydraulic system and valves. The device could be controlled by any laptop or smartphone with a wifi connection.

Each section (4 total) consists of a boom with 3 nozzles connected to a stepper motor for swinging. Each nozzle has a valve to interrupt the water supply to the nozzle. These sections can be connected linearly to increase the length of the rainfall area (to maximum 16 meters), or they can be used parallelly, thereby performing multiple replications at one time on multiple areas side by side. All these sections are computer-controlled and are independent of each other. Each section contains sensors for measuring soil moisture and tipping bucket rain gauges for continuous monitoring of actual soil properties and control of the rainfall. Remote control also allows for variable rainfall scenarios. The device allows the use of both pulsed and swinging rainfall formation or their combination and thus a large variability in the choice of nozzles according to the purpose of the experiment. Water is pumped by the gas water pump throughout the redistributions and pressure reducing valve, which can manage the required stable pressure. It also contains a datalogger so all measurements and parameters are collected in one device.

This study has been supported by the Grant Agency of the Czech Technical University in Prague, grant No. SGS20/156/OHK1/3T/11 and the Project QK1910029.

How to cite: Kavka, P., Neumann, M., Laburda, T., Devátý, J., and Dostal, T.: New opportunity of RS - variable rainfall simulator for plots variable plots area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6585, https://doi.org/10.5194/egusphere-egu22-6585, 2022.

14:01–14:07
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EGU22-4947
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ECS
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Virtual presentation
Martin Neumann, Petr Kavka, Romana Kubínová, Adam Tejkl, Michal Vrána, Jan-František Kubát, and Tomáš Laburda

Rainfall simulators (RS) are commonly used tools for soil erosion research under natural conditions. This research was focused on the plot scale effect in the formation of surface runoff and soil loss. Two surface conditions were tested - grass and bare soil. All experiments were performed in field conditions on undisturbed soil samples located on the experimental site Řisuty, where CTU has been performing experiments with rainfall simulators for many years. Three experiments were performed to investigate the formation of surface runoff depending on area size, surface type and precipitation intensity. These experiments were performed on a surface with grass cover and also on a plot of ​​cultivated bare soil. For the bare soil experiment, the area was prepared just prior to the experiment itself. The grass plots were left to develop naturally for 2 years after sowing. A large rainfall simulator with a maximal experimental area of 16 m2 (8 m length 2 m wide) was used for this experiment. Four plots with lengths of 1, 2, 4 and 8 m (with widths of 1 m) were placed under the RS. Soil moisture sensors were placed on the plot at various depths to monitor the evolution of soil moisture over time. For the plot with the grass cover, a rainfall with variable intensity over 75 minutes was used (rainfall intensities 40, 60, 90 mm/h). Two follow-up experiments were conducted on the plot with bare soil. Rainfall intensities were a constant 60 mm/h for 30 minutes after surface runoff starts. The second experiment started 15 minutes after the conclusion of the first one. This same methodology has been used in other, past, experiments with RS so our results are directly comparable to those previously conducted experiments. All results were recalculated to 1m2 and 1 minute intervals for comparison in addition to the cumulative values for each experiment.

Results from the plots with grassland showed significant differences between plots of different lengths. Experimental plots with bare soil provided higher variability in results on the plots in their natural moisture (dry condition), than those of the fully saturated samples. Results showed that the length of the plot is more important for soil loss than for surface runoff processes. The heterogeneity of the infiltration soil properties would play significant role on the experiment results.

This study has been supported by Grant Agency of the Czech Technical University in Prague, grant No. SGS20/156/OHK1/3T/11 and the Project QK1910029.

How to cite: Neumann, M., Kavka, P., Kubínová, R., Tejkl, A., Vrána, M., Kubát, J.-F., and Laburda, T.: Rainfall Simulators – how plot scale affects results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4947, https://doi.org/10.5194/egusphere-egu22-4947, 2022.

