Increase In Erosion Rate Research Articles

Maximized erosion at the last glacial maximum revealed by thermoluminescence thermochronometry

Increased erosion rates during the last 2 Myr of Earth history are commonly associated with widespread glaciation and global cooling. However, whether erosion rates actually increased during that period of time remains debated. This is in part because the respective role of fluvial and glacial erosion is difficult to assess, and because many existing techniques used to estimate erosion rates may be affected by averaging biases that may produce increased erosion rates towards the present. Here, we apply thermoluminescence thermochronometry to granitic bedrock samples of the southern-central Chilean Andes, a region which experienced a full transition from glacial-humid to fluvial-dry conditions during the Quaternary. Inverse modelling of the thermochronological data enables us to extract unbiased time series of erosion rates during the last ∼100 kyr. We find that erosion rates were systematically higher during around the last glacial maximum than at present, with differences exceeding an order of magnitude. Our findings indicate that glacial erosion is probably more efficient than fluvial erosion and imply that erosion has remained transient during the Quaternary. • Time series of erosion rates during the last 100 kyr in the southern-central Chilean Andes. • Evidences of transiency in Quaternary geomorphological processes. • First field application of thermoluminescence thermochronology.

RETRACTED: Investigating the peak outflow through a spatial embankment dam breach

Investigating the breach outflow hydrograph is an essential task to conduct mitigation plans and flood warnings. In the present study, the spatial dam breach is simulated by using a three-dimensional computational fluid dynamics model, FLOW-3D. The model parameters were adjusted by making a comparison with a previous experimental model. The different parameters (initial breach shape, dimensions, location, and dam slopes) are studied to investigate their effects on dam breaching. The results indicate that these parameters have a significant impact. The maximum erosion rate and peak outflow for the rectangular shape are higher than those for the V-notch by 8.85% and 5%, respectively. Increasing breach width or decreasing depth by 5% leads to increasing maximum erosion rate by 11% and 15%, respectively. Increasing the downstream slope angle by 4° leads to an increase in both peak outflow and maximum erosion rate by 2.0% and 6.0%, respectively.

Tyre Drop Structure Design for Erosion Handling in Mine Rehabillitation Area

Mining activities require large work areas that potentially cause environmental problems. One of the impacts that can be caused is an increase of erosion rate, which can reduce the function of the land, especially in the location that planned to be mine rehabilitation area. The potential for erosion formed must be predicted to prepare methods of prevention. Estimation of erosion potential was carried out at Tiung AB Dump PT. Kaltim Prima Coal uses the RUSLE (Revised Unified Soil Loss Equation) method which considers rain erosivity, material erodibility, slope factor, vegetation factor and conservation factor. Based on the results of the study, the average erosion rate was 292.4 tons/ha/month with a catchment area of ​​0.674 km2. Erosion reduction uses a conservation technique using the terracing method which is supported by the construction of an open channel to drain the rain discharge that enters the catchment area. Rainfall uses data from the last 15 years with the highest rainfall in January of 231.9 mm/month and the lowest in September of 118.3 mm/month. The 10-year return period of the highest rainfall is 121.49 mm/day. Peak runoff rainfall is 13.22 m3/s with infiltration discharge is 9.72 m3/s. The designed open channel has a flow rate of 21.09 m3/s with supercritical flow. The use of a tire drop structure can reduce the speed up to 3.8 m/s which is within the permissible speed based on the type of material so that erosion can be reduced to 11.7 tons/ha/month or 96% of the natural erosion rate.

Methodological procedures, analysis of the aridity, desertification and semi-arid index for the municipality of Santa Filomena, Piauí, Brazil

