Sample records for streambank erosion rates

  1. A watershed scale spatially-distributed model for streambank erosion rate driven by channel curvature

    McMillan, Mitchell; Hu, Zhiyong


    Streambank erosion is a major source of fluvial sediment, but few large-scale, spatially distributed models exist to quantify streambank erosion rates. We introduce a spatially distributed model for streambank erosion applicable to sinuous, single-thread channels. We argue that such a model can adequately characterize streambank erosion rates, measured at the outsides of bends over a 2-year time period, throughout a large region. The model is based on the widely-used excess-velocity equation and comprised three components: a physics-based hydrodynamic model, a large-scale 1-dimensional model of average monthly discharge, and an empirical bank erodibility parameterization. The hydrodynamic submodel requires inputs of channel centerline, slope, width, depth, friction factor, and a scour factor A; the large-scale watershed submodel utilizes watershed-averaged monthly outputs of the Noah-2.8 land surface model; bank erodibility is based on tree cover and bank height as proxies for root density. The model was calibrated with erosion rates measured in sand-bed streams throughout the northern Gulf of Mexico coastal plain. The calibrated model outperforms a purely empirical model, as well as a model based only on excess velocity, illustrating the utility of combining a physics-based hydrodynamic model with an empirical bank erodibility relationship. The model could be improved by incorporating spatial variability in channel roughness and the hydrodynamic scour factor, which are here assumed constant. A reach-scale application of the model is illustrated on ∼1 km of a medium-sized, mixed forest-pasture stream, where the model identifies streambank erosion hotspots on forested and non-forested bends.

  2. Is the BEHI Index (Part of the BANCS Model Good for Prediction of Streambank Erosion?

    Zuzana Allmanová


    Full Text Available Sedimentation of waterways and reservoirs, decreasing quality of drinking water and costs necessary for maintenance of these objects directly related to streambank erosion. This study provides a tool for water management that can help with estimation parts of a streambank which are prone to erosion. The Bank erosion hazard index (BEHI part of the BANCS (Bank Assessment for Non‑point source Consequences of Sediment model is one of the several procedures for assessing streambank erosion condition and potential (Rosgen, 2001. On May 15th 2014 a high precipitation occurred in the watershed of Sestrč torrent, in the eastern part of Chočské vrchy (Sp = 27.64 km2. It reached 102.7 mm per 24 hours. The rainfall resulted in extreme streambank erosion. We started the research of annual stream bank erosion on Sestrč in the beginning of May 2014 and we established 19 experimental sections on the stream. Occurrence of heavy rainfall allowed us to erosion rates after flash flood. The aim of this paper was to verify, if BEHI index can really determine the most vulnerable parts of a banks to erosion. We measured erosion rates Eb (m3/m using a bank pins and toe pin (Sass, 2011 on each experimental section and evaluated each section by BEHI index (Rosgen, 2001, 2008. The results were statistically verified and confirmed a strong relationship between BEHI and real damage of banks Eb (m3/m (R: 0.88, R2: 0.78.

  3. Modelling streambank erosion potential using maximum entropy in a central Appalachian watershed

    Pitchford, J.; Strager, M.; Riley, A.; Lin, L.; Anderson, J.


    We used maximum entropy to model streambank erosion potential (SEP) in a central Appalachian watershed to help prioritize sites for management. Model development included measuring erosion rates, application of a quantitative approach to locate Target Eroding Areas (TEAs), and creation of maps of boundary conditions. We successfully constructed a probability distribution of TEAs using the program Maxent. All model evaluation procedures indicated that the model was an excellent predictor, and that the major environmental variables controlling these processes were streambank slope, soil characteristics, bank position, and underlying geology. A classification scheme with low, moderate, and high levels of SEP derived from logistic model output was able to differentiate sites with low erosion potential from sites with moderate and high erosion potential. A major application of this type of modelling framework is to address uncertainty in stream restoration planning, ultimately helping to bridge the gap between restoration science and practice.

  4. Seepage and piping: Solitary and integrated mechanisms of streambank erosion and failure

    Recent work has shown that a majority of the sediment entering streams and rivers now comes from streambanks. We lack the understanding of the processes controlling streambank failure to be able to predict how erosion control methods will work for all conditions. Research underway at Oklahoma State...

  5. Hydrologic processes related to streambank erosion in three Minnesota agricultural watersheds

    Nieber, J. L.; Lenhart, C. F.; Holmberg, K.; Ulrich, J.; Peterson, H. M.


    Increased streamflow in many southern and west-central Minnesota rivers in recent decades has contributed to higher rates of streambank erosion. Some rivers in the region have experienced a doubling of mean annual flow in the past 30 years, yet the relative importance of changes in climate and land-use, and increases in sub-surface drainage to these flow increases is undetermined. We used oxygen and hydrogen isotopes, specific conductivity, nutrient ratios from riparian zone wells, stream erosion measurements and groundwater seepage surveys to assess the sources of water contributing to streamflow, the mechanisms of streambank collapse and the spatial distribution of streambank collapse in the main channels of three rural Minnesota watersheds. By volume most of the water in these streams is sourced from sub-surface drainage. Surface runoff events are rare and concentrated in the spring and fall. Fluvial erosion undercuts the toe of banks during high flow, thus decreasing bank stability, which then leads to a mass collapse after the hydrograph recedes. While most erosion occurs at high flow events, subsurface drainage may add to the peak of high streamflow events by increasing the initial stage of the hydrograph, particularly in the spring months of April-June. Monitoring wells within the riparian zone of two streams in west-central Minnesota showed that reaches of the streams may be gaining or losing depending on season and water stage. Loss of water to streambank storage may be substantial in regions with intermittent flow and permeable streambanks in late summer to fall. Groundwater seepage was very sporadic longitudinally and laterally along the study rivers yet is important for aquatic life health. Seepage occurred primarily low in the soil profile and was not a major contributor to mass wasting of banks, though it is thought to be a bigger factor in ravine and bluff erosion where different strata are exposed. The study points to the dynamic nature of riparian

  6. Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

    Fox, G. A.; Sheshukov, A.; Cruse, R.; Kolar, R. L.; Guertault, L.; Gesch, K. R.; Dutnell, R. C.


    The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

  7. Comparison of unmanned aircraft systems (UAS) to LiDAR for streambank erosion measurement at the site-specific and river network scales

    Hamshaw, S. D.; Dewoolkar, M. M.; Rizzo, D.; ONeil-Dunne, J.; Frolik, J.


    Measurement of rates and extent of streambank erosion along river corridors is an important component of many catchment studies and necessary for engineering projects such as river restoration, hazard assessment, and total maximum daily load (TMDL) development. A variety of methods have been developed to quantify streambank erosion, including bank pins, ground surveys, photogrammetry, LiDAR, and analytical models. However, these methods are not only resource intensive, but many are feasible and appropriate only for site-specific studies and not practical for erosion estimates at larger scales. Recent advancements in unmanned aircraft systems (UAS) and photogrammetry software provide capabilities for more rapid and economical quantification of streambank erosion and deposition at multiple scales (from site-specific to river network). At the site-specific scale, the capability of UAS to quantify streambank erosion was compared to terrestrial laser scanning (TLS) and RTK-GPS ground survey and assessed at seven streambank monitoring sites in central Vermont. Across all sites, the UAS-derived bank topography had mean errors of 0.21 m compared to TLS and GPS data. Highest accuracies were achieved in early spring conditions where mean errors approached 10 cm. The cross sectional area of bank erosion at a typical, vegetated streambank site was found to be reliably calculated within 10% of actual for erosion areas greater than 3.5 m2. At the river network-level scale, 20 km of river corridor along the New Haven, Winooski, and Mad Rivers was flown on multiple dates with UAS and used to generate digital elevation models (DEMs) that were then compared for change detection analysis. Airborne LiDAR data collected prior to UAS surveys was also compared to UAS data to determine multi-year rates of bank erosion. UAS-based photogrammetry for generation of fine scale topographic data shows promise for the monitoring of streambank erosion both at the individual site scale and river

  8. A West Virginia case study: does erosion differ between streambanks clustered by the bank assessment of nonpoint source consequences of sediment (BANCS) model parameters?

    Abby L. McQueen; Nicolas P. Zegre; Danny L. Welsch


    The integration of factors and processes responsible for streambank erosion is complex. To explore the influence of physical variables on streambank erosion, parameters for the bank assessment of nonpoint source consequences of sediment (BANCS) model were collected on a 1-km reach of Horseshoe Run in Tucker County, West Virginia. Cluster analysis was used to establish...

  9. Evaluating a process-based model for use in streambank stabilization and stream restoration: insights on the bank stability and toe erosion model (BSTEM)

    Streambank retreat is a complex cyclical process involving subaerial processes, fluvial erosion, seepage erosion, and geotechnical failures and is driven by several soil properties that themselves are temporally and spatially variable. Therefore, it can be extremely challenging to predict and model ...

  10. Quantifying streambank erosion: a comparative study using an unmanned aerial system (UAS) and a terrestrial laser scanner

    Rizzo, D.; Hamshaw, S. D.; Dewoolkar, M.; ONeil-Dunne, J.; Frolik, J.; Bryce, T. G.; Waldron, A. Y.


    Streambank erosion is a common non-point source contributing to suspended sediment and nutrient loading of waterways, and recently has been estimated to account for 30-80% of sediment loading into receiving waters. There is interest in developing reliable methods to quantify bank erosion in watersheds, so effective management strategies can be devised. However, current methods can be either cost prohibitive or unreliable. Direct measurement approaches (surveys and erosion pins) are labor intensive and yield site-specific measurements that are limited for extrapolation to larger scales. Similar issues arise with analytical methods such as slope stability analysis, which require material parameters that are resource intensive to determine. Newer approaches such as use of aerial LiDAR data have proved effective for watershed level assessment, but come with long turnaround times and high cost. Terrestrial laser scanning (TLS) is also effective and offers high accuracy, however collection over large areas is impractical and post-processing is labor intensive. New technology in the form of unmanned aerial systems (UAS) has the potential to significantly enhance the ability to monitor channel migration and quantify bank erosion at variable scales. In this study, 20 km of the Mad and Winooski Rivers in Vermont were flown using a senseFly eBee UAS. Flights were made in spring and fall 2015 in leaf-off conditions with selected portions also flown after large storms in the summer. Change in bank profiles between spring and fall flights provide a comprehensive estimate of bank erosion along the study reaches. Six sites with varying bank heights, erosion sensitivity, and vegetation conditions were selected for simultaneous surveying using a TLS. Point cloud data from both the TLS and UAS were compared to assess the accuracy of the UAS for capturing the bank profile. Changes in bank cross-sections and in volumes calculated from 3D digital surface models were used to compare the

  11. Rill erosion rates in burned forests

    Joseph W. Wagenbrenner; Peter R. Robichaud


    Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

  12. Juniper for Streambank Stabilization in Eastern Oregon

    Guy R. Sheeter; Errol W. Claire


    Cut juniper trees (Juniperous osteosperma Hook.) anchored along eroded streambanks proved beneficial in stabilizing 96 percent of the erosion on eight streams evaluated in eastern Oregon over a 14-year-period. Juniper revetment was a successful substitute for costly rock structures on straight or slightly curved banks, but failed when placed on outside curves or when...

  13. Natural and anthropogenic rates of soil erosion

    Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natur...

  14. Erosion of Perennially Frozen Streambanks,


    Miles 1977). Mixtures of fine and coarse material are autumn freezeup (Benedict 1976). varied in their response. Stratified banks or bluffs of Miles...season, and fall freezeup periods. Studies of this type bury 1974, Scott 1978). generally need 3 to 5 years to achieve representative -r. The following

  15. Natural and anthropogenic rates of soil erosion

    Mark A. Nearing


    Full Text Available Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natural, non-cropped conditions have been documented to be less than 2 Mg ha−1 yr−1. On-site rates of erosion of lands under cultivation over large cropland areas, such as in the United States, have been documented to be on the order of 6 Mg ha−1 yr−1 or more. In northeastern China, lands that were brought into production during the last century are thought to have average rates of erosion over this large area of as much as 15 Mg ha−1 yr−1 or more. Broadly applied soil conservation practices, and in particular conservation tillage and no-till cropping, have been found to be effective in reducing rates of erosion, as was seen in the United States when the average rates of erosion on cropped lands decreased from on the order of 9 Mg ha−1 yr−1 to 6 or 7 Mg ha−1 yr−1 between 1982 and 2002, coincident with the widespread adoption of new conservation tillage and residue management practices. Taking cropped lands out of production and restoring them to perennial plant cover, as was done in areas of the United States under the Conservation Reserve Program, is thought to reduce average erosion rates to approximately 1 Mg ha−1 yr−1 or less on those lands.

  16. Streambank Protection Guidelines for Landowners and Local Governments,


    Control of rainfall runoff oReo- ofthe ohme mabe xmr cat-effective &am than loss of a structure, road, or utility line, -Minimizing load on top of...REPRODUCE LEGIBLY. CONTENTS 2 Preface 3 Introduction 4 The Nature of Streams 7 Understanding Streambank Erosion and Failure 15 Developing a Plan of Action...Laboratory Layout and Design: Loriece M. Beall. Publications and Graphic Arts Division October 1983 %1% Preface Large-scale efforts to control soil erosion

  17. Runoff and erosion response of simulated waste burial covers in a semi-arid environment

    Bent, G.C.; Goff, B.F.; Rightmire, K.G.; Sidle, R.C.


    Control of runoff (reducing infiltration) and erosion at shallow land burials is necessary in order to assure environmentally safe disposal of low-level radioactive-waste and other waste products. This study evaluated the runoff and erosion response of two perennial grass species on simulated waste burial covers at Idaho National Engineering and Environmental Laboratory (INEEL). Rainfall simulations were applied to three plots covered by crested wheatgrass [Agropyron desertorum (Fischer ex Link) Shultes], three plots covered by streambank wheatgrass [Elymus lanceolatus (Scribner and Smith) Gould spp. lanceolatus], and one bare plot. Average total runoff for rainfall simulations in 1987, 1989, and 1990 was 42 percent greater on streambank wheatgrass plots than on crested wheatgrass plots. Average total soil loss for rainfall simulations in 1987 and 1990 was 105 percent greater on streambank wheatgrass plots than on crested wheatgrass plots. Total runoff and soil loss from natural rainfall and snowmelt events during 1987 were 25 and 105 percent greater, respectively, on streambank wheatgrass plots than on crested wheatgrass plots. Thus, crested wheatgrass appears to be better suited in revegetation of waste burial covers at INEEL than streambank wheatgrass due to its much lower erosion rate and only slightly higher infiltration rate (lower runoff rate).

  18. Time scale bias in erosion rates of glaciated landscapes.

    Ganti, Vamsi; von Hagke, Christoph; Scherler, Dirk; Lamb, Michael P; Fischer, Woodward W; Avouac, Jean-Philippe


    Deciphering erosion rates over geologic time is fundamental for understanding the interplay between climate, tectonic, and erosional processes. Existing techniques integrate erosion over different time scales, and direct comparison of such rates is routinely done in earth science. On the basis of a global compilation, we show that erosion rate estimates in glaciated landscapes may be affected by a systematic averaging bias that produces higher estimated erosion rates toward the present, which do not reflect straightforward changes in erosion rates through time. This trend can result from a heavy-tailed distribution of erosional hiatuses (that is, time periods where no or relatively slow erosion occurs). We argue that such a distribution can result from the intermittency of erosional processes in glaciated landscapes that are tightly coupled to climate variability from decadal to millennial time scales. In contrast, we find no evidence for a time scale bias in spatially averaged erosion rates of landscapes dominated by river incision. We discuss the implications of our findings in the context of the proposed coupling between climate and tectonics, and interpreting erosion rate estimates with different averaging time scales through geologic time.

  19. Responses of chemical erosion rates to transient perturbations in physical erosion rates, and implications for relationships between chemical and physical erosion rates in regolith-mantled hillslopes

    Ferrier, Ken L.; West, Nicole


    Understanding the relationship between chemical erosion rates (W) and physical erosion rates (E) is of wide interest due to their roles in driving landscape evolution, supplying nutrients to soils and streams, and modulating the global carbon cycle. Measured relationships between W and E vary around the globe, with some regions exhibiting positive correlations between W and E, some negative correlations, and others no correlation within uncertainty. Here we use a numerical model for mineral weathering in well-mixed ridgetop regolith to explore how complex W- E relationships can be generated by simple transient perturbations in E. We show that a Gaussian perturbation in E can produce positive or negative responses in W, and can result in a variety of hysteresis loops - clockwise, counterclockwise, or figure-eight - in plots of W against E. The nature of the transient response depends on the shape of the steady-state W- E relationship, which is set by regolith mineralogy, and the ratio of E to the maximum possible regolith production rate. The response time of W is controlled by the response time of soluble mineral concentrations at low E, where soluble mineral concentrations are low, and by the response time of regolith thickness at high E, where regolith thickness is low. These complex W- E relationships arise in the absence of variations in climate and lithology, which suggests that transients may account for some of the observed differences in W- E relationships among field sites, even among sites that share the same climate and lithology.

  20. Quantitative Model for Estimating Soil Erosion Rates Using 137Cs



    A quantitative model was developed to relate the amount of 137Cs loss from the soil profile to the rate of soil erosion,According th mass balance model,the depth distribution pattern of 137Cs in the soil profile ,the radioactive decay of 137Cs,sampling year and the difference of 137Cs fallout amount among years were taken into consideration.By introducing typical depth distribution functions of 137Cs into the model ,detailed equations for the model were got for different soil,The model shows that the rate of soil erosion is mainly controlled by the depth distrbution pattern of 137Cs ,the year of sampling,and the percentage reduction in total 137Cs,The relationship between the rate of soil loss and 137Cs depletion i neither linear nor logarithmic,The depth distribution pattern of 137Cs is a major factor for estimating the rate of soil loss,Soil erosion rate is directly related with the fraction of 137Cs content near the soil surface. The influences of the radioactive decay of 137Cs,sampling year and 137Cs input fraction are not large compared with others.

  1. Transport Rate of Surface Erosion by the Hydrodynamics


    The coherence and exposure degree are used in analyzing initiation of slope sediment.The initial ve- locity is built by using a critical roiling model.A transport rate formula of slope erosion is established using the Meyer-Peter model.The formula is tested by experiment and agrees well but the errors are big when the flow discharge and rain intensity are smaller.

  2. Extending Spectroscopic Capabilities for Mo PFC Erosion Rate Diagnostics

    Loch, S. D.; Ennis, D. A.; Pindzola, M. S.; Johnson, C. A.; Hartwell, G. J.; Maurer, D. A.; Griffin, D. C.; Ballance, C. P.; Reinke, M.; Lipschultz, B.; Soukhanovskii, V.


    The use of ionizations per photon coefficients (SXB) provides a useful means of measuring wall erosion rates. Two problems hindering the use of such diagnostics for high-Z materials are a lack of accurate atomic data and determining which lines from the complex spectral features should be used for accurate erosion measurements. We present a new approach for generating and selecting SXB coefficients for high-Z materials. The theoretical spectra show strong agreement with spectra from the Alcator C-Mod and Compact Toroidal Hybrid experiments. Mo II spectral features are identified, including a line ratio suitable for electron temperature measurements which constrains the SXB implementation. Applications of the new SXBs to NSTX-U edge plasmas is described and future plans for Mo and W influx diagnostics are outlined. Work supported by US DoE Cooperative agreement DE-FC02-99ER54512 at MIT using the Alcator C-Mod tokamak, a DOE Office of Science user facility. This work is also supported by US Department of Energy Grant No. DE-FG02-00ER54610 to Auburn University.


    A. S. Amar


    Full Text Available The construction of dams and reservoirs in a river can give significant impacts on its flow of water and sediment, and can cause long-term morphological changes on the river. Reservoir sedimentation can reduce a reservoir’s effective flood control volume, and in some severe cases can cause overtopping during floods. Sediment deposition against a dam can reduce its stability, and affect the operation of low-level outlet works, gates, and valves. The abrasive action of sediment particles can roughen the surface of release facilities and can cause cavitations and vibration. Sedimentation can also affect a reservoir’s water quality, and reduce its flood control, water supply, hydropower, and recreation benefits. Consequently, taking sedimentation into consideration not only in the planning and design, but also in the operation and maintenance of a dam and reservoir is important. Keywords: Erosion rate, reservoir deposit, shear stress.

  4. Contrasting Modern and 10Be- derived erosion rates for the Southern Betic Cordillera, Spain

    Bellin, N.; Vanacker, V.; Kubik, P.


    In Europe, Southeast Spain was identified as one of the regions with major treat of desertification in the context of future land use and climate change. During the last years, significant progress has been made to understand spatial patterns of modern erosion rates in these semi-arid degraded environments. Numerous European projects have contributed to the collection of modern erosion data at different spatial scales for Southeast Spain. However, these data are rarely analysed in the context of long-term changes in vegetation, climate and human occupation. In this paper, we present Modern and Holocene denudation rates for small river basins (1 to 10 km2) located in the Spanish Betic Cordillera. Long-term erosion data were derived from cosmogenic nuclide analyses of river-borne sediment. Modern erosion data were quantified through analysis of sediment deposition volumes behind check dams, and represent average erosion rates over the last 10 to 40 years. Modern erosion rates are surprisingly low (mean erosion rate = 0.048 mm y-1; n=36). They indicate that the steep, sparsely vegetated hillslopes in the Betic Cordillera cannot directly be associated with high erosion rates. 10Be -derived erosion rates integrate over the last 37500 to 3500 years, and are roughly of the same magnitude. They range from 0.013 to 0.243 mm y-1 (mean denudation rate = 0.062 mm y-1 ± 0.054; n=20). Our data suggest that the modern erosion rates are similar to the long-term erosion rates in this area. This result is in contrast with the numerous reports on human-accelerated modern erosion rates for Southeast Spain. Interestingly, our new data on long-term erosion rates show a clear spatial pattern, with higher erosion rates in the Sierra Cabrera and lower erosion rates in Sierra de las Estancias, and Sierra Torrecilla. Preliminary geomorphometric analyses suggest that the spatial variation that we observe in long-term erosion rates is related to the gradient in uplift rates of the Betic


    Kátia Kellem Rosa; Rosemary Vieira; Jefferson Cardia Simões


    Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands). This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the l...

  6. Prediction of Soil Erosion Rates in Japan where Heavily Forested Landscape with Unstable Terrain

    Nanko, K.; Oguro, M.; Miura, S.; Masaki, T.


    Soil is fundamental for plant growth, water conservation, and sustainable forest management. Multidisciplinary interest in the role of the soil in areas such as biodiversity, ecosystem services, land degradation, and water security has been growing (Miura et al., 2015). Forest is usually protective land use from soil erosion because vegetation buffers rainfall power and erosivity. However, some types of forest in Japan show high susceptibility to soil erosion due to little ground cover and steep slopes exceeding thirty degree, especially young Japanese cypress (Chamaecyparis obtusa) plantations (Miura et al., 2002). This is a critical issue for sustainable forest management because C. obtusaplantations account for 10% of the total forest coverage in Japan (Forestry Agency, 2009). Prediction of soil erosion rates on nationwide scale is necessary to make decision for future forest management plan. To predict and map soil erosion rates across Japan, we applied three soil erosion models, RUSLE (Revised Universal Soil Loss Equation, Wischmeier and Smith, 1978), PESERA (Pan-European Soil Erosion Risk Assessment, Kirkby et al., 2003), and RMMF (Revised Morgan-Morgan-Finney, Morgan, 2001). The grid scale is 1-km. RUSLE and PESERA are most widely used erosion models today. RMMF includes interactions between rainfall and vegetation, such as canopy interception and ratio of canopy drainage in throughfall. Evaporated rainwater by canopy interception, generally accounts for 15-20% in annual rainfall, does not contribute soil erosion. Whereas, larger raindrops generated by canopy drainage produced higher splash erosion rates than gross rainfall (Nanko et al., 2008). Therefore, rainfall redistribution process in canopy should be considered to predict soil erosion rates in forested landscape. We compared the results from three erosion models and analyze the importance of environmental factors for the prediction of soil erosion rates. This research was supported by the Environment

  7. Parabolic features and the erosion rate on Venus

    Strom, Robert G.


    The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.

  8. Parabolic features and the erosion rate on Venus

    Strom, Robert G.


    The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.

  9. Long-term erosion rates of Panamanian drainage basins determined using in situ 10Be

    Gonzalez, Veronica Sosa; Bierman, Paul R.; Nichols, Kyle K.; Rood, Dylan H.


    Erosion rates of tropical landscapes are poorly known. Using measurements of in situ-produced 10Be in quartz extracted from river and landslide sediment samples, we calculate long-term erosion rates for many physiographic regions of Panama. We collected river sediment samples from a wide variety of watersheds (n = 35), and then quantified 24 landscape-scale variables (physiographic, climatic, seismic, geologic, and land-use proxies) for each watershed before determining the relationship between these variables and long-term erosion rates using linear regression, multiple regression, and analysis of variance (ANOVA). We also used grain-size-specific 10Be analysis to infer the effect of landslides on the concentration of 10Be in fluvial sediment and thus on erosion rates. Cosmogenic 10Be-inferred, background erosion rates in Panama range from 26 to 595 m My- 1, with an arithmetic average of 201 m My- 1, and an area-weighted average of 144 m My- 1. The strongest and most significant relationship in the dataset was between erosion rate and silicate weathering rate, the mass of material leaving the basin in solution. None of the topographic variables showed a significant relationship with erosion rate at the 95% significance level; we observed weak but significant correlation between erosion rates and several climatic variables related to precipitation and temperature. On average, erosion rates in Panama are higher than other cosmogenically-derived erosion rates in tropical climates including those from Puerto Rico, Madagascar, Australia and Sri Lanka, likely the result of Panama's active tectonic setting and thus high rates of seismicity and uplift. Contemporary sediment yield and cosmogenically-derived erosion rates for three of the rivers we studied are similar, suggesting that human activities are not increasing sediment yield above long-term erosion rate averages in Panama. 10Be concentration is inversely proportional to grain size in landslide and fluvial samples

  10. Erosion Rates Over 40-Year and 5,000-Year Timescales at Caspar Creek, Northern California

    Ferrier, K. L.; Kirchner, J. W.; Finkel, R. C.


    Erosion rate measurements are essential for modeling landscape evolution and for discerning how sediment loading affects stream ecosystems. Cosmogenic nuclides such as 10Be in stream sediments can be used to measure whole-catchment erosion rates averaged over thousands of years, a timescale that is unobservable by other methods. Comparing long-term erosion rates from cosmogenic nuclides with short-term sediment yields can shed light on erosional processes and on the effects of land use on sediment delivery to streams. Using cosmogenic 10Be, we measured erosion rates averaged over the past 5,000 years at Caspar Creek, a small (9 km2) watershed in Mendocino County, California. Sediment yields have also been measured at Caspar Creek since 1963 using sediment trapping and gauging methods. The cosmogenic 10Be signature of Caspar Creek sediments yields an average long-term erosion rate of 0.2 mm/yr. This is 2-3 times faster than erosion rates calculated from traditional stream sediment fluxes averaged over the past 40 years. The long-term rates are comparable to the uplift rate of 0.3 mm/yr inferred from marine terrace ages (Merritts and Bull 1989). These results imply that sediment delivery to streams is episodic, and that conventional sediment yields may underestimate long-term average erosion rates.


    Kátia Kellem Rosa


    Full Text Available Glacial sediment yield results from glacial erosion and is influenced by several factors including glacial retreat rate, ice flow velocity and thermal regime. This paper estimates the contemporary subglacial erosion rate and sediment yield of Wanda Glacier (King George Island, South Shetlands. This work also examines basal sediment evacuation mechanisms by runoff and glacial erosion processes during the subglacial transport. This is small temperate glacier that has seen retreating for the last decades. In this work, we examine basal sediment evacuation mechanisms by runoff and analyze glacial erosion processes occurring during subglacial transport. The glacial erosion rate at Wanda Glacier, estimated using a numerical model that consider sediment evacuated to outlet streams, ice flow velocity, ice thickness and glacier area, is 1.1 ton m yr-1.

  12. Selecting and applying cesium-137 conversion models to estimate soil erosion rates in cultivated fields.

    Li, Sheng; Lobb, David A; Tiessen, Kevin H D; McConkey, Brian G


    The fallout radionuclide cesium-137 ((137)Cs) has been successfully used in soil erosion studies worldwide. However, discrepancies often exist between the erosion rates estimated using various conversion models. As a result, there is often confusion in the use of the various models and in the interpretation of the data. Therefore, the objective of this study was to test the structural and parametrical uncertainties associated with four conversion models typically used in cultivated agricultural landscapes. For the structural uncertainties, the Soil Constituent Redistribution by Erosion Model (SCREM) was developed and used to simulate the redistribution of fallout (137)Cs due to tillage and water erosion along a simple two-dimensional (horizontal and vertical) transect. The SCREM-predicted (137)Cs inventories were then imported into the conversion models to estimate the erosion rates. The structural uncertainties of the conversion models were assessed based on the comparisons between the conversion-model-estimated erosion rates and the erosion rates determined or used in the SCREM. For the parametrical uncertainties, test runs were conducted by varying the values of the parameters used in the model, and the parametrical uncertainties were assessed based on the responsive changes of the estimated erosion rates. Our results suggest that: (i) the performance/accuracy of the conversion models was largely dependent on the relative contributions of water vs. tillage erosion; and (ii) the estimated erosion rates were highly sensitive to the input values of the reference (137)Cs level, particle size correction factors and tillage depth. Guidelines were proposed to aid researchers in selecting and applying the conversion models under various situations common to agricultural landscapes.

  13. Evaluation of rate of swelling and erosion of verapamil (VRP) sustained-release matrix tablets.

    Khamanga, Sandile M; Walker, Roderick B


    Tablets manufactured in-house were compared to a marketed sustained-release product of verapamil to investigate the rate of hydration, erosion, and drug-release mechanism by measuring the wet and subsequent dry weights of the products. Swelling and erosion rates depended on the polymer and granulating fluid used, which ultimately pointed to their permeability characteristics. Erosion rate of the marketed product was highest, which suggests that the gel layer that formed around these tablets was weak as opposed to the robust and resistant layers of test products. Anomalous and near zero-order transport mechanisms were dominant in tests and commercial product, respectively.

  14. Determination of erosion rates with cosmogenic 26Al

    Strack, E.; Heisinger, B.; Dockhorn, B.; Hartmann, F. J.; Korschinek, G.; Nolte, E.; Morteani, G.; Petitjean, C.; Neumaier, S.


