Differences In Erosion Rates Research Articles

Effects of grain size, mineralogy, and acid-extractable grain coatings on the distribution of the fallout radionuclides 7Be, 10Be, 137Cs, and 210Pb in river sediment

Grain-size dependencies in fallout radionuclide activity have been attributed to either increase in specific surface area in finer grain sizes or differing mineralogical abundances in different grain sizes. Here, we consider a third possibility, that the concentration and composition of grain coatings, where fallout radionuclides reside, controls their activity in fluvial sediment. We evaluated these three possible explanations in two experiments: (1) we examined the effect of sediment grain size, mineralogy, and composition of the acid-extractable materials on the distribution of 7Be, 10Be, 137Cs, and unsupported 210Pb in detrital sediment samples collected from rivers in China and the United States, and (2) we periodically monitored 7Be, 137Cs, and 210Pb retention in samples of known composition exposed to natural fallout in Ohio, USA for 294days.Acid-extractable materials (made up predominately of Fe, Mn, Al, and Ca from secondary minerals and grain coatings produced during pedogenesis) are positively related to the abundance of fallout radionuclides in our sediment samples. Grain-size dependency of fallout radionuclide concentrations was significant in detrital sediment samples, but not in samples exposed to fallout under controlled conditions. Mineralogy had a large effect on 7Be and 210Pb retention in samples exposed to fallout, suggesting that sieving sediments to a single grain size or using specific surface area-based correction terms may not completely control for preferential distribution of these nuclides.We conclude that time-dependent geochemical, pedogenic, and sedimentary processes together result in the observed differences in nuclide distribution between different grain sizes and substrate compositions. These findings likely explain variability of measured nuclide activities in river networks that exceeds the variability introduced by analytical techniques as well as spatial and temporal differences in erosion rates and processes. In short, we suggest that presence and amount of pedogenic grain coatings is more important than either specific surface area or surface charge in setting the distribution of fallout radionuclides.

Rates of erosion and landscape change along the Blue Ridge escarpment, southern Appalachian Mountains, estimated from in situ cosmogenic 10Be

AbstractThe Blue Ridge escarpment, located within the southern Appalachian Mountains of Virginia and North Carolina, forms a distinct, steep boundary between the lower‐elevation Piedmont and higher‐elevation Blue Ridge physiographic provinces. To understand better the rate at which this landform and the adjacent landscape are changing, we measured cosmogenic beryllium‐10 (10Be) in quartz separated from sediment samples (n = 50) collected in 32 streams and from three exposed bedrock outcrops along four transects normal to the escarpment, allowing us to calculate erosion rates integrated over 104–105 years. These basin‐averaged erosion rates (5.4–49 m Myr−1) are consistent with those measured elsewhere in the southern Appalachain Mountains and show a positive relationship between erosion rate and average basin slope. Erosion rates show no relationship with basin size or relative position of the Brevard fault zone, a fundamental structural element of the region. The cosmogenic isotopic data, when considered along with the distribution of average basin slopes in each physiographic province, suggest that the escarpment is eroding on average more rapidly than the Blue Ridge uplands, which are eroding more rapidly than the Piedmont lowlands. This difference in erosion rates by geomorphic setting suggests that the elevation difference between the uplands and lowlands adjacent to the escarpment is being reduced but at extremely slow rates. Copyright © 2016 John Wiley & Sons, Ltd.