The municipality Santa Filomena that it was for is included in the Nucleus of Desertification of Gilbués, since all the other municipalities that are part of the same nucleus are. Data from the IBGE Demographic Census (2010) and the GDP of the municipalities published by IBGE (2009) were used. Social indicators of exclusion of education and income are sought. In addition to being reduced, GDP is far from ideal for a good quality of life. All the social indicators of the semiarid region are very bad. The evidence of the study allows us to conclude that, in fact, in this region, in relative terms, numbers are concentrated that allow the inclusion of these municipalities in the semi-arid area. In addition, the justifications for additional criteria because these municipalities belong to the Nucleus of Desertification of Gilbués, being the only one not yet contemplated with its inclusion in front of all the others already included, including those that belong to the other three nuclei existing in Brazil. The study of the aridity index and its tendency to desertification for the municipalities of Santa Filomena, Barreiras do Piauí, Gilbués and Monte Alegre do Piauí, Brazil was requested by a group of farmers, mayors and lawyers who intend to see the possibility of including these municipalities as a degraded area and its inclusions in the Brazilian semiarid region. The methodology used the calculations of aridity indexes by the water balance method developed by Thornthwaite and Mather (1948; 1955) with a field capacity (CAD) of 100 mm. The water balance graphs were used to demonstrate the variability of water surpluses and deficiencies, replacement and removal of water in the soil and visualization of interannual buoyancy. Electronic spreadsheets of evapotranspiration, evaporation, deficiency and annual water surplus were generated in order to understand their interannual fluctuations as an aid in erosive contributions and aridity indexes. The monthly rainfall for the period 1960-2017 was acquired from the climate bank of Superintendence for the development of the Northeast and from the Empresa de extensión Rural do Piauí where annual fluctuations, anomalies, moving averages, standard deviation, coefficient of variance, absolute maximums and minimums, in addition to studying the fluctuation of average temperatures and calculations of precipitation erosivity indices for the referred municipalities aiming at the objective of municipalities to be included in the semi-arid region and susceptible to desertification. The physiographic aspects, relief, fauna, flora and distance from the sea are evidenced and the edaphic contributions contribute to the incidence of aridity index and susceptibility to desertification in the studied area. The development of monoculture and improper planting techniques contributed to the increase in erosion rates and the tendency for changes in the semi-arid climate with very high risk of susceptibility. Areas identified as vulnerable to desertification, due to the lower aridity index, may not be located in the degraded area, and areas that present a higher aridity index and are not identified as vulnerability processes may be degraded to the point of being considered desertified areas. This variability may occur due to inappropriate use of the soil and environment. Temperature influences evapotranspiration, that is, the loss of water to the atmosphere, because the higher the temperature, the greater the evapotranspiration and, consequently, the lower the aridity index and, therefore, the greater the susceptibility to desertification. Possibly anthropic factors, the lack of afforestation in the beds of ponds, lakes, rivers, streams, streams, dams and water tables, the vertical construction and compaction of urban and rural soil plus transient meteorological systems and local factors may have contributed to periods ( months, years) with greater variability, however it is known that depending on the season, summer or winter, evapotranspiration and evaporation can really vary, as they are directly related to the seasons with higher and lower precipitation, variability in air temperature, air humidity between other variables such as solar radiation, cloud cover, wind speed and vapor saturation pressure, which can reduce the evaporative process.

Numerical investigation of erosion characteristics of coupling separators with different conical profiles

Solid particles exist widely in liquid–liquid systems. Although a separator coupled centrifugal and electric fields can achieve liquid–liquid separation efficiently, the solid particles are usually not considered, and the erosion characteristics are unclear. Thus, in this study, a numerical model was established to investigate the erosion characteristics of coupling devices. Two conical profiles, namely bi-cone and elliptical, were examined. The effect of structural parameters on erosion was investigated, and the relationships between the erosion rate and the inlet velocity, initial drop size and solid loading were explored. The results showed that maximum erosion occurred in the interaction regions of the two cones for the bi-cone, and that the cone with an elliptical profile had a lower erosion rate. The maximum erosion rate depended on the centrifugal force acting on the solid particles and the inertial effect of particles in the mixture. Furthermore, the precessing vortex core was the dominant factor influencing the position, including maximum erosion rate, which depended on the centrifugal force and the vortex core radial deviation. Moreover, the potential reason for the effect of geometric parameters on wall erosion is different. From the perspective of erosion resistance, the optimal values of straight and underflow pipe section diameters and conical structure length for the device with an elliptical profile cone were 35, 400, and 430 mm. Additionally, increasing inlet velocity, initial drop size and solid loading can increase average erosion rate on the walls, and strengthen of breakage effect can indirectly reflect that the increase in erosion rate.