    A preliminary depth profile of the long-lived cosmogenic radioisotope 26Al(5 +) in quartz samples from pre-drill cores of the continental deep drill core (KTB) at Egerer Waldhaeusl, Poppenreuth and Puellersreuth was measured with accelerator mass spectrometry (AMS). These drill cores are situated in Upper Palatinate (Oberpfalz, Germany) in a region with very low erosion. The cosmogenic production of 26Al in quartz was calculated. The calculation is based on two reactions: spallation reactions on silicon in the first few meters and the capture reaction of slow negative muons Si(μ -, ν μxn, which is the dominant process below a few meters. The branching ratio of the μ - capture reaction in silicon to 26Al(5 +) was determined by irradiating a quartz sample with slow negative muons at PSI in Villigen (Switzerland) and by measuring the produced 26Al by AMS. Calculations of 26Al depth profiles taking erosion into account were performed. The agreement between the depth profile calculated with no erosion and the measured preliminary profile is very satisfactory.

  15. Long-term cosmogenic 10Be catchment-wide erosion rates in the Kruger National Park

    Glotzbach, Christoph; Paape, Alexander; Reinwarth, Bastian; Baade, Jussi; Miller, Jordan; Rowntree, Kate


    In this study we estimated long-term catchment-wide erosion rates in the central and southern Kruger National Park with cosmogenic 10Be analyses. Samples were collected in small catchments (2-100 km2) upstream of dams, which were used to determine short-term sediment yield rates. 10Be-derived erosion rates vary from 4-15 mm/kyr. Although there are significant site-specific differences in geomorphic parameters and precipitation we could not identify a single parameter controlling long-term erosion. Geomorphic fieldwork reveals that an unknown fraction of sampled sand-sized channel sediments derived from partly extensive and up to a few-meters deep gully erosion, which may lead to an overestimation of 10Be-derived erosion rates. Cosmogenic nuclide production is rapidly decreasing with depth and consequently the measured 10Be concentration of stream sediments is a mixture of (i) sand with high 10Be concentration from colluvial creep or sheet flow from hillslopes and (ii) sand with low 10Be concentration from gully erosion. To correct erosion rates, we quantify sediments derived from gullies using a combination of mapping gullies using remote sensing data and field work and geochemical characterisation of intact hillslopes and gully side walls.

  16. Effects of Post-Fire Salvage Logging on Erosion Rates at Multiple Scales

    Wagenbrenner, J. W.; Robichaud, P. R.; MacDonald, L. H.; Brown, R. E.


    Forest managers sometimes harvest burned trees after wildfires to realize economic value, reduce fuel loads, or achieve other operational goals. This logging can be controversial because some ecosystem effects are negative, yet the potential impacts on erosion rates have not been clearly identified. Our objectives were to quantify hillslope-scale erosion rates and compare the hillslope erosion rates to rates from larger (swale) and smaller (rill) scales. Soil characteristics, vegetative regrowth, and erosion rates were measured in logged areas and unlogged controls at seven severely burned sites in the western US. One site had replicated measurements at all three scales, five sites had only hillslope or swale scale measurements, and one site had only rill measurements. Erosion rates from hillslopes (70-170 m2) and swales (0.1-2.6 ha) were measured with sediment fences. Rill erosion rates were measured with rill experiments, where water was applied to a hillslope at five flow rates for 12 min each; water samples were collected at a point 9 m downslope. At the hillslope scale the passage of heavy logging equipment reduced soil water repellency, compacted the soil, reduced vegetative regrowth rates, and generally increased erosion rates by one or two orders of magnitude relative to the controls. The rill experiments also showed greater rates of rill incision and erosion from the areas disturbed by heavy logging equipment relative to the controls. At the swale scale erosion rates were higher in the logged areas than the controls when measurements were replicated and simultaneous but there was no detectable change in the other study areas. Overall, the absolute erosion rates from both logged and unlogged areas tended to decline over time while the relative difference in erosion tended to increase due to the slower vegetative recovery in the more heavily disturbed areas. The potential adverse effects of salvage logging can be minimized by reducing compaction and

  17. Erosion Rates Over Millennial and Decadal Timescales: Measurements at Caspar Creek and Redwood Creek, Northern California

    Ferrier, K. L.; Kirchner, J. W.; Finkel, R. C.


    Erosion rate measurements are essential for modeling landscape evolution and for discerning how sediment loading affects stream ecosystems. Cosmogenic nuclides such as 10Be in stream sediments can be used to measure whole-catchment erosion rates averaged over thousands of years, a timescale that is unobservable by other methods. Comparing long-term erosion rates from cosmogenic nuclides with short-term sediment yields can shed light on erosional processes and on the effects of land use on sediment delivery to streams. Using cosmogenic 10Be, we measured erosion rates averaged over the past several thousand years at Caspar Creek and Redwood Creek in Northern California. Sediment yields have also been measured at Caspar Creek since 1963 using sediment trapping and gauging methods, and sediment yield data have been collected at Redwood Creek since 1974. The cosmogenic 10Be signature of Caspar Creek sediments indicates an average erosion rate of 0.13 mm/yr, which agrees with the short-term sediment yield data within error. The cosmogenic 10Be signature of Redwood Creek sediments implies an average long-term erosion rate of 0.3 mm/yr, which is in rough agreement with traditional measurements of stream sediment flux. These results imply that the rate of sediment delivery to Caspar Creek and Redwood Creek over the past few decades is broadly consistent with the long-term average rate of sediment production in these watersheds.

  18. Relationship between environmental conditions and rates of coastal erosion in Arctic Alaska

    Barnhart, K. R.; Anderson, R. S.; Overeem, I.; Wobus, C. W.; Clow, G. D.; Urban, F. E.; LeWinter, A. L.; Stanton, T. P.


    Rates of coastal cliff erosion are a function of the geometry and substrate of the coast; storm frequency, duration, magnitude, and wave field; and regional sediment sources. In the Arctic, the duration of sea ice-free conditions limits the time over which coastal erosion can occur, and sea water temperature modulates erosion rates where ice content of coastal bluffs is high. Predicting how coastal erosion rates in this environment will respond to future climate change requires that we first understand modern coastal erosion rates. Arctic coastlines are responding rapidly to climate change. Remotely sensed observations of coastline position indicate that the mean annual erosion rate along a 60-km reach of Alaska's Beaufort Sea coast, characterized by high ice content and small grain size, doubled from 7 m yr-1 for the period 1955-1979 to 14 m yr-1 for 2002-2007. Over the last 30 years the duration of the open water season expanded from ˜45 days to ˜95 days, increasing exposure of permafrost bluffs to seawater by a factor of 2.5. Time-lapse photography indicates that coastal erosion in this environment is a halting process: most significant erosion occurs during storm events in which local water level is elevated by surge, during which instantaneous submarine erosion rates can reach 1-2 m/day. In contrast, at times of low water, or when sea ice is present, erosion rates are negligible. We employ a 1D coastal cross-section numerical model of the erosion of ice-rich permafrost bluffs to explore the sensitivity of the system to environmental drivers. Our model captures the geometry and style of coastal erosion observed near Drew Point, Alaska, including insertion of a melt-notch, topple of ice-wedge-bounded blocks, and subsequent degradation of these blocks. Using consistent rules, we test our model against the temporal pattern of coastal erosion over two periods: the recent past (~30 years), and a short (~2 week) period in summer 2010. Environmental conditions used

  19. Soil erosion rates in rangelands of northeastern Patagonia: A dendrogeomorphological analysis using exposed shrub roots

    Chartier, Marcelo Pablo; Rostagno, César Mario; Roig, Fidel Alejandro


    Soil erosion is an important process of land degradation in many rangelands and a significant driver of desertification in the world's drylands. Dendrogeomorphology is an alternative to traditional methods for determining soil erosion rate. Specifically, the vertical distance between the upper portion of exposed roots and the actual soil surface can be used as a bioindicator of erosion since plant establishment. In this study, we determined (i) the soil erosion rate from exposed roots of the dwarf shrub Margyricarpus pinnatus [Lam.] Kuntze in two ecological sites in the northeastern rangelands of Patagonia and (ii) the relationship between shrub age and upper root diameter. We selected two ecological sites, a pediment-like plateau and a flank pediment, where the dominant soils were Xeric Haplocalcids and Xeric Calciargids, respectively. The soil erosion rates in the pediment-like plateau and in the flank pediment were 2.4 and 3.1 mm yr - 1 , respectively. Data clearly indicate a high rate of soil erosion during the mean 8-year life span of the dwarf shrubs in degraded patches, which represent ~ 10% of surface cover in the study area. Simple linear regression analysis yielded a highly significant predictive model for age estimation of M. pinnatus plants using the upper root diameter as a predictor variable. The measurement of ground lowering against datable exposed roots represents a simple method for the determination of soil erosion rates. In combination with other soil surface features, it was used to infer the episodic nature of soil erosion. This approach could be particularly useful for monitoring the effects of land management practices on recent soil erosion and for the establishment of records in regions where historical data regarding this process are scarce or absent.

  20. Study of Rock's Erosion Rate Based on the Determination of 36Cl by AMS

    WANGYue; WUShao-yong; GUANYong-jing; LIUCun-fu; WUWei-ming; JIANGShan


    It is very important for science and economy to study the erosion rate of geology. The advanced technology and method may be extended to study the flourishing of the earth's crust and date. Since the measurement of cosmogenic nuclide became reality by AMS, the cosmogenic nuclide becomes more important in geoscience. So the determination of rock's erosion rate with 36Cl by AMS was going on.

  1. Spatial distribution of soil erosion and suspended sediment transport rate for Chou-Shui river basin

    Chin-Ping Lin; Ching-Nuo Chen; Yu-Min Wang; Chih-Heng Tsai; Chang-Tai Tsai


    In this study, a Physiographic Soil Erosion–Deposition Model (PSED) is applied for better management of a watershed. The PSED model can effectively evaluate the key parameters of watershed management: surface runoff discharge, suspended sediment transport rate, quantity of soil erosion, and spatial distribution of soil erosion and deposition. A basin usually contains multiple watersheds. These watersheds may have complex topography and heterogeneous physiographic properties. The PSED model, containing a physiographic rainfall-runoff model and a basin scale erosion–deposition model, can simulate the physical mechanism of the entire erosion process based on a detailed calculation of bed-load transportation, surface soil entrainment, and the deposition mechanism. With the assistance of Geographic Information Systems (GIS), the PSED model can handle and analyze extremely large hydrologic and physiographic datasets and simulate the physical erosion process without the need for simplification. We verified the PSED model using three typhoon events and 40 rainfall events. The application of PSED to Chou-Shui River basin shows that the PSED model can accurately estimate discharge hydrographs, suspended sediment transport rates, and sediment yield. Additionally, we obtained reasonable quantities of soil erosion as well as the spatial distribution of soil erosion and deposition. The results show that the PSED model is capable of calculating spatially distributed soil erosion and suspended sediment transport rates for a basin with multiple watersheds even if these watersheds have complex topography and heterogeneous physiographic properties.

  2. Prediction of Erosion Rate at Several Land Units in Upper Watershed of Batang Mangau, West Sumatera

    Amrizal Saidi


    Full Text Available Assessment of erosion in a watershed is very important for the purpose of determining whether a watershed has been degraded and damaged or not, so it is useful for the planning of the future for the watershed areas so as to achieve sustainable land use and environmentally friendly.Study of erosion prediction and mapping erosion hazard rate (TBE, and determine the rate of erosion that can be tolerated in a variety of land units, and determining alternative land use followed by the appropriate conservation measures in order to suppress erosion as small as possible or equal to Etol (tolerable erosion has conducted research on upstream Mangau Padang Pariaman and Agam districts. The study lasted in September 2011 until January 2012. The experiment was conducted using the survey method. Secondary data obtained from statistical data, maps and the results of previous researches. The results showed that the greatest erosion occurs in people's gardens land units with steep slopes (KrF, with a percentage of 62% slope and slope length of 45 m. While the smallest erosion occurs in wetland units with a gentle slope (SWB, the percentage of 7% slope and slope length of 28 m. Land units experiencing mild erosion rate is 37.80%, of the total study area. Then the land units suffered heavy erosion rate is as much as 20.81%, and further land experiencing very severe erosion hazard level is sebayak 37.86% of the total study area. Actual erosion rate greater than can be tolerated erosion found 4 unit of land is the garden of the people with a rather steep slope (KrD, mixed garden with a rather steep slope (KcD, and their fields with steep slopes (KrF. Furthermore, there are 8 land unit value erosion rate is less than the erosion rates that can be tolerated so that the use of the land does not need changing. Alternative use of land for every land units that have greater erosion speed of the tolerable erosion is the land units of protected forest with steep slopes (Hl

  3. A Bayesian Hierarchical Modeling Scheme for Estimating Erosion Rates Under Current Climate Conditions

    Lowman, L.; Barros, A. P.


    Computational modeling of surface erosion processes is inherently difficult because of the four-dimensional nature of the problem and the multiple temporal and spatial scales that govern individual mechanisms. Landscapes are modified via surface and fluvial erosion and exhumation, each of which takes place over a range of time scales. Traditional field measurements of erosion/exhumation rates are scale dependent, often valid for a single point-wise location or averaging over large aerial extents and periods with intense and mild erosion. We present a method of remotely estimating erosion rates using a Bayesian hierarchical model based upon the stream power erosion law (SPEL). A Bayesian approach allows for estimating erosion rates using the deterministic relationship given by the SPEL and data on channel slopes and precipitation at the basin and sub-basin scale. The spatial scale associated with this framework is the elevation class, where each class is characterized by distinct morphologic behavior observed through different modes in the distribution of basin outlet elevations. Interestingly, the distributions of first-order outlets are similar in shape and extent to the distribution of precipitation events (i.e. individual storms) over a 14-year period between 1998-2011. We demonstrate an application of the Bayesian hierarchical modeling framework for five basins and one intermontane basin located in the central Andes between 5S and 20S. Using remotely sensed data of current annual precipitation rates from the Tropical Rainfall Measuring Mission (TRMM) and topography from a high resolution (3 arc-seconds) digital elevation map (DEM), our erosion rate estimates are consistent with decadal-scale estimates based on landslide mapping and sediment flux observations and 1-2 orders of magnitude larger than most millennial and million year timescale estimates from thermochronology and cosmogenic nuclides.

  4. Climatic controls on steady state erosion using the relationship between channel steepness and cosmogenic 10Be-derived catchment averaged erosion rates

    Rossi, M. W.; Whipple, K. X.; DiBiase, R. A.; Heimsath, A. M.


    To understand landscape response to climate change, baseline controls on erosion rates must be established for given climate conditions. Theory suggests a number of climate metrics should be important to erosion (i.e. precipitation, temperature, storminess, seasonality, snow fraction). Nevertheless, definitive field evidence quantifying how climate affects erosion rate has proven difficult to obtain. This is at least partly due to the difficulty of isolating climatic influences on erosion rates from topographic and rock strength influences. We circumvent this problem by evaluating how climate influences the relationship between erosion rate and topography in settings with similar rock types. At steady state, tectonic uplift dictates erosion rate, and climate and rock strength are manifest as changes in erosional efficiency - the topographic relief necessary to maintain the tectonically imposed erosion rate. In fluvial landscapes, bedrock rivers set the relevant scale of topographic relief, which can be described by the channel steepness index. A number of recent studies have shown that the relationship between channel steepness and millennial scale erosion rates is non-linear, implying that erosional efficiency increases with relief. Work in the San Gabriel Mountains suggests this relationship is due to erosion thresholds that limit incision of channels in low relief landscapes. By using a fluvial incision model that incorporates a range of daily discharge events coupled with an erosion threshold (Lague et al., 2005), the influence of flood frequency on the relationship between channel steepness and erosion rate can be explored. We apply this same modeling approach to five other landscapes that exhibit a range of channel steepness, have similar rock types (granitoids), but that are in dramatically different climate regimes ranging from desert to rainforest (annual rainfall, P, from 0.25 to 3 m/yr). Specifically, we present new cosmogenic 10Be erosion rate data from

  5. The relationship between drainage density, erosion rate, and hilltop curvature: Implications for sediment transport processes

    Clubb, Fiona J.; Mudd, Simon M.; Attal, Mikaël.; Milodowski, David T.; Grieve, Stuart W. D.


    Drainage density is a fundamental landscape metric describing the extent of the fluvial network. We compare the relationship between drainage density (Dd) and erosion rate (E) using the Channel-Hillslope Integrated Landscape Development (CHILD) numerical model. We find that varying the channel slope exponent (n) in detachment-limited fluvial incision models controls the relationship between Dd and E, with n > 1 resulting in increasing Dd with E if all other parameters are held constant. This result is consistent when modeling both linear and nonlinear hillslope sediment flux. We also test the relationship between Dd and E in five soil-mantled landscapes throughout the USA: Feather River, CA; San Gabriel Mountains, CA; Boulder Creek, CO; Guadalupe Mountains, NM; and Bitterroot National Forest, ID. For two of these field sites we compare Dd to cosmogenic radionuclide (CRN)-derived erosion rates, and for each site we use mean hilltop curvature as a proxy for erosion rate where CRN-derived erosion rates are not available. We find that there is a significant positive relationship between Dd, E, and hilltop curvature across every site, with the exception of the San Gabriel Mountains, CA. This relationship is consistent with an n exponent greater than 1, suggesting that at higher erosion rates, the transition between advective and diffusive processes occurs at smaller contributing areas in soil-mantled landscapes.

  6. Dental erosive wear and salivary flow rate in physically active young adults

    Mulic Aida


    Full Text Available Abstract Background Little attention has been directed towards identifying the relationship between physical exercise, dental erosive wear and salivary secretion. The study aimed i to describe the prevalence and severity of dental erosive wear among a group of physically active young adults, ii to describe the patterns of dietary consumption and lifestyle among these individuals and iii to study possible effect of exercise on salivary flow rate. Methods Young members (age range 18-32 years of a fitness-centre were invited to participate in the study. Inclusion criteria were healthy young adults training hard at least twice a week. A non-exercising comparison group was selected from an ongoing study among 18-year-olds. Two hundred and twenty participants accepted an intraoral examination and completed a questionnaire. Seventy of the exercising participants provided saliva samples. The examination was performed at the fitness-centre or at a dental clinic (comparison group, using tested erosive wear system (VEDE. Saliva sampling (unstimulated and stimulated was performed before and after exercise. Occlusal surfaces of the first molars in both jaws and the labial and palatal surfaces of the upper incisors and canines were selected as index teeth. Results Dental erosive wear was registered in 64% of the exercising participants, more often in the older age group, and in 20% of the comparison group. Enamel lesions were most observed in the upper central incisors (33%; dentine lesions in lower first molar (27%. One fourth of the participants had erosive wear into dentine, significantly more in males than in females (p = 0.047. More participants with erosive wear had decreased salivary flow during exercise compared with the non-erosion group (p Conclusion The study showed that a high proportion of physically active young adults have erosive lesions and indicate that hard exercise and decreased stimulated salivary flow rate may be associated with such

  7. Quantification of short-term erosion rates using the cosmogenic radionuclide {sup 7}Be

    Jha, Abhinand


    The fallout radionuclides {sup 137}Cs, {sup 210}Pb{sub ex} are used widely for obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over several spatial and temporal scales, and they are frequently seen to represent a valuable complement to conventional soil erosion measurement techniques. However, measurements of these radionuclides provide estimates of medium term (i.e. 40-100 years) soil erosion rates. The shorter-term perspective provided by the {sup 7}Be method has the potential to estimate soil erosion rates associated with individual events or short periods. The {sup 7}Be method has become increasingly relevant in an environment impacted by climate change, changing land use and other human activities. The present work establishes a mathematical model based on the physical processes of molecular diffusion and radioactive decay, to study the vertical behaviour of {sup 7}Be in soils. This model was further used to quantify erosion rates for 12 individual erosional events over a period of two years at our study site in Muencheberg, Germany. The scope of the model was explored analytically as well as numerically for Pulselike fallout initial condition, zero concentration initial condition and exponential distribution initial condition. The model was fitted to more than 15 depth distributions and the resulting model parameter, effective diffusion coefficient D, is evaluated. In general diffusion coefficients estimated were of the order of 10{sup -12}-10{sup -13} m{sup 2} s{sup -1} for loamy to sandy soil types. Diffusion coefficients estimated for our study site were about 10{sup -13} m{sup 2}s{sup -1}. The soil analyses indicate that the diffusion coefficient D is not merely a fitting parameter, but is related to the physico-chemical properties of radionuclide transport in soils. The erosion rates estimated at tilled and no-till plots at our study site were between <0.001-4.7{+-}0.4 kg m{sup -2} and

  8. Southern Appalachian hillslope erosion rates measured by soil and detrital radiocarbon in hollows

    Hales, T.C.; Scharer, K.M.; Wooten, R.M.


    Understanding the dynamics of sediment generation and transport on hillslopes provides important constraints on the rate of sediment output from orogenic systems. Hillslope sediment fluxes are recorded by organic material found in the deposits infilling unchanneled convergent topographic features called hollows. This study describes the first hollow infilling rates measured in the southern Appalachian Mountains. Infilling rates (and bedrock erosion rates) were calculated from the vertical distribution of radiocarbon ages at two sites in the Coweeta drainage basin, western North Carolina. At each site we dated paired charcoal and silt soil organic matter samples from five different horizons. Paired radiocarbon samples were used to bracket the age of the soil material in order to capture the range of complex soil forming processes and deposition within the hollows. These dates constrain hillslope erosion rates of between 0.051 and 0.111mmyr-1. These rates are up to 4 times higher than spatially-averaged rates for the Southern Appalachian Mountains making creep processes one of the most efficient erosional mechanisms in this mountain range. Our hillslope erosion rates are consistent with those of forested mountain ranges in the western United States, suggesting that the mechanisms (dominantly tree throw) driving creep erosion in both the western United States and the Southern Appalachian Mountains are equally effective. ?? 2011 Elsevier B.V.

  9. Moderate topsoil erosion rates constrain the magnitude of the erosion-induced carbon sink and agricultural productivity losses on the Chinese Loess Plateau

    Zhao, Jianlin; Van Oost, Kristof; Chen, Longqian; Govers, Gerard


    Despite a multitude of studies, overall erosion rates as well as the contribution of different erosion processes on Chinese Loess Plateau (CLP) remain uncertain, which hampers a correct assessment of the impact of soil erosion on carbon and nutrient cycling as well as on crop productivity. In this paper we used a novel approach, based on field evidence, to reassess erosion rates on the CLP before and after conservation measures were implemented (1950 vs. 2005). We found that current average topsoil erosion rates are 3 to 9 times lower than earlier estimates suggested. Under 2005 conditions, more sediment was produced by non-topsoil erosion (gully erosion (0.23 ± 0.28 Gt yr-1) and landsliding (0.28 ± 0.23 Gt yr-1) combined) than by topsoil erosion (ca. 0.30 ± 0.08 Gt yr-1). Overall, these erosion processes mobilized ca. 4.77 ± 1.96 Tg yr-1 of soil organic carbon (SOC): the latter number sets the maximum magnitude of the erosion-induced carbon sink, which is ca. 4 times lower than one other recent estimate suggests. The programs implemented from the 1950s onwards reduced topsoil erosion from 0.51 ± 0.13 to 0.30 ± 0.08 Gt yr-1 while SOC mobilization was reduced from 7.63 ± 3.52 to 4.77 ± 1.96 Tg C yr-1. Conservation efforts and reservoir construction have disrupted the equilibrium that previously existed between sediment and SOC mobilization on the one hand and sediment and SOC export to the Bohai sea on the other hand: nowadays, most eroded sediments and carbon are stored on land. Despite the fact that average topsoil losses on the CLP are still relatively high, a major increase in agricultural productivity has occurred since 1980. Fertilizer application rates nowadays more than compensate for the nutrient losses by (topsoil) erosion: this was likely not the case before the dramatic rise of fertilizer use that started around 1980. Hence, erosion is currently not a direct threat to agricultural productivity on the CLP but the long-term effects of erosion on

  10. Cosmogenic in situ production of radionuclides: Exposure ages and erosion rates

    Heisinger, B.; Nolte, E.


    Experimental data for the cosmogenic in situ production of radionuclides and its depth dependence are used for two applications, the determination of exposure ages and of erosion rates. Concentrations of the long-lived radionuclides 10Be, 14C and 26Al in quartz are presented as function of exposure age, depth before exposure and erosion rate after exposure. It is shown that the cosmogenic production before exposure can introduce important corrections to the representation without consideration of pre-exposure production. Depth profiles of 10Be, 14C and 26Al in quartz and sulfur, of 36Cl in K 2O, CaCO 3, granite and concrete and of 53Mn in Fe 2O 3 are given as function of erosion rate. Consequences to determinations of neutron fluences in Hiroshima are discussed.

  11. Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

    Li, Gen; Liu, Ming, E-mail:; Wang, Jinshi; Chong, Daotong; Yan, Junjie


    Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

  12. Age and weathering rate of sediments in small catchments: the role of hillslope erosion

    Dosseto, A.; Buss, H. L.; Chabaux, F.


    Erosion is intimately linked to chemical weathering, however we lack quantitative constraints on how erosion processes impact mineral weathering rates. Here we use the uranium-series isotope composition of river-borne material in small catchments of Puerto Rico and southeastern Australia to study the effect of contrasting erosion regimes on weathering. The U-series isotope composition of stream sediments was modelled to infer a weathering age, i.e. the average time elapsed since the sediment's minerals have started weathering. In southeastern Australia, the weathering age of stream sediments ranges between 346 ± 12 kyr and 1.78 ± 0.16 Myr, similar to values inferred from weathering profiles in the same catchment. Old weathering ages likely reflect the shallow origin of sediments mobilised via near-surface soil transport, the main mechanism of erosion in this catchment. Contrastingly, in Puerto Rico weathering ages are much younger, ranging from 5.1 ± 0.1 to 19.4 ± 0.4 kyr, reflecting that sediments are derived from less weathered, deeper saprolite, mobilised by landslides. Weathering ages of stream sediments are used to infer catchment-wide, mineral-specific weathering rates that are one to two orders of magnitude faster for Puerto Rico than for southeastern Australia. Thus, the type of erosion (near-surface soil transport vs. landslide) also affects the weathering rate of river sediments, because their weathering ages determine the potential for further weathering during sediment transport and storage in alluvial plains.

  13. Dynamics of erosion in a compressional mountain range revealed by 10Be paleoerosion rates

    Val, P.; Hoke, G. D.; Fosdick, J. C.; Wittmann, H.


    The temporal evolution of erosion over million-year timescales is key to understanding the evolution of mountain ranges and adjacent fold-and-thrust belts. While models of orogenic wedge evolution predict an instantaneous response of erosion to pulses of rock uplift, stream-power based landscape evolution models predict catchment-wide erosion maxima that lag behind a rock uplift pulse. Here, we explore the relationships between rock uplift, erosion, and sediment deposition in the Argentine Precordillera fold-and-thrust belt at 30°S where extensive previous work documents deformation, climate and sediment accumulation histories. Sandstone samples spanning 8.8 to 1.8 Ma were collected from the previously dated wedge-top (Iglesia) and foredeep basins (Bermejo) for quartz purification and 10Be extraction. 10Be concentrations due to burial and exhumation were estimated and subtracted from the measured concentrations and yielded the inherited 10Be concentrations, which were then corrected for sample magnetostratigraphic age. The inherited concentrations were then used to calculate paleoerosion rates. We modeled various pre-burial and post-burial exposure scenarios in order to assess potential sources of uncertainty in the recovered paleoerosion rates. The modeling results reveal that pre-burial and post-burial exposure periods only marginally affect our results. By combining the 10Be-derived paleoerosion rates and geomorphic observations with detrital zircon provenance, we document the isolation of the wedge-top basin, which was later reconnected by an upstream migrating pulse of erosion in a process that was directly controlled by thrust activity and base level. The data further indicate that the attainment of maximum upland erosion rates lags maximum rates of deformation and subsidence over million-year timescales. The magnitudes and causes of the erosional delays shed new light on the catchment erosional response to tectonic deformation and rock uplift in orogenic

  14. Erosive Augmentation of Solid Propellant Burning Rate: Motor Size Scaling Effect

    Strand, L. D.; Cohen, Norman S.


    Two different independent variable forms, a difference form and a ratio form, were investigated for correlating the normalized magnitude of the measured erosive burning rate augmentation above the threshold in terms of the amount that the driving parameter (mass flux or Reynolds number) exceeds the threshold value for erosive augmentation at the test condition. The latter was calculated from the previously determined threshold correlation. Either variable form provided a correlation for each of the two motor size data bases individually. However, the data showed a motor size effect, supporting the general observation that the magnitude of erosive burning rate augmentation is reduced for larger rocket motors. For both independent variable forms, the required motor size scaling was attained by including the motor port radius raised to a power in the independent parameter. A boundary layer theory analysis confirmed the experimental finding, but showed that the magnitude of the scale effect is itself dependent upon scale, tending to diminish with increasing motor size.

  15. Rates of fluvio-thermal erosion on Mars

    Aguirre-Puente, J.; Costard, Francois M.; Posado-Cano, R.


    In order to get some ideas about the order of magnitude of fluvio-thermal recession rate, a mathematical thermal model for Martian outflow channels is proposed. This model corresponds to a system undergoing a permanent thermal regime where the surface temperature is constant and equal to the phase change temperature (due to the immediate removal of melted materials). This is an ablation model. For its application, estimations of the heat transfer coefficient h and thermal flux q are necessary. Determination of these coefficients needs the calculation of dimensionless numbers (Reynolds, Prandtl, and Nusselt), and the consideration of turbulent regime of the flow.