Management of stress urinary incontinence

Female stress urinary incontinence (SUI) is a common condition with significant impact on a woman’s quality of life. The prevalence of SUI is about 50%. Previously, the majority of incontinence procedures were performed via an abdominal approach (Burch colposuspension). The tension-free procedures, with a synthetic tape material, have replaced almost completely the previous surgeries and is nowadays considered the gold standard option for surgical treatment of female SUI. A wide spectrum of tape-based surgical procedures and devices are currently available. Today, Burch colposuspension has a role in patients undergoing abdominal pelvic organ prolapse (POP) repair as a concomitant procedure in those patients with urethral hypermobility or those with contraindication to mid-urethral slings (MUS) placement. The objective success rate reported of this procedure ranges between 49% and 88%. Mid-urethral synthetic slings represent the most common procedures for SUI in North America and Europe. Cure rate of retropubic MUS approaches 86% with a satisfaction rate of about 75%. For transobturator tape MUS the objective success rate at 12 months is 87% and the satisfaction rate is 85%. Single incision mini-slings (SIMS) were introduced in 2003 and they have a different anchoring mechanism, located at the two extremities, that allows the stabilization of the tape in the obturator internal muscle or deeper in the obturator channel trough a single vaginal incision. Reported objective cure rate is 78% and satisfaction rate is 82%. According to the most recent EAU guidelines about incontinence and the UK National Institute for Healthcare and Clinical Excellence (NICE), the surgeon must be able to offer alternative surgical treatments and have the knowledge of efficacy and safety of these approaches at counseling of the patient. The objective cure rate is rather similar among the different types and routs of mid-urethral slings and the difference vs. Burch colposuspension seems to disappear at 5 years follow-up, when effectiveness is comparable. There is no significant difference in erosion rates between transobturator and retropubic approaches among mid-urethral tapes, but they are lower when compared to SIMS. The injury rate of nearby organs is quite low for all types of approaches, except for retropubic slings.

A 13‐year record of erosion on badland sites in the Karoo, South Africa

AbstractLand degradation in South Africa has been of concern for more than 100 years with both climate change and inappropriate land management (overgrazing) being proposed as primary drivers. However, there are few quantitative studies of degradation and, in particular, few of erosion by water. Badlands, taken here to be the landform which results from extreme erosion, have been notably neglected. We report on 13 consecutive years of erosion pin measurements of badland erosion on 10 study sites in the Sneeuberg uplands of the eastern Karoo in South Africa. The study sites are on Holocene colluvium which mantles footslopes. They have been subject to overgrazing for at least 100 years, c. 1850–1950. Currently they are lightly grazed by sheep. The area receives about 500 mm rainfall per year. The sites are remote, with only informal, farmer‐operated, daily raingauges nearby. The nearest sub‐daily raingauge is c. 55 km distant. Also we report on an analysis of the erosion pin data which focuses on establishing the origins and context of the badlands, including the relationship between study sites and adjacent valley‐bottom gully systems; compare erosion rates on our study sites with rates determined by erosion pins on other badland sites; and discuss the implications of these erosion rates for landscape development and off‐site impacts. Net erosion rates on the study sites are relatively high compared with global badland rates and range from 3.1 to 8.5 mm yr‐1 which may be extrapolated to 53 to 145 t ha yr‐1 (using a measured bulk density of 1.7 g cm‐3). However, comparisons with badland sites elsewhere are difficult because of different measuring methodologies, lithologies, climate and dominant processes. Erosion rates on the study sites are strongly influenced by rainfall amounts and, in particular, by daily rainfall events which exceed ~10 mm: this is the threshold intensity at which runoff has been observed to commence on badlands. Of significance, but of lesser influence, is weathering, mainly by wetting and drying: this prepares bare surfaces for erosion. However, questions remain regarding the role of site characteristics, and of processes at each site, in determining between‐site differences in erosion rate. Crude extrapolation of current rates of erosion, in conjunction with depths of incision into the badlands, suggests that badland development started around 200 years ago, probably as a response to the introduction of European‐style stock farming which resulted in overgrazing. We assume, but cannot quantify, the additional influence of periods of drought and burning in the erosional history of the area. Intermittent connection of these badlands to valley‐bottom gullies and therefore to small farm dams and ultimately to large water storage reservoirs increases their impact on local water resources. Copyright © 2015 John Wiley & Sons, Ltd.

The influence of crustal strength fields on the patterns and rates of fluvial incision

AbstractGradients in the bedrock strength field are increasingly recognized as integral to the rates and patterns of landscape evolution. To explore this influence, we incorporate data from fault strength profiles into a landscape evolution model, under the assumption that erodibility of rock is proportional to the inverse square root of cohesion for bedrock rivers incised by bedload abrasion. Our model calculations illustrate how patterns in the crustal strength field can play a dominant role in local fluvial erosion rates and consequently the development of fluvial network patterns. Fluvial incision within weak zones can be orders of magnitude faster than that for resistant bedrock. The large difference in erosion rate leads to the formation of a straight, high‐order channel with short, orthogonal tributaries of low order. In comparison, channels incising into homogeneous strength fields produce dendritic drainage patterns with no directional dependence associated with erodibility gradients. Channels that cross the strength gradient experience local variations in knickpoint migration rate and the development of stationary knickpoints. Structurally confined channels can shift laterally if they incise into weak zones with a shallow dip angle, and this effect is strongly dependent on the magnitude of the strength difference, the dip angle, and the symmetry and thickness of the weak zone. The influence of the strength field on drainage network patterns becomes less apparent for erodibility gradients that approach homogeneity. There are multiple natural examples with drainage network patterns similar to those seen in our numerical experiments.