14:07–14:13
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EGU22-2582
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ECS
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Virtual presentation
Lea Epple, Anne Bienert, Oliver Grothum, and Anette Eltner

High-resolution information on the processes and rates of soil erosion, transport, and deposition, offer important knowledge for soil erosion modelling, and the protection and sustainable management of soil. It helps improve the cross-scale understanding on aspects as aggregate breakdown, rill erosion, swelling and shrinking effects, and rill-network evolution. As a non-invasive, high-resolution, and cost as well as time-efficient method, Structure from Motion (SfM) presents a valuable tool to calculate soil loss, depict soil surface change detection, and offer high-resolution information on soil and soil erosion processes. Even though SfM shows in general higher erosion rates, due to the influence of non-erosive processes, the technique is altogether in good agreement with the sampling data at the outlet. We monitor soil erosion on multiple erosional plots and with spatial and temporal high-resolution photogrammetry to assess its feasibility over time.

For this purpose, we conduct 12 rainfall simulations on a three times one metre plot, on different sides, with different vegetation cover, tillage, and initial soil conditions. Seven to ten synchronized time-lapse cameras are set up around the plot, taking pictures every 10-60 seconds. The data thus obtained allow change detection assessment via digital elevation models of difference at least once per minute. The elevation change by SfM is validated via bulk density measurements, and sampling at the plot’s outlet assessing runoff, and sediment concentration at minute intervals. During an overflow experiment, we measure flow velocity via video using particle tracer and manually via colour tracer, gaining spatial and temporal distribution information on the flow velocity. Using low-cost sensors, we furthermore monitor the progress of the soil moisture and temperature during the whole rainfall simulation.

We present sampled and photogrammetric results based on a dozen rainfall simulations at the micro-scale with a very high temporal and spatial resolution. This gives an insight into spatial distribution and development of soil erosion processes on a sub-minute resolution. We compare these data to gain knowledge on the feasibility of temporal and spatial high-resolution SfM soil erosion assessment and their usability for the validation and calibration of process-based soil erosion models.

How to cite: Epple, L., Bienert, A., Grothum, O., and Eltner, A.: Soil erosion assessment via temporal and spatial high-resolution time-lapse Structure from Motion on rainfall simulation plots, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2582, https://doi.org/10.5194/egusphere-egu22-2582, 2022.

14:13–14:19
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EGU22-4865
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ECS
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On-site presentation
Tamara Kuzmanić and Matjaž Mikoš

The Dynamic Image Analysis (DIA), standardised in ISO 13322-2:2006 and ISO 9276-6:2008 standards, introduces a simple and fast analysis of diverse particle shape and size parameters, compared to a manual method or static image analysis, respectively. While the DIA method is time conserving, as it is a quasi-3D method, it is susceptible to greater variations in results compared to a real-3D, time consuming static image analysis. A variation analysis of the DIA results as a function of the analysed particles’ shape was the focus of our study. The particle shape plays a role in various processes, including wearing off (mechanical abrasion) during sediment transport or due to in-situ abrasion of larger sediment particles in fluvial environments.

More than 40 particles were randomly selected for the DIA analysis. Analysed particles included quarried, angular rock particles and rounded fluvial sediment particles. The selected particles had a geometric mean diameter in the range between 15 mm and 70 mm (coarse gravel to cobble size). The mass of particles was between 10 and 400 g. All particles were divided into four shape groups (bladed, prolate, equant, and oblate) according to Zingg’s shape classification. Axes' lengths used for shape classification were manually measured using a caliper. All particles were also individually analysed in a dynamic image analyser (quasi-3D image analyser) Microtrac Camsizer XL, using the accompanying software, PartAn 3D. The software evaluates 33 size and shape parameters of analysed particles, including dimensional (e.g. length, width, thickness, surface area, etc.) and dimensionless (e.g. ellipticity, sphericity, convexity, etc.) parameters. Three DIA repetitions of each particle were applied to estimate the mean values and variation (coefficients of variation, CV) in its results.