  16. Influence of topography and human activity on apparent in situ 10Be-derived erosion rates in Yunnan, SW China

    Schmidt, Amanda H.; Neilson, Thomas B.; Bierman, Paul R.; Rood, Dylan H.; Ouimet, William B.; Sosa Gonzalez, Veronica


    In order to understand better if and where erosion rates calculated using in situ 10Be are affected by contemporary changes in land use and attendant deep regolith erosion, we calculated erosion rates using measurements of in situ 10Be in quartz from 52 samples of river sediment collected from three tributaries of the Mekong River (median basin area = 46.5 km2). Erosion rates range from 12 to 209 mm kyr-1 with an area-weighted mean of 117 ± 49 mm kyr-1 (1 standard deviation) and median of 74 mm kyr-1. We observed a decrease in the relative influence of human activity from our steepest and least altered watershed in the north to the most heavily altered landscapes in the south. In the areas of the landscape least disturbed by humans, erosion rates correlate best with measures of topographic steepness. In the most heavily altered landscapes, measures of modern land use correlate with 10Be-estimated erosion rates but topographic steepness parameters cease to correlate with erosion rates. We conclude that, in some small watersheds with high rates and intensity of agricultural land use that we sampled, tillage and resultant erosion has excavated deeply enough into the regolith to deliver subsurface sediment to streams and thus raise apparent in situ 10Be-derived erosion rates by as much as 2.5 times over background rates had the watersheds not been disturbed.

  17. Bank stability analysis for fluvial erosion and mass failure

    The central objective of this study was to highlight the differences in magnitude between mechanical and fluvial streambank erosional strength with the purpose of developing a more comprehensive bank stability analysis. Mechanical erosion and ultimately failure signifies the general movement or coll...

  18. A closer look at the Neogene erosion and accumulation rate increase

    Willenbring, J.; von Blanckenburg, F.


    Glacial erosion and Quaternary cold-stage warm-stage climate cycling have been cited as mechanisms to explain observations of increased Neogene marine sedimentation rates. Quantification of long-term glacial erosion rates from cosmogenic radionuclides from large areas mostly covered by cold-based ice during the Quaternary show very low erosion rates over several glacial cycles. In addition, isotope ratio proxies of dissolved metals in seawater, measured in chemical ocean sediments, lack clear evidence for an increase in terrigenous denudation. In particular, the stable isotope 9Be, derived from continental erosion, shows no change in its ratio to meteoric cosmogenic nuclide 10Be, derived from rain over the past 10 My. Radiogenic Pb and Nd isotopes, mainly show a change in the style of denudation from more chemical to more physical processes in the Quaternary. These data are at odds with a suggested increase in marine sedimentation rates during the late Cenozoic. In order to resolve this contradiction we have scrutinized these sedimentation rate calculations from ocean cores to identify whether they might show only apparent increases in the Neogene sections. Potential explanations are that in some cases, measured sediment thicknesses for different time intervals lack corrections for sediment compaction. Compaction of the lower portions of the cores drastically increases the apparent thickness of the more recent (Quaternary) sediment. In addition, sedimentation rates often only appear higher for recent sections in cores due to an artifact of an averaging timescale that decreases up-core. Such an averaging time scale decrease arises from better chronological resolution in recent times (Sadler et al., 1999). Cannibalization of older sediment might add to this effect. Together, these data question a clear, global-scale Quaternary climate-erosion connection that would be unique in Earth's history.

  19. Role of mechanical erosion in controlling the effusion rate of basaltic eruptions

    Piombo, Antonello; Tallarico, Andrea; Dragoni, Michele


    In many basaltic eruptions, observations show that the effusion rate of magma has a typical dependence on time: the effusion rate curves show first a period of increasing and later a decreasing phase by a maximum value. We present a model to explain this behavior by the emptying of a magma reservoir through a vertical cylindrical conduit with elliptical cross section, coupled with the its widening due to mechanical erosion, produced by the magma flow. The model can reproduce the observed dependence on time of effusion rate in basaltic eruptions. Eruption duration and the maximum value of effusion rate depend on the size of magma chamber, on lava viscosity and strongly on erosion rate per unit traction.

  20. Long-term stability of global erosion rates and weathering during late-Cenozoic cooling.

    Willenbring, Jane K; von Blanckenburg, Friedhelm


    Over geologic timescales, CO(2) is emitted from the Earth's interior and is removed from the atmosphere by silicate rock weathering and organic carbon burial. This balance is thought to have stabilized greenhouse conditions within a range that ensured habitable conditions. Changes in this balance have been attributed to changes in topographic relief, where varying rates of continental rock weathering and erosion are superimposed on fluctuations in organic carbon burial. Geological strata provide an indirect yet imperfectly preserved record of this change through changing rates of sedimentation. Widespread observations of a recent (0-5-Myr) fourfold increase in global sedimentation rates require a global mechanism to explain them. Accelerated uplift and global cooling have been given as possible causes, but because of the links between rates of erosion and the correlated rate of weathering, an increase in the drawdown of CO(2) that is predicted to follow may be the cause of global climate change instead. However, globally, rates of uplift cannot increase everywhere in the way that apparent sedimentation rates do. Moreover, proxy records of past atmospheric CO(2) provide no evidence for this large reduction in recent CO(2) concentrations. Here we question whether this increase in global weathering and erosion actually occurred and whether the apparent increase in the sedimentation rate is due to observational biases in the sedimentary record. As evidence, we recast the ocean dissolved (10)Be/(9)Be isotope system as a weathering proxy spanning the past approximately 12 Myr (ref. 14). This proxy indicates stable weathering fluxes during the late-Cenozoic era. The sum of these observations shows neither clear evidence for increased erosion nor clear evidence for a pulse in weathered material to the ocean. We conclude that processes different from an increase in denudation caused Cenozoic global cooling, and that global cooling had no profound effect on spatially and

  1. Long-term erosion rate measurements in gypsum caves of Sorbas (SE Spain) by the Micro-Erosion Meter method

    Sanna, Laura; De Waele, Jo; Calaforra, José Maria; Forti, Paolo


    The present work deals with the results of long-term micro-erosion measurements in the most important gypsum cave of Spain, the Cueva del Agua (Sorbas, Almeria, SE Spain). Nineteen MEM stations were positioned in 1992 in a wide range of morphological and environmental settings (gypsum floors and walls, carbonate speleothems, dry conduits and vadose passages) inside and outside the cave, on gypsum and carbonate bedrocks and exposed to variable degree of humidity, different air flow and hydrodynamic conditions. Four different sets of stations have been investigated: (1) the main cave entrance (Las Viñicas spring); (2) the main river passage; (3) the abandoned Laboratory tunnel; and (4) the external gypsum surface. Data over a period of about 18 years are available. The average lowering rates vary from 0.014 to 0.016 mm yr- 1 near the main entrance and in the Laboratory tunnel, to 0.022 mm - 1 on gypsum floors and 0.028 mm yr- 1 on carbonate flowstones. The denudation data from the external gypsum stations are quite regular with a rate of 0.170 mm yr- 1. The observations allowed the collecting of important information concerning the feeding of the karst aquifer not only by infiltrating rainwater, but under present climate conditions also by water condensation of moist air flow. This contribution to the overall karst processes in the Cueva del Agua basin represents over 20% of the total chemical dissolution of the karst area and more than 50% of the speleogenetically removed gypsum in the cave system, thus representing all but a secondary role in speleogenesis. Condensation-corrosion is most active along the medium walls, being slower at the roof and almost absent close to the floor. This creates typical corrosion morphologies such as cupola, while gypsum flowers develop where evaporation dominates. This approach also shows quantitatively the morphological implications of condensation-corrosion processes in gypsum karst systems in arid zones, responsible for an

  2. Developing an Erosion Rate Map for Myanmar Using USLE, GIS and Remote Sensing

    Emtehani, Sobhan; Rutten, Martine


    Predicting erosion and estimating sediment loads in rivers are of major tasks in water resources system planning and management. In Myanmar erosion and collapse of river banks is common during the rainy season and riverine communities are frequently forced to relocate as their homes are dangerously close to the disintegrating river banks (Mann 2013). Myanmar is one of climatically most diverse countries located in Southeast Asia, where sheet, rill, and gully erosion affect crop yields as well as livelihood strategies of many people (Htwe, Brinkmann et al. 2015). In Myanmar, soil erosion measurement and monitoring approaches are increasingly important for land management planning to effectively avoid erosion and soil degradation, but such monitoring is limited by the availability of data and budgetary constraints. Therefore, spatial modeling approaches using GIS and remote sensing techniques play an important role for rapid risk assessments (Htwe 2016). In this study ''Model Builder'' tool in ArcGIS was used to create a model which generates an erosion rate map using Universal Soil Loss Equation (USLE). USLE is the product of five factors: rainfall erosivity factor (R), soil erodibility factor (K), slope length and steepness factor (LS), crop management factor (C), and support practice factor (P). Input data files for this model were acquired from online open source databases. Precipitation data was downloaded from Tropical Rainfall Measuring Mission (TRMM) for calculation of R factor. The resolution of TRMM data is very coarse (0.25 degree × 0.25 degree), therefore it was spatially downscaled by developing a relation between TRMM and Normalized Difference Vegetation Index (NDVI) using regression analysis method. Soil maps depicting percentages of sand, clay and silt were obtained from soilgrids website for calculation of K factor. Digital Elevation Model (DEM) with resolution of 90 meters was taken from Shuttle Radar Topography Mission (SRTM) for calculation of LS

  3. Simulating CRN derived erosion rates in a transient Andean catchment using the TTLEM model

    Campforts, Benjamin; Vanacker, Veerle; Herman, Frédéric; Schwanghart, Wolfgang; Tenrorio Poma, Gustavo; Govers, Gerard


    Assessing the impact of mountain building and erosion on the earth surface is key to reconstruct and predict terrestrial landscape evolution. Landscape evolution models (LEMs) are an essential tool in this research effort as they allow to integrate our growing understanding of physical processes governing erosion and transport of mass across the surface. The recent development of several LEMs opens up new areas of research in landscape evolution. Here, we want to seize this opportunity by answering a fundamental research question: does a model designed to simulate landscape evolution over geological timescales allows to simulate spatially varying erosion rates at a millennial timescale? We selected the highly transient Paute catchment in the Southeastern Ecuadorian Andes as a study area. We found that our model (TTLEM) is capable to better explain the spatial patterns of ca. 30 Cosmogenic Radio Nuclide (CRN) derived catchment wide erosion rates in comparison to a classical, statistical approach. Thus, the use of process-based landscape evolution models may not only be of great help to understand long-term landscape evolution but also in understanding spatial and temporal variations in sediment fluxes at the millennial time scale.

  4. Spatial and Temporal Changes in Bank Retreat Rates in a Small Headwater Stream

    Utley, B. C.; Wynn, T. M.


    Streambank retreat varies both spatially and temporally within any given system due to natural variability in both soil characteristics and hydraulic flow patterns. This study analyzes one year of monthly erosion pin data for Stroubles Creek, a small, urban, headwater stream in southwestern Virginia near the town of Blacksburg. The 400-m long study reach has 250 erosion pins installed on actively eroding streambanks. The pins are spaced every 10 m along the stream length, with 2-m spacing on more active section. Vertical pin spacing is 30 cm, starting at the bank toe. Streambank retreat rates were measured monthly from August 2005 to May 2007. The retreat data were evaluated for significant spatial patterns and correlation to climatic factors using Shapiro-Wilk test for normality and Kruskal-Wallis test for difference between groups. While spatial differences in retreat rates were not statistically significant, temporal variation was (p=0.0007): the highest erosion occurred during winter months of 2006 and 2007. The only exception to this trend occurred in July 2006, when a large, out-of-bank storm event occurred. Monthly erosion rates were calculated by two methods. The volume of bank eroded is often calculated from erosion pin data by averaging the measurements from several pins over a bank area then multiplying the average by the rough area of that bank. This study compared the results of the averaging method to a spatial interpolation and integration method computed with the computer program SURFER. The surfer analysis compared two surfaces, a surface of change to a plane with a value of zero. Theoretically, the spatial interpolation/integration technique allows more of the natural variability of system to be recognized and included in the calculations. The significant difference between volume calculation techniques is interesting, for 12 of 15 bank areas the averaging method estimated more erosion during the study period than the interpolation technique

  5. Swelling and erosion properties of hydroxypropylmethylcellulose (Hypromellose) matrices--influence of agitation rate and dissolution medium composition.

    Kavanagh, Nicole; Corrigan, Owen I


    The effect of dissolution medium variables, such as medium composition, ionic strength and agitation rate, on the swelling and erosion of Hypromellose (hydroxypropylmethylcellulose, HPMC) matrices of different molecular weights was examined. Swelling and erosion of HPMC polymers was determined by measuring the wet and subsequent dry weights of matrices. It was possible to describe the rate of dissolution medium uptake in terms of a square root relationship and the erosion of the polymer in terms of the cube root law. The extent of swelling increased with increasing molecular weight, and decreased with increasing agitation rate. The erosion rate was seen to increase with decrease in polymer molecular weight, with a decrease in ionic strength and with increasing agitation rate. The sensitivity of polymer erosion to the degree of agitation may influence the ability of these polymers to give reproducible, agitation-independent release, compared to more rigid non-eroding matrix materials, in the complex hydrodynamic environment of the gastrointestinal tract.

  6. Quantification of long-term erosion rates from root exposure/tree age relationships in an alpine meadow catchment

    Scuderi, Louis A.


    Erosion rates derived using dendrogeomorphology have been used to quantify slope degradation in many localities globally. However, with the exception of the western United States, most of these estimates are derived from short-lived trees whose lifetimes may not adequately reflect the complete range of slope processes which can include erosion, deposition, impacts of extreme events and even long-term hiatuses. Erosion rate estimates at a given site using standard techniques therefore reflect censored local point erosion estimates rather than long-term rates. We applied a modified dendrogeomorphic approach to rapidly estimate erosion rates from dbh/age relationships to assess the difference between short and long-term rates and found that the mean short-term rate was 0.13 cm/yr with high variability, while the uncensored long-term rate was 0.06 cm/yr. The results indicate that rates calculated from short-lived trees, while possibly appropriate for local short-term point estimates of erosion, are highly variable and may overestimate regional long-term rates by > 50%. While these findings do not invalidate the use of dendrogeomorphology to estimate erosion rates they do suggest that care must be taken to select older trees that incorporate a range of slope histories in order to best approximate regional long-term rates.

  7. Quantifying coastal erosion rates using anatomical change in exposed tree roots at Porquerolles Island (Var, France).

    Morel, Pauline; Corona, Christophe; Lopez-Saez, Jérôme; Rovéra, Georges; Dewez, Thomas; Stoffel, Markus; Berger, Frédéric


    Rocky coasts are the most common type of ocean-land contacts and can be found in all types of morphogenetic environments. Most work on rocky environments focused on the impacts of modern sea level rise on cliff stability derived from sequential surveys, direct measurements or erosional features in anthropogenic structures. Studies mainly focused on rapid erosion so that little is known about erosion rates of the French Mediterranean coastal area. Using anatomical reactions in roots, has been successfully used in various environments in the past to quantify continuous denudation rates, mostly in relation with gullying processes (Vandekerckhove, 2001; Malik, 2008), aerial (or sheet) (Bodoque et al., 2005; Lopez Saez et al., 2011; Lucia et al., 2011), river bank (Malik, 2006; Hitz et al., 2008a; Stoffel et al., 2012), or lake shore (Fantucci, 2007) erosion, but never so far on coastal cliffs environment. This study aims at exploring the potential of dendrogeomorphic approach to quantify multidecadal changes in coastal environments on Porquerolles Island (Var, France). We sampled 56 discs from Pinus halepensis Mill. roots on former alluvial deposits eroded by present day sea level (escarpments of a few meter in height) and on sandy-gravelly cliffs. We were able to dates erosion pulses as well as changes in cliff geometry with annual resolution over 30-40 years showing an average erosion rate of 2.1 cm yr-1. Our results are consistent with those found in the study of Giuliano (2015) on Mediterranean coastal environment. This contribution therefore demonstrates that dendrogeomorphic analyses of roots clearly have significant potential and are a powerful tool for the quantification of multidecadal cliff retreats rates in areas where measurements of past erosion is lacking. References: Bodoque J, Díez-Herrero A, Martín-Duque J, Rubiales J, Godfrey A, Pedraza J, Carrasco R, Sanz M. 2005. Sheet erosion rates determined by using dendrogeomorphological analysis of exposed

  8. The new conversion model MODERN to derive erosion rates from inventories of fallout radionuclides

    Arata, Laura; Meusburger, Katrin; Frenkel, Elena; A'Campo-Neuen, Annette; Iurian, Andra-Rada; Ketterer, Michael E.; Mabit, Lionel; Alewell, Christine


    The measurement of fallout radionuclides (FRNs) has become one of the most commonly used methods to quantify soil erosion and depositional processes. FRNs include anthropogenic radionuclides (e.g. 137Cs, 239+240Pu) released into the atmosphere during nuclear bomb tests and power plant accidents (e.g Chernobyl, Fukushima-Daiichi), as well as natural radiotracers such as 210Pbex and 7Be. FRNs reach the land surface by dry and wet fallouts from the atmosphere. Once deposited, FRNs are tightly adsorbed by fine soil particles and their subsequent redistribution is mostly associated with soil erosion processes. FRNs methods are based on a qualitative comparison: the inventory (total radionuclide activity per unit area) at a given sampling site is compared to that of a so called reference site. The conversion of FRN inventories into soil erosion and deposition rates is done with a variety of models, which suitability is dependent on the selected FRN, soil cultivation (ploughed or unploughed) and movement (erosion or deposition). The authors propose a new conversion model, which can be easily and comprehensively used for different FRNs, land uses and soil redistribution processes. This new model i.e. MODERN (MOdelling Deposition and Erosion rates with RadioNuclides) considers the precise depth distribution of a given FRN at a reference site, and allows adapting it for any specific site conditions. MODERN adaptability and performance has been tested on two published case studies: (i) a 137Cs study in an alpine and unploughed area in the Aosta valley (Italy) and (ii) a 210Pbex study on a ploughed area located in Romania. The results show a good agreement and a significant correlation (r= 0.91, p<0.0001) between the results of MODERN and the published models currently used by the FRN scientific community (i.e. the Profile Distribution Model and the Mass Balance Model). The open access code and the cost free accessibility of MODERN will ensure the promotion of a wider

  9. Soil erosion rates by wind-driven rain from a sandy soil in Denmark

    Fister, W.; Kuhn, N. J.; Itin, N.; Tesch, S.; Heckrath, G.; Ries, J. B.


    Soil erosion by wind and water is able to cause severe soil loss from agricultural fields. Laboratory studies in recent years have shown that wind most probably has an increasing effect on soil erosion rates by water. However, field studies have so far not been able to quantify and proof this assumption explicitly. Especially the differentiation between the influence of windless and wind-driven erosion seems to be the major issue. The objectives of this study were, therefore, to explicitly investigate the importance of wind-driven rain in relation to erosion rates without the effect of wind by applying a newly developed Portable Wind and Rainfall Simulator (PWRS) that is able to simulate the processes both separately and simultaneously. The PWRS was used on bare sandy soil near Viborg, Denmark. Prior to simulation the soil was ploughed and after consolidation harrowed to create surface structures and roughness representing typical conditions after seed bed preparation. To facilitate the separation of specific influences by wind-driven rain and to avoid systematic errors a defined order of four consecutive test runs was established: 0) single wind test run for 10 min, 1) single rainfall test run on dry soil, 2) single rainfall test run on moist soil, 3) simultaneous wind and rainfall test run (wind-driven rainfall). Each rainfall simulation lasted for 30 minutes with a 30 min break in between to allow for initial drainage of the soil and for remounting sediment catchers. By utilizing a gutter in combination with wedge-shaped sediment traps it was possible to separate between splash and runoff erosion from the 2.2 m2 plot. The results show a wide range of soil detachment raging from zero up to more than 500 g m-2 in 30 minutes. Five out of nine test sequences support the theory that wind-driven rain causes more erosion than windless rain. The relation between the two processes is therefore not as clear as expected and seems to be dominated by the natural variability

  10. Numerical Modelling of Wire-EDM for Predicting Erosion Rate of Silicon

    Joshi, Kamlesh; Sharma, Gaurav; Dongre, Ganesh; Joshi, Suhas Sitaram


    Recently, a lot of work is carried out in photovoltaic industry for slicing Si ingots using non-conventional technique like wire-EDM apart from conventional techniques like inner diameter saw and multi-wire saw. It is an emerging technology in field of Si wafer slicing and has a potential to be cost efficient. It reduces the kerf-loss and produces crack-free Si wafers. In general, the process of Si wafer cutting using wire-EDM is less understood due to its complex nature. In this work, the complex phenomena like formation of plasma channel, melting and erosion of Si material has been modelled mathematically. Further, the effect of input energy parameters like current, open voltage and pulse on-time on plasma and plasma-ingot interface temperature has been studied. The model is further extended along the length of the wire to evaluate the erosion depth and rate. The effect of process parameters on erosion depth and rate was validated experimentally. The model considers variation in material removal through the `plasma flushing efficiency'.

  11. Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold

    Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.


    In tropical watersheds, hillslope changes are producing increasing amounts of fine sediment that can be quickly carried to reefs by channels. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic level of 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of watersheds from soil creep to overland flow erosion increased both magnitude and frequency of sediment flooding adjacent reefs. We combined surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the Molokai reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located a subset of overland flow areas with vegetation cover below a threshold value preventing erosion. Here, feral goat grazing exposed cohesive volcanic soils whose low matrix hydraulic conductivities (1-20 mm/hour) promote Horton overland flow erosion. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshall flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance here and elsewhere to overland flow erosion, we deployed a Cohesive Strength Meter (CSM) to simulate the stresses of flowing water. At the 13.5 km 2 watershed mouth we used a USGS stream gage and ISCO sediment sampler to estimate total load. Over 2 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm depth for bare soil erosion. Sediment ratings curves for both hillslope and downstream catchment gages show strong clock-wise hysteresis during the first intense storms in the Fall, becoming linear later in the rainy

  12. Chemical weathering and erosion rates in the Lesser Antilles: An overview in Guadeloupe, Martinique and Dominica

    Rad, Sétareh; Rivé, Karine; Vittecoq, Benoit; Cerdan, Olivier; Allègre, Claude Jean


    Guadeloupe, Martinique and Dominica islands, like numerous tropical environments, have extreme weathering regimes. Physical denudation is mainly controlled by landslides, which reflect the torrential dynamics of the rivers. In Guadeloupe, the mechanical weathering rates vary between 800 and 4000 t/km2/yr. The lithology is very porous with high infiltration rates, which suggests that most of the element fluxes are produced in the subsurface, with chemical erosion rates 2-5 times higher than the rates from surface water. We show how the kinetics of chemical weathering rates depend on the age of the lava and subsurface circulation. In addition, erosion timescales were calculated from U-series analyses of river sediments. Our results show a broad range: 0-150 ka in Martinique and 0-60 ka in Guadeloupe. We evaluated residence times in river water on the basis of the dissolved load analyses. It appears that water circulation is globally 3-fold longer for subsurface water than for surficial water (Rad et al. 2011a,b). Moreover, these islands are highly impacted by agriculture. However, contrary to what one might think, our results show that human activity does not disturb critical zone processes. Indeed, we show that among the combined impacts of all parameters (climate, runoff, slope, vegetation, etc.), the basin's age seems to be the control parameter for chemical weathering and land use—the younger the basin, the higher the weathering rates. We could observe a combined effect between the higher erodibility and a higher climate erosivity of the younger reliefs.

  13. Sediment budget for Murder Creek, Georgia, USA, from Pu239+240 - determined soil erosion rates

    Stubblefield, A. P.; Matissoff, G.; Ketterer, M. E.; Whiting, P. J.


    Soil inventories of the radionuclides Cs137 and Pb210 have been used in a variety of environments as indicators for erosion and depositional processes. Development of sediment budgets for entire watersheds from radionuclide data has been somewhat constrained because limited sample numbers may not adequately characterize the wide range of geomorphic conditions and land uses found in heterogeneous environments. The measurement of Pu239+240 shows great potential for developing quantitative watershed sediment budgets. With inductively-coupled plasma mass spectrometry, hundreds of samples may be processed in dramatically shorter times than the gamma spectrometry method used for Cs137 or alpha spectrometry method used for Pb210. We collected surface soil samples from Murder Creek in the Piedmont region of Georgia, USA, to compare Pu239+240 inventories with Cs137 and Pb210 inventories for a range of land uses in a predominantly forested watershed. Excellent correlations were found for radionuclide inventories (r2 =0.88, n = 38) and high resolution (4 mm) depth profiles. The second objective was to generate a sediment budget using the full Pu239+240 dataset (n = 309). Average Pu239+240 inventories were 70.0 Bq/m2 for hardwood forest, 60.0 Bq/m2 for pine plantation, 65.1 Bq/m2 for pine forest, 66.7 Bq/m2 for row crop agriculture and 67.9 Bq/m2 for pasture. The sediment budget will be constructed by converting inventories into site-specific erosion rates. Erosion rates will be scaled up to the watershed scale using GIS coverages of land use, soil, slope, and slope position. Results will be compared with Murder Creek sediment budgets in the scientific literature generated from RUSLE erosion modeling, USGS monitoring networks and reservoir sedimentation.

  14. Decadal Erosion Rates Derived From An Earthquake-Induced Landslide Region, Central Taiwan

    Chan, Y.; Lu, C.; Chang, K.; Chen, R.


    The island of Taiwan is resulted from the collision between the Philippine sea plate and the Eurasian plate. The subtropical climate and averaging four typhoons annually, combined with frequent earthquakes, influence much of the Taiwan region. Due to the factors above, not only the active orogeny of Taiwan causes the high uplift rate at about 4 mm/yr, but also drive amazing erosion rate of about 3-6 mm/yr. Previous study indicated approximately 1.9% of global suspended sediment is derived from the small island of Taiwan, which is only about 0.024% of Earth’s subaerial surface. Furthermore, modern erosion rates are strongly influenced by large earthquakes and typhoons, and the sediment fluxes after the Mw 7.6 Chi-Chi earthquake of Taiwan are much higher than those before the earthquake. Here we study the Chiufenerhshan landslide, which is one of the large landslides triggered by the Chi-Chi earthquake in the central Taiwan. The avalanche transported a mass of sedimentary rock about 60 m thick and 1.5 km long. Based on the high-resolution topographic data sets from LiDAR or photogrammetry at various years and rain fall data, we have reached the following conclusions: In the period of 8.5 years after the Chi-Chi earthquake, almost 4.2% of the landslide deposits were transported out of the landslide system. Comparing with the mean annual erosion rate of 3-6 mm/yr in Taiwan, the sediment brought out of Chiufenerhshan landslide area is 89.4 mm/yr, a significant amount contributed by the landslide. The mean sediment discharge from this small system is as large as 0.064% of the sediment discharge from the whole Taiwan annually; while the area is only about 0.005% of Taiwan’s subaerial surface. Thus, the landslide process has contributed much more to the surface erosion of the Taiwan mountain than other erosion processes.

  15. Erosion rates across space and timescales from a multi-proxy study of rivers of eastern Taiwan

    Fellin, Maria Giuditta; Chen, Chia-Yu; Willett, Sean D.; Christl, Marcus; Chen, Yue-Gau


    We derive erosion rates from detrital zircon fission-track ages and cosmogenic nuclide concentrations from sediments from the modern rivers of eastern Taiwan in order to investigate how surface erosional processes vary in space and time across the young arc-continent collisional orogen of Taiwan. Taiwan is characterized by rapid rates of exhumation, a fluvial and landslide-dominated landscape, high seismicity, high relief and frequent typhoons. The obliquity between the convergence direction and the trend of the plate boundary provides a gradient in uplift and variations in longevity of orogenic activity with a young, immature orogen in the south, a mature orogen in central and northern Taiwan, and perhaps even the cessation of orogeny in the far north. The modern zircon fission-track detrital record is consistent with basement ages that show that much of the orogen is eroding at high rates with basin-wide mean zircon fission-track cooling ages as young as 0.9 Ma. The erosion rates derived from concentrations of cosmogenic nuclides (10Be) provide erosion rates averaged over much shorter timescales, but these two proxies provide estimates of erosion rates that are within error of each other across most of the collisional belt. Erosion rates are lowest in the immature zone of the orogen (erosion rates, suggesting that fluvial erosion is the dominant exhumation process and that landscape evolution is reacting primarily to tectonic forcing, fast enough to keep the landscape in a state of quasi-equilibrium where erosion rates and rock uplift rates are nearly equal. We find no measurable effects due to rock erodibility or precipitation rate, but if these parameters co-vary with tectonic uplift rate, our data could not resolve the influence of each.

  16. The contribution of mulches to control high soil erosion rates in vineyards in Eastern Spain

    Cerdà, Artemi; Jordán, Antonio; Zavala, Lorena; José Marqués, María; Novara, Agata


    Soil erosion take place in degraded ecosystem where the lack of vegetation, drought, erodible parent material and deforestation take place (Borelli et al., 2013; Haregeweyn et al., 2013; Zhao et al., 2013). Agriculture management developed new landscapes (Ore and Bruins, 2012) and use to trigger non-sustainable soil erosion rates (Zema et al., 2012). High erosion rates were measured in agriculture land (Cerdà et al., 2009), but it is also possible to develop managements that will control the soil and water losses, such as organic amendments (Marqués et al., 2005), plant cover (Marqués et al., 2007) and geotextiles (Giménez Morera et al., 2010). The most successful management to restore the structural stability and the biological activity of the agriculture soil has been the organic mulches (García Orenes et al; 2009; 2010; 2012). The straw mulch is also very successful on bare fire affected soil (Robichaud et al., 2013a; 2013b), which also contributes to a more stable soil moisture content (García-Moreno et al., 2013). The objective of this research is to determine the impact of two mulches: wheat straw and chipped branches, on the soil erosion rates in a rainfed vineyard in Eastern Spain. The research site is located in the Les Alcusses Valley within the Moixent municipality. The Mean annual temperature is 13 ºC, and the mean annual rainfall 455 mm. Soil are sandy loam, and are developed at the foot-slope of a Cretaceous limestone range, the Serra Grossa range. The soils use to be ploughed and the features of soil erosion are found after each thunderstorm. Rills are removed by ploughing. Thirty rainfall simulation experiments were carried out in summer 2011 during the summer drought period. The simulated rainfall lasted during 1 hour at a 45 mmh-1 intensity on 1 m2 plots (Cerdà and Doerr, 2010; Cerdà and Jurgensen 2011). Ten experiments were carried out on the control plots (ploughed), 10 on straw mulch covered plots, and 10 on chipped branches covered

  17. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.


    The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area

  18. Quantification of subaerial and episodic subglacial erosion rates on high latitude upland plateaus: Cumberland Peninsula, Baffin Island, Arctic Canada

    Margreth, Annina; Gosse, John C.; Dyke, Arthur S.