Parametric investigation of sand erosion rates in gas pipeline bends under typical industry conditions using simplified method

ABSTRACT The production and transport of sand from oil and gas wells into production and transport facilities results in flow assurance and structural problems. A critical operational issue is the erosion of oil and gas facilities by the suspended sand particles, particularly around flow diversions. This study investigated the effects of four key parameters, namely particle size, sand load, fluid velocity, and fluid density, on the rate of sand erosion in gas pipeline bends using DNV GL-RPO501 and Star CCM+ software package, a Computational Fluid Dynamics (CFD) tool developed by CD – adapco. Sand concentration and particle sizes both cause a linear increase in erosion rate. The particle sizes affected the location of maximum erosion. The single and mixture component gas densities showed an inverse linear and non-uniform relationship with erosion rate. The CFD models underpredicted erosion rates by about 90% compared to the experimental data. An exponential relation exists between the erosion rate and gas/sand velocity especially velocities above 10 m/s. The CFD method largely predicted more realistic values of erosion rate than the DNV GL-RPO501 due to some oversimplified assumptions made in the latter. The CFD tool however compared favorably with the DNV GL-RPO501 at high velocities. Both CFD and DNV GL-RPO501 models are recommended for erosion studies at higher fluid velocities, while the CFD modeling is better at lower velocities by incorporating drag and inertial forces which are important forces at low gas velocities. The particle and fluid velocity affected the sand erosion rate more than the other factors considered. However, future studies should consider modeling erosion rates under transient conditions and investigate the effects of various turbulence models. Different sand mixtures with various particle sizes and other gases such as CO2 should be considered.

Anatomical changes in dwarf shrub roots provide insight into aeolian erosion rates in northeastern Iceland

Iceland is known for having strong aeolian erosion events, as evidenced by erosional escarpments on the soil surface; these are known locally as rofabards. The aim of the study was to estimate aeolian erosion rates at two research plots affected by severe erosion, using anatomic features of the roots of Arctic, woody, dwarf shrubs. Ours is the first study to utilize dendrochronological analyses of exposed roots of dwarf willows (Salix herbacea L.) as an indicator of aeolian erosion. When dwarf shrub roots are exposed to the atmosphere by erosion, cell sizes are reduced by >50 %, with maximum changes in individual plants exceeding 150–200 %. We detected the erosion signal by analyzing changes in cell-size and width of growth rings in the roots. Using this relationship, were able to estimate erosion rates (the retreat of escarpments) since the 1970s for the study area. During the 1970s and 1980s, erosion rates were fairly constant, with retreat ranging from 1.0 to 2.5 cm yr−1. Rapid increases in erosion rates were observed after the late 1990s, occasionally as much as 4.4–5.4 cm yr−1. Increased aeolian erosion rates may be linked to continuous heavy grazing by sheep and climate change, as this period coincides with increased numbers of hot and warm, and dusty days. Our results indicate that dendrochronological methods can be highly useful in determining past geomorphic activity, due to modern environmental changes observed in the Arctic. The methods employed here can be applied even in treeless areas.

Late erosion pulse triggered by rapid melt in the cold‐based interior of the last Fennoscandian Ice Sheet, an example from Rogen

AbstractIce sheet interiors are conventionally regarded as non‐erosive. Yet subglacial conditions may be transformed during deglaciation by the arrival of large volumes of meltwater at the ice sheet bed. The development of a dynamic meltwater drainage system and the onset of basal sliding have potential to increase erosion rates in bedrock and sediment. Here, we examine the impact of late deglacial thawing on the Rogen plateau, located near the former ice divide of the Fennoscandian Ice Sheet. We provide new maps of glacial and glacifluvial landforms which we combine with existing data on Quaternary sediments and landforms. Cross‐cutting and overlapping relations allow for an event sequence to be established of the deglaciation period. In the Early Holocene (< 11 ka), an ice lobe onset zone developed at the Rogen plateau. In places where meltwater reached the bed and where pressures rose to overpressure, it caused fracture dilation in horizontally bedded sandstones and rock brecciation. The onset of sliding and application of drag resulted in the mobilization of bedrock sheets. The establishment of meltwater corridors led to fluidization of sediments at the bed, dissection and modification of ribbed moraines and formation of murtoos and hummock corridors. During final stagnation of the ice sheet, meltwater drained through channels forming axial eskers. Bedrock erosion during deglaciation reached depths up to 4 m, and in conjunction with some recycling of till, generated 317 km2 of boulder cover. The average erosion depths by removal and reworking of sediment are 0.9–1.1 m across areas below 900 m elevation. This study shows that when the cold‐based interiors of ice sheets become briefly activated by large subglacial meltwater delivery late in deglaciation, there can be significant reworking and erosion of rock and sediment.