Investigations with a field wind tunnel to estimate the wind erosion risk of row crops

Soil protection against wind erosion on arable land has mostly been investigated in the field with plant residues – as practiced in reduced and no-tillage systems or in wind tunnels with artificial roughness elements. Results from growing plants, such as row crops in conventional tillage systems, are rare, despite these fields being the most affected by wind erosion. Wind tunnel investigations were carried out at the field scale on an Arenic Gleysol with sugar beet (Beta vulgaris) and maize (Zea mays). These crops were chosen because they are the preferred row crops in Germany, and are cultivated predominantly in conventional tillage systems, and represent examples of mono- and dicotyledonous plants. The influence of the plants on wind erosion was calculated as the ratio between the measured soil flux of a plot covered by plants and the soil flux of the same plot without plants (soil flux ratio, RQ). This ratio was then tested for correlation with vegetative soil cover, silhouette area or dry mass, and row orientation. As a new approach, an empirical vegetation parameter was introduced into a sand transport equation of the form q= A(u*−u*t) u*2, which was used to compare the measured with the modeled soil fluxes.The results demonstrate the high susceptibility of row crops in conventional tillage systems to wind erosion. The results also show significant differences in erosion rates between mono- and dicotyledonous plants. The row orientation only has influence in the case of sugar beet. To describe the reductive effects of vegetation on the soil fluxes over a wide range of wind velocities, an empirical soil cover parameter can be integrated into a sand transport equation.

Influence of suspended mussel lines on sediment erosion and resuspension in Lagune de la Grande Entrée, Îles-de-la-Madeleine, Québec, Canada

Downward fluxes of organically rich biodeposits under suspended mussel lines can cause benthic impacts such as changes in benthic community structure or microbial mat production. Quantifying sediment erosion in these coastal ecosystems is important for understanding how fluxes of organic matter and mussel biodeposits contribute to benthic–pelagic coupling. Critical shear velocity (u*crit), erosion rates and particle size distributions of resuspended sediment were measured at four stations distributed along a transect perpendicular to a mussel farm in Lagune de la Grande Entree, Iles-de-la-Madeleine (Quebec, Canada). Stations were selected underneath the outer-most mussel line (0 m) and at distances of 15, 30 m and at a reference station (500 m) further along the transect. Shear velocity was measured using a calibrated portable Particle Erosion Simulator, also referred to as the BEAST (Benthic Environmental Assessment Sediment Tool). Undisturbed sediment cores obtained by divers were exposed to shear stress to compare differences between stations. Erosion sequences indicated no significant differences in u*crit between stations, but there were significant differences in erosion rates beneath mussel lines compared to other stations. Erosion rates were the highest in cores from beneath mussel lines, but paradoxically had the lowest u*crit. Mean erosion rates at u*crit varied between 25 and 47 g m− 2 min− 1 and critical erosion thresholds varied between 1.58 and 1.73 cm s− 1, which compare with intensive mussel culture sites elsewhere in eastern Canada. Significant differences existed in biotic and abiotic properties of sediments which could explain variation in maximum erosion rates within and between stations. Particle sizes measured by videography of resuspended sediment at different shear velocities ranged from 0.2 to 3.0 mm. Quantifying sediment erosion from intact marine sediments helps to improve our mechanistic understanding of these processes, and the BEAST further contributes to predictive capability in benthic–pelagic coupling modeling.