    Long-term rates of subaerial and episodic subglacial erosion by predominately cold-based ice cover are determined for tors on weathered plateaus on Cumberland Peninsula. By measuring terrestrial cosmogenic nuclide concentrations in differentially weathered surfaces on a given tor, we reconstruct the complex exposure and erosion history involving recurring cold-based ice cover. The style and rate of subaerial and subglacial erosion at multiple tor sites on Cumberland Peninsula are assessed with a Monte Carlo approach that computes plausible exposure histories based on a proxy record of global ice volume. Constant subaerial erosion rates by weathering are low (tors located on coastal ridge crests that have likely never been glaciated. Summit plateaus intermittently covered by cold-based ice throughout the Quaternary have experienced episodic subglacial erosion by plucking of fractured bedrock with rates between 1 and 16 mm ka-1. Variation of episodic erosion rates is associated with topographic position of the sampled tors and bedrock fracture density. Most of the tors were last glacially plucked in pre-ultimate glaciations, not during the Wisconsinan glaciation. Furthermore, the new approach provides evidence for the extent of ice coverage during the late Wisconsinan, which is significant if no erratics are available for exposure dating. Despite late Pleistocene intervals of ice cover and glacial plucking, tor-studded landscapes of Cumberland Peninsula are of considerable antiquity.

  19. Evaluation of soil erosion rates in the southern half of the Russian Plain: methodology and initial results

    Golosov, Valentin; Gusarov, Artem; Litvin, Leonid; Yermolaev, Oleg; Chizhikova, Nelly; Safina, Guzel; Kiryukhina, Zoya


    The Russian Plain (RP) is divided into two principally different parts. The northern half of the RP is a predominantly forested area with a low proportion of arable fields. In contrast, the southern half of the RP has a very high proportion of arable land. During the last 30 years, this agricultural region of the RP has experienced considerable land use transformation and changes in precipitation due to climate change have altered soil erosion rates. This paper describes the use of erosion model calculations and GIS spatial analytical methods for the evaluation of trends in erosion rates in the RP. Climate change (RIHMI World Data Center, 2016), land use transformation and crop rotation modification (Rosstat, 2016; R Core Team, 2016) are the main factors governing erosion rates in the region during recent decades. It was determined that mean annual erosion rates have decreased from 7.3 to 4.1 t ha-1 yr-1 in the forest zone mostly because of the serious reduction in the surface runoff coefficient for periods of snowmelt. At the same time, the erosion rates have increased from 3.9 to 4.6 t ha-1 yr-1 in the steppe zone due to the increasing frequency of heavy rain-storms.

  20. The effects of plant density of Melastoma malabathricum on the erosion rate of slope soil at different slope orientations

    Aimee Halim n; Osman Normaniza


    abstract Malaysia's cut slopes, especially for road lines accommodation, are prone to erosions and landslides. These problems mainly occur due to lack of vegetation cover and strong erosive forces. In addition, the topography factors have also become a major factor affecting soil degradation. Thus, this study is aimed at determining the effects of planting density of a selected species, namely Melastoma malabathricum;one, two, and three seedlings per box, on the erosion rate at selected slopes of different orientation (morning and evening sun) at the Guthrie Corridor Expressway, Selangor. In six months of observation, treatment with three seedlings/box on the morning sun slope showed a lower erosion rate by 69.2%than those with the same treatment on the evening sun slope. In addition, the treatment of the three seedlings recorded at month six (final observation) had the highest reduction of soil saturation level (STL), by 23.6%. Furthermore, the physiological values of the species studied, grown on the morning sun slope, were higher in terms of stomatal conductance and photosynthetic rate by 12.1%and15.8%(three seedlings/box), respectively. The overall results showed that plant density was inversely related to the STL and erosion rate on the slope. In conclusion, a planting density of three seedlings/box and morning sun orientation gave positive effects on the plant's physiological performance of the slope, reducing the STL, as well as alleviating the erosion rate of slope soils.

  1. Debris-flow deposits and watershed erosion rates near southern Death Valley, CA, United States

    Schmidt, K.M.; Menges, C.M.; ,


    Debris flows from the steep, granitic hillslopes of the Kingston Range, CA are commensurate in age with nearby fluvial deposits. Quaternary chronostratigraphic differentiation of debris-flow deposits is based upon time-dependent characteristics such as relative boulder strength, derived from Schmidt Hammer measurements, degree of surface desert varnish, pedogenesis, and vertical separation. Rock strength is highest for Holocene-aged boulders and decreases for Pleistocene-aged boulders weathering to grus. Volumes of age-stratified debris-flow deposits, constrained by deposit thickness above bedrock, GPS surveys, and geologic mapping, are greatest for Pleistocene deposits. Shallow landslide susceptibility, derived from a topographically based GIS model, in conjunction with deposit volumes produces watershed-scale erosion rates of ???2-47 mm ka-1, with time-averaged Holocene rates exceeding Pleistocene rates. ?? 2003 Millpress.

  2. Subcritical crack growth and mechanical weathering: a new consideration of how moisture influences rock erosion rates.

    Eppes, Martha-Cary; Keanini, Russell; Hancock, Gregory S.


    average contrast in thermal properties of adjacent minerals, and 4) cracking is suppressed with increasing depth at meter scales due to increasing confining pressure, and decreasing range of temperature cycling. We incorporated our crack growth model into a simple rock erosion model, describing only the case of intergranular cracking and associated granular disaggregation and spalling. Using this rock erosion model and local climate data, we will compare rock erosion rates calculated for different localities and rock types with those independently derived from 10Be cosmogenic radionuclide analysis of bedrock outcrops. Our analysis will potentially provide some of the first quantification of mechanistic links between mechanical weathering rates and climate at Earth's surface.

  3. The positive impact of European subsidies on soil erosion rates in orange plantations

    Keesstra, Saskia; Jordán, Antonio; Novara, Agata; Taguas, Tani; Pereira, Paulo; Brevik, Eric C.; Cerdà, Artemi


    Soil erosion in orchards and vineyards has been found non-sustainable due to bare soils due to the use of herbicides and tillage (Novara et al., 2011; Taguas et al., 2015; Ochoa et al., 2016; Rodrigo Comino et al., 2016a; 2016b; 2016c). Citrus plantations in sloping terrains are also non-sustainable from the soil erosion point of view due high erosion rates and the damage caused on infra-structures (Cerdà et al., 2009; 2009b; Cerdà et al., 2011; Pereira et al., 2015). This is not uncommon in Mediterranean type Ecosystems (Cerdà et al., 2010) but there is a need to reduce the soil and water losses to achieve sustainability (Brevik et al., 2015; Keesstra et al., 2016). The use of mulches, geotextiles, catch crops, and vegetation was found to be very successful as a sustainable strategy to reduce the soil losses (Giménez Morera et al., 2010; Mwango et al., 2016; Nawaz et al., 2016; Nishigaki et al., 2016; Prosdocimi et al., 2016). Nowadays, chipped branches are applied in orchards and vineyards because of European subsidies; however little scientific data is available on the impact of the chipped branches mulch on soil erosion. In an orange plantation in Eastern Valencia, at the L'Alcoleja experimental station the impact of these chipped branches was tested under 45 mm h-1 rainfall simulations on laboratory plots of 0.5 m2 under with different covers of chipped branches. The results show that with a cover of 20 % with chipped branches soil erosion reduces by 78 %. Acknowledgements The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement 603498 (RECARE project) and the CGL2013- 47862-C2-1-R and CGL2016-75178-C2-2-R national research projects. References Brevik, E. C., Cerdà, A., Mataix-Solera, J., Pereg, L., Quinton, J. N., Six, J., and Van Oost, K. 2015. The interdisciplinary nature of SOIL, SOIL, 1, 117-129, doi:10.5194/soil-1-117-2015, Cerdà, A. and M. F. Jurgensen

  4. Evaluating the Impacts of Climate Change on Soil Erosion Rates in Central Mexico

    Santos Martínez-Santiago


    Full Text Available Although water-eroded soil (WES resulting from human activities has been recognized as the leading global cause of land degradation, the soil erosion risks from climate change are not clear. Studies have reported that WES is the second most significant cause of soil loss in Mexico, and its future trajectory has not been sufficiently evaluated. The aims of this study are to 1 determine the impacts of climate change on WES and its distribution for the State of Aguascalientes, Mexico, and to 2 compare the present and future soil loss rates for the study unit (SU. The State of Aguascalientes is located in the “Region del Bajio.” The impact of climate change on WES was evaluated using the near-future divided world scenario (A2 presented in the IPCC Fourth Assessment Report. Daily temperature and precipitation data from 18 weather stations were downscaled to model historic laminar water erosion (HLWE and changes therein in the A2 near-future scenario for 2010–2039 (LWEScA2. Due to future changes in mean annual rainfall (MAR levels, a change in the LWEScA2 of between 1.6 and 8.9% could result in average soil losses up to 475.4 t ha-1 yr-1, representing a loss of slightly more than a 30-mm layer of mountain soil per year. The risk zones, classified as class 4 for LWE, are located to western of the State in part of municipalities of Calvillo, Jesus María, San José de Gracia y Cosio, where there are typical hills and falls with soil very sensitive to rain erosion.

  5. Assessment of soil erosion and deposition rates in a Moroccan agricultural field using fallout 137Cs and 210Pbex.

    Benmansour, M; Mabit, L; Nouira, A; Moussadek, R; Bouksirate, H; Duchemin, M; Benkdad, A


    In Morocco land degradation - mainly caused by soil erosion - is one of the most serious agroenvironmental threats encountered. However, only limited data are available on the actual magnitude of soil erosion. The study site investigated was an agricultural field located in Marchouch (6°42' W, 33° 47' N) at 68 km south east from Rabat. This work demonstrates the potential of the combined use of (137)Cs, (210)Pb(ex) as radioisotopic soil tracers to estimate mid and long term erosion and deposition rates under Mediterranean agricultural areas. The net soil erosion rates obtained were comparable, 14.3 t ha(-1) yr(-1) and 12.1 ha(-1) yr(-1) for (137)Cs and (210)Pb(ex) respectively, resulting in a similar sediment delivery ratio of about 92%. Soil redistribution patterns of the study field were established using a simple spatialisation approach. The resulting maps generated by the use of both radionuclides were similar, indicating that the soil erosion processes has not changed significantly over the last 100 years. Over the previous 10 year period, the additional results provided by the test of the prediction model RUSLE 2 provided results of the same order of magnitude. Based on the (137)Cs dataset established, the contribution of the tillage erosion impact has been evaluated with the Mass Balance Model 3 and compared to the result obtained with the Mass Balance Model 2. The findings highlighted that water erosion is the leading process in this Moroccan cultivated field, tillage erosion under the experimental condition being the main translocation process within the site without a significant and major impact on the net erosion.

  6. Determining eruption ages and erosion rates of Quaternary basaltic volcanism from combined U-series disequilibria and cosmogenic exposure ages

    Sims, Kenneth W. W.; Ackert, Robert P., Jr.; Ramos, Frank C.; Sohn, Robert A.; Murrell, Michael T.; Depaolo, Donald J.


    We present 238U-230Th -226Ra disequilibria and cosmogenic 3He and 36Cl data for the Bluewater flow of the Zuni-Bandera volcanic field in western New Mexico. The 238U-230Th disequilibria measured on separated groundmass phases yield an internal isochron age of 68 ka (+24/ 20 ka; 2σ). This value cannot be directly compared with surface exposure ages unless erosion rates are known. The apparent (zero erosion) ages determined from both the 3He concentration (47.5 ± 5 ka; 2σ) and the 36Cl concentration (41.2 ± 8.8 ka; 2σ) are significantly younger than the U-Th isochron age. When minimum estimates of surface erosion based on flow morphology are considered, the 3He concentrations indicate a minimum exposure age of 60 ka, in good agreement with the U-Th isochron age, with a minimum erosion rate of 1.7 mm/k.y. and an erosion rate as high as 5 mm/k.y. in other locations. Correcting for erosion has little effect on the model 36Cl age and, as a result, the 36Cl age is significantly younger than the U-Th isochron age and erosion-corrected 3He ages; this discordance is attributed to a lack of closed-system behavior in the 36Cl system. These new ages have local significance for the geochronology of the Zuni-Bandera volcanic field; however, their larger significance is in their applicability to dating Quaternary basalts and quantifying erosion rates.

  7. Erosion rates at the Mars Exploration Rover landing sites and long-term climate change on Mars

    Golombek, M.P.; Grant, J. A.; Crumpler, L.S.; Greeley, R.; Arvidson, R. E.; Bell, J.F.; Weitz, C.M.; Sullivan, R.J.; Christensen, P.R.; Soderblom, L.A.; Squyres, S. W.


    Erosion rates derived from the Gusev cratered plains and the erosion of weak sulfates by saltating sand at Meridiani Planum are so slow that they argue that the present dry and desiccating environment has persisted since the Early Hesperian. In contrast, sedimentary rocks at Meridiani formed in the presence of groundwater and occasional surface water, and many Columbia Hills rocks at Gusev underwent aqueous alteration during the Late Noachian, approximately coeval with a wide variety of geomorphic indicators that indicate a wetter and likely warmer environment. Two-toned rocks, elevated ventifacts, and perched and undercut rocks indicate localized deflation of the Gusev plains and deposition of an equivalent amount of sediment into craters to form hollows, suggesting average erosion rates of ???0.03 nm/yr. Erosion of Hesperian craters, modification of Late Amazonian craters, and the concentration of hematite concretions in the soils of Meridiani yield slightly higher average erosion rates of 1-10 nm/yr in the Amazonian. These erosion rates are 2-5 orders of magnitude lower than the slowest continental denudation rates on Earth, indicating that liquid water was not an active erosional agent. Erosion rates for Meridiani just before deposition of the sulfate-rich sediments and other eroded Noachian areas are comparable with slow denudation rates on Earth that are dominated by liquid water. Available data suggest the climate change at the landing sites from wet and likely warm to dry and desiccating occurred sometime between the Late Noachian and the beginning of the Late Hesperian (3.7-3.5 Ga). Copyright 2006 by the American Geophysical Union.

  8. Estimation of Soil Erosion Rates in Oil Palm Plantation with Different Land Cover

    Sahat, S.; Yusop, Z.; Askari, M.; Ziegler, A. D.


    Soil losses from hill slopes in oil palm plantation in Sedenak Estate, Johor were measured using runoff plot and rainfall simulator. The plot was designed to be removable but the size was fixed at 8 x 3.75m. Four types of surface covers were investigated for the plots, i.e. half bare soil and half grass cover (HGC), half bare soil and half dry frond (HDF), fully grass cover (FG), and fully bare soil (BS). The influence of initial soil moisture, saturated hydraulics conductivity, Ks, bulk density and slope on rates of soil loss were also evaluated. The rainfall simulator produced rainfall intensities between 90 and 160 mm/hr with durations from 45 to 60 min per run. BS plot exhibited the highest Ks value among all plots but the percentage of initial soil moisture on this surface was low. BS plot recorded the highest runoff coefficient (C) and soil loss values of 73.6 ± 4 percent and 5.26 ± 3.2 t/ha respectively, while the lowest was from plot FG with 41.7 ± 5.7 percent and soil loss of 2.85 ± 2.1 t/ha. Meanwhile, the results suggested that the ground cover had the ability to reduce soil loss by 67% and 17%, respectively for plots BS-HGC and BS-HDF. Overall, soil erosion control such as surface is effective measures in reducing level of runoff and soil erosion.

  9. Do higher erosion rates lead to topographic highs or lows? An example from the Puli Embayment, West-Central Taiwan

    Upton, P.; Mueller, K.; Tucker, G.; Wilcox, T.; Yanites, B.


    The Puli embayment, a 50 km wide, 1500m deep depression within the Foothills belt, Hsueshan Range and Backbone Ranges of western Taiwan, coincides with a >50 mgal negative bouguer gravity anomaly. The gravity low is consistent with a deep basin filled with lower density sediment, likely inherited from the passive margin presently being caught up in the collision between the Eurasian margin and the Luzon Arc forming Taiwan. The topography, specifically the Puli embayment, suggests the existence of an along strike variation in one or more of the parameters which control wedge development; the strength of the basal decollement or wedge material, the dip of the basal decollement or erosion rates. Three dimensional mechanical models show that a region of lower density fill within the outboard wedge of an actively deforming two-sided wedge will experience relatively more uplift while the main divide region behind the basin will experience relatively less uplift, the opposite of what is observed in Puli. It has previously been suggested that increased erosion was associated with this region of relatively lower relief. Localised high erosion rates have been shown to significantly influence the mechanical behaviour of collisional mountain belts on timescales of 1-5Ma where the wavelength of the erosional signal is on the order of the thickness of the brittle crust. Crustal aneurysms, such as those recognised in the indentor corners of the Himalaya, link enhanced erosion rates with the topographic highs of Nanga Parbat and Namche Bawa. Development of such an aneurysm is dependant upon both rapid uplift of hot lower crustal rocks and continued high erosion rates. While erosion rates in the Puli may have been higher in the past, leading to the topographic hole, they appear to have slowed in the last 50 ka, possibly due to a reduction in the rainfall associated with the lower topography, unlike the indentor corners where orogen-scale rivers maintain enhanced erosion rates.

  10. The barley straw residues avoid high erosion rates in persimmon plantations. Eastern Spain

    Cerdà, Artemi; González Pelayo, Óscar; Giménez-Morera, Antonio; Jordán, Antonio; Novara, Agata; Pereira, Paulo; Mataix-Solera, Jorge


    World persimmon production is 4 Millions tones and China produce more than 80 % of the total world yield. Korea and Japan are the second and the third producers respectively with 0.4 and 0.2 millions tones, and all three Asian countries concentrate more than 95 % of the world production. Spain produce less than 0.1 million tones but there is a sudden increase in new plantations due to the high prices and the new marked developed in Europe, Brazil and Arabic countries. The new chemically managed and highly mechanized plantations in Eastern Spain are using high doses of herbicides and the lack of vegetation is triggering high erosion rates. This paper aims to contribute with information about the soil losses on this new persimmon plantations and to develop strategies to reduce the soil and water losses. A 15 years old plantation of persimmon (Dyospirus lotus) was selected in Eastern Spain (Canals Municipality, La Costera District) to measure the soil losses on No-Tillage bare (herbicide treatments) management and on barley straw covered plots. The straw cover was applied 3 days before the expereriments at at doses that cover more than 50 % of the soil surface using 75 gr of straw per m2. Rainfall simulations under 55 mm h-1 rainfall intensity during one hour on 0.25 m2 plots were carried out on plots paired plots: bare and covered with straw. The measurements were carried out during July 2014 on paired plots, under very dry soil moisture contents ranging from 4.65 to 7.87 %. The results show that the 3% cover of vegetation of the control plots moved to more than 60% due to the application of the straw. This induced a delayed ponding (from 60 to 309 seconds) and surface runoff (from 262 to 815 seconds) and runoff outlet (418 to 1221 seconds). The runoff coefficients moved from 60 % in the control plots to 29 % in the straw covered and the runoff sediment concentration was dramatically reduced from 11 to 1 g l-1. The total soil losses were higher that 1 Kg per plot in

  11. Erosion rates deduced from Seasonal mass balance along an active braided river in Tianshan

    Y. Liu


    Full Text Available We report measurements performed during two complete flow seasons on the Urumqi River, a proglacial mountain stream in the northeastern ank of the Tianshan, an active mountain range in Central Asia. This survey of flow dynamics and sediment transport (dissolved, suspended and bed loads, together with a 25-year record of daily discharge, enables the assessment of secular denudation rates on this high mountain catchment of Central Asia. Our results show that chemical weathering accounts for more than one third of the total denudation rate. Sediment transported as bed load cannot be neglected in the balance given that sand and gravel transport accounts for one third of the solid load of the river. Overall, the mean denudation rates are low, averaging 46 t × km−2 × yr−1 (17–18 m Myr−1. We furthermore analyse the hydrologic record to show that the long-term sediment budget is not dominated by extreme and rare events but by the total amount of rainfall or annual runoff. The rates we obtain are in agreement with rates obtained from the mass balance reconstruction of the Plio-Quaternary gravely deposits of the foreland but signicantly lower than the rates recently obtained from cosmogenic dating of river sand. We show that the resolution of this incompatibility has an important consequence for our understanding of the interplay between erosion and tectonics in the semi-humid ranges of Central Asia.

  12. Ultrasonic monitoring of erosion/corrosion thinning rates in industrial piping systems.

    Honarvar, Farhang; Salehi, Farzaneh; Safavi, Vahid; Mokhtari, Arman; Sinclair, Anthony N


    Monitoring pipe wall erosion/corrosion thinning rates is an important issue in petrochemical and power generation industries. In this paper, two signal processing techniques are utilized for estimating the thinning rate based on ultrasonic pipe wall thickness data collected over a short period of time. The first is a combination of cross-correlation and polynomial curve fitting and the second is a model-based estimation (MBE) scheme. These techniques are applied to data collected from an accelerated thinning rate apparatus and both show that they are capable of estimating the thinning rates quickly in short time periods with good accuracy. In laboratory applications, thinning rates as low as 10 μm/year were measured within 15 days with an uncertainty of ±1.5 μm/year by both techniques. Although the MBE technique can yield marginally better accuracy, the greater stability and computational speed of the cross-correlation technique make it the preferred choice for industrial use.

  13. Web access and dissemination of Andalusian coastal erosion rates: viewers and standard/filtered map services.

    Álvarez Francoso, Jose; Prieto Campos, Antonio; Ojeda Zujar, Jose; Guisado-Pintado, Emilia; Pérez Alcántara, Juan Pedro


    The accessibility to environmental information via web viewers using map services (OGC or proprietary services) has become more frequent since newly information sources (ortophotos, LIDAR, GPS) are of great detailed and thus generate a great volume of data which barely can be disseminated using either analogue (paper maps) or digital (pdf) formats. Moreover, governments and public institutions are concerned about the need of facilitates provision to research results and improve communication about natural hazards to citizens and stakeholders. This information ultimately, if adequately disseminated, it's crucial in decision making processes, risk management approaches and could help to increase social awareness related to environmental issues (particularly climate change impacts). To overcome this issue, two strategies for wide dissemination and communication of the results achieved in the calculation of beach erosion for the 640 km length of the Andalusian coast (South Spain) using web viewer technology are presented. Each of them are oriented to different end users and thus based on different methodologies. Erosion rates has been calculated at 50m intervals for different periods (1956-1977-2001-2011) as part of a National Research Project based on the spasialisation and web-access of coastal vulnerability indicators for Andalusian region. The 1st proposal generates WMS services (following OGC standards) that are made available by Geoserver, using a geoviewer client developed through Leaflet. This viewer is designed to be used by the general public (citizens, politics, etc) by combining a set of tools that give access to related documents (pdfs), visualisation tools (panoramio pictures, geo-localisation with GPS) are which are displayed within an user-friendly interface. Further, the use of WMS services (implemented on Geoserver) provides a detailed semiology (arrows and proportional symbols, using alongshore coastaline buffers to represent data) which not only

  14. Geomorphic Flux From Himalayan Flashflood Equates to 1000 yrs Average Erosion Rate

    Sinclair, Hugh; Mudd, Simon; LeDivellec, Tom; Dallas, Kirsten; Andy, Hein


    Extreme flood events are increasingly reported from the western Himalaya; we use geomorphic analyses to reconstruct both the spatial distribution and approximate the recurrence interval for these events. During the summer of 2010, an enhanced monsoon resulted in extensive flooding of the Indus Valley of Pakistan. An unusual aspect of this event was the intense precipitation in the arid upper reaches of the Indus River in Ladakh. On August 5th, a mesoscale convective system caused intense, short-lived precipitation, with estimates of 75-100 mm falling in approximately 30 minutes. The short-lived convective nature of the rainfall meant TRMM data was unable to locate the main event. However, a geomorphic reconstruction of river discharge and hillslope activity demonstrates that the precipitation was limited to a 3 to 6 km wide band on the southward facing slopes of the Ladakh Range, and that this can be traced approximately 120 km along the strike of the range. In addition to mapping out the extent of the event, we also reconstruct the total flux mobilised on selected hillslopes by debris flows; this was achieved by measuring width/depth ratios across a range of scales, and then assigning a stream order to the debris flows which are then mapped over selected sub-catchments. This process provided a volume of mass flux which was then compared to background erosion rates derived from detrital cosmogenic 10Be measurements. This comparison reveals that the Ladakh event mobilised the equivalent of 800-1200 yrs of the mean background erosion rate in these catchments. Repeat 10Be measurements from the same catchments before and after the event record a reduction in concentrations which are explored in terms of the scale of debris flows principally responsible for the flux. Two years after the Ladakh event, another major flood event occurred in Uttarakhand, resulting in >5700 deaths. Initial investigations of the erosion of dated moraines and the deposition of new terraces

  15. The impact of standard preparation practice on the runoff and soil erosion rates under laboratory conditions

    Khaledi Darvishan, Abdulvahed; Homayounfar, Vafa; Hamidreza Sadeghi, Seyed


    The use of laboratory methods in soil erosion studies, rainfall simulation experiments, Gerlach troughs, and other measurements such as ring infiltrometer has been recently considered more and more because of many advantages in controlling rainfall properties and high accuracy of sampling and measurements. However, different stages of soil removal, transfer, preparation and placement in laboratory plots cause significant changes in soil structure and, subsequently, the results of runoff, sediment concentration and soil loss. Knowing the rate of changes in sediment concentration and soil loss variables with respect to the soil preparation for laboratory studies is therefore inevitable to generalize the laboratory results to field conditions. However, there has been little attention given to evaluate the effects of soil preparation on sediment variables. The present study was therefore conducted to compare sediment concentration and soil loss in natural and prepared soil. To achieve the study purposes, 18 field 1 × 1 m plots were adopted in an 18 % gradient slope with sandy-clay-loam soil in the Kojour watershed, northern Iran. A portable rainfall simulator was then used to simulate rainfall events using one or two nozzles of BEX: 3/8 S24W for various rainfall intensities with a constant height of 3 m above the soil surface. Three rainfall intensities of 40, 60 and 80 mm h-1 were simulated on both prepared and natural soil treatments with three replications. The sediment concentration and soil loss at five 3 min intervals after time to runoff were then measured. The results showed the significant increasing effects of soil preparation (p ≤ 0.01) on the average sediment concentration and soil loss. The increasing rates of runoff coefficient, sediment concentration and soil loss due to the study soil preparation method for laboratory soil erosion plots were 179, 183 and 1050 % (2.79, 2.83 and 11.50 times), respectively.

  16. Extreme soil erosion rates in citrus slope plantations and control strategies. A literature review

    Cerdà, Artemi; Ángel González Peñaloza, Félix; Pereira, Paulo; Reyes Ruiz Gallardo, José; García Orenes, Fuensanta; Burguet, María


    Soil Erosion is a natural process that shapes the Earth. Due to the impact of agriculture, soil erosion rates increase, landforms show gullies and rills, and soils are depleted. In the Mediterranean, wheat, olive and vineyards were the main agriculture products, but new plantations are being found in sloping terrain due to the drip-irrigation. This new strategy results in the removal of the traditional terraces in order to make suitable for mechanization the agriculture plantation. Citrus is a clear example of the impact of the new chemical agriculture with a high investment in herbicides, pesticides, mechanisation, land levelling and drip computer controlled irrigation systems. The new plantation of citrus orchards is found in the Mediterranean, but also in California, Florida, China and Brazil. Chile, Argentina, and South Africa are other producers that are moving to an industrial production of citrus. This paper shows how the citrus plantations are found as one of the most aggressive plantation due to the increase in soil erosion, and how we can apply successful control strategies. The research into the high erosion rates of citrus orchard built on the slopes are mainly found in China (Wu et al., 1997; Xu et al., 2010; Wang et al., 2011; Wu et al., 2011; Liu et al., 2011; Lü et al., 2011; Xu et al., 2012) and in the Mediterranean (Cerdà and Jurgensen, 2008; 2009; Cerdà et al., 2009a; 2009b; Cerdà et al., 2011; 2012) Most of the research done devoted to the measurements of the soil losses but also some research is done related to the soil properties (Lu et al., 1997; Lü et al., 2012; Xu et al., 2012) and the impact of cover crops to reduce the soil losses (Lavigne et al., 2012; Le Bellec et al., 2012) and the use of residues such as dried citrus peel in order to reduce the soil losses. There are 116 million tonnes of citrus produced yearly, and this affects a large surface of the best land. The citrus orchards are moving from flood irrigated to drip

  17. Comparison of two methodologies used to estimate erosion rates in Mediterranean ecosystems: (137)Cs and exposed tree roots.

    Rubio-Delgado, J; Guillén, J; Corbacho, J A; Gómez-Gutiérrez, Á; Baeza, A; Schnabel, S


    The (137)Cs deposited in soil and exposed tree roots have been widely applied to estimate medium-term soil erosion rates. However, comparative studies between these methods are scarce. For this purpose, three hillsides in two Mediterranean dehesas (rangeland with disperse tree cover) were selected. Regarding the (137)Cs technique, a reference site close to the study areas and with similar altitude and rainfall was selected. In order to reduce uncertainties related to the use of point soil profiles, all those collected in an area were combined to form a representative composite profile. The total inventory was 2790±50Bq/m(2), and the relaxation coefficient indicated it was an undisturbed soil. The radiocaesium inventory in the study areas was 14-23% lower than in the reference area. The erosion rates for (137)Cs were in the range 20.9-38.1tha(-1)y(-1). The exposed root technique was applied to holm oak trees (age about 90years), and the erosion rates were in the range 22-34tha(-1)y(-1). The ratio between exposed root and (137)Cs techniques was 1.02±0.11 (S.D.) within the range 0.89-1.2. Both methods produced very similar results equally with respect to the mean erosion rate as well as the relative difference between the hillslope sections, i.e. displaying the same spatial variation in the study areas. As the accounting time for these two techniques is different, 50 and 90y for (137)Cs and exposed roots respectively, results suggest that no change in mid-term erosion rates was implied for these areas for almost a century. The use of (137)Cs and exposed roots methodology for the determination of mean erosion rates can be reproduced in other ecosystems, but a careful selection of the reference site for (137)Cs is essential. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Predicting the Rate of River Bank Erosion Caused by Large Wood Log

    Zhang, N.; Rutherfurd, I.; Ghisalberti, M.