Furthermore, the effect of particles’ size, mass, and Zingg’s shape on the variability of the DIA results was investigated. Particles’ size, as well as particles’ angularity, showed no obvious effect on the variation in the DIA results. Quarried, angular particles had CV of 3.54% on average for all parameter results, while rounded, fluvial particles had CV of 3.68% for all parameter results. On the other hand, Zingg’s shape class showed an effect on the variation of both, dimensional and dimensionless DIA resulting parameters. Bladed particles displayed the greatest variations of all the resulting parameter values, with an average CV of 6.85%, and the greatest scatter of parameters’ CVs. When analysing such particles, it would be beneficial to conduct more than three repetitions for more accurate results. Since the DIA analysis is a fast method, this is not a problem in order to get a robust estimation of coarse particle shape. Additionally, observing the parameters themselves, “concavity” and “angularity” had the highest CVs, namely 13.35% and 10.24%, as well as the greatest scatter of the CVs. Parameters “convexity”, “solidity”, and “sphericity” had the lowest CVs, namely 0.12%, 0.26%, and 0.96%, respectively, as well as the lowest scatter of the CVs.

How to cite: Kuzmanić, T. and Mikoš, M.: Effect of coarse gravel and cobble size particles’ shape on their dynamic image analysis results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4865, https://doi.org/10.5194/egusphere-egu22-4865, 2022.

14:19–14:25
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EGU22-12186
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Virtual presentation
Agata Sochan, Krzysztof Lamorski, and Andrzej Bieganowski

The phenomenon of multiphase splash can be a mechanism for transporting various types of pollution (e.g. petroleum substances), which makes it especially interesting in the context of environmental protection.

In this paper, the water splash phenomenon caused by the impact of a petrol drop on the water surface was simulated using the multiphaseInterFoam solver, i.e. a part of the OpenFOAM computational fluid dynamics software implementing the finite volume method (FVM) for space discretization. The simulations were experimentally validated based on splash images obtained with the use of a high-speed camera (2800 fps). Several variants of simulations with a varying drop size (in 0.10-mm steps) or drop velocity (in 0.025-m/s steps) were conducted.

Our experiments showed the importance of even a slight underestimation/overestimation of the properties of a falling drop on the simulation of the size and dynamics of splash in an immiscible liquid system. On the other hand, correct simulation made it possible to analyse aspects of the phenomenon that were difficult or even impossible to achieve experimentally due to the limitations of the image analysis method. This concerned the determination of the cavity width, the moment of cavity disappearance, the moment of jet formation (still below the water level), and the height of the jet. In addition, based on the validated simulation of splash in immiscible liquids, the scale of the spread of petroleum contamination as a result of the impact of a single droplet was determined.

The study was partly funded by the National Science Centre (Poland), based on decision no. 2017/26/D/ST10/01026.

How to cite: Sochan, A., Lamorski, K., and Bieganowski, A.: Effect of underestimation/overestimation of falling drop parameters on the result of splash simulation in an immiscible liquid system, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12186, https://doi.org/10.5194/egusphere-egu22-12186, 2022.

14:25–14:31
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EGU22-2558
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Virtual presentation
Tina Katika and Panagiotis Michalis

The level and type of saturation of the petroleum reservoirs is an essential parameter in reserve estimation because it determines the effective volume of the hydrocarbon that is being stored. At the same time, rock wettability influences the displacement of oil by water from oil-producing reservoirs, especially during water-flooding processes. Low-field Nuclear Magnetic Resonance (NMR) spectrometry evaluates the pore size distribution and has proved a powerful tool in determining the type of saturation and assessing the solid-fluid affinity (Katika et al., 2017).

However, assessing the pore-fluid distribution of rocks with complex mineral composition at laboratory conditions, such as chalk and argillaceous sandstones, that are commonly found in the North Sea oil reservoirs, often requires further investigation. NMR data are combined with a visual inspection or with traditional techniques, such as MICP, to evaluate the microtexture of rocks (Katika et al., 2018, Faÿ-Gomord et al., 2016). Considering that laboratory low-field NMR can be used as a guide to interpreting logging data, improving the evaluation of lab measurements has a profound influence on the field.

