Erosion Component Research Articles

Energy Dissipation Potential of Square Tubular Steel Columns Subjected to Axial Compression

Coastal hazards affect the majority of sandy shores, and are responsible for damage to, and destruction of settlements, infrastructures, public services and sacred places in Bali’s shorelines. However, there is an absence of information regarding the extent of the erosion hazard in Klungkung Regency coastal area. This study aims to assess the suitabilityerosion prone area components and method for assessing them for Klungkung Regency Coastal Area based on available secondary data. Literature review is conducted to evaluate the existingerosion setbacks and previous studies of the location. Then the available information iscorresponded with the erosion components required. For the study location, several erosion setback components that need to be assessed include short-term erosion component, long-term erosion component, sea level rise, dune stability component, and factor safety. Subsequently, shoreline response model is utilized for assessing short-term erosion component, whilst dune scarp migration is conducted to evaluate long-term erosion component. Furthermore, Bruun’s Rule is applied to estimate the sea level rise component. It is expected that for future study, a different approach of erosion prone area assessment will be conducted, so the result from this study can be compared with. Additionally, the result of this study is expected to provide the information about coastal erosion assessment methods and reference about coastal erosion for future stud

Experimental Study on Erosion⁻Corrosion of TP140 Casing Steel and 13Cr Tubing Steel in Gas⁻Solid and Liquid⁻Solid Jet Flows Containing 2 wt % NaCl.

To study the erosion–corrosion characteristics of TP140 casing steel and 13Cr tubing steel in oil fields, we performed gas–solid and liquid–solid jet flow experiments to control particle addition, jet angle, and flow velocity and measure erosion and corrosion components. Meanwhile, we used a standard three-electrode system to study the changes in electrochemical parameters on a metal surface in a two-phase flow containing 2 wt % NaCl. Results showed that erosion is mainly dominated by the flow velocities and impact angles of particles, and corrosion rate is mainly affected by liquid flow rate. The erosion rates of the two materials increase with flow velocity, and the critical angle of maximum erosion rate exists. Meanwhile, flow velocity growth increases the current density on the TP140 surface while reducing the corrosion potential of 13Cr, but the effect of the angle on the two parameters is relatively small. The uniform corrosion of TP140 increases the erosion rate in the range of 10–20%, and the pitting of 13Cr increases the erosion rate in the range of 30–90%, indicating that the interaction between the erosion and corrosion of stainless steel is obvious.

Капельная эрозия катода в сильноточной вакуумной дуге

AbstractIt is shown that high-current vacuum arcs accompanied by partial melting of the cathode surface and its droplet erosion can generate, in addition to the well-known droplets formed immediately in the cathode spot (first type droplets), a second component of erosion. The liquid part of the cathode surface can emit droplets with significantly different sizes and velocities, which may be called second type droplets. The mechanisms of the formation of first and second type droplets are also substantially different.

Impact of Plaque Erosion on Stress/Strain and Flow Shear Stress Calculation: An OCT-Based FSI Modeling Study