    When a single tree falls into a river channel, flow is deflected and accelerated between the tree roots and the bank face, increasing shear stress and scouring the bank. The scallop shaped erosion increases the diversity of the channel morphology, but also causes concern for adjacent landholders. Concern about increased bank erosion is one of the main reasons for large wood to still be removed from channels in SE Australia. Further, the hydraulic effect of many logs in the channel can reduce overall bank erosion rates. Although both phenomena have been described before, this research develops a hydraulic model that estimates their magnitude, and tests and calibrates this model with flume and field measurements, with logs with various configurations and sizes. Specifically, the model estimates the change in excess shear stress on the bank associated . The model addresses the effect of the log angle, distance from bank, and log size and flow condition by solving the mass continuity and energy conservation between the cross section at the approaching flow and contracted flow. Then, we evaluate our model against flume experiment preformed with semi-realistic log models to represent logs in different sizes and decay stages by comparing the measured and simulated velocity increase in the gap between the log and the bank. The log angle, distance from bank, and flow condition are systemically varied for each log model during the experiment. Final, the calibrated model is compared with the field data collected in anabranching channels of Murray River in SE Australia where there are abundant instream logs and regulated and consistent high flow for irrigation. Preliminary results suggest that a log can significantly increase the shear stress on the bank, especially when it positions perpendicular to the flow. The shear stress increases with the log angle in a rising curve (The log angle is the angle between log trunk and flow direction. 0o means log is parallel to flow with

  19. Towards quantifying long-term erosion rates in the Campine Basin, NE Belgium

    Beerten, Koen; Vanacker, Veerle


    The Campine Basin, NE Belgium, is situated between the uplifting Ardennes Massif and rapidly subsiding Roer Valley Graben. It contains a thick series of marine, estuarine and continental Neogene and Quaternary sediments, locally more than 300 m. As a result of relief inversion during the Quaternary, the Campine Plateau is nowadays a distinct morphological feature in this basin. Its surface elevation dips from 100 m in the south to 30 m in the north over a distance of about 60 km, which is the result of differential uplift. The Campine Plateau is covered by Early and Middle Pleistocene erosion-resistant fluvial sediments from the Rhine and Meuse and can thus be regarded as a fluvial terrace. The age of deposition and time of abandonment of the terrace have not yet been resolved by direct numerical dating. In this study, we apply the cosmogenic radionuclide (CRN) profiling technique that, in ideal circumstances, allows one to constrain the exposure age, burial age and amount of post-depositional erosion of the landform. Samples were taken from a 3.5 m deep cross-section in coarse river sands that were deposited by the river Rhine, and now situated at an altitude of about 50 m (a.s.l.). Nine of them were prepared for CRN measurements according to state-of-the-art techniques. The in-situ 10Be concentration of the samples was determined using accelerator mass spectrometry (ETH, Zurich). The in-situ 10Be concentrations are 1.5x10e5 atoms/g for the uppermost sample (at 0.3 m depth) and 0.9x10e5 at/g for the lowermost sample (at 3.1 m depth), yielding an estimated 0.6x10e5 at/g of radionuclide accumulation following sediment deposition. Using forward modelling, we solved for the exposure duration and erosion rate that best fit the measured in-situ 10Be depth profile data, nuclide inheritance and their associated analytical uncertainties. Model optimisation is here based on the sum of chi-squared between the measured and modelled 10Be concentrations. When taking previous

  20. CFD evaluation of erosion rate around a bridge near a sand dune

    He, Wei; Huang, Ning; Dun, Hongchao; Wang, Wenbo


    This study performs a series of simulations through solving the Navier-Stokes equations and the RNG k-ε turbulence model to investigate the wind erosion rates around a bridge in a desert area with sand dunes. The digital elevation model of sand dunes and the bridge model are obtained respectively from hypsographic map and construction drawings. Through combining them into the CFD software of Fluent the simulation zone was formed. The data of wind speed obtained from field observation is fitted into a logarithm format, which was imported into Fluent model as a inlet wind speed condition. Then, the effect of Dun-Go railway on wind-blown sand movement of the neighbouring environment is simulated. The results exhibit that affected by both the sand dune and bridge, the flow field is in a complex condition. It is also shown that the bridge in upstream of the sand dune will not increase the sand transport rate intensively, but change both wind velocity gradient and turbulence kinetic energy over surface of sand dune. On the other hand, when the bridge is built downstream the sand dune, simulation results show that sand deposition rate would be decreased in reference region downstream the pier.

  1. The Beryllium-10(meteoric)/ Beryllium-9 ratio as a new tracer of weathering and erosion rates

    von Blanckenburg, F.; Bouchez, J.; Wittmann, H.; Dannhaus, N.


    A perfect clock of the stability of the Earth surface is one that combines a first isotope the flux of which depends on the release rate during erosion, and a second isotope produced at constant rate. The ratio of the meteoric cosmogenic nuclide 10Be to stable 9Be, suggested to serve as proxy for weathering and erosion over the late Cenozoic [1], is such a system. We provide a quantitative framework for its use. In a weathering zone some of the 9Be, present typically in 2ppm concentrations in silicate minerals, is released and partitioned between a reactive phase (adsorbed to clay and hydroxide surfaces, given the high partition coefficients at intermediate pH), and into the dissolved phase. The combined mass flux of both phases is defined by the soil formation rate and a mineral dissolution rate - and is hence proportional to the chemical weathering rate and the denudation rate. At the same time, the surface of the weathering zone is continuously exposed to fallout of meteoric 10Be. This 10Be percolates into the weathering zone where it mixes with dissolved 9Be. Both isotopes may exchange with the adsorbed Be, given that equilibration rate of Be is fast relative to soil residence times. Hence a 10Be/9Be(reactive) ratio results from which the total denudation rate can be calculated. A prerequisite is that the flux of meteoric 10Be is known from field experiments or from global production models [2]. In rivers, when reactive Be and dissolved Be equilibrate, a catchment-wide denudation rate can be determined from both sediment and a sample of filtered river water. We have tested this approach in sediment-bound Be [3] and dissolved Be in water [4] of the Amazon and Orinoco basin. The reactive Be was extracted from sediment by combined hydroxylamine and HCl leaches. In the Amazon trunk stream, the Orinoco, Apure, and La Tigra river 10Be/9Be(dissolved) agrees well with 10Be/9Be(reactive), showing that in most rivers these two phases equilibrate. 10Be/9Be ratios range

  2. Climatically controlled increase in Quaternary erosion rates: An exploration of real and perceived biases from thermochronology data

    van der Beek, Peter; Schildgen, Taylor


    The potential increase of erosion rates over the last few million years in response to climate change and Quaternary glaciations remains controversial. Such an increase was initially inferred from the sedimentary record, but several authors have argued that this record is biased due to unresolved erosional hiatuses, and therefore the inferred increase in sedimentation rates is an artefact. More recently, the discussion has focused on erosional records from the source areas themselves; in particular records extracted from low-temperature thermochronology data. A global compilation of such data appears to show increasing erosion rates toward the present, but it has been argued that this increase may also be an artefact, for similar reasons that affect the sedimentary record. Here we assess real and perceived biases in the thermochronological record that might affect the inference of temporal variations in erosion rates from such data. We argue that it is unlikely that erosional hiatuses affect thermochronology data because the temporal and spatial scales at which such hiatuses might occur are significantly smaller than those that are resolved by the data. Instead, we explore the potential bias introduced by the erosional response time of thermochronological systems (defined as the time required to exhume rocks that are fully reset for the thermochronological system considered, i.e. to attain exhumational steady state). These response times are typically longer than the timescale of Quaternary glacial-interglacial cycles, implying that thermochronological systems are insensitive to such variations. For thermochronological data to record an overall increase in erosion rates, the increase must occur over longer time periods, independent of superimposed shorter-term variations. However, because the erosional response times depend strongly on the final exhumation rate, it is much easier to detect increases in erosion rates with thermochronological data than to detect

  3. Hillslope erosion rates in the oak savannas of the southwestern borderlands region

    Aaron T. Kauffman; Cody L. Stropki; Peter F. Ffolliott; Gerald J. Gottfried; Daniel G. Neary


    Hillslope soil erosion on watershed landscapes can lower the productivity of upland sites and adversely impact water quality and downstream (off-site) areas. It is not surprising, therefore, that excessive soil erosion and the consequent sedimentation can represent significant costs to the land and people that are affected. The first known estimates of hillslope soil...

  4. Laboratory soil piping and internal erosion experiments: evaluation of a soil piping model for low-compacted soils

    Soil piping has been attributed as a potential mechanism of instability for embankments, hillslopes, dams, and streambanks. In fact, deterministic models have been proposed to predict soil piping and internal erosion. However, limited research has been conducted under controlled conditions to evalua...

  5. The Diagnostic Utility of Anti-cyclic Citrullinated Peptide Antibodies, Matrix Metalloproteinase-3, Rheumatoid Factor, Erythrocyte Sedimentation Rate, and C-reactive Protein in Patients with Erosive and Non-erosive Rheumatoid Arthritis

    O. Shovman


    Full Text Available Objective: To compare the diagnostic utility of laboratory variables, including matrix metalloproteinase-3 (MMP-3, anti-cyclic citrullinated peptide (CCP antibodies, rheumatoid factor (RF, erythrocyte sedimentation rate (ESR, and C-reactive protein (CRP in patients with erosive and non-erosive rheumatoid arthritis (RA.

  6. A database on post-fire erosion rates and debris flows in Mediterranean-Basin watersheds

    Parise, M.; Cannon, S. H.


    proceedings. The database derives from critical analysis of the existing literature, integrated by case studies directly studied by the authors. Studies on recently burned areas in the Mediterranean basin are most frequently carried out on small experimental plots, often with simulated rainfall A problem of scale therefore exists when trying to extrapolate the erosion rates (also reported as sediment yields or as sediment losses) from these studies to a watershed scale. Very few articles, on the other hand, were found that document the watershed-scale response of basins to rainfall-induced erosion and debris flows following wildfires. The few reported cases of debris flows in the Mediterranean Basin describe erosion of sediment from the hillslopes and the channels (sometimes down to bedrock), and, for a limited number of sites, failure of discrete landslides. This information indicates that debris-flow generation from recently burned areas in the Mediterranean basin appears to occur primarily through sediment bulking processes. Nevertheless, the database so far compiled shows a distribution of post-fire erosion and debris flows in the western Mediterranean basin (Spain, essentially, but also Portugal), followed by the eastern Mediterranean area (Israel), and then by France, Italy and Greece. Even though still in a preliminary version, that needs to be integrated and updated from further sources, our data compilation allows for the unique opportunity to examine issues related to the generation of post-wildfire debris flows across a variety of environments and under a variety of conditions, and to move from a qualitative conception of the controls on post-fire debris-flow generation to the definition of specific conditions that result in their occurrence. Future activities of the project will include: i) updating and integration of the preliminary version of the database; ii) development of models that can be used to identify the probability of debris-flow occurrence and the

  7. Modeling the annual soil erosion rate in the mouth of river Pineios' sub-basin in Thessaly County, Greece.

    Ilia, Ioanna; Loupasakis, Constantinos; Tsangaratos, Paraskevas


    Erosion is a natural - geomorphological phenomenon, active through geological time that is considered as one of the main agents that forms the earth surface. Soil erosion models estimate the rates of soil erosion and provide useful information and guidance for the development of appropriate intervention and soil conservation practices and strategies. A significant number of soil erosion models can be found in literature; however, the most extensively applied model is the Revised Universal Soil Loss Equation (RUSLE) established in 1997 by Renard KG, Foster GR, Weesies GA, McCool DK and Yoder DC. RUSLE is an empirically based model that enables the estimation of the average annual rate of soil erosion for an area of interest providing several alternative scenarios involving cropping systems, management methods and erosion control strategies. According to RUSLE model's specifications five major factors (rainfall pattern, soil type, topography, crop system, and management practices) are utilized for estimating the average annual erosion through the following equation: A=RxKxLxSxCxP, PIC where A is the computed spatial average soil loss and temporal average soil loss per unit area (tons ha-1 year-1), R the rainfall-runoff erosivity factor (MJ mm ha-1h-1 year-1), K the soil erodibility factor (tons h MJ-1 mm-1), L the slope - length factor, S the slope steepness factor, C the cover management factor and P the conservation support practice factor. L, S, C and P factors are all dimensionless. The present study aims to utilize a GIS-based RUSLE model in order to estimate the average annual soil loss rate in the sub-basin extending at the mouth of Pineios river in Thessaly County, Greece. The area covers approximate 775.9 km2 with a mean slope angle of 7.8o. The rainfall data of 39 gauge station from 1980 to 2000 where used in order to predict the rainfall-runoff erosivity factor (R). The K-factor was estimated using soil maps available from the European Soil Portal with a

  8. The wildgeographer avatar shows how to measure soil erosion rates by means of a rainfall simulator

    Cerdà, Artemi; González Pelayo, Óscar; Pereira, Paulo; Novara, Agata; Iserloh, Thomas; Prosdocimi, Massimo


    This contribution to the immersed worlds wish to develop the avatar that will teach the students and other scientists how to develop measurements of soil erosion, surface runoff and wetting fronts by means of simulated rainfall experiments. Rainfall simulation is a well established and knows methodology to measure the soil erosion rates and soil hydrology under controlled conditions (Cerdà 1998a; Cerdà, 1998b; Cerdà and Jurgensen, 2011; Dunkerley, 2012; Iserloh et al., 2012; Iserloh et al., 2013; Ziadat and Taimeh, 2013; Butzen et al., 2014). However, is a method that requires a long training and expertise to avoid mismanagement and mistaken. To use and avatar can help in the teaching of the technique and the dissemination of the findings. This contribution will show to other avatars how to develop an experiment with simulated rainfall and will help to take the right decision in the design of the experiments. Following the main parts of the experiments and measurements the Wildgeographer avatar must develop: 1. Determine the objectives and decide which rainfall intensity and distribution, and which plot size to be used. Choose between a laboratory or a field rainfall simulation. 2. Design of the rainfall simulator to achieve the objectives: type of rainfall simulator (sprayer or drop former) and calibrate. 3. The experiments are carried out. 4. The results are show. Acknowledgements To the "Ministerio de Economía and Competitividad" of Spanish Government for finance the POSTFIRE project (CGL2013- 47862-C2-1-R). The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7-ENV-2013- supported this research. References Butzen, V., Seeger, M., Wirtz, S., Huemann, M., Mueller, C., Casper, M., Ries, J. B. 2014. Quantification of Hortonian overland flow generation and soil erosion in a Central European low mountain range using rainfall experiments. Catena, 113, 202-212. Cerdà, A

  9. Assessment of Holocene soil erosion rates on the loess plateau in East Poland using sedimentary archives from closed depressions

    Kołodyńska-Gawrysiak, Renata; Poesen, Jean; Gawrysiak, Leszek


    Closed depressions (CDs) are typical geomorphological features of the European loess belt. They are closed sedimentation basins that enable the estimation of long-term soil erosion rates for different land use environments. This study was conducted in eastern Poland (Nałęczów Plateau). In this region CDs are rather small landforms and the area of 70% of all CDs does not exceed 1500 m2. The study objective was to assess Holocene soil erosion rates in the loess plateau based on a quantitative analysis of colluvial sediments deposited in CDs. Two representative CDs were selected for this study: one CD is located in an old (long-term) forest and the other is situated in a long-term agricultural land. The maximum depth of the CD in the forest, the mean slope gradient and area of the corresponding catchment are 4.9 m, 3.410 and 7568 m² respectively. For the CD in agricultural land these values are 3.2 m, 2.760 and 5156 m² respectively. In both CDs several dozen of drillings and two trenches (2 m long, 1m wide, 2 m deep) were made in the deepest point of the CDs. Mean long-term soil erosion rates were calculated based on the stratigraphy of the soil-sediment sequence infilling the CDs. C-14 and OSL datings of soils and colluvial sediments within the CDs were obtained. For the long-term agricultural used catchment of the CD it was calculated that since 6.31 ± 0.35 ka BP the mean annual soil loss due to water and tillage erosion is 0.63-0.7 t/ha/year or 279.3 mm. In the prehistoric period since 6.31 ± 0.35 ka BP until 1026-1162 AD the mean annual soil erosion rate amounted to 0,10-0.11 t/ha/year or 41.5 mm. During the last ca. 1000 years mean soil erosion rates increased to 3.99-4.63 t/ha/year or 249.2 mm. Results of long-term soil erosion rates (calculated using colluvial sediment sequences in CDs) from agricultural catchments in the loess regions of eastern Poland (this study) and Central Belgium (Gillijns et al. 2005) are quite similar. For the forested catchment

  10. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel

    Ligotke, M.W.; Klopfer, D.C.


    Protective barriers have been identified as integral components of plans to isolate defense waste on the Hanford Site. The use of natural materials to construct protective barriers over waste site is being considered. Design requirements for protective barriers include preventing exposure of buried waste, and restricting penetration or percolation of surface waters through the waste zone. Studies were initiated to evaluate the effects of wind erosion on candidate protective barrier surfaces. A wind tunnel was used to provide controlled erosive stresses and to investigate the erosive effects of wind forces on proposed surface layers for protective barriers. Mixed soil and gravel surfaces were prepared and tested for resistance to wind erosion at the Pacific Northwest Laboratory Aerosol Wind Tunnel Research Facility. These tests were performed to investigate surface deflation caused by suspension of soil from various surface layer configurations and to provide a comparison of the relative resistance of the different surfaces to wind erosion. Planning, testing, and analyzing phases of this wind erosion project were coordinated with other tasks supporting the development of protective barriers. These tasks include climate-change predictions, field studies and modeling efforts. This report provides results of measurements of deflation caused by wind forces over level surfaces. Section 2.0 reviews surface layer characteristics and previous relevant studies on wind erosion, describes effects of erosion, and discusses wind tunnel modeling. Materials and methods of the wind tunnel tests are discussed in Section 3.0. Results and discussion are presented in Section 4.0, and conclusions and recommendations Section 5.0. 53 refs., 29 figs., 7 tabs.

  11. Modelling Deposition and Erosion rates with RadioNuclides (MODERN) - Part 1: A new conversion model to derive soil redistribution rates from inventories of fallout radionuclides.

    Arata, Laura; Meusburger, Katrin; Frenkel, Elena; A'Campo-Neuen, Annette; Iurian, Andra-Rada; Ketterer, Michael E; Mabit, Lionel; Alewell, Christine


    The measurement of fallout radionuclides (FRN) has become one of the most commonly used tools to quantify sediment erosion or depositional processes. The conversion of FRN inventories into soil erosion and deposition rates is done with a variety of models, which suitability is dependent on the selected FRN, soil cultivation (ploughed or unploughed) and movement (erosion or deposition). The authors propose a new conversion model, which can be easily and comprehensively used for different FRN, land uses and soil redistribution processes. The new model MODERN (Modelling Deposition and Erosion rates with RadioNuclides) considers the precise depth distribution of any FRN at the reference site, and allows adapting it for any specific site conditions. MODERN adaptability and performance in converting different FRN inventories is discussed for a theoretical case as well as for two already published case studies i.e. a (137)Cs study in an alpine and unploughed area in the Aosta valley (Italy) and a (210)Pbex study on a ploughed area located in the Transylvanian Plain (Romania). The tests highlight a highly significant correspondence (i.e. correlation factor of 0.91) between the results of MODERN and the published results of other models currently used by the FRN scientific community (i.e. the Profile Distribution Model and the Mass Balance Model). The development and the cost free accessibility of MODERN (see will ensure the promotion of wider application of FRNs for tracing soil erosion and sedimentation.

  12. 33 CFR 263.25 - Authority for emergency streambank and shoreline protection of public works and nonprofit public...


    ... streambank and shoreline protection of public works and nonprofit public services (Section 14). 263.25... and shoreline protection of public works and nonprofit public services (Section 14). (a) Legislative... year, for the construction, repair, restoration, and modification of emergency streambank and...

  13. Influence of streambank fencing on the environmental quality of cattle-excluded pastures.

    Miller, J J; Chanasyk, D S; Curtis, T; Willms, W D


    Limited information exists on the effect of streambank fencing on riparian zone pastures. The objective of this study was to test the hypothesis that 4 to 6 yr of streambank fencing would improve the environmental quality of the cattle-excluded pasture compared with the grazed pasture and cause the fenced pasture to act as a buffer or filter strip. Rangeland health, vegetative and soil properties, and rainfall simulation runoff were measured in the cattle-excluded and adjacent grazed native pastures along the fenced reach of the Lower Little Bow River in southern Alberta, Canada, for 3 yr (2005-2007). Rangeland health was improved (health score increase from 55 to 72%); vegetation cover (13-21%) and standing litter (38-742%) were increased; and bare soil (72-93%) and soil bulk density (6-8%) were decreased under cattle exclusion, indicating an improvement in environmental quality from streambank fencing. In contrast, other vegetation (total and live basal area, fallen litter) and soil properties (soil water and soil C, N, and P) were not improved by cattle exclusion. Cattle exclusion significantly (P fenced pasture may act as a buffer for certain runoff variables. In contrast, other runoff variables (turbidity, electrical conductivity, pH, concentrations and loads of total suspended solids, and certain N and P fractions) in the cattle-excluded pasture were generally not improved by streambank fencing. Overall, streambank fencing improved the quality of certain environmental variables within the cattle-excluded pasture.

  14. The use of 137Cs to establish longer-term soil erosion rates on footpaths in the UK.

    Rodway-Dyer, S J; Walling, D E


    There is increasing awareness of the damage caused to valuable and often unique sensitive habitats by people pressure as degradation causes a loss of plant species, disturbance to wildlife, on-site and off-site impacts of soil movement and loss, and visual destruction of pristine environments. This research developed a new perspective on the problem of recreational induced environmental degradation by assessing the physical aspects of soil erosion using the fallout radionuclide caesium-137 ((137)Cs). Temporal sampling problems have not successfully been overcome by traditional research methods monitoring footpath erosion and, to date, the (137)Cs technique has not been used to estimate longer-term soil erosion in regard to sensitive recreational habitats. The research was based on-sites within Dartmoor National Park (DNP) and the South West Coast Path (SWCP) in south-west England. (137)Cs inventories were reduced on the paths relative to the reference inventory (control), indicating loss of soil from the path areas. The Profile Distribution Model estimated longer-term erosion rates (ca. 40 years) based on the (137)Cs data and showed that the combined mean soil loss for all the sites on 'paths' was 1.41 kg m(-2) yr(-1) whereas the combined 'off path' soil loss was 0.79 kg m(-2) yr(-1), where natural (non-recreational) soil redistribution processes occur. Recreational pressure was shown to increase erosion in the long-term, as greater soil erosion occurred on the paths, especially where there was higher visitor pressure.

  15. The effect of wet-dry weathering on the rate of bedrock river channel erosion by saltating gravel

    Inoue, Takuya; Yamaguchi, Satomi; Nelson, Jonathan M.


    Previous work has shown that the bedrock erosion rate E because of collisions of saltating bedload can be expressed by E = βqb(1-Pc), where qb is the sediment transport rate, Pc is the extent of alluvial cover, and β is the abrasion coefficient. However, the dependence of the abrasion coefficient on the physical characteristics of the bedrock material is poorly known, and in particular, the effects of wet-dry weathering on the saltation-abrasion bedrock incision has not been specifically characterized. Observation suggests that the typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the incision rate of the material when subjected to impacts of moving sediment. In this study, flume experiments are performed to develop an understanding of how wet-dry cycling affects the rock tensile strength and the bedrock erosion rate. To represent the physical effects of weathering, boring cores taken from natural bedrock channel are exposed to artificial wet-dry cycles. The experimental results suggest the following: (1) the abrasion coefficient for fresh bedrock is estimated by β = 1.0 × 10- 4σT- 2(d/ksb)0.5, where σT is the tensile strength, d is the diameter of colliding gravel, and ksb is the hydraulic roughness height of bedrock; (2) the tensile strength of the bedrock decreases exponentially as a result of repeated wet-dry cycles, σT/σT0 = exp (-CTNWa0/σT0), where σT0 is the initial tensile strength, Wa0 is the initial normalized rate of water absorption., N is the number of wet-dry cycles, and CT is a constant; (3) the erosion rate of fresh bedrock depends on the inverse of the square of tensile strength, but the erosion rate of weathered bedrock depends on the - 1.5 power of tensile strength.

  16. Temporal and spatial variations in erosion rate in the Sikkim Himalaya as a function of climate and tectonics

    Abrahami, Rachel; Huyghe, Pascale; van der Beek, Peter; Carcaillet, Julien


    The Tista River is a major tributary of the Brahmaputra drainage system (Eastern Himalaya). Its headwaters are located in the glaciated northernmost parts of the Sikkim and its catchment area amounts to more than 12,000 km2 including a depositional megafan (extending mostly in Bangladesh and West Bengal-India). The Tista has recently incised its megafan at the topographic front of the mountain range by about 30 meters. Neither the timing of deposition/incision of the megafan sediments, nor the erosion rates of the source areas as well as their potential relationships, have been investigated in detail. Comparing these data is essential to distinguish between a climatic and/or tectonic control of the evolution of the Sikkim Himalaya and piedmont. To constrain erosion rates in the hinterland at different temporal scales (respectively millenial and geological timescales), we report cosmogenic nuclide (10Be) and thermochronological (apatite fission-tracks) data on modern river sands. Results were mapped to evidence spatial variations of erosion/exhumation rates in the Tista catchment. Cosmogenic nuclides were also used to date the onset of incision of the megafan and relate it to potential changes in hinterland erosion. In addition, isotope geochemistry (ɛNd and 87Sr/86Sr) performed on modern river sands and Late-Quaternary megafan sediments allows characterizing the isotopic signature of the different source areas and constraining variations in provenance of the Tista megafan deposits through time in response to changing climatic conditions. Results show that the Tista fan deposits are mainly sourced from the High Himalayan Crystalline domain with excursions more influenced by the Lesser Himalaya domain. These data provide a new comprehensive view on modern erosion and long-term exhumation of the Sikkim Himalaya. This study of a "closed system" will help our knowledge and understanding of erosional processes and sediment fluxes in mountainous environments as a

  17. Analysis of methods to determine the sediment retained by check dams and to estimate erosion rates in badlands.

    Ramos-Diez, Iván; Navarro-Hevia, Joaquín; San Martín Fernández, Roberto; Díaz-Gutiérrez, Virginia; Mongil-Manso, Jorge


    Check dams are useful structures at a catchment scale to determine erosion rates using the sediment retained in their wedges. Several studies employ different complex, accurate methods to estimate them. We likewise evaluate which catchment variables affect these erosion rate values. Our study aims to compare five frequently used methods (two prismatic and three topographic) to evaluate how they estimate total sediment yield (TSY) at two locations in Central Spain. For this purpose, we determine the sediment trapped in each area by 25 check dams built during the twentieth century. We also evaluate the catchment variables influencing TSY rates. Results show differences between methods in TSY determinations at the 90 % confidence level, although there are no differences between locations or the location-method iteration. We found that the natural logarithm of the drainage area was the factor that best explained TSY, presenting a negative trend (partial correlation coefficient, 0.83). Vegetation cover factor had no influence in estimating TSY for the two locations. We conclude that the determination of TSY rates depends on the chosen method and four related variables: check dam length, check dam height, wedge length and check dam drainage area. Furthermore, it is important to analyse and select the best method to estimate erosion rates based on the sediment retained by check dams depending on the characteristics of the study area (channel and sediment wedge shape), method accuracy and field effort. A more accurate estimation of erosion rates will allow researchers to determine the role of check dams in controlling sediment in each specific restoration project.

  18. Constructing a sequence of palaeoDEMs to obtain erosion rates in a drainage basin.N

    Castelltort, F. Xavier; Carles Balasch, J.; Cirés, Jordi; Colombo, Ferran


    DEMs made in a present-day drainage basin, considering it as a geomorphic unit, represent the end result of a landscape evolution. This process has had to follow a model of erosion. Trying to establish a conceptual erosion model in landscape evolution represents the first difficulty in constructing a sequence of palaeoDEMs. But if one is able to do it, the result will be easier and believable. The next step to do is to make a catalogue of base level types present in the drainage basin. The list has to include elements with determinate position and elevation (x, y, z) from the centre of the basin until hillslopes. A list of base level types may contain fluvial terrace remnants, erosive surfaces, palaeosols, alluvial covers of glacis, alluvial fans, rockfalls, landslides and scree zones. It is very important to know the spatial and temporal relations between the elements of the list, even if they are disconnected by erosion processes. Relative chronologies have to be set for all elements of the catalogue, and as far as possible absolute chronologies. To do it,it is essential to have established first the spatial relations between them, including those elements that are gone. Moreover, it is also essential to have adapted all the elements to the conceptual erosion model proposed. In this step, it has to be kept in mind that erosion rates can be very different in determinate areas within the same geomorphic unit. Erosion processes are focused in specific zones while other areas are maintained in stability. A good technique to construct a palaeoDEM is to start making, by hand, a map of contour lines. At this point, it is valuable to use the elements' catalogue. The use of those elements belonging to the same palaeosurface will result in a map. Several maps can be obtained from a catalogue. Contour maps can be gridded into a 3D surface by means of a specific application and a set of surfaces will be obtained. Algebraic operations can be done with palaeoDEMs obtaining

  19. Differential erosion by different-sized glaciers as reflected in 10Be-derived erosion rates of glacier valley walls, Kichatna Mts., Alaska

    Ward, D.; Anderson, R. S.