Identification et évaluation du risque d’érosion sur le bassin versant du K’sob (Est Algérien)

The estimated of soil losses by erosion in semi-arid regions is often difficult due to the complex interaction of many factors such as climate, geology, land use, topography and human activities. RUSLE, Gravilovic and ICONA models are used to evaluate soil losses and characterize degraded areas in the K’sob watershed (1,482 km2), located north eastern Algeria, in order to implement management intervention. The results show that 90 % of the basin surface is subject to low to moderate risk erosion and only 10 % is vulnerable to erosion with sediment loss estimated at 4.6 t ha−1 year−1. Areas with excessive risk of gully and sheet erosion cover respectively 10 and 1 % of the basin and zones suffering the combined effects of these two processes would total more than 3 % of the basin. Finally, the sites subject to potential landslide cover just over 0.3 km2. The K’sob dam’s reservoir is surrounded by potentially sides degraded by sheet erosion and gully. However, larger areas degraded by these processes are located near urban areas as Rabta, Bordj Ghdir and K’sour. Spatial differences in erosion rates in the K’sob watershed are mainly caused by differences in the type of land cover and slope gradient. RUSLE, Gravilovic and ICONA models provide a useful tool for identifying soil erosion and can be successfully used for prioritization of vulnerable areas in semi-arid watersheds.

Bedrock composition regulates mountain ecosystems and landscape evolution

Earth's land surface teems with life. Although the distribution of ecosystems is largely explained by temperature and precipitation, vegetation can vary markedly with little variation in climate. Here we explore the role of bedrock in governing the distribution of forest cover across the Sierra Nevada Batholith, California. Our sites span a narrow range of elevations and thus a narrow range in climate. However, land cover varies from Giant Sequoia (Sequoiadendron giganteum), the largest trees on Earth, to vegetation-free swaths that are visible from space. Meanwhile, underlying bedrock spans nearly the entire compositional range of granitic bedrock in the western North American cordillera. We explored connections between lithology and vegetation using measurements of bedrock geochemistry and forest productivity. Tree-canopy cover, a proxy for forest productivity, varies by more than an order of magnitude across our sites, changing abruptly at mapped contacts between plutons and correlating with bedrock concentrations of major and minor elements, including the plant-essential nutrient phosphorus. Nutrient-poor areas that lack vegetation and soil are eroding more than two times slower on average than surrounding, more nutrient-rich, soil-mantled bedrock. This suggests that bedrock geochemistry can influence landscape evolution through an intrinsic limitation on primary productivity. Our results are consistent with widespread bottom-up lithologic control on the distribution and diversity of vegetation in mountainous terrain.

Factors and processes of permanent gully evolution in a Mediterranean marly environment (Cape Bon, Tunisia)

Gully erosion is considered to be one of the most important soil erosion processes in Mediterranean marly environments, but its actual contribution to total soil loss is still under discussion. The objectives of this paper are: (a) to acquire the distributed value of erosion rate in a permanent gully developed on a marly substratum in a Mediterranean environment; and (b) to quantify the key factors responsible for the spatial and temporal differences in erosion rates observed within the gully. A permanent gully located in Cap Bon (northeastern Tunisia) has been intensively and regularly monitored over a 7-year period with electronic survey equipment (total station) to give five field topographic surveys, as well as hydrological measurements at the gully outlet. The net soil loss for the 7-year period comprised a denudation of 51 m3 of sediment on the gully bank slopes, which corresponds to a mean soil loss of 61 m3 ha−1 year−1 or 6.1 mm year−1. Denudation was observed on bed units with a slope gradient greater than 20%, while the remainder showed deposition. By confirming the factors involved in gully evolution, and by refining the statistical link between factors and erosion rates within the gully, the results provide important information to predict gully erosion rates in Mediterranean marly environments.Editor Z.W. Kundzewicz; Associate editor G. MahéCitation El Khalili, A., Raclot, D., Habaieb, H., and Lamachère, J.M., 2013. Factors and processes of permanent gully evolution in a Mediterranean marly environment (Cape Bon, Tunisia). Hydrological Sciences Journal, 58 (7), 1519–1531.