Numerical study on effect of operating condition and solid concentration on hydro-abrasive erosion of high head Francis turbine

The powerplants in the Himalayan region are generally subjected to hydro-abrasive erosion. The deterioration of components due to erosion causes reduction in performance, changes the fluid flow pattern and even the breakdown of the turbine. In the present work, the Bhilangana-III powerplant Francis turbine is considered a reference turbine for numerical investigation using the computational fluid dynamics (CFD) tool. The study presented an evaluation of hydro-abrasive erosion of high head Francis turbine for the different operating conditions and sediment concentrations. The modified Grant and Tabakoff erosion model is used for the erosion rate calculation. To investigate the effect of various operating conditions, the study is conducted at part load, best efficiency point (BEP) and high load. Also, to examine the impact of suspended sediment on the erosion of turbine components, the solid concentration varies from 500, 1200, 2000, 3000 and 4000 ppm. The observed erosion pattern is similar at all operating conditions for the stay vane, guide vane and runner, but the density of erosion is different. The observed deterioration density due to erosion is higher for part and full load than in the BEP condition. The guide vanes and runner vanes are highly susceptible to erosion due to higher absolute velocity and relative velocity at guide vane and runner vane, respectively. The observed erosion rate variation is qualitatively in-line with the on-field turbine erosion condition. It is also found that the increase in erosion rate with the sediment concentration is almost linear but more than 90% and 79% higher for the runner than stay vane and guide vane, respectively.

Comparing long‐term observations of sediment yield with estimates of soil erosion rate based on recent 137Cs measurements. Results from an experimental catchment in Southern Italy

AbstractRecent increase of soil erosion rates in Southern Italy emphasizes the need to identify areas subjected to higher environmental risks. Over the last few decades, several techniques have been used to this purpose. They include mainly experimental sites, like plots and catchments of different size, and the use of prediction models calibrated using local parameters. More recently, some of the limitations associated with these techniques suggested the use of radiotracers, mainly 137Cs, both as alternative and complementary tools to traditional methods. However, some of the assumptions associated with the application of the 137Cs technique still require testing and validation to provide robust estimates of soil erosion rate. These assumptions relate mainly the 137Cs spatial variability on the reference area and the effects of possible additional fallout due to nuclear accidents (e.g., Chernobyl and/or Fukushima). In this contribution, a small experimental catchment located in Calabria, Southern Italy, was selected as a study area by virtue of its long‐term record (29 years) of sediment yield measurements. This database made it possible a comparison between long‐term observations and estimates of soil erosion rate provided by recent measurements of 137Cs. The overall results indicate that if the uncertainty of the reference value is taken into account and the Chernobyl additional flux is incorporated into a physically based conversion model, the latter is able to provide robust estimates of soil erosion rate in the area.

Multiscale modeling of seepage-induced suffusion and slope failure using a coupled FEM–DEM approach

Suffusion refers to the detachment and migration of fine particles through voids among coarse particles and is one of the major causes of slope failure. This study investigates the seepage-induced suffusion and slope instability using a hierarchical multiscale finite–discrete element method (FEM–DEM). An erosion law with the critical hydraulic gradient for the onset of suffusion is proposed. Two examples, including one-dimensional suffusion and biaxial compression tests, are performed to verify the proposed scheme. Emphases are placed on reproducing suffusion and progressive slope failure process under seepage flow. The results indicate that a shear band is initiated from the slope toe and gradually extends to the crest. The increase of erosion rate accelerates the process of suffusion and slope failure, whereas a higher critical hydraulic gradient plays an opposite role. In addition, fines loss caused by suffusion occurs mainly on the slope surface, especially near the slope toe. Microscopic analyses on locally embedded representative volume elements (RVEs) indicate that RVEs inside the shear band experience severe deformation and microstructural changes, manifested by the rearrangement of soil skeletons and variation of contact force chains.