Plaque erosion, one of the primary causes for coronary thrombosis, is responsible for about one third of the patients with acute coronary syndrome (ACS) [1]. Histological studies characterized the eroded plaque as a plaque with following morphological features: 1) plaque intima having direct contact with intraluminal thrombus due to the absence of endothelium or endothelial injury; 2) without rupture in the fibrous cap; 3) abundance of proteoglycans and smooth muscle cells on the luminal surface under the thrombus [2]. These characteristics has been applied in in vivo diagnosis of plaque erosion using optical coherence tomography (OCT) image technology and specific treatment strategy has also been developed for plaque erosion related ACS [3]. However, The pathogenesis mechanisms that cause plaque erosion are not fully understood [2]. It is postulated that plaque erosion has close association with biomechanical conditions in the coronary vessel [2]. In this work, a patient-specific OCT-based modeling approach was develop 3D fluid-structure interaction (FSI) models to investigate the biomechanical conditions in eroded plaque and investigate the impact of erosion-induced inflammation on plaque stress/strain conditions. Patient-specific OCT data of eroded coronary plaque were acquired from one male patient (age: 64) with frequency-domain OCT C7XR system and the Dragon Fly catheter (Lightlab Imaging/St. Jude Medical). Erosion sites were identified as the luminal surface having direct contact with intraluminal thrombus on the OCT images. Biplane X-ray angiographic data (Allura Xper FD10 System, Philips, Bothel, WA) were also acquired with the information of the location of the coronary artery stenosis and vessel curvature. OCT images were segmented manually with external elastic membrane (EEM) contour assumed to have positive remodeling ratio 1.1 for this plaque. The trailing edge of the lipid-rich necrotic core (lipid) was also assumed since it cannot be seen on the OCT images. Co-registration of OCT and angiographic data were performed to reconstruct the 3D coronary geometry. Our FSI modeling procedures with pre-shrink–stretch process and anisotropic material properties were previously developed. Blood flow was assumed to be laminar, Newtonian and incompressible, with arbitrary Lagrangian–Eulerian formulation of the Navier–Stokes equations used as the governing equations. The governing equations of the structure models included equations of motion, the nonlinear Cauchy–Green strain–displacement relation and Mooney–Rivlin material properties. To reflect tissue weakening caused by erosion-induced inflammation, the material stiffness of plaque intima at the erosion site was adjust to one tenth of un-eroded fibrous plaque tissue [2]. Three FSI models were constructed to investigate the impacts of erosion-induced inflammation and lipid component on plaque stress/strain conditions: M1, without erosion (this means plaque intima at the erosion sites were not softened) and without inclusion of lipid component; M2, with erosion but no lipid component; M3, with erosion and inclusion of lipid component. Pulsating pressure conditions were prescribed at the inlet and outlet of the vessel segment. Fluid–structure interaction boundary conditions including force balance and no-slip conditions were imposed to the fluid–structure interface between blood flow and vessel lumen surface. Results for plaque wall stress/strain (PWS/PWSn) and flow wall shear stress (WSS) from the FSI models corresponding to peak blood pressure were extracted for analysis. Table 1 summarizes the average values of the biomechanical factors both at erosion sites and fibrous cap overlaying lipid component for 3 models. By comparing M1 and M2 at the erosion sites, Mean PWS value decreases from 49.98 kPa to 18.83 kPa (62.32% decrease) while Mean PWSn value increases from 0.1231 to 0.1384 (12% increase) as the material stiffness becomes 10 times soft. At the fibrous cap, M3 (with inclusion of lipid) will elevates mean PWS and PWSn values by 48.59% and 16.09%, respectively. The impacts of erosion and lipid on flow shear stress were limited (<2%). Table 1: Average values of three biomechanical factors over erosion sites and fibrous cap overlaying lipid core. Average values of biomechanical factors over Erosion sites for 3 Models M1 M2 M3 Mean PWS (kPa) 49.9759 18.8318 18.8298 Mean PWSn 0.1231 0.1384 0.1384 Mean WSS (dyn/cm2) 101.0637 99.9383 99.4303 Average values of biomechanical factors over fibrous cap overlaying lipid for 3 Models M1 M2 M3 Mean PWS (kPa) 68.3209 68.3199 101.5173 Mean PWSn 0.0870 0.0870 0.1010 Mean WSS (dyn/cm2) 18.5260 18.4634 18.1910 To conclude, erosion-induced inflammation on blood vessel would lead to lower stress distribution but larger strain distribution, while lipid component would elevate both stress and strain conditions. This shows the influence of erosion and lipid component has impacts on stress/strain calculations which are closely related to plaque assessment.

Contribution of the bone and cartilage/soft tissue components of the joint damage to the level of disability in rheumatoid arthritis patients: a longitudinal study.