The morphology and evolution of channels on the Wax Lake Delta, Louisiana, USA

AbstractRiver deltas are classic depositional systems, but a growing body of literature shows that their channel networks can be erosional. Furthermore, this erosion can attack channel beds of consolidated mud that acts as bedrock. To better understand the channel networks of natural deltas and engineered river diversions, we investigate bathymetric and planimetric change, bed cover, and sediment transport in the Wax Lake Delta (WLD) in coastal Louisiana, USA. Channels have eroded up to 40% of modern flow depth between the WLD's initiation in 1973 and 1999. Aerial image analysis shows that channels have widened by 11% between 1991 and 2009, forcing the downstream migration of islands. Channel beds are composed of 85–98% muddy bedrock, with the remainder covered by alluvial sands. Water velocity, grain size, and suspended sand concentration measurements during the 2009 spring flood show that almost all available grain sizes are transported in suspension. Flow was supply limited during this period, with the calculated sand concentration at the height of the bed load layer is 1–4 orders of magnitude smaller than predicted for saturated sand transport. We test “the cover effect” and “the tools effect” previously proposed for bedrock erosion in upland river channels. Bedrock erosion and alluvial cover are anti‐correlated (the cover effect), but the observations do not closely follow previously proposed relationships. The difference in erosion rate between clear water and sand‐rich water shows that abrasion by sand (the tools effect) accounts for 51% ± 56% of bedrock erosion when it is present.

Assessment of soil erosion risk using SWAT model

Soil erosion is one of the most serious land degradation problems and the primary environmental issue in Mediterranean regions. Estimation of soil erosion loss in these regions is often difficult due to the complex interplay of many factors such as climate, land uses, topography, and human activities. The purpose of this study is to apply the Soil and Water Assessment Tool (SWAT) model to predict surface runoff generation patterns and soil erosion hazard and to prioritize most degraded sub-catchment in order to adopt the appropriate management intervention. The study area is the Sarrath river catchment (1,491 km2), north of Tunisia. Based on the estimated soil loss rates, the catchment was divided into four priority categories for conservation intervention. Results showed that a larger part of the watershed (90 %) fell under low and moderate soil erosion risk and only 10 % of the watershed was vulnerable to soil erosion with an estimated sediment loss exceeding 10 t ha−1 year−1. Results indicated that spatial differences in erosion rates within the Sarrath catchment are mainly caused by differences in land cover type and gradient slope. Application of the SWAT model demonstrated that the model provides a useful tool to predict surface runoff and soil erosion hazard and can successfully be used for prioritization of vulnerable areas over semi-arid catchments.

Chromite vs. magnetite as an erodent for coatings to be applied in steam turbines

Erosion of steam turbine components by magnetite, generated in the boiler and superheater tubes, can become an issue that affects the aerodynamics of the steam turbine and hence its efficiency. The use of coatings to protect the turbines from impact damage is gaining ground, which has prompted laboratory scale testing to help down select coatings for in-situ testing.This paper examines the pros and cons of using magnetite and chromite as erodents at room temperature. Although there was very little difference between the erosion rates of the uncoated NiCr alloy when eroded with the two different erodents, the coatings exhibited a large difference in erosion rates.

Erosion rates and erosion patterns of Neogene to Quaternary stratovolcanoes in the Western Cordillera of the Central Andes: An SRTM DEM based analysis

Erosion patterns and rates of 33 stratovolcanoes in the arid to hyperarid Central Andean Volcanic Zone (14°S to 27°S) have been constrained by morphometric modelling. All selected volcanoes belong to the short-lived, symmetrical, circular andesitic stratocone type, with ages spanning 14 Ma to recent. Starting from the initial, youthful volcano morphology of this type, represented in our study by Parinacota volcano, and comparing reconstructed volumes of progressively eroded volcanoes, such a time span allows us to infer long-term erosion rates. Typical erosion rates of < 10 to 20 m/Ma have been obtained for the Altiplano–Puna Plateau. Lowest erosion rates typify the hyperarid Puna plateau (7–9 m/Ma), while somewhat higher values (13–22 m/Ma) are recorded for volcanoes in the more humid South Peru, suggesting climatic control on differences in erosion rates. By contrast, much higher short-term erosion rates of 112 to 66 m/Ma, decreasing with age, are found for young (Late Quaternary) volcanoes, which indicates that juvenile volcanoes erode more rapidly due to their unconsolidated cover and steeper slopes; surface denudation slows down to approximately one tenth of this after a few Ma. An inverse correlation is observed between the degree of denudation (defined as volume removed by erosion/original volume) and edifice height from base to top after erosion. This relationship is independent of climate and original edifice elevation. The degree of denudation vs. volcano age provides a rough morphometric tool to constrain the time elapsed since the extinction of volcanic activity. This method can, however, only be applied to the volcanoes of the Altiplano (i.e. under uniform, long-term arid climate) with an uncertainty of ~ 1 Ma. Finally, an erosional pathway is suggested for volcanoes of the Altiplano–Puna preserving a peculiar “edelweiss” valley pattern related to glaciations. This pattern may have overprinted previous drainages and resulted in a discontinuous height reduction of the degrading stratovolcanoes.