Coastal dune dynamics in embayed settings with sea-level rise – Examples from the exposed and macrotidal north coast of SW England

Coastal dune systems are natural forms of coastal defence, but are expected to exhibit increased erosion rates due to climate change impacts, notably sea-level rise and, potentially, increased storminess. This is especially the case in embayed coastal settings, i.e., where there are no significant sediment inputs into the beach/dune system from longshore sources. Dune development is closely linked to that of beaches that lie seaward, but their temporal dynamics tend to be asynchronous. So, whereas beaches are generally highly variable over a short- to medium-term (event–decadal) time scales, potentially obscuring a longer-term (decadal–centennial) sea-level signal, dunes display a low-pass filtered response which may contain a sea-level signal.In this study, we investigate the decadal-scale, inter-annual dynamics of 25 embayed coastal dune systems along the exposed and macrotidal north coast of SW England. We then compare the observed behaviour with that hindcasted from simple parametric models and forecast future dune retreat rates due to sea-level rise. We show that practically all exposed dune systems show retreat with a regionally-averaged retreat rate of the dune foot of 0.5 m yr−1. The majority of retreat occurred over a small number of especially energetic winters and it was found that dune retreat is not automatically linked to dune volumetric change. Many of the retreating dune systems display so called ‘dune roll-over’, characterised by removal of sediment from the dune face and deposition at the dune top. Observed dune retreat rates were 2–3 times larger than predicted using simple parametric retreat models forced by sea-level rise. This suggests that the retreat models are inappropriate and/or that sea-level rise in itself may be insufficient to explain the observed retreat and that increased winter storminess may be implicated.A key factor in driving dune retreat is considered to be the number of hours that waves reach the dune foot or the excess runup energy present at the dune foot elevation. Both sea-level rise and enhanced storminess will increase exposure of the dune foot to energetic wave action and this is expected to accelerate dune retreat rates in these settings. Application of parametric shoreline retreat models that account for the acceleration in rate of sea-level rise predicts c. 40 m of dune retreat by 2100 with a considerable range in retreat (20–75 m), resulting from uncertainty in model choice and parameterisation. Simply extrapolating the current dune retreat rate also results in c. 40 m of dune retreat by 2100, but this approach ignores the potential acceleration in dune retreat rate due to an increase in the rate of sea-level rise.The combination of analysis of multi-annual coastal dune morphological change along with application of dune retreat models can provide useful insights into future dune evolution for coastal planners and managers.

Accumulation of windblown sand in impact craters on Mars

Abstract Loose sand, blown away from source regions by winds, is transported across Mars's surface into sand sheets and dunes and accumulates within topographic sinks. In the absence of plate tectonics, impact craters constitute a dominant sink for windblown sediments on Mars today. We analyzed the volume of all mapped eolian sands in martian craters >1 km in diameter to reveal spatiotemporal patterns of sediment accumulation on the planet's surface. We combined our results with global climate simulations, maps of depth to the ice table and dust cover, as well as lithologic and age information of the underlying geologic units, to better understand the controls on intracrater sand accumulation rates. We find that crater age, latitude, and lithology influence the accumulation rate of windblown sand and, notably, that it is enhanced in mechanically weaker substrates, high-latitude craters (suggesting that modern cryogenic processes may enhance sand production), and in Late Noachian and Early Hesperian craters (possibly hinting at increased erosion rates at that time).

Global rainfall erosivity projections for 2050 and 2070

The erosive force of rainfall (rainfall erosivity) is a major driver of soil, nutrient losses worldwide and an important input for soil erosion assessments models. Here, we present a comprehensive set of future erosivity projections at a 30 arc-second (∼1 km2) spatial scale using 19 downscaled General Circulation Models (GCMs) simulating three Representative Concentration Pathways (RCPs) for the periods 2041–2060 and 2061–2080. The future rainfall erosivity projections were obtained based on a Gaussian Process Regression (GPR) approach relating rainfall depth to rainfall erosivity through a series of (bio)climatic covariates. Compared to the 2010 Global Rainfall erosivity baseline, we estimate a potential average increase in global rainfall erosivity between 26.2 and 28.8% for 2050 and 27–34.3% for 2070. Therefore, climate change and the consequential increase in rainfall erosivity is the main driver of the projected + 30–66% increase in soil erosion rates by 2070.Our results were successfully compared with 20 regional studies addressing the rainfall erosivity projections. We release the whole dataset of future rainfall erosivity projections composed of 102 simulation scenarios, with the aim to support further research activities on soil erosion, soil conservation and climate change communities. We expect these datasets to address the needs of both the Earth system modeling community and policy makers. In addition, we introduce a modeling approach to estimate future erosivity and make further assessments at global and continental scales.