The study aims to analyze the association between the bone and cartilage/periarticular components of the radiographic joint damage and disability over the course of disease, in a cohort of rheumatoid arthritis (RA) patients from a day-to-day clinical practice. The secondary aim is to study the role of demographic and disease-related variables in this association. We performed a retrospective longitudinal study including 736 RA patients. Disability was assessed with the health assessment questionnaire (HAQ), and radiographic joint damage of hands and wrists with the Sharp van-der-Heijde score (total (SHS), erosion (ES), and narrowing/(sub)luxation (NSLS) components]. Generalized estimating equations models, adjusted by disease activity, demographic and disease-related variables, were used to test the relationship between SHS and medium-term (median value of the HAQs performed in the following year after each radiograph) and long-term (set of HAQ measures performed during follow-up, at least 1year apart from the first x-ray) disability. Interaction terms between the SHS and demographic and disease-related variables were introduced in the models. To account for multiple testing, Bonferroni correction was applied. NSLS was independently associated with medium-term disability, even after Bonferroni correction. We observed significant and positive interactions between NSLS and age at x-ray, and with the ES. SHS showed no association with long-term disability. The cartilage/soft tissue component of the radiographic joint damage seems to exert a much more important role in medium-term disability than the erosive component. This association could be modulated by the age at the x-ray and by the magnitude of the erosive damage.

Erosion-corrosion interactions of X65 carbon steel in aqueous CO2 environments

When sand is present in carbon dioxide (CO2) corrosion environments in carbon steel oil and gas pipelines, wear rates can be particularly severe. The wear mechanism when surfaces are exposed to impact by a solid-laden corrosive fluid is known as erosion-corrosion and consists of erosion and corrosion components with total erosion-corrosion degradation enhanced by interactions between erosion and corrosion. The causes of corrosion-enhanced erosion and erosion-enhanced corrosion of carbon steel, in this regime, are not fully understood and are the subject of study in this work in a 60 °C, pH 4.7, 2% NaCl solution, containing 1000 mg/L of sand particles with an average diameter of 250 µm, flowing through a submerged impinging jet (SIJ) nozzle at 20 m/s. Particle impact angles and velocities were predicted on the SIJ sample surface using computational fluid dynamics (CFD) to improve the understanding of how particle impingement contributes to erosion-enhanced corrosion and corrosion-enhanced erosion. Corrosion-enhanced erosion accounted for up to 20% of total erosion-corrosion degradation, with focused ion beam scanning electron microscopy (FIB-SEM) analysis showing that removal of work hardened layers and subsurface cracking were causes of enhanced degradation. Erosion-enhanced corrosion was not significant in the conditions tested.

Clast abrasion of a rock shore platform on the Atlantic coast of Ireland

AbstractThe abrasion of coastal rock platforms by individual or clusters of clasts during transport has not been quantitatively assessed. We present a study which identifies the types of abrasion and quantifies erosion due to the transport of clasts during three storms in February and March 2016. We explore relationships between platform roughness, determined by the fractal dimension (D) of the topographic profiles, geomorphic controls and the type and frequency of abrasion feature observed. Clast transport experiments were undertaken in conjunction with the measurement of wave energy to assess transport dynamics under summer and winter (non‐storm) conditions.Platform abrasion occurred extensively during the storms. We identify two types of clast abrasion trails: simple and complex. In addition, we find two forms of erosion occur on these trails: Scratch marks and Percussion marks. An estimated 13.6 m2 of the platform surface was eroded by clast abrasion on simple abrasion trails during the three storms. We attribute approximately two thirds of this to scratch‐type abrasion. The total volume of material removed by abrasion was 67 808 cm3. Despite the larger surface area affected by scratch marks, we find that the volume of material removed through percussion impact was almost seven times greater. We also find that the type and frequency of abrasion features is strongly influenced by the effect of platform morphometry on transport mode, with impact‐type abrasion dominating areas of higher platform roughness. Results of the clast transport experiments indicate that abrasion occurs under non‐storm wave energy conditions with observable geomorphological effects. We suggest that abrasion by clasts is an important component of platform erosion on high energy Atlantic coastlines, particularly over longer timescales, and that the morphogenetic link between the cliff and the platform is important in this context as the sediment supplied by the cliff is used to abrade the platform. © 2018 John Wiley &amp; Sons, Ltd.