Deep Learning (DL), as an artificial intelligence technique utilizing neural networks, has the potential to transform low-field NMR into a more efficient and powerful tool in reservoir characterization.

The various peaks in NMR T2 relaxation spectra differ in rocks with multiple types and levels of saturation, rock-fluid affinity, or pore size distribution. In the present study, we aim to improve the interpretation of the T2 spectra and automate peak picking. Using laboratory data for reservoir rocks from the literature (Katika et al., 2017), a Deep Neural Network (DNN) was trained to optimize the internal network parameters and successfully evaluate the type of peaks existing in T2 spectra. The successful evaluation is confirmed with visual inspection and correlated with geophysical data derived from the same literature.

References

Katika, K., Saidian, M., Prasad, M. and Fabricius, I.L., 2017. Low-Field NMR Spectrometry of Chalk and Argillaceous Sandstones: Rock-Fluid Affinity Assessed from T1/T2 Ratio. Petrophysics-The SPWLA Journal of Formation Evaluation and Reservoir Description, 58(02), pp.126-140. SPWLA-2017-v58n2a4

Faÿ-Gomord, O., Soete, J., Katika, K., Galaup, S., Caline, B., Descamps, F., Lasseur, E., Fabricius, I.L., Saïag, J., Swennen, R. and Vandycke, S., 2016. New insight into the microtexture of chalks from NMR analysis. Marine and Petroleum Geology, 75, pp.252-271. https://doi.org/10.1016/j.marpetgeo.2016.04.019

Katika, K., Alam, M.M., Alexeev, A., Chakravarty, K.H., Fosbøl, P.L., Revil, A., Stenby, E., Xiarchos, I., Yousefi, A. and Fabricius, I.L., 2018. Elasticity and electrical resistivity of chalk and greensand during water flooding with selective ions. Journal of Petroleum Science and Engineering, 161, pp.204-218. https://doi.org/10.1016/j.petrol.2017.11.045

How to cite: Katika, T. and Michalis, P.: Machine Learning for low-field NMR to improve pore fluid characterization , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2558, https://doi.org/10.5194/egusphere-egu22-2558, 2022.

14:31–14:37
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EGU22-7850
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Virtual presentation
Adam Tejkl and Petr Kavka

Water erosion is the physical wearing of the earth’s surface. Erosion removes surface soil material (topsoil), reduces levels of soil organic matter, and contributes to the breakdown of soil structure.

The large amount of time required for manual identification of the rills is an obstacle in effective erosion research. Nevertheless, a significant number of rills have already been manually marked for various studies. It is therefore possible to use these already obtained data to train an algorithm, which will then automatically identify the grooves. The experiment is carried out using a rain simulator. The first part of the precipitation lasts 30 minutes, followed by a 15-minute break and another 30-minute precipitation. Photos for SfM method of creation detailed DMT are taken in three states a) before the simulation, b) between the simulations and c) after the experiment. On the finished DMT rills are manually digitalized in ArcGIS Pro, and their cover polygons are thus created.

Nhu et al. 2020 in his work dealt with the evaluation of the capabilities of the Keras deep learning model and their optimization algorithms. Keras is a deep learning API written in Python, running on top of the machine learning platform TensorFlow.

The image is converted to a matrix using the Raster to Array tool. The corresponding square is selected from each band and a mosaic is then created from these squares. The length of the square edge is chosen. The resulting mosaic consists of individual squares of the image spectrum bands placed side by side to form a rectangular image.

The Kaggle Cat Dog model was used as the basis for creating the model. This is a model designed to sort color images into two groups. This model was modified by inserting mosaics into the model instead of images. The training dataset is loaded into the model and divided into calibration and validation parts for the purpose of model calibration. This distribution was chosen to be 20%. The image size was specified as 100x200 pixels, with pixel of size 0,1 cm.

The individual mosaics not used for model training are then classified by this trained model. Loading mosaics for classification is controlled by a CSV file, which contains the name of the mosaic, the position of the mosaic in the image and whether it is intended for training or not. The probability value with which the mosaic is classified as erosive or not is then added to this CSV file. Training mosaics are omitted and assigned a no_data value.