    The Kichatna Mountains, Alaska Range, Alaska comprise a dramatic landscape carved into a small ~65 Ma granitic pluton about 100 km west of Denali, in which kilometer-tall rock walls and “cathedral” spires tower over a radial array of over a dozen individual valley glaciers. The sheer scale of the relief speaks to the relative rates of valley incision by glaciers and rockwall retreat, but absolute rates are difficult to determine. We use cosmogenic 10Be to measure rockwall backwearing rates (and discuss several very important caveats to this use) on timescales of 103-104 yr, with a straightforward sampling strategy that exploits ablation-dominated medial moraines. In simple cases, a medial moraine and its associated englacial debris serve as a conveyor belt that brings supraglacial rockfall debris from the accumulation zone valley wall to a moraine crest in the ablation zone. Our samples come from the largest medial moraine on each of three glaciers. The northeast-flowing Trident glacier is the largest (15 km long, 1.4 km wide) and most deeply incised, and it has the lowest modern snowline in the range (~1200 m). Its primary medial moraine is sourced from west-facing sidewalls. The north-flowing Shadows glacier is slightly smaller (13 km long, 0.8 km wide) and has a large moraine sourced in dominantly east-facing sidewalls. The south-flowing Caldwell glacier is the smallest of the three (7 km long, 0.7 km wide), has a high modern snowline (~1500 m), and is nearly completely covered in debris. Its primary moraine is sourced from all south-facing aspects. These three glaciers share divides in their headwaters, and so are sourced in identical rock. Sidewall relief is similar (~1 km) in all three catchments. Each sample was amalgamated from 25-35 clasts collected over a 1 km longitudinal transect of each moraine. Replicate samples are internally consistent. The lowest 10Be concentrations (8000 at/g), and thus the highest inferred sidewall erosion rates (1.4 mm

  20. In-situ buildup of cosmogenic isotopes at the earth`s surface: measurement of erosion rates and exposure times

    Fifield, L.K.; Allan, G.L.; Stone, J.O.H.; Evans, J.M.; Cresswell, R.G.; Ophel, T.R. [Australian National Univ., Canberra, ACT (Australia)


    Cosmic rays produce a number of nuclides in rocks that can be used to determine the geomorphic history of surfaces. The most useful are the radioactive isotopes {sup 10}Be (t{sub 1/2} = 1.5Ma), {sup 26}Al (0.7Ma) and {sup 36}Cl (0.3Ma). Within the top 2m of the surface, these are produced principally by fast neutrons. At greater depths, production is dominated by the capture of negative muons. Measurements of a single nuclide produced in situ can be used to determine total exposure times or erosion rates. The use of multiple nuclides with different half-lives makes it possible to determine more complex histories, such as exposures interrupted by periods of burial. At the ANU, all three of the isotopes above are being used to study a variety of problems in geomorphology and paleoclimatology, although to date, most of the work has concentrated on {sup 36}Cl. The accumulation of cosmogenic {sup 36}Cl in calcite (CaCO{sub 3}) provides a means of measuring erosion rates on limestone surfaces. Sensitivity is achieved over a wide range of erosion rates due to the high production rate of {sup 36}Cl in calcite (typically greater than 30 atoms/g/yr) and a detection limit of ca. 5000 atoms/g attainable with the ANU AMS system. The method is simplified by the predominance of Ca reactions (principally spallation) over other sources of {sup 36}Cl in calcite, and the ease of sample preparation. This presentation discuss the results of measurements of {sup 36}Cl in calcite from limestone samples from Australia and Papua New Guinea. Erosion rates derived from these measurements range from 3 microns per year (Australia) to over 200 microns per year in the New Guinea highlands. 3 refs.

  1. The periglacial engine of mountain erosion – Part 1: Rates of frost cracking and frost creep

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou


    With accelerating climate cooling in the late Cenozoic, glacial and periglacial erosion became more widespread on the surface of the Earth. The resultant shift in erosion patterns significantly changed the large-scale morphology of many mountain ranges worldwide. Whereas the glacial fingerprint....... Here we investigate the important role that periglacial processes also play in less steep parts of mountain landscapes. Understanding the influences of frost-driven processes in low-relief areas requires a focus on the consequences of an accreting soil mantle, which characterises such surfaces. We...

  2. Erosion and its rate on an accumulative Polish dune coast: the effects of the January 2012 storm surge

    Tomasz A. Łabuz


    Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

  3. Patterns, rates and possible causes of saltmarsh erosion in the Greater Thames area (UK)

    Van der Wal, D.; Pye, K.


    The estuary-dominated coast of the Greater Thames in England has experienced rapid lateral erosion and internal dissection of saltmarshes. This paper provides an overview of saltmarsh development in this area, and re-examines the role of environmental and human forcing factors. It draws on documenta

  4. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    Ligotke, M.W.


    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs.

  5. Determining soil erosion rates on semi-arid watersheds using radioisotope-derived sedimentation chronology 2327

    This study investigates erosion dynamics of the past 90 years on three small semi-arid watersheds with histories of grazing and vegetation change. Activity of 137Cs and excess 210Pb from 18 cores collected from sedimentation ponds were measured using a gamma spectrometer. The sediment was dated usi...

  6. Soil erosion rates caused by wind and saltating sand stresses in a wind tunnel

    Ligotke, M.W.


    Wind erosion tests were performed in a wind tunnel in support of the development of long-term protective barriers to cap stabilized waste sites at the Hanford Site. Controlled wind and saltating sand erosive stresses were applied to physical models of barrier surface layers to simulate worst-case eolian erosive stresses. The goal of these tests was to provide information useful to the design and evaluation of the surface layer composition of an arid-region waste site barrier concept that incorporates a deep fine-soil reservoir. A surface layer composition is needed that will form an armor resistant to eolian erosion during periods of extreme dry climatic conditions, especially when such conditions result in the elimination or reduction of vegetation by water deprivation or wildfire. Because of the life span required of Hanford waste barriers, it is important that additional work follow these wind tunnel studies. A modeling effort is planned to aid the interpretation of test results with respect to the suitability of pea gravel to protect the finite-soil reservoir during long periods of climatic stress. It is additionally recommended that wind tunnel tests be continued and field data be obtained at prototype or actual barrier sites. Results wig contribute to barrier design efforts and provide confidence in the design of long-term waste site caps for and regions.

  7. Grazing impacts on the susceptibility of rangelands to wind erosion: The effects of stocking rate, stocking strategy and land condition

    Aubault, Hélène; Webb, Nicholas P.; Strong, Craig L.; McTainsh, Grant H.; Leys, John F.; Scanlan, Joe C.


    An estimated 110 Mt of dust is eroded by wind from the Australian land surface each year, most of which originates from the arid and semi-arid rangelands. Livestock production is thought to increase the susceptibility of the rangelands to wind erosion by reducing vegetation cover and modifying surface soil stability. However, research is yet to quantify the impacts of grazing land management on the erodibility of the Australian rangelands, or determine how these impacts vary among land types and over time. We present a simulation analysis that links a pasture growth and animal production model (GRASP) to the Australian Land Erodibility Model (AUSLEM) to evaluate the impacts of stocking rate, stocking strategy and land condition on the erodibility of four land types in western Queensland, Australia. Our results show that declining land condition, over stocking, and using inflexible stocking strategies have potential to increase land erodibility and amplify accelerated soil erosion. However, land erodibility responses to grazing are complex and influenced by land type sensitivities to different grazing strategies and local climate characteristics. Our simulations show that land types which are more resilient to livestock grazing tend to be least susceptible to accelerated wind erosion. Increases in land erodibility are found to occur most often during climatic transitions when vegetation cover is most sensitive to grazing pressure. However, grazing effects are limited during extreme wet and dry periods when the influence of climate on vegetation cover is strongest. Our research provides the opportunity to estimate the effects of different land management practices across a range of land types, and provides a better understanding of the mechanisms of accelerated erosion resulting from pastoral activities. The approach could help further assessment of land erodibility at a broader scale notably if combined with wind erosion models.

  8. Above the threshold for motion: erosion rates recorded in the bedload transport capacity of West Coast channels?

    Pfeiffer, A.; Finnegan, N. J.; Willenbring, J. K.


    Gravel-bedded river channels commonly evolve so that median sized grains on the bed surface are at, or near, the threshold for motion when the flow reaches bankfull stage. In addition, theory predicts the near- equivalence of the bankfull (bf) and critical (c) non-dimensional shear stresses (τ*bf ~= τ*c) for straight, cohesionless gravel channels. However, not all natural gravel channels conform to this simple relationship. To understand why some channels maintain bankfull stresses far in excess of what is needed to initiate sediment motion, we compile a dataset of the hydraulic geometry and median grain sizes of ~300 reaches from gravel-bedded rivers in North America. Notably, we find that the ratio of bankfull to critical Shields stresses is significantly higher in West Coast river reaches (2.6, n=77) than in river reaches in the rest of the continent (1.0, n=216). We explore the hypothesis that these reaches have adjusted to maintain a high excess shear stress at bankfull flows to accommodate elevated sediment supplies resulting from rapid erosion along the tectonically active margin of western North America. As a test of this hypothesis, we explore spatial patterns in calculated transport capacity and 10Be-derived erosion rates across North America. We find that an order of magnitude decrease in sediment transport capacity away from the Pacific plate boundary parallels an order of magnitude decrease in 10Be-derived erosion rates. These findings suggest that tectonically sustained high erosion rates on the West Coast may be recorded in the channel geometry and bed surface grain size of gravel-bedded channels.

  9. The Rise of Late Tertiary and Quaternary Erosion and Weathering Rates revisited (Ralph Alger Bagnold Medal Lecture)

    von Blanckenburg, Friedhelm


    The analyses of both modern river loads and chemical and physical hillslope denudation show that rates of weathering and erosion are tightly interlinked. An increase in silicate weathering through increased mountain erosion should therefore lead to global cooling by increased drawdown of atmospheric CO2. A five-fold increase of global sediment delivery was suggested for the last 5 Million years from a global compilation of sedimentation rates (1), and was also specifically suggested for the European Alps (2) and the India-Asia collisional area (3). While much research effort is currently being directed at explaining this increase, we should have been suspicious because this apparent increase in global erosion rate was not accompanied by a similar concomitant decrease in atmospheric CO2 as recorded by ocean alkalinity proxies. One possibility is that the increase in Neogene sedimentation rates is an artifact introduced by the discrepant time scale over which sedimentation is measured (4). The older the age, the longer the observational integration time will be, which in turn include longer periods of hiatus, and hence decreasing sedimentation rates with geologic time. An analysis of the records named above for time scale bias indeed suggests the possibility that erosion in these mountain belts might have been constant throughout the Neogene. An independent test of this hypothesis is provided by marine records of the isotopes of Beryllium (5). Be-10 is a rare radioactive cosmogenic nuclide, is produced mostly in the atmosphere and introduced to the surface oceans with a flux that can be considered to be globally uniform when averaged over time scales exceeding those of climate cycles. Be-9, in contrast, is stable, and enters the oceans from the continents mainly by river particulates (which are dissolved to some extent in the water column and during early diagenesis), in the dissolved form, and in minor amounts from dust. Should the global erosion rates have

  10. Soil water erosion under different cultivation systems and different fertilization rates and forms over 10 years

    Ildegardis Bertol


    Full Text Available The action of rain and surface runoff together are the active agents of water erosion, and further influences are the soil type, terrain, soil cover, soil management, and conservation practices. Soil water erosion is low in the no-tillage management system, being influenced by the amount and form of lime and fertilizer application to the soil, among other factors. The aim was to evaluate the effect of the form of liming, the quantity and management of fertilizer application on the soil and water losses by erosion under natural rainfall. The study was carried out between 2003 and 2013 on a Humic Dystrupept soil, with the following treatments: T1 - cultivation with liming and corrective fertilizer incorporated into the soil in the first year, and with 100 % annual maintenance fertilization of P and K; T2 - surface liming and corrective fertilization distributed over five years, and with 75 % annual maintenance fertilization of P and K; T3 - surface liming and corrective fertilization distributed over three years, and with 50 % annual maintenance fertilization of P and K; T4 - surface liming and corrective fertilization distributed over two years, and with 25 % annual maintenance fertilization of P and K; T5 - fallow soil, without liming or fertilization. In the rotation the crops black oat (Avena strigosa , soybean (Glycine max , common vetch (Vicia sativa , maize (Zea mays , fodder radish (Raphanus sativus , and black beans (Phaseolus vulgaris . The split application of lime and mineral fertilizer to the soil surface in a no-tillage system over three and five years, results in better control of soil losses than when split in two years. The increase in the amount of fertilizer applied to the soil surface under no-tillage cultivation increases phytomass production and reduces soil loss by water erosion. Water losses in treatments under no-tillage cultivation were low in all crop cycles, with a similar behavior as soil losses.

  11. Interim Field Evaluation of Windrow Revetment. Missouri River, Section 32, Streambank Erosion Control.


    CLY’,ON ’v AT v 9 eo - 0 C-.~ .. 0. 00. ( i 0O 0 CEA CONY 0 0 0 .. 0 0r 1 ~ . L0ON~~ DEMONSTRATION SIT ::X___ __ 0 0 CEA CONT DIO CUT LEGEN ZLITCN TETIR...RIE loo 3lIRVE 00 RANGE *6 AVG. VEL. FOR CHANNEL = 3.90 FPS 10 NOV. 1976 RAN %Q’:=S%-SEE NOTE I QGP = 35.000 CFS SEE Qvs = 3S,00CFS rNOTE 4 QLrv

  12. Report on: Connecticut River Streambank Erosion Study, Massachusetts, New Hampshire and Vermont


    streams having discharges less than 500,000 cfs ( Keown , Oswalt, Perry, and Bardeau, 1977). VEGETAT ION Vegetation of the banks has been observed to...the eroding values, and conse- qjuently, deposition of sediment may follow. Keown et al. (1977) reported that a well-established stand of selected...Vermont, Journal of the Boston Society of Civil Engineers, Vol. XXXVI, No. 1, January. Webster- Martin , Inc. 1971. Ecological Studies of the Connecticut

  13. Runoff erosion

    Evelpidou, Niki; Cordier, Stephane; Merino, Agustin (Ed.); Figueiredo, Tomás; Centeri, Csaba



  14. PENGKLASTERAN EROSI DI SUB DAS NGRANCAH KULONROGO (Soil Erosion Rates Clustering of Ngrancah Sub Watershed, Kulon Progo

    Ambar Kusumandari


    Full Text Available ABSTRAK Penelitian ini dilakukan di Sub DAS Ngrancah yang merupakan daerah tangkapan air Waduk Sermo. Luas wilayah penelitian ini sekitar 2.200 ha. Mayoritas lahan di Sub DAS Ngrancah tergolong kritis yang ditunjukkan oleh tingginya tingkat erosi. Dengan demikian, wilayah ini sangat mendesak untuk dapat dikelola dengan benar agar degradasi lahan dapat dihambat. Untuk memprediksi erosi, diterapkan Model USLE, dengan rumus: A = RKLSCP. Wilayah studi dapat dipilahkan menjadi 77 unit lahan. Sampel tanah diambil dari seluruh unit lahan, demikian pula pengamatan lereng, vegetasi, dan penerapan konservasi tanah. Untuk menganalisis data digunakan analisis kluster. Hasil penelitian menunjukkan bahwa tingkat erosi bervariasi dari yang paling rendah sebesar 2,54 ton/ha/th sampai dengan yang tertinggi sebesar 489,30 ton/ha/th. Sekitar 68% wilayah studi termasuk dalam kelas erosi sedang dan sekitar 15% wilayah studi termasuk dalam kelas erosi tinggi. Pengklasteran unit lahan secara statistik menunjukkan bahwa pada jarak klaster terpendek terbentuk 8 klaster tingkat erosi. Uji diskriminan menunjukkan bahwa faktor K (erodibilitas dan P (praktek konservasi tanah dan air merupakan faktor yang paling dominan untuk terbentuknya klaster-klaster tersebut. Hasil penelitian ini diharapkan bermanfaat dalam merancang teknik konservasi tanah dan air untuk menangani erosi di Sub DAS Ngrancah. ABSTRACT The research was carried out at Ngrancah Sub Watershed which is located at the upper area of Sermo Dam and covers an area of almost 2.200 hectares.  The area is mostly critical showed by the high rates of erosion, so, it is  urgently required to manage properly in order to combat  land degradation. In this research, to study the erosion rates of the area, the USLE method was used, i.e. A = RxKxLSxCxP. The area was devided into 77 land units and the soil samples were taken from each land units as well as the observation of slopes, vegetation and soil conservation practices

  15. Using Landsat imagery and GIS to constrain late Miocene paleorelief and rates of erosion in the Hangay Dome, Mongolia

    Smith, S. G.; Wegmann, K. W.; Bayasgalan, G.; Ancuta, L. D.; Gosse, J. C.


    Existing hypotheses maintain that the Hangay Dome of central Mongolia, situated significantly above continental freeboard and flanked by large strike-slip faults, is the result of relatively recent uplift, but ongoing geomorphological investigations of erosion rates, river incision, and paleotopography yield evidence to the contrary. For instance, Landsat Thematic Mapper (TM) imagery provides a unique opportunity to establish a 1st order approximation of local topographic relief at ~10 Ma. This age corresponds to the lowest layer in a thick (>600m) sequence of lava flows capping a 525 km2 area of high topography in the Hangay Dome (47.15°N, 100.05°E). The lava flows filled in and now preserve paleovalleys with ~700 m of local relief that are cut into basement. These paleovalleys exhibit similar relief to modern day, and are exposed along valley walls carved by Quaternary alpine glaciers. We quantify paleorelief in this remote mountain range by mapping the contact between basalt flows and granitic basement with ArcGIS and Landsat TM imagery. Spectral contrast between basalt and granite is maximized in a 1-5-6 band combination, and field mapping served to ground-truth the contact in certain areas. From this contact, a basal surface was interpolated and inferred to represent local topography at the time of the lowermost basalt flow (~10 Ma). Hypsometry, zonal statistics and topographic profile analysis indicate that relief of the relict surface is analogous to that of the present day. A similar GIS technique was applied to calculate the volume of rock removed since 6.13 Ma, which is the age for the uppermost, ridge-top basalt flow. In this experiment, a post-eruptive landscape was constructed by ';filling in' the post-lava flow valleys that are now incised into the upper lava flow surface. Subtracting the modern landscape from the post-eruptive surface yields the removal of 118 km3 of rock. Normalized for the study area, this results in a late Miocene to present net

  16. Assessing Soil Erosion Rates on Manually-Tilled Hillslopes in the Sichuan Hilly Basin Using 137Cs and 210Pbex Measurements

    ZHENG Jin-Jun; HE Xiu-Bin; D. WALLING; ZHANG Xin-Bao; D. FLANAGAN; QI Yong-Qing


    Purple soils are widely distributed in the Sichuan Hilly Basin and are highly susceptible to erosion, especially on the cultivated slopes. Quantitative assessment of the erosion rates is, however, difficult due to small size of the plots of the manually-tilled land, the complex land use, and steep hillslopes. 137Cs and 210Pbex (excess 210Pb) tracing techniques were used to investigate the spatial pattern of soil erosion rates associated with slope-land under hoe tillage in Neijiang of the Sichuan Hilly Basin. The 137Cs and 210Pbex inventories at the top of the cultivated slope were extremely low, and the highest inventories were found at the bottom of the cultivated slope. By combining the erosion rates estimates provided by both 137Cs and 210Pbex measurements, the weighted mean net soil loss from the study slope was estimated to be 3100 t km-2 year-1, which was significantly less than 6930 t km-2 year-1 reported for runoff plots on a 10°cultivated slope at the Suining Station of soil Erosion. The spatial pattern of soil erosion rates on the steep agricultural land showed that hoe tillage played an important role in soil redistribution along the slope. Also, traditional farming practices had a significant role in reducing soil loss, leading to a lower net erosion rate for the field.

  17. The effect of wet-dry weathering on the rate of bedrock river channel erosion by saltating gravel

    Inoue, Takuya; Yamaguchi, Satomi; Nelson, Jonathan M.


    Previous work has shown that the bedrock erosion rate E because of collisions of saltating bedload can be expressed by E = βqb(1-Pc), where qb is the sediment transport rate, Pc is the extent of alluvial cover, and β is the abrasion coefficient. However, the dependence of the abrasion coefficient on the physical characteristics of the bedrock material is poorly known, and in particular, the effects of wet-dry weathering on the saltation-abrasion bedrock incision has not been specifically characterized. Observation suggests that the typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the incision rate of the material when subjected to impacts of moving sediment. In this study, flume experiments are performed to develop an understanding of how wet-dry cycling affects the rock tensile strength and the bedrock erosion rate. To represent the physical effects of weathering, boring cores taken from natural bedrock channel are exposed to artificial wet-dry cycles. The experimental results suggest the following: (1) the abrasion coefficient for fresh bedrock is estimated by β = 1.0 × 10− 4σT− 2(d/ksb)0.5, where σT is the tensile strength, d is the diameter of colliding gravel, and ksb is the hydraulic roughness height of bedrock; (2) the tensile strength of the bedrock decreases exponentially as a result of repeated wet-dry cycles, σT/σT0 = exp (-CTNWa0/σT0), where σT0 is the initial tensile strength, Wa0 is the initial normalized rate of water absorption., N is the number of wet-dry cycles, and CT is a constant; (3) the erosion rate of fresh bedrock depends on the inverse of the square of tensile strength, but the erosion rate of weathered bedrock depends on the − 1.5 power of tensile strength.

  18. The Rates and Spatial Patterns of Annual Riverbank Erosion Revealed Through Terrestrial Laser Scanner Surveys of the South River, Virginia

    O'Neal, M. A.; Pizzuto, J. E.


    Between 2006 and 2008 A.D., we completed annual surveys of two mercury-contaminated eroding banks, one forested and the other grass covered, along the gravel-bed, bedrock South River in Virginia. Gridded digital terrain models with a resolution of 0.05 m were created from bank topography data collected using a terrestrial laser scanner. The forested bank retreated nearly 1 m around two leaning trees, while elsewhere the extent of bank retreat was negligible. On the grassy bank, retreat was controlled by the creation of small overhanging clumps of turf at the top of the bank, their occasional failure, and the ultimate removal of failed debris from the bank toe. Partial autocorrelation analysis of vertically integrated bank retreat demonstrates that bank profile erosion is virtually uncorrelated at horizontal distances greater than about 1 m on both banks, a length scale of approximately 1/2 the bank height. This extensive streamwise variability suggests that widely spaced profile data cannot adequately represent bank erosion at these sites. Additional analysis of our comprehensive spatial data also indicates that traditional bank profile surveys with any spacing greater than 1 m would result in measurement errors exceeding 10%, an important conclusion for assessing annual rates of mercury loading into the South River from bank erosion. Our results suggest that 3-dimensional gridded bare-earth models of bank topography may be required to accurately measure annual bank retreat in similar river systems.

  19. Surface reconstruction and derivation of erosion rates over several glaciations (1 Ma) in an alpine setting (Sinks Canyon, Wyoming, USA)

    Züst, Fabian; Dahms, Dennis; Purves, Ross; Egli, Markus


    At middle to high latitudes, many alpine valleys have been shaped by glaciers associated with periods of Pleistocene glaciation. Present glaciated valleys are characterised by broadened valley floors and U-shaped cross sections, continuously formed by glacial activity from initially V-shaped, fluvial cross sections. Sinks Canyon (Wind River Range, USA) is a glaciated valley characterised by a typical U-shaped cross section, containing till from several glacial advances over a range of at least 1 Ma. The morphostratigraphic records indicate a fourfold difference in ice surface elevation between the youngest and oldest glacial periods, which is not easily explained by the present-day valley topography. To assess possible evolution scenarios of Sinks Canyon, we modelled the palaeovalley topography using a geographic information system (GIS) filtering technique in combination with temporal reference points from relative and numerically dated glacial deposits. Ice thicknesses were calculated using the shallow ice approximation. In our model, the valley became shallower and the topography smoother with increasing years back in time. The results suggest that valley topography with ages between 640 and 1000 ka can clearly be distinguished from the present-day topography. Surfaces with ages of 130-200 ka (attributable to MIS 6; Bull Lake glaciation) still could be discerned from present-day topography, but with relatively high uncertainties. The method did not work for topography less than ~ 100 ka or older than ~ 1 Ma. Erosion depths were calculated using the differences between present-day elevation and the modelled surfaces. Calculated erosion rates were within the range of reference values for glacial erosion (0.001 to 1 mm a- 1). Glacial erosion appears to have removed 0.52 to 0.72 mm a- 1 of rock within a time frame of 1 Ma, assuming 200 ka of aggregated glacial flow. If the glacial occupation was longer or the impact of fluvial erosion was not negligible (as assumed

  20. Extreme Uplift and Erosion Rates in Eastern Himalayas (Siang-Brahmaputra Basin) Revealed by Detrital (U-Th)/He Termochronology

    Tibari, B.; Pik, R.; France-Lanord, C.; Carignan, J.; Lave, J.


    The distribution of erosion intensity in a major mountain range such as the Himalaya is a fundamental clue to investigate the interaction between climatic, tectonic and erosion processes that govern the morphology and evolution of an orogen. At the first order, the sediment flux measured on the two major rivers - Ganga and Brahmaputra - suggest higher mean denudation rates for the Eastern Himalaya than Western Himalaya (Galy and France-Lanord, 2001). However, the distribution of erosion in the Brahmaputra basin is not uniform and the Namche Barwa area, drained by the Siang-Tsangpo, appears to supply up to 50 % of the total sediment flux of the Brahmaputra (Singh and France-Lanord, 2002). In order to further constrain the relationships between such localized erosion and the associated exhumation rate of basement, we measured (U-Th)/He ages in detrital zircons from river sediments in the Brahmaputra basin. This thermochronological system (Z-He) is particularly interesting for detrital material because: (i) zircon is preserved during weathering and erosion processes, (ii) its closure temperature (150-180°C, Reiners et al., 2004) corresponds to a depth which is close to the surface but deep enough to avoid perturbations by topography variations, and (iii) the error associated to single grain measurement (8-10 %) allows a good definition of population ages. Z-He ages from the Brahmaputra river in Bangladesh range from 0.4 to 77 Ma. 40 % of the zircon population exhibit Z-He ages between 0.4 and 1 Ma defining the major distribution peak centred at 0.5 Ma. These very young ages correspond to extreme denudation rates of 5 to 7 mm/yr. Dispersed Z-He ages from 12 to 77 Ma do not define any population groups, whereas the remaining 40 % of the zircons have ages distributed between 2.5 and 7 Ma, which correspond to the pool of ages recorded by preliminary Z-He ages on the other Himalayan rivers of the basin. Therefore, such very high denudation rates (5-7 mm/yr) seems to

  1. The diagnostic utility of anti-cyclic citrullinated peptide antibodies, matrix metalloproteinase-3, rheumatoid factor, erythrocyte sedimentation rate, and C-reactive protein in patients with erosive and non-erosive rheumatoid arthritis.

    Shovman, O; Gilburd, B; Zandman-Goddard, G; Sherer, Y; Orbach, H; Gerli, R; Shoenfeld, Y


    To compare the diagnostic utility of laboratory variables, including matrix metalloproteinase-3 (MMP-3), anticyclic citrullinated peptide (CCP) antibodies, rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) in patients with erosive and non-erosive rheumatoid arthritis (RA). We assembled a training set, consisting of 60 patients with RA, all fulfilling the revised criteria of the American College of Rheumatology. A commercial enzyme linked immunosorbent assay (ELISA) was used both to test for anti-CCP antibodies (second generation ELISA kit) and MMP; RF were detected by latex-enhanced immunonephelometric assay. CRP was measured by latex turbidimetric immunoassay. The levels of anti-CCP antibody titers and ESR were significantly higher in patients with erosive disease than those in non-erosive RA patients (p elevated titers of anti-CCP antibodies was found in RA patients with erosions compared to patients with non-erosive RA (78.3% vs. 43.2% respectively). The ROC curves of anti-CCP passed closer to the upper left corner than those other markers and area under the curve (AUC) of anti-CCP was significantly larger than AUC of other markers (0.755 for anti-CCP, 0.660 for ESR, 0.611 for CRP, 0.577 for RF, and 0.484 for MMP-3 female). A positive predictive value was higher for anti-CCP antibodies in comparison to other markers. We did not find significant statistical correlation between anti-CCP antibody titers and inflammatory markers such as ESR or CRP. However, we confirmed the correlation of elevated titers of anti-CCP antibodies and RF in both groups of patients whereas the degree of correlation was more significant in non-erosive patients. The results of our study suggest that the presence of elevated anti-CCP antibody titers have better diagnostic performance than MMP-3, RF, CRP and ESR in patients with erosive RA.

  2. A theoretical approach to evaluate the release rate of acetaminophen from erosive wax matrix dosage forms.

    Agata, Yasuyoshi; Iwao, Yasunori; Shiino, Kai; Miyagishima, Atsuo; Itai, Shigeru


    To predict drug dissolution and understand the mechanisms of drug release from wax matrix dosage forms containing glyceryl monostearate (GM; a wax base), aminoalkyl methacrylate copolymer E (AMCE; a pH-dependent functional polymer), and acetaminophen (APAP; a model drug), we tried to derive a novel mathematical model with respect to erosion and diffusion theory. Our model exhibited good agreement with the whole set of experimentally obtained values pertaining to APAP release at pH 4.0 and pH 6.5. In addition, this model revealed that the eroding speed of wax matrices was strongly influenced by the loading content of AMCE, but not that of APAP, and that the diffusion coefficient increased as APAP loading decreased and AMCE loading increased, thus directly defining the physicochemical properties of erosion and diffusion. Therefore, this model might prove a useful equation for the precise prediction of dissolution and for understanding the mechanisms of drug release from wax matrix dosage forms. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Erosion and Errors

    Huisman, H.; Heeres, Glenn; Os, van Bertil; Derickx, Willem; Schoorl, J.M.


    Slope soil erosion is one of the main threats to archaeological sites. Several methods were applied to establish the erosion rates at archaeological sites. Digital elevation models (DEMs) from three different dates were used. We compared the elevations from these three models to estimate erosion. We

  4. Mercury flow experiments. 4th report Measurements of erosion rate caused by mercury flow

    Kinoshita, H; Hino, R; Kaminaga, M


    The Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a construction plan of the Material-Life Science Facility, which is consisted of a Muon Science Facility and a Neutron Scattering Facility, in order to open up the new science fields. The Neutron Scattering Facility will be utilized for advanced fields of Material and Life science using high intensity neutron generated by the spallation reaction of a 1 MW pulsed proton beam and mercury target. Design of the spallation mercury target system aims to obtain high neutron performance with high reliability and safety. Since the target system is using mercury as the target material and contains large amount of radioactive spallation products, it is necessary to estimate reliability for strength of instruments in a mercury flow system during lifetime of the facility. Piping and components in the mercury flow system would be damaged by erosion with mercury flow, since these components will be we...