Erosion at extended continental margins: Insights from new aerogeophysical data in eastern Dronning Maud Land

Modelling-, rock cooling-, sedimentation- and exposure-based interpretations of the mechanisms by which topography evolves at extended continental margins vary widely. Observations from the margin of Dronning Maud Land, Antarctica, have until now not strongly contributed to these interpretations. Here, we present new airborne gravity and radar data describing the eastern part of this margin. Inland of a tall (2.5 km) great escarpment, a plateau topped by a branching network of valleys suggests preservation of a fluvial landscape with SW-directed drainage beneath a cold-based ice sheet. The valley floor slopes show that this landscape was modified during a period of alpine-style glaciation prior to the onset of the current cold-based phase around 34 Ma. The volume of sediments in basins offshore in the Riiser-Larsen Sea balances with the volume of rock estimated to have been eroded and transported by north-directed drainage from between the escarpment and the continental shelf break. The stratigraphy of these basins shows that most of the erosion occurred during the ~40 Myr following late Jurassic continental breakup. This erosion is unlikely to have been dominated by backwearing because the required rate of escarpment retreat to its present location is faster than numerical models of landscape evolution suggest to be possible. We suggest an additional component of erosion by downwearing seawards of a pre-existing inland drainage divide. The eastern termination of the great escarpment and inland plateau is at the West Ragnhild trough, a 300 km long, 15–20 km wide and up to 1.6 km deep subglacial valley hosting the West Ragnhild glacier. Numerous overdeepened (by >300 m) segments of the valley floor testify to its experience of significant glacial erosion. Thick late Jurassic and early Cretaceous sediments fanning out from the trough's mouth into the eastern Riiser-Larsen Sea betray an earlier history as a river valley. The lack of late Jurassic relief-forming processes in this river's catchment in the interior of East Antarctica suggests this erosion was related to regional climatic change.

Effect of land use on interrill erosion in a montane catchment of Northern Laos: An analysis based on a pluri-annual runoff and soil loss database

The introduction of cash crops and the evolution of farming practices in the uplands of Southeast Asia have drastically changed the agricultural landscape of the region during these last decades. This evolution has significantly increased soil erosion leading to important on and off-site effects. A long-term multi-scale monitoring of soil erosion was initiated in the early 2000’s in the Houay Pano catchment located near the city of Luang Prabang in Northern Laos to assess these effects and propose sustainable land management solutions. We report here the analysis and the modelling of the soil erosion measurements made during the whole period on 1m2 plots for different land uses. As expected, land use has an important impact on runoff production and soil erosion. The mean annual runoff coefficient increased from 0.05 for established fallow (4 years) to 0.45 for old teak trees plantation (14 years) with intermediate values for crops. The mean soil loss followed the same trend with respect to land use, from 25g m-2y-1 to 3765g m-2y-1. These measurements confirm that established fallow promotes infiltration and reduces erosion and, at the opposite, teak tree increases soil crusting, lowers the infiltration rate and enhances soil detachment. The splash and wash erosion component of a process-oriented model developed for terrace erosion was used. This model describes the soil loss after a rainfall event as the product of an effective soil detachability, the rainfall kinetic energy, the runoff coefficient and different attenuation factors linked to soil surface features. The agreement is good, both at the event and the yearly scales. When aggregated by land use, surface features percentages have low standard deviations and soil detachability variability may be described by a log-normal distribution. This suggests that each land use has a unique signature in the erosion process given by the percentages and the distribution. We conclude that: (i) leaving the litter layer and an understorey in crops and trees plantations is the best way to minimize soil erosion, and (ii) the splash and wash model may be helpful to set up optimal agronomic strategies for a sustainable land use of Southeast Asia uplands.

The synergistic effect of cavitation erosion and corrosion of nickel-aluminum copper surface layer on nickel-aluminum bronze alloy

A completely nickel-aluminum-copper (Ni-Al-Cu) layer was obtained through thermal diffusion process on a nickel-aluminum-bronze (NAB) substrate. The cumulative mass loss of the NAB alloy during the cavitation erosion tests was about 6.4 times and 5.5 times as large as that of the Ni-Al-Cu layer in distilled water and 3.5 wt% sodium chloride (NaCl), respectively. Electrochemical measurements under quiescence and cavitation erosion conditions were conducted to investigate the synergistic effects of cavitation erosion and corrosion. The results showed that the synergism had measurable effect on the cavitation erosion-corrosion process for both the NAB alloy and the Ni-Al-Cu layer. The total contribution of the cavitation erosion component including WE and WCIE was more than 80% and WE occupied the largest percentage. Thus, the improved cavitation erosion resistance of the Ni-Al-Cu layer was mainly due to mechanical factors, which implied a homogeneous and refined microstructure and the formation of hardened Ni3Al phase.