The CSV file of the classified image is loaded back into the GIS environment using a Python script. The script loads the CSV file and creates an according classified raster.

The research is funded by the Technological Agency of the Czech Republic (research project SS01020366) and an internal student CTU grant (SGS20/156/OHK1/3T/11).

How to cite: Tejkl, A. and Kavka, P.: Identification of erosion rills via machine learning, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7850, https://doi.org/10.5194/egusphere-egu22-7850, 2022.

14:37–14:50
Coffee break
Chairpersons: Thomas Iserloh, Anette Eltner
2. Block Experimental Geomorphology, Hydrology and Soil Science
15:10–15:16
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EGU22-8329
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Virtual presentation
Itzhak Katra

Soil erosion has environmental and socioeconomic significances. Most of the loess soils throughout the world are subjected to increased land uses such, which increased soil destruction and dust emission to the atmosphere. There is a distinguish interest in applications for dust control and soil stabilization. This study examines empirically the use of a metakaolin-based geopolymer for dust control and soil stabilization in a semi-arid loess soil that is subjected to land uses and erosional processes. The application of the geopolymer for dust control in comparison with common products (brine, bitumen, PVA) resulted with no soil erosion and dust emission by wind tunnel simulations. As a soil stabilizer, the geopolymer tested in this study provides remarkably good results in the tensile test. The most successful composition of the geopolymer, which is activation solution of sodium silicate and sodium hydroxide (NaOH) together with an addition of 30% metakaolin, obtained soil strength of 23900N after 28 days. The attempt to replace NaOH with lime (CaO) in the activation solution was far inferior to the original composition.

How to cite: Katra, I.: A clay-based geopolymer in loess stabilization to water and wind soil erosion, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8329, https://doi.org/10.5194/egusphere-egu22-8329, 2022.

15:16–15:22
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EGU22-3891
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ECS
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Virtual presentation
lior saban, Itzhak Katra, and Hezi Yizhaq

Aeolian megaripples are a landscape formation widespread on Earth and Mars that develop in sand surfaces with a bimodal grain size distribution of coarse and fine grains. Megaripples are relatively high with a greater wavelength compared with normal sand ripples. Previous works provided quantitative information on the morphological characteristics, development, flattening mechanisms, longevity, and transverse instability of megaripples. It has been hypothesized that the sorting process of the initial bimodal size distribution is a key factor in megaripple formation. In this study, we experimentally explored the impact of the grain size distribution on the crest characteristics under different wind velocities in a boundary-layer wind tunnel. The controlled experiments allowed measurements of sand fluxes, particle size distributions, and ripple morphology by a laser module. The results reveal links between the rate of growth of the incipient megaripples, ripple height, and the armoring layer thickness and composition to wind velocity. The ripples grow higher as the wind velocity increases, and the armoring layer is thicker up to a certain wind velocity when erosion of the crest starts. In addition, the correlation between the armoring layer's nonlinear thickening rate and the ripples growth rate seems to indicate a fundamental connection between ripples height and the formation of the armoring layer, which is crucial for megaripples formation.

How to cite: saban, L., Katra, I., and Yizhaq, H.: Impact of grain size distribution and wind velocity on the armoring layer of aeolian megaripples, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3891, https://doi.org/10.5194/egusphere-egu22-3891, 2022.

15:22–15:28
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EGU22-9688
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ECS
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Virtual presentation
Miriam Marzen, Mario Kirchhoff, Irene Marzolff, Ali Aït Hssaine, and Johannes B. Ries

The Souss-Massa basin features unique and centuries old human–environment interactions in a vulnerable arid ecosystem. A high pressure caused by intense agriculture combined with increasing water scarcity causes degradation of soils and vegetation cover. The test sites are located on alluvial fans from the flanking High Atlas Mountains in the north and the northern talus of the Anti Atlas in the south. Wind-tunnel tests were applied to investigate susceptibility to wind erosion from sparse argan forest, badland and wadi surfaces. The results show diverse potential for emission of coarser and finer mineral dust with highest values found on freshly tilled surfaces in the extensively managed argan forest and sandy wadi surfaces. For one tested wadi section, very erodible areas were found in close vicinity to areas with much lower sediment yield. The wind-erosion dynamics are thus closely related to fluvial processes previously influencing surface characteristics as well as previous sorting processes by wind impact. The strongly crusted surfaces attributed to badland environments are least susceptible to wind erosion, with the exception of higher emissions measured on the wadi rim.