Dynamics of Anthropogenic Wildfire on Babeldaob Island (Palau) as Revealed by Fire History

Wildfire is an understudied threat to biodiversity in many tropical landscapes, including island nations of the Pacific, such as The Republic of Palau—a global biodiversity hotspot with ridge-to-reef resources. Fires are known to occur on Palau’s main island of Babeldaob, where they can result in increased erosion rates and sediment delivery to near-shore areas with impacts to streams and coral reefs. Fire-adapted native plant species are found in savanna habitats, but fires often extend into adjacent forest areas where they kill overstory trees. To assess this serious biodiversity and human health threat, we mapped wildland fires on Babeldaob Island using ground-based surveys and aerial photographs between 2012 and 2015, and satellite imagery between 2012 and 2021. Data on causal factors, vegetation type, and the presence of invasive species were collected between 2012 and 2015, with hunting, arson, and agricultural clearing being the principal causes of ignitions. Wildfires occurred in all months and in all 10 states of Babeldaob, and both numbers of wildfires and total burned area were substantially greater during dry seasons, with the highest totals occurring in the one El Niño drought year in our record. Overall, wildfires appear to have a minor impact on forest vegetation because they are largely confined to savanna systems, but rainfall on burned savanna is a major cause of erosion and the sedimentation of streams and near-shore habitats.

Investigation of the Flow and Heat Transfer Characteristics and Erosion Law of Particulate in LBE on the Subchannel

A triangle subchannel model was established to study the flow and heat transfer characteristics of lead-bismuth eutectic (LBE) alloy and the erosion rate of the core channel by the particulate in LBE. Under different inlet velocities, particle types, particle diameters, and particle concentrations, the erosion law of the channel wall in LEB was investigated by using a discrete phase model (DPM). The results of this study showed that with the increase of inlet velocity, the outlet temperature of the LEB decreases and the heat transfer capacity was strengthened. The increase of inlet velocity will lead to the increase of erosion rate on the wall, and the change is exponential. The erosion rate of particulate in the low concentration is small but cannot be ignored; with increasing concentration of particulates, the erosion of the wall by particulates becomes serious. The effect of particulate density on the wall erosion rate can be ignored. The effect of changing the particle size on the erosion rate is more significant when the particle size is small, and at the same time, the erosion rate of the particles on the wall increases with the increase of the particle size.

Geoarchaeology and Heritage Management: Identifying and Quantifying Multi-Scalar Erosional Processes at Kisese II Rockshelter, Tanzania

Natural and anthropogenically induced soil erosion can cause serious loss of the archaeological record. Our work shows the value of multi-scalar geoarchaeological study when excavating and re-excavating rockshelters in a highly dynamic sedimentary environment where erosion is prominent. Here we present our work on Kisese II rockshelter, Tanzania, originally excavated in the 1950s and largely unpublished, that preserves an important Pleistocene-Holocene archaeological record integral to understanding the deep history of the Kondoa Rock-Art World Heritage Center. Unlike rockshelters in quiescent tectonic settings, like much of central Europe or South Africa, Kisese II exists in highly dynamic sedimentary environments associated with the active tectonics of the Great Rift Valley system exacerbated by human-induced environmental and climate change. We report on our 2017 and 2019 exploratory research that includes integrated regional-, landscape-, and site-scale geoarchaeological analyses of past and present sedimentary regimes and micromorphological analyses of the archaeological sediments. Historical records and aerial photographs document extensive changes in vegetation cover and erosional regimes since the 1920s, with drastic changes quantified between 1960 and 2019. Field survey points to an increased erosion rate between 2017 and 2019. To serve future archaeologists, heritage specialists, and local populations we combine our data in a geoarchaeological catena that includes soil, vegetation, fauna, and anthropogenic features on the landscape. At the site, micromorphological coupled with chronological analyses demonstrate the preservation of in situ Pleistocene deposits. Comparison of photographs from the 1956 and 2019 excavations show a maximum sediment loss of 68 cm in 63 years or >10% of >6-m-thick sedimentary deposit. In the studied area of the rockshelter we estimate ~1 cm/yr of erosion, suggesting the ongoing removal of much of the higher archaeological sediments which, based on the coarse stratigraphic controls and chronology of the original Inskeep excavations, would suggest the loss of much of the archaeological record of the last ~4000 years. These multi-scalar data are essential for the construction of appropriate mitigation strategies and further study of the remaining stratigraphy.