Erosion Associated with Seismically-Induced Landslides in the Middle Longmen Shan Region, Eastern Tibetan Plateau, China

The 2008 Wenchuan earthquake and associated co-seismic landslide was the most recent expression of the rapid deformation and erosion occurring in the eastern Tibetan Plateau. The erosion associated with co-seismic landslides balances the long-term tectonic uplift in the topographic evolution of the region; however, the quantitative relationship between earthquakes, uplift, and erosion is still unknown. In order to quantitatively distinguish the seismically-induced erosion in the total erosion, here, we quantify the Wenchuan earthquake-induced erosion using the digital elevation model (DEM) differential method and previously-reported landslide volumes. Our results show that the seismically-induced erosion is comparable with the pre-earthquake short-term erosion. The seismically-induced erosion rate contributes ~50% of the total erosion rate, which suggests that the local topographic evolution of the middle Longmen Shan region may be closely related to tectonic events, such as the 2008 Wenchuan earthquake. We propose that seismically-induced erosion is a very important component of the total erosion, particularly in active orogenic regions. Our results demonstrate that the remote sensing technique of differential DEM provides a powerful tool for evaluating the volume of co-seismic landslides produced in intermountain regions by strong earthquakes.

Erosion-corrosion mechanism and comparison of erosion-corrosion performance of API steels

During the transportation of oil and gas, pipes are exposed to flowing corrosive environment which causes erosion-corrosion. The high degradation rates attributed to this mechanism can create increased challenges to project economy and operation where material integrity, accurate erosion-corrosion rate prediction and long term performance are key concerns. Although the problem caused by the interaction of erosion and corrosion is severe, the mechanism of synergy is still not thoroughly understood because of its complexity. This research focuses on understanding the degradation processes of pipeline steels (API X42, API X70 and API X100) in CO2 containing salt water. The application of cyclic erosion-corrosion allowed the individual contribution of erosion and corrosion components of mass loss to be quantified and mechanisms by which erosion affects corrosion and vice-versa to be identified. The present research also compares the erosion-corrosion performance of different API steels.

Erosion-corrosion behaviour of aluminum alloy 6063 hybrid composite

Aluminum alloy 6063 (AA6063) composite with varying proportion of snail-shell-ash (SSA) and silicon carbide (SiC) reinforcement has been developed by stir-casting. Hardness and erosion-corrosion characteristics of the composite were studied. Erosion-corrosion behaviour of the composite was studied in a mono-ethylene glycol (MEG)-water environment with 20% v/v of ethylene glycol and 0.1g/L silica sand particles using a re-designed miniature submerged impinging jet rig. SEM-EDX of the as-cast composites showed the presence of the particulates distributed in the matrix. The hardness of the aluminum alloy was enhanced up to a maximum value (with the addition of 7.5wt % SiC+7.5wt % SSA). However, hardness values declined when (10wt % SSA+10wt % SiC) was used as reinforcing phase. Erosion-corrosion studies showed that erosion component dominates the total material loss and the composite with highest hardness displaying better erosion-corrosion resistance. Also, addition of MEG to the slurry resulted in lower erosion-enhance corrosion and total material loss due to erosion-corrosion. SEM images of the damaged composite showed that the damage mechanism is dominated by ploughing and indentation.

Синдром Пейтца–Егерса как причина железодефицитной анемии у ребенка 5 лет: диагностическое значение видеокапсульной энтероскопии

This clinical case demonstrates the diagnostic value of capsule endoscopy for the detection of polyposis of gastro-intestinal tract (Peutz–Jeghers syndrome). We report the case of a 5-year-old male presenting with a chronic iron refractory iron deficiency anemia. Multiple polyps of the stomach and small intestine with an erosive and hemorrhagic component were identified by the method of capsule endoscopy.