  5. Estimating rates of coastal cliff erosion in a small island using terrestrial laser scanning and RPAS-based SfM-MVS photogrammetry

    Hayakawa, Yuichi S.; Obanawa, Hiroyuki


    Rapid erosion of coastal cliffs has been historically observed to be more than 1 m/y in the outer Boso Peninsula area, eastern Japan. However, due to the modern work of coastal protection, the erosion rates of the coastal cliffs have significantly decreased. This caused coastal erosion in the nearby sand beach, to which sands had been supplied from the formerly eroded rocky coast. In order to assess the relationships between erosion and protection in both rocky and sandy coasts, quantitative evaluation of erosion rates by natural processes would be necessary. The Suzume-jima Island, a small coastal island in the outer Boso Peninsula area, is an ideal site, which is located outside of the coastal protection and natural processes of erosion can still be observed. Here we carried out multiple measurements of the entire shape of the island using remotely piloted aerial system (RPAS) and structure-from-motion multi-view stereo (SfM-MVS) photogrammetry. Terrestrial laser scanning is also performed for the accuracy assessment. The high-frequency (3 times a year) and high-resolution (cm) measurements of the small island for 3 years revealed spatially variable rockfalls and wave erosion, whose volume of mass has been quantitatively revealed from the 3-D point cloud obtained. The relatively short-term measurements are also compared with the long-term 2-D topographic changes in the island by aerial photographs for 50 years.

  6. Catchment-scale denudation and chemical erosion rates determined from 10Be and mass balance geochemistry (Mt. Lofty Ranges of South Australia)

    Bestland, Erick A.; Liccioli, Caterina; Soloninka, Lesja; Chittleborough, David J.; Fink, David


    Global biogeochemical cycles have, as a central component, estimates of physical and chemical erosion rates. These erosion rates are becoming better quantified by the development of a global database of cosmogenic radionuclide 10Be (CRN) analyses of soil, sediment, and outcrops. Here we report the denudation rates for two small catchments (~ 0.9 km2) in the Mt. Lofty Ranges of South Australia as determined from 10Be concentrations from quartz sand from the following landscape elements: 1) dissected plateaux, or summit surfaces (14.10 ± 1.61 t km- 2 y- 1), 2) sandstone outcrops (15.37 ± 1.32 t km- 2 y- 1), 3) zero-order drainages (27.70 ± 1.42 t km- 2 y- 1), and 4) stream sediment which reflect a mix of landscape elements (19.80 ± 1.01 t km- 2 y- 1). Thus, the more slowly eroding plateaux and ridges, when juxtaposed with the more rapidly eroding side-slopes, are leading to increased relief in this landscape. Chemical erosion rates for this landscape are determined by combining cosmogenic denudation rates with the geochemical mass balance of parent rock, soil and saprolite utilizing zirconium immobility and existing mass balance methods. Two different methods were used to correct for chemical weathering and erosion in the saprolite zone that is shielded at depth from CRN production. The corrected values are higher than uncorrected values: total denudation of 33.24 or 29.11 t km- 2 y- 1, and total chemical erosion of 15.64 or 13.68 t km- 2 y- 1. Thus, according to these methods, 32-40% of the denudation is taking place by chemical weathering and erosion in the saprolite below CRN production depth. Compared with other similar areas, the overall denudation and chemical erosion rates are low. In most areas with sub-humid climates and tectonic uplift, physical erosion is much greater than chemical erosion. The low physical erosion rates in these Mt. Lofty Range catchments, in what is a relatively active tectonic setting, are thought to be due to low rainfall intensity

  7. Fast rates of subduction erosion along the Costa Rica Pacific margin: Implications for nonsteady rates of crustal recycling at subduction zones

    Vannucchi, P.; Ranero, C.R.; Galeotti, S.; Straub, S.M.; Scholl, D. W.; McDougall-Ried, K.


    At least since the middle Miocene (???16 Ma), subduction erosion has been the dominant process controlling the tectonic evolution of the Pacific margin of Costa Rica. Ocean Drilling Program Site 1042 recovered 16.5 Ma nearshore sediment at ???3.9 km depth, ???7 km landward of the trench axis. The overlying Miocene to Quaternary sediment contains benthic foraminifera documenting margin subsidence from upper bathyal (???200 m) to abyssal (???2000 m) depth. The rate of subsidence was low during the early to middle Miocene but increased sharply in the late Miocene-early Pliocene (5-6.5 Ma) and at the Pliocene-Pleistocene boundary (2.4 Ma). Foraminifera data, bedding dip, and the geometry of slope sediment indicate that tilting of the forearc occurred coincident with the onset of rapid late Miocene subsidence. Seismic images show that normal faulting is widespread across the continental slope; however, extension by faulting only accounts for a minor amount of the post-6.5 Ma subsidence. Basal tectonic erosion is invoked to explain the subsidence. The short-term rate of removal of rock from the forearc is about 107-123 km3 Myr-1 km-1. Mass removal is a nonsteady state process affecting the chemical balance of the arc: the ocean sediment input, with the short-term erosion rate, is a factor of 10 smaller than the eroded mass input. The low 10Be concentration in the volcanic arc of Costa Rica could be explained by dilution with eroded material. The late Miocene onset of rapid subsidence is coeval with the arrival of the Cocos Ridge at the subduction zone. The underthrusting of thick and thermally younger ocean crust decreased the subduction angle of the slab along a large segment of the margin and changed the dynamic equilibrium of the margin taper. This process may have induced the increase in the rate of subduction erosion and thus the recycling of crustal material to the mantle. Copyright 2003 by the American Geophysical Union.

  8. Dating of small gully formation and establishing erosion rates in old gullies under forest by means of anatomical changes in exposed tree roots (Southern Poland)

    Malik, Ireneusz


    Small gullies occur in forested gully systems on the undulating loess plateau in southern Poland. The old gully hillslopes are mainly covered with 200-year old beech trees in contrast with the surface of the summit plateau, which is cultivated agricultural land. Beech roots are exposed in the gullies through erosion. Wood vessels in the root tree rings divide into early wood and late wood and, after the roots are exposed, start to make fewer vessels. These anatomical changes in root tree rings allow us to date erosion episodes. Small gullies form in a different manner on the valley floor and on hillslopes. In valley bottoms, erosion features are often formed at some distance from one another, and in time small gullies combine to form a single, longer one. Depending on local conditions, such as the hillslope profile, hillslopes may exhibit headward erosion or may be eroded downwards. Hilllope gullies may be transformed into side valleys as a result of gradual widening and deepening. Dating the exposure of roots indicates that small gullies had already formed in the valley system by 1949. Intensive gully erosion was recorded between 1984 and 2002, during intense precipitation in 1984 and, of particular note, during the extraordinary flood of 1997 which affected all of Central Europe. The mean rate of small gully erosion in the old gully system studied is 0.63 m/year. On hillslopes the mean gully erosion rate is 0.21-0.52 m/year, and on the valley bottoms 0.18-1.98 m/year. High bottom erosion rates resulted from the emergence of long gullies during the erosion episodes in 1984 and 1997. Sheet flow in valley floors intensifies at times of heavy rainfall which causes long gullies to form. Taking into account the fact that conditions favoured erosion, the rate at which the old gullies under forest were transformed should be considered slow. New side gullies form slowly within the valley and it appears that if erosion progressed at the rate observed, new side valleys

  9. Explicit expression to predict the erosive burning rate of solid propellants

    Wang, S.


    Using the theory of gas dynamics and heat transfer from a turbulent gas flow to the burning surface of propellant along a permeable wall, an explicit expression is derived to predict the burning rate of the solid propellant with crossflow. Results of the calculation have been compared with experimental data and proved to be correct.

  10. Influence of riparian vegetation on near-bank flow structure and erosion rates on a large meandering river

    Konsoer, K. M.; Rhoads, B. L.; Langendoen, E. J.; Johnson, K.; Ursic, M.


    Rates of meander migration are dependent upon dynamic interactions between planform geometry, three-dimensional flow structure, sediment transport, and the erodibility and geotechnical properties of the channel banks and floodplains. Riparian vegetation can greatly reduce the rate of migration through root-reinforcement and increased flow resistance near the bank. In particular, forested riverbanks can also provide large woody debris (LWD) to the channel, and if located near the outer bank, can act to amour the bank by disrupting three-dimensional flow patterns and redirecting flow away from the bank-toe, the locus of erosion in meandering rivers. In this paper, three-dimensional flow patterns and migration rates are compared for two meander bends, one forested and one non-forested, on the Wabash River, near Grayville, Illinois. Flow data were obtained using acoustic Doppler current profilers (ADCP) for two large flow events in May and June 2011. LWD was mapped using a terrestrial LiDAR survey, and residence times for the LWD were estimated by comparing the survey data to time-series aerial photography. Rates of migration and planform evolution were determined through time-series analysis of aerial photography from 1938-2011. Results from this study show that near-bank LWD can have a significant influence on flow patterns through a meander bend and can disrupt helical flow near the outer bank, thereby reducing the effect of the high velocity core on the toe of the bank. Additionally, these effects influence migration rates and the planform evolution of meandering rivers.

  11. A first attempt to derive soil erosion rates from 137Cs airborne gamma measurements in two Alpine valleys

    Arata, Laura; Meusburger, Katrin; Bucher, Benno; Mabit, Lionel; Alewell, Christine


    The application of fallout radionuclides (FRNs) as soil tracers is currently one of the most promising and effective approach for evaluating soil erosion magnitudes in mountainous grasslands. Conventional assessment or measurement methods are laborious and constrained by the topographic and climatic conditions of the Alps. The 137Cs (half-life = 30.2 years) is the most frequently used FRN to study soil redistribution. However the application of 137Cs in alpine grasslands is compromised by the high heterogeneity of the fallout due to the origin of 137Cs fallout in the Alps, which is linked to single rain events occurring just after the Chernobyl accident when most of the Alpine soils were still covered by snow. The aim of this study was to improve our understanding of the 137Cs distribution in two study areas in the Central Swiss Alps: the Ursern valley (Canton Uri), and the Piora valley (Canton Ticino). In June 2015, a helicopter equipped with a NaI gamma detector flew over the two study sites and screened the 137Cs activity of the top soil. The use of airborne gamma measurements is particularly efficient in case of higher 137Cs concentration in the soil. Due to their high altitude and high precipitation rates, the Swiss Alps are expected to be more contaminated by 137Cs fallout than other parts of Switzerland. The airborne gamma measurements have been related to several key parameters which characterize the areas, such as soil properties, slopes, expositions and land uses. The ground truthing of the airborne measurements (i.e. the 137Cs laboratory measurements of the soil samples collected at the same points) returned a good fit. The obtained results offer an overview of the 137Cs concentration in the study areas, which allowed us to identify suitable reference sites, and to analyse the relationship between the 137Cs distribution and the above cited parameters. The authors also derived a preliminary qualitative and a quantitative assessment of soil redistribution

  12. Using 10Be erosion rates and fluvial channel morphology to constrain fault throw rates in the southwestern Sacramento River Valley, California, USA

    Cyr, A. J.


    The Sacramento - San Joaquin River Delta, California, USA, is a critical region for California water resources, agriculture, and threatened or endangered species. This landscape is affected by an extensive set of levees that enclose artificial islands created for agricultural use. In addition to their importance for sustaining agriculture, this levee system also supports extensive transport and power transmission infrastructure and urban/suburban development. These levees are susceptible to damage from even moderate ground shaking by either a large earthquake on one of the high-activity faults in the nearby San Francisco Bay region, or even a moderate earthquake on one of the low-activity faults in the Delta region itself. However, despite this danger the earthquake hazards in this region are poorly constrained due to our lack of understanding of faults in and near the Delta region. As part of an effort to better constrain the seismic hazard associated with known, but poorly constrained, faults in the region, a geomorphic analysis of the Dunnigan Hills, northwest of Woodland, CA, is being combined with cosmogenic 10Be catchment-averaged erosion rates. The Dunnigan Hills are a low-relief (maximum elevation 87 m) landscape generated by fault-bend folding above the west-vergent Sweitzer reverse fault that soles into a blind east-vergent reverse fault. These faults have been imaged by seismic reflection data, and local microseismicity indicates that this system is actively propagating to the east. However, the throw rates on the faults in this system remain unconstrained, despite the potential for significant shaking such as that experienced in the nearby April, 1892 earthquake sequence between Winters and Vacaville, Ca, ~25 km to the south, which has been estimated at magnitude 6.0 or greater. Geomorphic and cosmogenic 10Be analyses from 12 catchments draining the eastern flank of the Dunnigan Hills will be used to infer vertical rock uplift rates to better constrain

  13. Determination of Erosion/Corrosion Rates in Hanford Tank Farms Radioactive Waste Transfer System Pipelines

    Washenfelder, D. J.; Girardot, C. L.; Wilson, E. R.; Page, J. A.; Engeman, J. K.; Gunter, J. R.; Johnson, J. M.; Baide, D. G.; Cooke, G. A.; Larson, J. D.; Castleberry, J. L.; Boomer, K. D.


    The twenty-eight double-shell underground radioactive waste storage tanks at the U. S. Department of Energy’s Hanford Site near Richland, WA are interconnected by the Waste Transfer System network of buried steel encased pipelines and pipe jumpers in below-grade pits. The pipeline material is stainless steel or carbon steel in 51 mm to 152 mm (2 in. to 6 in.) sizes. The pipelines carry slurries ranging up to 20 volume percent solids and supernatants with less than one volume percent solids at velocities necessary to prevent settling. The pipelines, installed between 1976 and 2011, were originally intended to last until the 2028 completion of the double-shell tank storage mission. The mission has been subsequently extended. In 2010 the Tank Operating Contractor began a systematic evaluation of the Waste Transfer System pipeline conditions applying guidelines from API 579-1/ASME FFS-1 (2007), Fitness-For-Service. Between 2010 and 2014 Fitness-for-Service examinations of the Waste Transfer System pipeline materials, sizes, and components were completed. In parallel, waste throughput histories were prepared allowing side-by-side pipeline wall thinning rate comparisons between carbon and stainless steel, slurries and supernatants and throughput volumes. The work showed that for transfer volumes up to 6.1E+05 m3 (161 million gallons), the highest throughput of any pipeline segment examined, there has been no detectable wall thinning in either stainless or carbon steel pipeline material regardless of waste fluid characteristics or throughput. The paper describes the field and laboratory evaluation methods used for the Fitness-for-Service examinations, the results of the examinations, and the data reduction methodologies used to support Hanford Waste Transfer System pipeline wall thinning conclusions.

  14. Riparian erosion vulnerability model based on environmental features.

    Botero-Acosta, Alejandra; Chu, Maria L; Guzman, Jorge A; Starks, Patrick J; Moriasi, Daniel N


    Riparian erosion is one of the major causes of sediment and contaminant load to streams, degradation of riparian wildlife habitats, and land loss hazards. Land and soil management practices are implemented as conservation and restoration measures to mitigate the environmental problems brought about by riparian erosion. This, however, requires the identification of vulnerable areas to soil erosion. Because of the complex interactions between the different mechanisms that govern soil erosion and the inherent uncertainties involved in quantifying these processes, assessing erosion vulnerability at the watershed scale is challenging. The main objective of this study was to develop a methodology to identify areas along the riparian zone that are susceptible to erosion. The methodology was developed by integrating the physically-based watershed model MIKE-SHE, to simulate water movement, and a habitat suitability model, MaxEnt, to quantify the probability of presences of elevation changes (i.e., erosion) across the watershed. The presences of elevation changes were estimated based on two LiDAR-based elevation datasets taken in 2009 and 2012. The changes in elevation were grouped into four categories: low (0.5 - 0.7 m), medium (0.7 - 1.0 m), high (1.0 - 1.7 m) and very high (1.7 - 5.9 m), considering each category as a studied "species". The categories' locations were then used as "species location" map in MaxEnt. The environmental features used as constraints to the presence of erosion were land cover, soil, stream power index, overland flow, lateral inflow, and discharge. The modeling framework was evaluated in the Fort Cobb Reservoir Experimental watershed in southcentral Oklahoma. Results showed that the most vulnerable areas for erosion were located at the upper riparian zones of the Cobb and Lake sub-watersheds. The main waterways of these sub-watersheds were also found to be prone to streambank erosion. Approximatively 80% of the riparian zone (streambank

  15. Erosion by an Alpine glacier.

    Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N; Leprince, Sébastien; Adatte, Thierry; Lin, Jiao Y Y; Avouac, Jean-Philippe; Cox, Simon C


    Assessing the impact of glaciation on Earth's surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years. Copyright © 2015, American Association for the Advancement of Science.

  16. Late Cenozoic tephrostratigraphy offshore the southern Central American Volcanic Arc: 2. Implications for magma production rates and subduction erosion

    Schindlbeck, J. C.; Kutterolf, S.; Freundt, A.; Straub, S. M.; Vannucchi, P.; Alvarado, G. E.


    Pacific drill sites offshore Central America provide the unique opportunity to study the evolution of large explosive volcanism and the geotectonic evolution of the continental margin back into the Neogene. The temporal distribution of tephra layers established by tephrochonostratigraphy in Part 1 indicates a nearly continuous highly explosive eruption record for the Costa Rican and the Nicaraguan volcanic arc within the last 8 Myr. The widely distributed marine tephra layers comprise the major fraction of the respective erupted tephra volumes and masses thus providing insights into regional and temporal variations of large-magnitude explosive eruptions along the southern Central American Volcanic Arc (CAVA). We observe three pulses of enhanced explosive volcanism between 0 and 1 Ma at the Cordillera Central, between 1 and 2 Ma at the Guanacaste and at >3 Ma at the Western Nicaragua segments. Averaged over the long-term the minimum erupted magma flux (per unit arc length) is ˜0.017 g/ms. Tephra ages, constrained by Ar-Ar dating and by correlation with dated terrestrial tephras, yield time-variable accumulation rates of the intercalated pelagic sediments with four prominent phases of peak sedimentation rates that relate to tectonic processes of subduction erosion. The peak rate at >2.3 Ma near Osa particularly relates to initial Cocos Ridge subduction which began at 2.91 ± 0.23 Ma as inferred by the 1.5 Myr delayed appearance of the OIB geochemical signal in tephras from Barva volcano at 1.42 Ma. Subsequent tectonic re-arrangements probably involved crustal extension on the Guanacaste segment that favored the 2-1 Ma period of unusually massive rhyolite production.

  17. Mars sedimentary rock erosion rates constrained using crater counts, with applications to organic-matter preservation and to the global dust cycle

    Kite, Edwin S.; Mayer, David P.


    Small-crater counts on Mars light-toned sedimentary rock are often inconsistent with any isochron; these data are usually plotted then ignored. We show (using an 18-HiRISE-image, > 104-crater dataset) that these non-isochron crater counts are often well-fit by a model where crater production is balanced by crater obliteration via steady exhumation. For these regions, we fit erosion rates. We infer that Mars light-toned sedimentary rocks typically erode at ∼102 nm/yr, when averaged over 10 km2 scales and 107-108 yr timescales. Crater-based erosion-rate determination is consistent with independent techniques, but can be applied to nearly all light-toned sedimentary rocks on Mars. Erosion is swift enough that radiolysis cannot destroy complex organic matter at some locations (e.g. paleolake deposits at SW Melas), but radiolysis is a severe problem at other locations (e.g. Oxia Planum). The data suggest that the relief of the Valles Marineris mounds is currently being reduced by wind erosion, and that dust production on Mars < 3 Gya greatly exceeds the modern reservoir of mobile dust.

  18. Mars sedimentary rock erosion rates constrained using crater counts, with applications to organic matter preservation and to the global dust cycle

    Kite, Edwin S


    Small-crater counts on Mars light-toned sedimentary rock are often inconsistent with any isochron; these data are usually plotted then ignored. We show (using an 18-HiRISE-image, >10^4 crater dataset) that these non-isochron crater counts are often well-fit by a model where crater production is balanced by crater obliteration via steady exhumation. For these regions, we fit erosion rates. We infer that Mars light-toned sedimentary rocks typically erode at ~10^2 nm/yr, when averaged over 10 km^2 scales and 10^7-10^8 yr timescales. Crater-based erosion-rate determination is consistent with independent techniques, but can be applied to nearly all light-toned sedimentary rocks on Mars. Erosion is swift enough that radiolysis cannot destroy complex organic matter at some locations (e.g. paleolake deposits at SW Melas), but radiolysis is a severe problem at other locations (e.g. Oxia Planum). The data suggest that the relief of the Valles Marineris mounds is currently being reduced by wind erosion, and that dust pr...

  19. Review of denudation processes and quantification of weathering and erosion rates at a 0.1 to 1 Ma time scale

    Olvmo, Mats (Univ. of Goeteborg, Goeteborg (Sweden). Dept. of Earth Sciences)


    The Forsmark and Laxemar areas are quite similar from a geomorphological point of view. Both sites are situated within intact parts of the Sub-Cambrian Peneplain with extremely low relief. The peneplain is considered to be intact at both sites, i.e. the present relief is quite close to the original surface of this old denudation surface. The total amount of glacial erosion up to present is estimated to be relatively low at both sites (less than 10 m on average), but may have been quite important for stripping of old regolith, especially along fracture zones. This is most obvious in the vicinity of the Forsmark site where the dissected coastline 15 km south of the site is interpreted as a result of glacial erosion along old fracture zones. Therefore, from a strict glacial erosion perspective the Laxemar site is somewhat better than Forsmark. However, given the presented long-term denudation up to present, the expected amount of glacial erosion during a future glacial cycle, if similar to the last glacial cycle, is probably very limited for both sites, in the order of 2-5 m. Excluding glacial erosion, the long-term denudation rates of the two sites is fairly low as a consequence of the very low relief and the proximity to base level. The figures estimated for the long term denudation rates are in agreement with reports of denudation rates in shield areas and lie within the range 0 to 10 m/Ma for both sites. A scenario with a five-fold increase of relief that could be the effect of tectonic uplift, in a time perspective considerably longer than the coming 100,000 years, does not significantly change the picture. Even if the local relief is raised to above 100 m at both sites the estimated non-glacial denudation is very low. However, it should be noted that the effect of a relief change on the glacial system is not included in the calculations. Again, such a change on the pattern of glacial erosion would be more pronounced in the Forsmark area, since the coastline is

  20. Increasing the Stability of Streambanks through the Hydrologic Effects of Riparian Vegetation: Experimental Results

    Simon, A.; Pollen, N. L.


    Riparian vegetation can provide both mechanical and hydrologic benefits to the shear strength of streambanks. Recent research has shown that the hydrologic effects of water withdrawal on streambank stability can be significant, and far exceeds that provided by root reinforcement during certain times of the year. To accurately quantify the hydrologic effects of riparian vegetation on streambank stability and to determine optimum species for bank stabilization, experiments with common riparian species (planted in 2000) were conducted in large soil monoliths. Pore-water pressure data from depths of 30 and 70 cm within soil monoliths containing Black Willow, River Birch, Eastern Sycamore, and bare soil were monitored for the period February through June, 2002 (Figure XX1). This period was selected because it represents the wettest and, therefore, the most critical period for streambank stability. With rainfall, all of the tensiometers showed decreases in matric suction (negative pore-water pressure) or increases in positive pore-water pressure reflecting the addition of water. However, both the magnitude of the changes and the absoulute values attained within the soil monoliths differed by treatment. At both 30 cm and 70 cm depths, the soil in the control monoliths became the wettest during and after rainfall indicating the role of the woody species in maintaining matric suction and enhancing shear strength. During late February and early March before leaves appeared on stems and branches, there appeared to be little difference in matric suction values between individual species although matirc suction values within these monoliths were still greater than within the control monoliths. This lack of significant differences between the vegetated monoliths and the controls are at least in part a function of the young age of the specimens and the lack of a carryover of high values of matric suction from the previous summer that can be typical in more mature stands of trees

  1. Dual 10Be isotope systems constrain the source of sediment and rate of erosion for the tropical Barron River catchment, Queensland, Australia

    Nichols, K. K.; Bierman, P. R.; Reusser, L. J.; Portenga, E.; Matmon, A.; Rood, D. H.


    In order to understand source of sediment and rate of erosion for Barron River catchment, which heads on the Atherton Tablelands of northeast Australia, crosses the northern Queensland escarpment and drains into the Coral Sea, we collected fluvial sediment and measured both in situ and meteoric 10Be contents on the medium sand fraction. We collected fourteen samples from rivers and streams including large regional drainages and small tributaries. The upland basins are characterized by lower relief and less precipitation than the steeper and wetter escarpment basins. One sample is quartz sand from the Coral Sea beach at Yorkey's Knob, below the escarpment. Sand from the Barron River upstream of the escarpment integrates the upland basins and has an in situ 10Be concentration of 2.31±0.84 x105atoms/g and an erosion rate of 17.2 m/My (calculated using the CRONOS on-line calculator). This is similar to a major upland tributary (2.51±0.40 x105 atoms/g; 15.2 m/My) and two smaller upstream tributaries (20.5 m/My and 21.4 m/My). Escarpment streams have less in situ 10Be in their sediment (mean = 1.64±0.55 x 105 atoms/g, n=8) and higher basin area-weighted erosion rates (37.2 m/My). Based on the in situ measurements, the uplands are eroding at approximately half the rate of the escarpment basins. The beach sand has an in situ 10Be concentration (2.75±0.19 x 105 atoms/g) similar to the upland sediment suggesting that the source of beach sand is the larger but more slowly eroding Tablelands. In contrast, the meteoric 10Be concentrations of Barron River sand-sized sediment collected above the escarpment is ~4 fold lower (2.55x107 atoms/g) than the average meteoric 10Be concentration of the 8 escarpment samples (9.94±4.49 x107 atoms/g). This discrepancy cannot be explained by differences in annual average precipitation which ranges only from 1.9 to 2.3 m/yr but likely results from the deep mobility of meteoric 10Be in oxic Tableland soils. Considering meteoric 10Be as a

  2. Chemical Weathering in the San Gabriel Mountains of California: The influence of erosion rates, soil depth, and transport processes on soil chemical losses (Invited)

    Dixon, J. L.; Hartshorn, A. S.; Heimsath, A. M.; Dibiase, R. A.; Whipple, K. X.


    What controls the chemical weathering of soils in actively eroding landscapes? In this study, we explore the tectonic signature on soil weathering in the San Gabriel Mountains (SGM) of California, where propagating waves of incision triggered by increasing rock uplift have resulted in distinctly different hillslope morphologies and erosion rates across the range. We quantify downslope patterns of soil weathering across this landscape using sites that bracket low-gradient hillslopes of the stable upland plateau and hillslopes near the margins of the incising landscape. We use elemental mass balances in rock and soil to index the weathered extent of soils, and couple these extents with previously measured 10Be-derived soil production rates to calculate rates of soil weathering and erosion. Across all sites, Tau-Si—the fractional loss or gain of Si from parent material—averages -0.32±0.04, and the weathered extent of soils generally increases with increasing distance from the hillcrest. However, weathering intensities decrease as hillslope gradients steepen beyond 30°. Chemical weathering extents on slopes controlling mineral supply and residence time. These patterns are consistent with previously published predictive models for denudation-weathering relationships based on mineral weathering kinetics. Variable weathering extents in soils indicate that soil weathering in the SGM is largely kinetically limited. This work provides a field-based quantification of the complex relationship between soil erosion and chemical weathering, and together our data suggest that tectonic forcing strongly influences soil weathering rates and extents through its control on erosion rates, transport processes and soil thickness.

  3. Distinguishing between tectonic and lithologic controls on bedrock channel longitudinal profiles using cosmogenic 10Be erosion rates and channel steepness index

    Cyr, Andrew J.; Granger, Darryl E.; Olivetti, Valerio; Molin, Paola


    Knickpoints in fluvial channel longitudinal profiles and channel steepness index values derived from digital elevation data can be used to detect tectonic structures and infer spatial patterns of uplift. However, changes in lithologic resistance to channel incision can also influence the morphology of longitudinal profiles. We compare the spatial patterns of both channel steepness index and cosmogenic 10Be-determined erosion rates from four landscapes in Italy, where the geology and tectonics are well constrained, to four theoretical predictions of channel morphologies, which can be interpreted as the result of primarily tectonic or lithologic controls. These data indicate that longitudinal profile forms controlled by unsteady or nonuniform tectonics can be distinguished from those controlled by nonuniform lithologic resistance. In each landscape the distribution of channel steepness index and erosion rates is consistent with model predictions and demonstrates that cosmogenic nuclide methods can be applied to distinguish between these two controlling factors.

  4. A New Approach for Estimating Background Rates of Erosion Using Concentration of Meteoric 10-Be Adhered to River Sediment: Application to the Rapidly Eroding Waipaoa Basin, New Zealand

    Reusser, L. J.; Bierman, P. R.; Pavich, M.; Finkel, R.


    New and existing data suggest that the concentration of atmospherically- produced, meteoric 10-Be adhered to river sediment provides a proxy for basin-scale erosion rates. Although the widely applied method of analyzing in situ produced 10-Be in river sediments has proven useful for estimating pre-anthropogenic rates of erosion in a variety of environments, there are lithologic limitation. In contrast, measuring the concentration of meteoric 10-Be adhered to river sediment allows erosion rate analysis in landscapes underlain by quartz-deficient or fine-grained lithologies, as well as in basins where the concentration of quartz varies spatially. By assuming that basins are in an overall isotopic steady-state, that erosion is rapid enough that decay is negligible, and that the integrated delivery rate of 10-Be from the atmosphere (D10-Be) can be estimated, basin-scale mass loss rates (Ms) can be solved by equating the 10-Be flux in from the atmosphere with the flux of 10-Be out of the basin on sediment (C10-Be) and expressed as sediment yield per unit area (Ys). Fin = Fout D10-Be * A = Ms * C10-Be Ms = (D10-Be * A)/ C10-Be Ys = D10-Be / C10-Be To validate this new approach, we examined the limited data that do exist and found reasonable correspondence between erosion rates estimated from meteoric 10-Be concentrations and estimated by other means. As a first application, we use meteoric 10-Be in river sediment to estimate basin-scale erosion rates from catchments within and near the mud-stone dominated Waipaoa River Basin draining the tectonically active east coast of New Zealand's North Island. Near total conversion of indigenous forest to pasture over the past century in the Waipaoa Basin has resulted in some of the most dramatic and widespread erosional features on the planet, and contemporary sediment yields that rank among the highest in the world (~7 million kg/(km2 * yr)). The amount of meteoric 10-Be adhered to eight river sediment samples suggests that modern

  5. Using cosmogenic nuclides to contrast rates of erosion and sediment yield in a semi-arid, arroyo-dominated landscape, Rio Puerco Basin, New Mexico

    Bierman, P.R.; Reuter, J.M.; Pavich, M.; Gellis, A.C.; Caffee, M.W.; Larsen, J.