Assessing the use of land system archetypes to increase regional variability representation in country-specific characterization factors: a soil erosion case study

PurposeThe characterization of land use impacts in life cycle assessment (LCA) requires a constant compromise between highly specific impacts models and coarse geographical scales available in life cycle inventory, where most information is provided at country level as the highest degree of geographical specificity. The derivation of country-specific characterization factors is usually done estimating impacts with the use of land cover and potential natural vegetation maps, assuming the most predominant biome per country as representative. This study explores the use of land system archetypes to derive country-specific characterization factors for land use-related soil erosion impacts that can better represent intra-national variations, while accounting for several biogeographical and socioeconomic differences.MethodsLand use-specific characterization factors were derived as the potentially enhanced soil erosion rate, using the soil erosion rates of each archetype as a reference state, and correction factors to reflect the relative increase or decrease in soil erosion rates associated with each of the eight land use types assessed: forest, permanent crops, grassland, farmland, fallow ground, moorland, urban/industrial, and mining/landfill. Country-specific characterization factors for land use erosion impacts of occupation (in ton/(m2·year)) were calculated by taking into account the land system archetypes present in each country, the land use-specific characterization factors, and the likelihood of each land use type occurring across archetypes (based on rule of thumb expert estimates). The country-specific characterization factors were produced specifically for occupation impacts for each of the eight land use types, and covering 263 countries and territories/dependencies.Results and discussionThe resulting 2,104 country-specific characterization factors displayed in average a considerably greater variation in comparison with characterization factors produced when only the most predominant archetype per country is assumed as representative per country. The results indicate that world generic values might underestimate up to 10 times the degree of impacts associated with land use types such as permanent crops, fallow ground, mining, and landfill. The use of land system archetypes presents a viable approach to derive country-specific characterization factors while taking into account key intra-national variations, as well as biogeographical and socioeconomic factors.

Increased Erosion Rates Following the Onset of Pleistocene Periglaciation at Bear Meadows, Pennsylvania, USA

AbstractDirect measurements of erosional response to past climate change are scarce, but mid‐latitude landscapes can record how shifts between cold and warm periods altered erosion outside glacial margins. To study hillslope responses to periglaciation, we measured bulk geochemistry and cosmogenic 10Be and 26Al concentrations in colluvium and weathered bedrock in an 18 m regolith core from Bear Meadows, Pennsylvania, ∼100 km south of maximum glacial extent. Using core lithology, cosmogenic nuclide concentrations, and regional 10Be‐derived erosion rates, we show the onset of 100‐Kyr glacial cycles at the Mid‐Pleistocene Transition (1.2–0.7 Ma) instigated multiple periglacial episodes in central Appalachia, increasing erosion rates compared to the relatively warmer Neogene. Our results show the higher efficiency of periglacial versus temperate erosion processes and highlight a pervasive Pleistocene periglacial erosion signal preserved in the 10Be inventory of surface sediments in central Appalachia, where erosion rates are slow enough to integrate previous cold‐climate processes.

Alpine rockwall erosion patterns follow elevation-dependent climate trajectories

Mountainous topography reflects an interplay between tectonic uplift, crustal strength, and climate-conditioned erosion cycles. During glaciations, glacial erosion increases bedrock relief, whereas during interglacials relief is lowered by rockwall erosion. Here, we show that paraglacial, frost cracking and permafrost processes jointly drive postglacial rockwall erosion in our research area. Field observations and modelling experiments demonstrate that all three processes are strongly conditioned by elevation. Our findings on catchment scale provide a potential multi-process explanation for the increase of rockwall erosion rates with elevation across the European Alps. As alpine basins warm during deglaciation, changing intensities and elevation-dependent interactions between periglacial and paraglacial processes result in elevational shifts in rockwall erosion patterns. Future climate warming will shift the intensity and elevation distribution of these processes, resulting in overall lower erosion rates across the Alps, but with more intensified erosion at the highest topography most sensitive to climate change.