The Directional Components of Splash Erosion at Different Raindrop Kinetic Energy in the Chinese Mollisol Region

Core Ideas Directional components of splash erosion and effects of raindrop kinetic energy were investigated. Lateral splash erosion played a significant role in supplying detached particles to adjacent areas. We fit equations for total and net splash erosion to rainfall physical parameters. We used cross‐validation to test the equations. Splash erosion is an important process of hillslope erosion. However, there is little information available in the literature to show how rainfall physical parameters affect the directional components of splash erosion. Therefore, the objectives of this study were to investigate the effects of rainfall physical parameters (rainfall intensity [RI], raindrop kinetic energy [KE], and raindrop diameter) on the directional components (upslope, lateral, downslope) of splash erosion characteristics in the Chinese Mollisol region. A specially designed soil pan, which can measure the directional components of splash erosion, was subjected to designed rainfall intensities of 50 and 100 mm h−1 and varying raindrop KE. The results showed that the total splash erosion (downslope plus upslope plus lateral splash erosion), directional components of splash erosion, and net splash erosion (downslope minus upslope erosion) on hillslopes significantly increased as RI and raindrop KE increased (p &lt; 0.05). Furthermore, splash erosion from downslope, lateral slope, and upslope contributed 32.2, 26.3, and 14.5%, respectively, of total splash erosion. Additionally, raindrop KE and raindrop median volume diameter (D50) were the key indicators affecting both total and net splash erosion. The equations between total and net splash erosion with both parameters of raindrop KE and raindrop D50 were fitted. The cross validation results showed that the two equations had acceptable accuracy. Therefore, preventing raindrop impact by using conservation tillage methods, such as retaining crop residue or mulch cover, can effectively reduce splash erosion in the Mollisol region of Northeast China.

Evaluation of Sediment Deposition in a Mediterranean Reservoir: Comparison of Long Term Bathymetric Measurements and SWAT Estimations

AbstractThis study aims to demonstrate that the SWAT model can be used to predict discharge and sediment yield values in reservoir contributing catchments helping also to define the main factors that determine sedimentation rates in semi‐arid Mediterranean environments. This aim was achieved by comparing SWAT simulation results with water flows (over 29 years) and sediment deposition (over 47 years) volumes collected (by a campaign of bathymetric surveys) in a Sicilian reservoir. The mean monthly runoff coefficient calculated for the period 1980–2008 was 0·17. The mean sedimentation volume in the reservoir during the period 1963–2009 was 51,000 m3 year−1. Field surveys and collection of spatially distributed databases of soil, topography and climate were carried out in order to characterize the contributing catchment. The SWAT model was applied to simulate sediment volumes cumulated over group of years as well as water flow volumes reaching annual and monthly the reservoir. The performance of the hydrological and erosion components of the model was evaluated by a combination of both summary and difference statistical measures after a sensitivity analysis and a calibration/validation process. The model was able to simulate observed runoff volumes at both annual and monthly scale. The mean sedimentation volume simulated by SWAT during the whole period was 8·1% lower than the value obtained by the bathymetric measurements (equal to 72·103 Mg) with very good values of the efficiency coefficient (equal to 0·91). Copyright © 2016 John Wiley &amp; Sons, Ltd.

Effects of subsequent rainfall events on runoff and soil erosion components from small plots treated by vinasse

Soil erosion control is the most essential principle for the sound utilization of soil and water. The application of soil amendments is considered as an appropriate and new strategy for soil erosion control. Despite the application of different amendments used for soil and water conservation, the durability of the effects of soil amendments during subsequent rainfalls has not been considered yet. The present study, therefore, aimed to analyze the effect of vinasse application as one of the important wastes of cane agro-industries on runoff and soil erosion components during subsequent rainfalls for a sandy clay loam soil sampled from the Alborz summer rangeland. The study was conducted under laboratory conditions using a field rainfall simulator and three small plots with a 20% slope in three replicates. The duration and intensities of rainfall were respectively designated as 15min for 50 and 90mmh−1 to one initial and four subsequent rainfalls. Experiments were then set up as a control and two treated plots with doses of 4.5 and 8lm−2 of vinasse subjected to one initial and four subsequent rainfalls, respectively. The results of the study indicated that the application of the different amounts of vinasse had negative effects on the runoff commencement time, coefficient, and volume during the subsequent rainfall with an intensity of 50mmh−1. While the application of both levels of vinasse decreased soil loss and sediment concentration and had negative effects on the runoff components during the subsequent rainfall with the intensity of 90mmh−1. A high dose of vinasse decreased soil loss and sediment concentration, whereas a low dose of vinasse increased soil loss and sediment concentration. Overall, the high level of vinasse controlled hydrologic parameters better than the low level of vinasse during subsequent rainfall with different intensities. The results also revealed a significant effect of rainfall sequence on runoff commencement time, runoff volume, runoff coefficient, and soil loss (P<0.01), and a non-significant effect (P=0.13) on sediment concentration. On the other hand, rainfall sequence increased runoff volume and soil loss, which pointed to the need of the reapplication of vinasse soil amendment after a few rainfall events for efficient soil and water conservation.