The data give insight into possible wind-erosion patterns under non-extreme wind regime and are a valuable basis for investigation of interactions between fluvial and aeolian processes in wadi structures.

How to cite: Marzen, M., Kirchhoff, M., Marzolff, I., Aït Hssaine, A., and Ries, J. B.: Experimental wind erosion study in argan woodlands, badlands and wadis in the Souss-Massa Basin, Morocco, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9688, https://doi.org/10.5194/egusphere-egu22-9688, 2022.

15:28–15:34
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EGU22-1841
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Presentation form not yet defined
Benjamin Huxol, Gunnar Pruß, Anne Voigtländer, Michael Dietze, and Jens M Turowski

Have you ever applied the Schmidt hammer method and wondered what the R‑value represents? What SI unit it would have and which material properties it actually assesses? The Schmidt rebound hammer is a device initially intended to test the curing state and strength of concrete. Since then, the concept has been transferred to determine the strength, weathering, and sometime even surface exposure age of rocks in geomorphology. The advantage of the Schmidt hammer that it is non-destructive, easy to handle, light, and readily applicable in the field. However, the method is only based on correlation, without physical explanation of the measured value being provided, and using a seemingly arbitrary resolution of the scale without reference. Here we present our approach to put the Schmidt hammer and especially the physics behind the R‑value on solid ground. Using a dataset of material properties and R‑Values, we find that the Schmidt hammer best represents the elasticity of the material. The elasticity and, along with it, the elastic modulus, can be independently and complementarily assessed with other geophysical methods. Both metrics are known to vary with i) moisture level, ii) stress state, and iii) temperature. Consequently, we conducted controlled experiments to constrain the influence of these conditions on R‑values. A major disadvantage of the Schmidt hammer, the resolution of the scale, remains and needs further calibration.

How to cite: Huxol, B., Pruß, G., Voigtländer, A., Dietze, M., and Turowski, J. M.: Making the Schmidt Hammer Great Again!, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1841, https://doi.org/10.5194/egusphere-egu22-1841, 2022.

15:34–15:40
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EGU22-6569
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ECS
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On-site presentation
Morena Galešić Divić, Vladimir Divić, Marija Kvesić, Mak Kišević, and Roko Andričević

The levels of monitoring quality and quantity for environmental factors present continuous challenges for engineers, scientists, and related decision-making bodies. This is particularly highlighted in complex ecosystems such as coastal areas and estuaries with the pronounced intersection of numerous natural gradients. On the other hand, constant technological advances of different measurement equipment, including the remotely operated vehicles and their modular design, are introducing vast opportunities for gathering various data. Furthermore, readily available open-source solutions for hardware and software domains present additional potential in developing the framework for multipurpose monitoring. We are developing a multimodal approach to monitoring coastal zones, particularly in estuarine waters, which comprises using commercially available measurement equipment (multisensory probes) and, more importantly, building task-oriented drifters with relevant sensors. Furthermore, we are implementing the usage of remotely operated vehicles, both areal and underwater, which present a suite of measurement devices for data amplification (metadata), collection, and verification, especially when coupled with satellite data. Moreover, the use of drones has additional value in reducing the disturbance of natural conditions and improving the safety of researchers. So far, the monitored data include conductivity, temperature, pressure, wave heights, water velocity, dissolved oxygen, chlorophyll, colored dissolved organic matter, turbidity, hyperspectral properties, and further research including thermal camera and LIDAR technology. Different measurement approaches also contain several issues such as temporal and spatial scale comparability and interoperability, while drone use implicates some concerns about privacy, noise, and the general social attitude. These issues are currently being investigated, generating some challenges for future progress. Through current multiple research projects, we are testing the presented multimodal approach on the case study of the river Jadro estuary near the city of Split (Croatia), aiming to develop a field laboratory with the potential to be replicated in any similar hydrological monitoring.