Soil carbon and material fluxes across the eroding Alaska Beaufort Sea coastline

[1] Carbon, nitrogen, and material fluxes were quantified at 48 sampling locations along the 1957 km coastline of the Beaufort Sea, Alaska. Landform characteristics, soil stratigraphy, cryogenic features, and ice contents were determined for each site. Erosion rates for the sites were quantified using satellite images and aerial photos, and the rates averaged across the coastline increased from 0.6 m yr−1 during circa 1950–1980 to 1.2 m yr−1 during circa 1980–2000. Soils were highly cryoturbated, and organic carbon (OC) stores ranged from 13 to 162 kg OC m−2 in banks above sea level and averaged 63 kg OC m−2 over the entire coastline. Long-term (1950–2000) annual lateral fluxes due to erosion were estimated at −153 Gg OC, −7762 Mg total nitrogen, −2106 Tg solids, and −2762 Tg water. Total land area loss along the Alaska Beaufort Sea coastline was estimated at 203 ha yr−1. We found coastal erosion rates, bank heights, soil properties, and material stores and fluxes to be extremely variable among sampling sites. In comparing two classification systems used to classifying coastline types from an oceanographic, coastal morphology perspective and geomorphic units from a terrestrial, soils perspective, we found both systems were effective at differentiating significant differences among classes for most material stores, but the coastline classification did not find significant differences in erosion rates because it lacked differentiation of soil texture.

Timescale dependence of glacial erosion rates: A case study of Marinelli Glacier, Cordillera Darwin, southern Patagonia

[1] Erosion rates have been estimated for a number of glaciated basins around the world, mostly based on modern observations (last few decades) of sediment fluxes to fjords. We use time-constrained sediment volumes delivered by Marinelli Glacier (55°S), an outlet glacier of the Cordillera Darwin ice cap, southern Patagonian Andes, Tierra del Fuego, to determine erosion rates across different timescales. Sediment volumes are derived using a dense grid of high- and low-frequency single channel seismic data and swath bathymetry data along with piston and Kasten cores. Our results show dramatic differences in erosion rates over different timescales. Erosion rates at Marinelli Glacier diminish about 80% (or by factor of ∼5) with each ten-fold increase in the time span over which erosion rates are averaged: 29.3 mm/yr for the last 45 years, 5.3 mm/yr for the last 364 years, and 0.5 mm/yr for the last 12,500 years. These results indicate that modern sediment yields and erosion rates from temperate tidewater glaciers can exceed long-term values over the time of deglaciation after the Last Glacial Maximum (centennial and millennial timescales) by up to 2 orders of magnitude. In view of the low exhumation rates of Cordillera Darwin (∼0.07 mm/yr average for the last 30 Myr), modern erosion rates could be up to 3 orders of magnitude higher than rates over geological time. We conclude that the pattern of erosion rate variation with time reflects the sensitivity of glaciers to climate variability.

Rates and spatial variations of soil erosion in Europe: A study based on erosion plot data