THE MAIN REGULARITIES OF THE RATIO BETWEEN RIVERBED AND BASIN COMPONENTS OF EROSION AND SUSPENDED SEDIMENT FLUX IN THE NORTHERN EURASIA’S RIVER BASINS

Suspended sediment flux is one of the objective and sufficiently accurate measures of the erosion activity in basins. Using the database for mean monthly values of water and suspended sediments runoff created for 460 rivers of the territory of the former USSR, the ratio of channel and basin components of erosion was analyzed. For this purpose the author proposed the special hydrological method (published early). For all analyzed river basins the share of riverbed erosion (δr) calculated by suspended sediment fluxes doesn’t exceed 15%. It amounts to 10.4±1.5% for the plain (lowland) rivers, to 4.9±0.9% for the low-altitude mountain rivers, and to 4.0±0.8% for the middle-altitude mountain rivers. The average δr for the whole Northern Eurasia is 7.2±0.8%. The ratio of channel and basin (δb) components depends distinctly on the landscape-climatic conditions, especially on latitudinal zoning. Thus, within the plains of Northern Eurasia the biggest δr occurs in the zones of tundra, taiga and mixed forests – more than 15–16% (15.0±9.6% in the tundra zone, 16.6±3.1% in the zone of taiga and mixed forests). In arid zones this value on the average does not exceed 5% (4.5±1.3 % in the steppes, 0.8% in the semi-deserts). Intermediate areas have a share of channel products of 5 to 10% (8.9±2.0% in the zone of broad-leaf forests, 5.2±1.6% in the forest-steppe zone). The same trend is observed in the low mountains but less distinctly than in the plains. There is a hyperbolic relationship between a total suspended sediment flux and its riverbed component. This dependence is clearly pronounced in the plains of the Northern Eurasia, but diminishes with increasing elevation of river basins. It’s shown also that the lithological factor (surface rocks’ composition) doesn’t play a significant role in the spatial variability of the δb/δr ratio.

Soil losses due to potato harvesting: a case study in western Turkey

AbstractHarvesting of potato (Solanum tuberosum L.) may cause soil losses, but the magnitude of such losses has not been widely documented. We quantified the amount of soil lost with the mechanical harvesting of potatoes in 39 fields in western Turkey in 2013. The amount of soil lost was 1.81 Mg/ha/harvest and increased with increased gravimetric water content and plant density. The cost to replace nutrients lost with soil was about US$3 per hectare. Overall, soil loss due to potato harvesting is an important component of total erosion in the study region.

Mechanical and Electrochemical Synergism of API X42 Pipeline Steel During Erosion–Corrosion

Hydro-transportation is an economic and flexible way to transport natural resources such as oil and gas from excavation to the extraction plants, refineries, and consumer-ready products to markets. However, interaction between solid particles, corrosive fluid, and target material often results in significant mutual reinforcement due to the combined action of erosion and corrosion. In this study, erosion–corrosion behavior of API pipeline steel has been assessed in 2 g l−1 NaCl solution purged with CO2 as the corrosive media and aluminum oxide as the erodent. Four different particle velocities (36, 47, 63, and 81 m s−1) were employed, while the angle of incidence was kept constant at 90°. The synergism between erosion and corrosion has been studied by means of a newly designed test approach to mitigate the limitations of the in situ method and to identify the effect of erosion on corrosion and vice versa. The corrosion process was monitored using potentiodynamic polarization and weight loss measurements. Total material loss rate and the components of erosion, corrosion, and their synergistic interactions have been determined. Scanning electron microscopy examination and experimental results show that there is an immense correlation between erosion and corrosion. Significant synergism was observed due to the interaction of different erosion and corrosion mechanisms.