How to cite: Galešić Divić, M., Divić, V., Kvesić, M., Kišević, M., and Andričević, R.: Development of a multimodal approach to monitoring of coastal waters, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6569, https://doi.org/10.5194/egusphere-egu22-6569, 2022.

15:40–15:46
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EGU22-4928
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ECS
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Virtual presentation
Jan-František Kubát, Michal Vrána, David Zumr, and Petr Kavka

Good stability of soil aggregates is an essential characteristic that positively affects soil health, increases agronomic productivity, decreases susceptibility to soil erosion and can improve carbon sequestration. The most common laboratory procedure for determining soil aggregate stability is a water resistance index (WRI) which is based on a wet sieving method. Within this contribution we introduce a newly developed method which utilizes laser diffraction for estimating the water resistance index of soil aggregates (WRILD). Recently, this newly introduced method has been tested and compared with the Kemper & Rosenau equation. This new method was developed with an emphasis on comparability to the standard sieving procedure performed with the Eijkelkamp wet sieving apparatus. The water stability of the aggregates was tested across five different soil types (haplioc Luvisol, Chernozem, Regosol, Fluvisol, Cambisol). The pH of each sample was measured and according to this value, either hexametaphosphate or sodium hydroxide was used to disrupt the stable aggregates along with ultrasound. The resulting WRILD is determined based on a fraction of undisturbed aggregates recorded for each fictitious sieve size. Initial results show promising agreement between the standard sieving and laser diffractometer methods. The advantage of the latter is a much faster processing time of a large number of samples and their replicates. This new method has a lower variability of results. However, further measurements are needed to validate the method.

This study has been supported by the Grant Agency of the Czech Technical University in Prague, grant No. SGS20/156/OHK1/3T/11 and EC H2020 Project 101000224 (TuDi).

How to cite: Kubát, J.-F., Vrána, M., Zumr, D., and Kavka, P.: Testing of soil aggregate stability by means of laser diffractometer Mastersizer 3000, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4928, https://doi.org/10.5194/egusphere-egu22-4928, 2022.

15:46–15:52
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EGU22-5032
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ECS
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Virtual presentation
Laura Kögler, Thomas Iserloh, Alina Helmer, Andreas Ruby, Miriam Marzen, Manuel Seeger, and Johannes B. Ries

There is a knowledge gap concerning the identification and quantification of transported soil particles in subsurface flows. If these soil particles reach relevant amounts, protective measures against soil erosion applied on the surface may be partially ineffective, and the soil may degrade further and unnoticed. In consequence, there is a need to develop a method to determine this subsurface particle transport in situ. A laboratory flume experiment was developed to examine the processes of fine soil material transport as well as the development of sediment traps for in situ measurements. Since, steep-slope vineyard soils are especially prone to subsurface flows they were subject of first investigations: The shallow steep-slope vineyard soils of the Mosel wine region are mainly developed from Devonian argillaceous schists and Pleistocene terrace sediments. Among the main physical characteristics are a very high rock fragment content and a loose surface layer over a strongly compacted layer caused by the combined action of tillage and weathering. This structure is presumably prone to subsurface flows within the upper horizon, especially in periods of very high soil moisture. The results of this laboratory experiment clearly confirm the presence of subsurface particle transport and the applicability of a sediment trap prototype consisting of a relatively simple and low-cost drain structure. 

How to cite: Kögler, L., Iserloh, T., Helmer, A., Ruby, A., Marzen, M., Seeger, M., and Ries, J. B.: Experimental laboratory setup for identification and quantification of transported soil particles in subsurface flows, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5032, https://doi.org/10.5194/egusphere-egu22-5032, 2022.

15:52–15:55