An extensive database of short to medium-term erosion rates as measured on erosion plots in Europe under natural rainfall was compiled from the literature. Statistical analysis confirmed the dominant influence of land use and cover on soil erosion rates. Sheet and rill erosion rates are highest on bare soil; vineyards show the second highest soil losses, followed by other arable lands (spring crops, orchards and winter crops). A land with a permanent vegetation cover (shrubs, grassland and forest) is characterised by soil losses which are generally more than an order of magnitude lower than those on arable land. Disturbance of permanent vegetation by fire leads to momentarily higher erosion rates but rates are still lower than those measured on arable land. We also noticed important regional differences in erosion rates. Erosion rates are generally much lower in the Mediterranean as compared to other areas in Europe; this is mainly attributed to the high soil stoniness in the Mediterranean. Measured erosion rates on arable and bare land were related to topography (slope steepness and length) and soil texture, while this was not the case for plots with a permanent land cover. We attribute this to a fundamental difference in runoff generation and sediment transfer according to land cover types. On the basis of these results we calculated mean sheet and rill erosion rates for the European area covered by the CORINE database: estimated rill and interrill erosion rates are ca. 1.2 t ha − 1 year − 1 for the whole CORINE area and ca. 3.6 t ha − 1 year − 1 for arable land. These estimates are much lower than some earlier estimates which were based on the erroneous extrapolation of small datasets. High erosion rates occur in areas dominated by vineyards, the hilly loess areas in West and Central Europe and the agricultural areas located in the piedmont areas of the major European mountain ranges.

The solid particle erosion behaviour of dental enamel using a novel air abrasion system

The erosion rate of the enamel of human premolars, molars and canines was measured at various angles of attack using a dental air abrasion unit equipped with a novel particle containment system consisting of a conical water spray surrounding the central air/particle jet. This water curtain minimised the amount of airborne abrasive particles and erosion debris. No statistically significant difference in erosion rate was found between samples blasted with or without the particle containment system. The dental enamel was found to behave in a brittle erosive manner, exhibiting a maximum in erosion rate with the abrasive jet oriented perpendicular to the surface. The observed dependency of erosion rate on the type of tooth could be explained on the basis of differing hardness. Artificial dental block samples showed significantly lower erosion rates compared to human dental enamel, implying that they are not suitable for simulating the solid particle erosion behaviour of teeth.

Experimental research on the influence of two cultivation practices on rainfall runoff-and (sandy and muddy) sediment-generating processes in purple soil environment

Rainfall simulations have been conducted to study the soil erosion process of purple soil in two cultivation practices—contour cultivation and downslope cultivation. Results showed that under the two cultivation practices, the surface runoff can be described by the logarithmic function formula. In the initial period of rainfall, the amount of runoff increased with the rainfall duration and 20 minutes later it became relatively constant. The changing process of soil erosion rate may be described by the logarithmic function formula. The erosion rate increased with the rainfall duration and 20 minutes later it also became constant. Under downslope cultivation condition, the soil erosion rate increased more significantly than that under contour cultivation condition in the case of gentle rainfall intensity, and there is no obvious difference in erosion rate for downslope cultivation and contour cultivation practices. However, with increasing rainfall intensity the soil erosion rate under the downslope cultivation condition could be more than 30 times that under the contour cultivation condition. But this kind of difference would be reduced to some extent in the case of heavy rain.

The relationship between landform and the distribution of soil C, N and P under conventional and minimum tillage

The objective of this study was to examine the interactive effects of tillage and land forms (erodibility) on the redistribution of C, N and P within an agricultural landscape. Soils were sampled from an undulating maize field in central Belgium. Half of the field was under conventional tillage (CT), while the rest was under minimum tillage (MT) management. Based on slope and curvature characteristics, depositional and erodible zones were identified in both tillage treatments. We analyzed 400 surface (0–5 cm) soil samples, and 25 soil profiles (0–100 cm). Concentrations of native C, maize-derived C, total N, Olsen P, and moisture content in the 0–5 cm soil layer showed distinct spatial patterns with variogram ranges from 30 to 90 m. These patterns were related to local differences in texture and landform. In general, nutrient concentrations were greater in lower, depositional areas, and smaller in higher, erodible areas. In addition, the impact of landform was more pronounced in CT than MT. Three years after the implementation of the tillage treatments, native C, total N and Olsen P stocks (0–46 cm) in erodible zones were about 40% less under CT than under MT. However, in depositional zones, nutrient stocks were equal between the tillage treatments. Differences in erosion rates, the distribution of Olsen P and maize-derived C indicated that this pattern was mainly caused by soil transport induced by erosion since the implementation of the tillage treatments, rather than local differences in decomposition rates. We concluded that the influence of landforms on the stabilization and redistribution processes of nutrients is greater within CT than MT. Therefore, interactions between landform and agricultural management need to be considered in regional soil organic matter inventory assessments.