    Analysis of in-situ-produced 10Be and 26Al in 52 fluvial sediment samples shows that millennial-scale rates of erosion vary widely (7 to 366 m Ma-1) through the lithologically and topographically complex Rio Puerco Basin of northern New Mexico. Using isotopic analysis of both headwater and downstream samples, we determined that the semi-arid, Rio Puerco Basin is eroding, on average, about 100 m Ma-1. This rapid rate of erosion is consistent with estimates made using other techniques and is likely to result from a combination of easily eroded lithologies, sparse vegetation, and monsoon-dominated rainfall. Data from 331 stream water samples collected by the US Geological Survey between 1960 and 1995 are consistent with basin-wide, average chemical denudation rates of only about 1??4 m Ma-1; thus, the erosion rates we calculate may be considered rates of sediment generation because physical weathering accounts for almost 99 per cent of mass loss. The isotopic data reveal that sediment is generally well mixed downstream with the area-weighted average sediment generation rate for 16 headwater samples (234 ton km-2 a-1 for basin area 170 to 1169 km2) matching well that estimated from a single sample collected far downstream (238 ton km-2 a-1, basin area = 14 225 km2). A series of 15 samples, collected from an arroyo wall and representing deposition through the late Holocene, indicates that 10Be concentration in sediment delivered by the fluvial system has not changed appreciably over the last 1200 years despite at least two cycles of arroyo cutting and filling. Other samples (n = 21) were collected along the drainage network. Rio Puerco erosion rates scale directly with a variety of metrics describing vegetation, precipitation, and rock erodibility. Using the headwater basins for calibration, the erosion rates for both the downstream samples and also the data set as a whole, are best modelled by considering a combination of relief and vegetation metrics, both of which co

  6. Estimating Long to Short-Term Erosion Rates of Fluvial vs Mass Movement Processes: An Example from the Axial Zone of the Southern Italian Apennines

    Maurizio Lazzari


    Full Text Available Estimates of erosion rates related to fluvial and landslides processes have been performed for several temporal ranges on the basis of different viable methods. The study area includes three catchment sub-basins of the north-eastern flank of the Agri Valley, a tectonically active morpho-structural low located in the axial zone of the southern Apennines and affected by desertification processes in its middle part. Long and mid-term rates have been estimated evaluating the missing volume of eroded rocks, on the grounds of GIS-aided calculations linked to geomorphological markers corresponding to ancient base-levels of the erosion. Short-term rates have been calculated converting the parameter related to the turbid transport of streams (Tu, derived from the quantitative geomorphic analysis, adopting an average value for the specific weight of the outcropping rocks, Such an approximation has to be considered acceptable because of the presence of conditions of lithological homogeneity in two of the chosen basins. In the light of this, the third basin, characterized by a certain geological heterogeneity, has been assumed as test-site with regard to the other two sub-basins. The average value of the long-term erosion rate from the entire study area is 0.25 mm/y, mainly due to fluvial processes. The comparison of the erosion rates related to the fluvial network activity from early Pleistocene to Present with those related to the mass movements occurred in a more recent (and shorter time-span indicates that mass movements contribute just for the 1% of the whole erosion estimated in the two homogeneous basins, but they refer to a short time-span (10 ky to Present. A theoretical extrapolation to the past (0.5 to 1 My allows to consider the contribution of landslides to the total erosion inside the catchment areas as almost equal to the fluvial aliquot. The conversion of the Tu values shows that the short-term rates are generally greater than the rates

  7. Particle erosion of infrared materials


    Erosion test of some infrared (IR) optical crystals (Ge,ZnS,MgF2,and quartz) was conducted with a number of different erodents (glass bead,and angular SiC,SiO2,Al2O3 by a homemade gas-blasting erosion tester.The influence of impact angle,impact velocity,erodent,and erosion time on the erosion rate and the effect of erosion on their IR transmittance were studied.The damaged surface morphology was characterized by scanning electron microscopy,and the erosion mechanism was explored.All of the materials show the maximum in wear versus impact angle at 90°,confirming their brittle failure behavior.It is found that the erosion rate is dependent on the erodent velocity by a power law,and it is highly correlated to the hardness of the erodent.The erosion rate-time curves do not show an incubation state,but an accelerated erosion period followed a maximum erosion (steady state).The decrease of IR transmittance is direct proportion to the erosion rate.Although the material loss occurs primarily by brittle process,ductile behavior is clearly an important feature,especially for MgF2 and ZnS.

  8. Constraints on regolith formation and erosion rates at the Susquehanna Shale Hills Critical Zone Observatory, PA, determined using meteoric 10Be

    West, N.; Kirby, E.; Bierman, P. R.; Rood, D. H.


    New meteoric 10Be data from 73 samples of bulk regolith collected along north- and south-facing hillslopes at the Susquehanna Shale Hills Critical Zone Observatory (SSHO) provide first-order constraints on the timescales of regolith formation. The SSHO is located in the presently temperate climate zone of central Pennsylvania; however, sustained periglacial climate during the time of maximal extent of the Laurentide ice sheet (~19-21 ka) and deforestation during mid-19th Century charcoal production may have exerted significant influence on regolith production. Here, we quantify soil residence times and corresponding rates of regolith production and erosion on the north- and south-facing slopes at SSHO, using meteoric 10Be in samples of regolith collected at 25 locations along each hillslope from ridge top to toe slope. Hillslopes within the SSHO are relatively planar, but exhibit a pronounced asymmetry; north-facing slopes are steeper (~20°) than south-facing slopes (~15°). Meteoric 10Be concentrations decrease systematically with depth at all 6 profile sites. Meteoric 10Be inventories are similar at the north and south ridgetop sites (1.89 ± 0.55 at/cm2 and 1.63 ± 0.41 at/cm2, respectively) and generally increase with position downslope. Assuming that the delivery of meteoric 10Be to regolith is balanced by its removal via erosion, the total meteoric 10Be inventories at the north and south ridgetops are consistent with soil 10Be residence times of 10.5 ± 3 ky and 9.1 ± 2 ky, and with steady lowering rates of ~ 16 m/My and ~ 19 m/My, respectively. Increases in meteoric 10Be inventories downslope are consistent with relatively slow creep, with transport velocities of 0.45 cm/y and 0.38 cm/y for the north and south hillslopes, respectively. Comparison of our results with previously-published estimates of regolith production rates inferred from U-series disequilibrium reveals that estimates of steady-state erosion calculated using meteoric 10Be are considerably

  9. Rates of landscape development in the Transhimalaya of northern India: A framework for testing the links among climate, erosion, and tectonics

    Dortch, Jason Michael

    Models linking Earth's surficial (exogenic) processes and internal processes (endogenetic) have been evolved recently, specifically involving the role of glaciation and fluvial incision in unloading rock mass and inducing surface uplift, and the influence of glacial, fluvial, and mass wasting systems in limiting and/or creating topography. However, these models are poorly defined due to a lack of quantified studies of the rates and magnitudes of geomorphic processes that control erosion and landscape development. Furthermore, the regional variability of erosive processes and the role of high magnitude-low frequency processes in landscape development are poorly defined. A key area of the Himalaya-Tibetan orogen, northern Ladakh was therefore examined using field mapping, satellite remote sensing and terrestrial cosmogenic nuclide (TCN) methods to quantify the relative role of these processes and to provide a framework to test the newly developing geologic models. The new data allows linkages between climatic change, long-term temporal variation in the rates of geomorphic processes, and catastrophic events are assessed. Study of glaciation shows in Ladakh shows showed that glaciations was approximately twice as extensive on the northern side of the Ladakh Range during the same glaciation, which would implies that that erosion should be greater on the northern slopes of the range. To test this assumption, TCN basin wide erosion methods that integrate long-term erosion were undertaken and show that catchments on the southern side of the range erode at ˜0.025 mm/yr while three catchments on the northern side erode at ˜0.050 m mm/yr. This suggests that erosion rates are dominantly controlled by glaciation. Seventeen strath terraces in the Himalaya and Transhimalaya were dated using TCN methods to test the temporal variations in the rates of incision. These data were combined with previous studies that show that Holocene fluvial incision rates range from ˜0.02 mm/yr to

  10. A new Approach for Quantifying Root-Reinforcement of Streambanks: the RipRoot Model

    Pollen, N. L.; Simon, A.


    Riparian vegetation plays an important role in controlling geotechnical and fluvial processes acting along and within streambanks through the binding effects of roots. Quantification of this mechanical effect is therefore essential to accurately model streambank stability. Until now, most attempts to include the effects of root reinforcement by riparian vegetation have used root-cohesion values estimated using the Wu et al. (1979) equation, requiring the tensile strengths and diameters of the roots crossing the potential shear-plane. However, the Wu et al. equation is a static model that assumes that all roots break, and that they all break simultaneously. Field observations and laboratory experiments have shown that in reality the roots do not all break simultaneously, and that the breaking of roots during mass failure is in fact a dynamic process. Static models such as the Wu et al. equation are therefore likely to produce overestimations of cohesion due to roots. As a response to this concern, a dynamic root reinforcement model (RipRoot) was developed, based on the concepts of fiber bundle models (FBM's) used in materials science. Within the model the root-soil system is loaded incrementally resulting in progressive root breaking and redistribution of stresses from the broken roots to the remaining intact roots in the soil matrix. The redistribution and loading process continues until either all of the roots have broken, or equilibrium is reached where the root network supports the driving force imposed on the bank. The increase in bank cohesion using the static Wu et al. equation are 18% to 38% higher than RipRoot for riparian tree species, including Black Willow, Sandbar Willow, Cottonwood, River Birch and Eastern Sycamore, and 49% higher for Switch Grass. These variations in cohesion values can have a significant impact on streambank Factor of Safety (Fs) values calculated using the Simon et al. (2000) bank-stability model. For example, a 3m high silt

  11. Using (1)(0)Be cosmogenic isotopes to estimate erosion rates and landscape changes during the Plio-Pleistocene in the Cradle of Humankind, South Africa.

    Dirks, Paul H G M; Placzek, Christa J; Fink, David; Dosseto, Anthony; Roberts, Eric


    Concentrations of cosmogenic (10)Be, measured in quartz from chert and river sediment around the Cradle of Humankind (CoH), are used to determine basin-averaged erosion rates and estimate incision rates for local river valleys. This study focusses on the catchment area that hosts Malapa cave with Australopithecus sediba, in order to compare regional versus localized erosion rates, and better constrain the timing of cave formation and fossil entrapment. Basin-averaged erosion rates for six sub-catchments draining the CoH show a narrow range (3.00 ± 0.28 to 4.15 ± 0.37 m/Mega-annum [Ma]; ±1σ) regardless of catchment size or underlying geology; e.g. the sub-catchment with Malapa Cave (3 km(2)) underlain by dolomite erodes at the same rate (3.30 ± 0.30 m/Ma) as the upper Skeerpoort River catchment (87 km(2)) underlain by shale, chert and conglomerate (3.23 ± 0.30 m/Ma). Likewise, the Skeerpoort River catchment (147 km(2)) draining the northern CoH erodes at a rate (3.00 ± 0.28 m/Ma) similar to the Bloubank-Crocodile River catchment (627 km(2)) that drains the southern CoH (at 3.62 ± 0.33 to 4.15 ± 0.37 m/Ma). Dolomite- and siliciclastic-dominated catchments erode at similar rates, consistent with physical weathering as the rate controlling process, and a relatively dry climate in more recent times. Erosion resistant chert dykes along the Grootvleispruit River below Malapa yield an incision rate of ∼8 m/Ma at steady-state erosion rates for chert of 0.86 ± 0.54 m/Ma. Results provide better palaeo-depth estimates for Malapa Cave of 7-16 m at the time of deposition of A. sediba. Low basin-averaged erosion rates and concave river profiles indicate that the landscape across the CoH is old, and eroding slowly; i.e. the physical character of the landscape changed little in the last 3-4 Ma, and dolomite was exposed on surface probably well into the Miocene. The apparent absence of early Pliocene- or Miocene-aged cave deposits and

  12. Time since plantation is the most important determining factor for soil erosion rates in vineyards. A case study in the valley of Les Alcusses valley, Eastern Spain

    Rodrígo Comino, Jesús; Keesstra, Saskia; Novara, Agata; García Díaz, Andrés; Jordán, Antonio; Brevik, Eric C.; Cerdà, Artemi


    Vineyards are known to suffer from soil erosion around the world (Novara et al., 2011; 2013; 2015; Rodrigo Comino et al., 2015; Prosdocimi et al., 2016; Rodrigo-Comino et al., 2016a; 2016b, 2016b). As in other crops in the Mediterranean such as citrus (Cerdà et al., 2009), olives (Taguas et al., 2015), persimmon (Cerdà et al., 2016) or apricot (Keesstra et al., 2016) plantations, there is a need to survey the spatial and temporal changes in soil erosion in vineyards. Soil redistribution in agricultural land is determined by human management due to the control it exerts on the vegetation cover and soil properties. This is why the time since plantation is important in soil erosion spatial and temporal distribution. Especially because during the plantation of the saplings, the soil is compacted and all other vegetation is removed. In our experiment we selected four paired plot research sites in the Les Alcusses valley, in Eastern Spain. We selected recently planted vineyards (1-year old) and 40-years old plantations. In total 80 rainfall simulations were performed with an intensity of 55 mm h-1 on small 0.25 m2 circular plots to determine the soil detachment by rainfall. The results show that soil erosion rates in the 40-year old vineyards were high (### a rate??), and in the recently planted ones were extremely high, on average six times higher. Acknowledgements The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n 603498 (RECARE project) and the CGL2013- 47862-C2-1-R and CGL2016-75178-C2-2-R national research projects. References Cerdà, A., González-Pelayo, O., Giménez-Morera, A., Jordán, A., Pereira, P., Novara, A., Brevik, E.C., Prosdocimi, M., Mahmoodabadi, M., Keesstra, S., García Orenes, F., Ritsema, C., 2016. The use of barley straw residues to avoid high erosion and runoff rates on persimmon plantations in Eastern Spain under low frequency - high magnitude

  13. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Main Report.


    of long-term. comprehensive studies ins ols ing channel alignment, bank stabilization, or navigation channeli/ation. (U. S. ArmN Engineer Civil Works...Program of the Civil Works Investigation Study on Materials U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi Technical Report...Pearl River Basin Development District, Mississippi; (64) La Asociacion De Santa Rosa De Lima De Abiquiu. Inc., New Mexico; (65) Pittsylvania Soil and

  14. Effects of Streambank Fencing of Near-Stream Pasture Land on a Small Watershed in Lancaster County, Pennsylvania

    Galeone, Daniel G.; Low, Dennis J.; Brightbill, Robin A.


    This study indicated that a small buffer width along a stream in pasture land can have a positive influence on surface-water quality, benthic macroinvertebrates, and near-stream shallow ground-water quality. Overland runoff processes that move suspended sediment to the stream were controlled (or reduced) to some extent by the vegetative buffer established. Results indicated streambank fencing resulted in decreases in N-species, total-P, and suspended-sediment concentrations and yields at the outlet of the treatment basin relative to untreated sites; however, dissolved-P concentrations and yields increased. These results indicate that nutrient management, in conjunction with streambank fencing, is important in helping to control nutrient loadings to streams in this agricultural setting. An upstream site (T-2) in the treatment basin showed post-treatment reductions in suspended-sediment yields and increases in N and P yields. The different results for these treated sites indicates the effects of streambank fencing should be studied at as large a scale as possible because field-scale influences on water quality as drainage area decreases can mute the effects of fencing. Benthic-macroinvertebrate data indicated streambank fencing had a positive influence on benthic macroinvertebrates and their habitat. More improvement was detected at the outlet of the treatment basin than the upstream sites. Probably the most important biological metric, taxa richness, indicated a greater number of benthic-macroinvertebrate taxa at treated relative to control sites after fencing. Results indicated fencing improved shallow ground-water quality (for the well nest in a stream-gaining area), as noted by decreased concentrations of N species and fecal-streptococcus counts. This improvement only occurred at the well nest where the stream was gaining water from the shallow ground-water system.

  15. Physical weathering and regolith behaviour in a high erosion rate badland area at the Pyrenees: research design and first results

    Regües, D.


    Full Text Available Previous studies on badland areas in the Vallcebre basin (High Llobregat suggested that the erosion rates are controlled by weathering rate of mudrocks. The present work was started to characterize the physical weathering processes and rates in relationship with thermal and moisture conditions.
    The method used consists of the continuous monitoring of regolith temperatures at different conditions of aspect, depth and lithology (color, and the periodical sampling of regolith moisture and bulk density, the last taken as an indicator of the weathering status. Besides this quantitative information, the changes of the surface of the regolith have been monitored with the help of photographic techniques, using a especially designed tripod. To complete the field observations, a laboratory experiment is being performed, analyzing the volumetric changes suffered by undisturbed rock samples subject to thermal and moisture oscillations.
    The results obtained emphasize the role of frost action, especially during wet conditions. Aspect and lithologic differences introduce significant nuances in thermal regime and volumetric changes respectively.

    [es] Estudios anteriores en zonas acarcavadas de la cuenca de Vallcebre (Alto Llobregat sugieren que las tasas de erosión están limitadas por la meteorización de las rocas arcillosas que las constituyen. El presente trabajo ha sido planteado para caracterizar y evaluar los procesos de meteorización física en relación con los regímenes térmico e hídrico.
    El método empleado consiste en la monitorización continua de temperaturas del aire y del regolito en diversas condiciones de profundidad, exposición y litología (color, así como el muestreo periódico de humedad y densidad aparente, considerada ésta última como indicadora del grado de meteorización. Además de esta información cuantitativa, se ha realizado un seguimiento de los cambios en la micromorfología superficial, mediante

  16. Enhanced Droplet Erosion Resistance of Laser Treated Nano Structured TWAS and Plasma Ion Nitro-Carburized Coatings for High Rating Steam Turbine Components

    Pant, B. K.; Arya, Vivek; Mann, B. S.


    This article deals with surface modification of twin wire arc sprayed (TWAS) and plasma ion nitro-carburized X10CrNiMoV1222 steel using high power diode laser (HPDL) to overcome water droplet erosion occurring in low pressure steam turbine (LPST) bypass valves and LPST moving blades used in high rating conventional, critical, and super critical thermal power plants. The materials commonly used for high rating steam turbines blading are X10CrNiMoV1222 steel and Ti6Al4V titanium alloy. The HPDL surface treatment on TWAS coated X10CrNiMoV1222 steel as well as on plasma ion nitro-carburized steel has improved water droplet resistance manifolds. This may be due to combination of increased hardness and toughness as well as the formation of fine grained structure due to rapid heating and cooling rates associated with the laser surface treatment. The water droplet erosion test results along with their damage mechanism are reported in this article.

  17. Effect of farmyard manure rate on water erosion of a Mediterranean soil: determination of the critical point of inefficacy

    Annabi, Mohamed; Bahri, Haithem; Cheick M'Hamed, Hatem; Hermessi, Taoufik


    Intensive cultivation of soils, using multiple soil tillage, led to the decrease of their organic matter content and structural stability in several cultivated area of the Mediterranean countries. In these degraded soils, the addition of organic products, traditionally the animal manure, should improve soil health among them the resistance of soil to water erosion. The aim of this study was to evaluate after 1 year of the addition to a cambisoil different doses of farmyard manure on soil organic matter content, on microbial activity and on aggregate stability (proxy to soil resistance to water erosion). The statistical process (bilinear model) was used to found a point at which the addition of the organic product no longer influences the soil resistance to erosion. The farmyard manure issued from a cow breeding was composted passively during 4 months and used to amend a small plots of a cultivated cambisol (silty-clay texture, 0.9% TOC) located in the northeast of Tunisia (Morneg region). The manure was intimately incorporate to the soil. The manure organic matter content was 31%, and its isohumic coefficient was 49%. Twelve dose of manure were tested: from 0 to 220 t C.ha-1. The experiment was started on September 2011. In November 2012, soil sampling was done and soil organic carbon content (Walkley-Black method) and soil aggregate stability (wet method of Le Bissonnais) were assessed. A laboratory incubations of soil+manure mixtures, with the same proportions as tested in the field conditions, was carried at 28°C and at 75% of the mixture field capacity water retention. Carbon mineralization was monitored during three months incubation. Results show that the addition of farmyard manure stimulated the microbial activity proportionally to the added dose. This activation is due to the presence of easily biodegradable carbon in the manure, which increases with increasing manure dose. On the other hand, the addition of manure increased the aggregate stability with

  18. Remobilization Rates and Cumulative Contributions of Floodplains and Legacy Sediments from Piedmont Tributaries

    Miller, A. J.; Donovan, M.; Baker, M. E.; Gellis, A.


    The disparity between watershed erosion rates and downstream sediment delivery has been an important theme in geomorphology for many decades, with the role of floodplains in sediment storage as a frequent focus. In the Piedmont province of the eastern US, post-settlement upland deforestation and agricultural land use led to accumulation of thick packages of overbank sediment ("legacy deposits") in valley bottoms. Previous authors have argued that legacy sediment is a potentially important source of sediment being remobilized by lateral migration of channels. We seek to address 1) How rapidly sediment is remobilized from floodplains by channel migration and bank erosion, 2) the proportion of streambank sediment derived from legacy sediment, and 3) the potential contributions of net stream bank erosion and legacy sediments to downstream sediment yields within the Piedmont of Baltimore County, Maryland. We measured gross erosion and deposition rates over 45 years within the fluvial corridor along 30 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 by comparing channel and floodplain morphology from LiDAR-based digital elevation data collected in 2005 with channel positions recorded on 1:2400-scale topographic maps from 1959-1961. Measured deposition within channel and point bars accounted for an average of 46% (28-75%) of gross erosion, with deposition increasingly important in larger drainages. Legacy sediments accounted for 6-90% of bank erosion at individual study segments, represented about 60% of bank height at most exposures, and accounted for 57% of the measured gross erosion. Extrapolating the results indicated that first- and second-order streams account for 62% of total stream bank erosion from northern Baltimore County. After accounting for estimated redeposition, extrapolated net stream bank sediment yields (72 Mg/km2/yr) are equivalent to 70% of average Piedmont watershed yield (104 Mg/km2/yr) cited in studies by previous

  19. Validating a mass balance accounting approach to using 7Be measurements to estimate event-based erosion rates over an extended period at the catchment scale

    Porto, Paolo; Walling, Des E.; Cogliandro, Vanessa; Callegari, Giovanni


    Use of the fallout radionuclides cesium-137 and excess lead-210 offers important advantages over traditional methods of quantifying erosion and soil redistribution rates. However, both radionuclides provide information on longer-term (i.e., 50-100 years) average rates of soil redistribution. Beryllium-7, with its half-life of 53 days, can provide a basis for documenting short-term soil redistribution and it has been successfully employed in several studies. However, the approach commonly used introduces several important constraints related to the timing and duration of the study period. A new approach proposed by the authors that overcomes these constraints has been successfully validated using an erosion plot experiment undertaken in southern Italy. Here, a further validation exercise undertaken in a small (1.38 ha) catchment is reported. The catchment was instrumented to measure event sediment yields and beryllium-7 measurements were employed to document the net soil loss for a series of 13 events that occurred between November 2013 and June 2015. In the absence of significant sediment storage within the catchment's ephemeral channel system and of a significant contribution from channel erosion to the measured sediment yield, the estimates of net soil loss for the individual events could be directly compared with the measured sediment yields to validate the former. The close agreement of the two sets of values is seen as successfully validating the use of beryllium-7 measurements and the new approach to obtain estimates of net soil loss for a sequence of individual events occurring over an extended period at the scale of a small catchment.

  20. Erosion rates, sediment transport and characteristic discharge in a transient landscape in the Entle catchment (northern border of the Central Alps, Switzerland)

    van den Berg, Fabien; Schlunegger, Fritz; Norton, Kevin


    The 65 km2-large Entle catchment is located at the northern border of the Central Alps of Switzerland and is underlain by various lithologies including Flysch, carbonate sequences, Molasse deposits and glacial till. It has been subjected to headward knickpoint migration since the termination of the LGM (16 ± 3 ka), due to a base level fall upon glacial retreat. The incised portions of the catchment were delineated within a GIS environment in an effort to calculate volumetric differences between the glacial surface and the modern topography. The sediment budget estimates yield an average erosion rate of 1.93 ± 0.36 mm.yr-1 in the incised reaches, and a maximum local erosion rate of 11.47 ± 2.15 mm.yr-1. Assuming that there has been no erosion elsewhere, the basin-wide averaged erosion rate is estimated at 0.31 ± 0.06 mm.yr-1. This is consistent with 10Be-based denudation rates measured in adjacent catchments. Although constant erosion rates are generally assumed for studies involving 10Be analysis, field evidence indicate that headward knickzone migration through bedrock and unconsolidated glacial till has destabilized the surrounding hillslopes, resulting in supply of large volumes of sediment to the trunk channel by landsliding and/or debris flows downstream the knickzone. This additional influx of sediments may raise the local base level within the incised reach, thus perturbing the migration of the knickzone for a limited time interval. This time span critically depends on the relative importance between the probability density function (PDF) of the sediment particle size supplied by mass failure processes and debris flows, and the characteristic water discharge magnitude to remove that material. Measurements of the PDFs of the sediment particles along the incised Entle reach together with the application a simple long profile stream-power model for the entrainment and transport of sediment allow the identification of characteristic bed-forming discharge

  1. Modeling the fluid/soil interface erosion in the Hole Erosion Test

    Kissi B.


    Full Text Available Soil erosion is a complex phenomenon which yields at its final stage to insidious fluid leakages under the hydraulic infrastructures known as piping and which are the main cause of their rupture. The Hole Erosion Test is commonly used to quantify the rate of piping erosion. In this work, The Hole Erosion Test is modelled by using Fluent software package. The aim is to predict the erosion rate of soil during the hole erosion test. The renormalization group theory – based k–ε turbulence model equations are used. This modelling makes it possible describing the effect of the clay concentration in flowing water on erosion. Unlike the usual one dimensional models, the proposed modelling shows that erosion is not uniform erosion along the hole length. In particular, the concentration of clay is found to increase noticeably the erosion rate.

  2. Tube erosion in bubbling fluidized beds

    Levy, E.K. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center; Stallings, J.W. [Electric Power Research Inst., Palo Alto, CA (United States)


    This paper reports on experimental and theoretical studies that were preformed of the interaction between bubbles and tubes and tube erosion in fluidized beds. The results are applicable to the erosion of horizontal tubes in the bottom row of a tube bundle in a bubbling bed. Cold model experimental data show that erosion is caused by the impact of bubble wakes on the tubes, with the rate of erosion increasing with the velocity of wake impact with the particle size. Wake impacts resulting from the vertical coalescence of pairs of bubbles directly beneath the tube result in particularly high rates of erosion damage. Theoretical results from a computer simulation of bubbling and erosion show very strong effects of the bed geometry and bubbling conditions on computed rates of erosion. These results show, for example, that the rate of erosion can be very sensitive to the vertical location of the bottom row of tubes with respect to the distributor.

  3. A test of the cosmogenic 10Be(meteoric)/9Be proxy for simultaneously determining basin-wide erosion rates, denudation rates, and the degree of weathering in the Amazon basin

    Wittmann, H.; Blanckenburg, F.; Dannhaus, N.; Bouchez, J.; Gaillardet, J.; Guyot, J. L.; Maurice, L.; Roig, H.; Filizola, N.; Christl, M.


    We present an extensive investigation of a new erosion and weathering proxy derived from the 10Be(meteoric)/9Be(stable) ratio in the Amazon River basin. This new proxy combines a radioactive atmospheric flux tracer, meteoric cosmogenic 10Be, with 9Be, a trace metal released by weathering. Results show that meteoric 10Be concentrations ([10Be]) and 10Be/9Be ratios increase by >30% from the Andes to the lowlands. We can calculate floodplain transfer times of 2-30 kyr from this increase. Intriguingly however, the riverine exported flux of meteoric 10Be shows a deficit with respect to the atmospheric depositional 10Be flux. Most likely, the actual area from which the 10Be flux is being delivered into the mainstream is smaller than the basin-wide one. Despite this imbalance, denudation rates calculated from 10Be/9Be ratios from bed load, suspended sediment, and water samples from Amazon Rivers agree within a factor of 2 with published in situ 10Be denudation rates. Erosion rates calculated from meteoric [10Be], measured from depth-integrated suspended sediment samples, agree with denudation rates, suggesting that grain size-induced variations in [10Be] are minimized when using such sampling material instead of bed load. In addition, the agreement between erosion and denudation rates implies minor chemical weathering intensity in most Amazon tributaries. Indeed, the Be-specific weathering intensity, calculated from mobilized 9Be comprising reactive and dissolved fractions that are released during weathering, is constant at approximately 40% of the total denudation from the Andes across the lowlands to the Amazon mouth. Therefore, weathering in the Amazon floodplain is not detected.

  4. Study and simulation of a multi-lithology stratigraphic model under maximum erosion rate constraint; Etude et simulation d'un modele statigraphique multi-lithologique sous contrainte de taux d'erosion maximal

    Gervais, V.


    The subject of this report is the study and simulation of a model describing the infill of sedimentary basins on large scales in time and space. It simulates the evolution through time of the sediment layer in terms of geometry and rock properties. A parabolic equation is coupled to an hyperbolic equation by an input boundary condition at the top of the basin. The model also considers a unilaterality constraint on the erosion rate. In the first part of the report, the mathematical model is described and particular solutions are defined. The second part deals with the definition of numerical schemes and the simulation of the model. In the first chap-ter, finite volume numerical schemes are defined and studied. The Newton algorithm adapted to the unilateral constraint used to solve the schemes is given, followed by numerical results in terms of performance and accuracy. In the second chapter, a preconditioning strategy to solve the linear system by an iterative solver at each Newton iteration is defined, and numerical results are given. In the last part, a simplified model is considered in which a variable is decoupled from the other unknowns and satisfies a parabolic equation. A weak formulation is defined for the remaining coupled equations, for which the existence of a unique solution is obtained. The proof uses the convergence of a numerical scheme. (author)

  5. Spaced planar laminations formed by repetitive basal erosion and resurgence to high-sedimentation-rate regime: new insight from a bedform-like structures and laterally continuous exposures

    Ishihara, Yoshiro; Yuri, Onishi; Tsuda, Keisuke; Yokokawa, Miwa


    Spaced planar laminations (SPL), or so-called traction carpet deposits, are frequently observed in deposits of sediment gravity flows. Several sedimentation models for a succession of inversely graded units have been suggested from field observations and flume experiments. The formation of the inversely graded unit could be summarized as follows: (1) abrupt sedimentation on freezing of an inversely graded layer, or (2) interruptions in flow causing a freezing of an inversely graded layer at the most basal part of flow. In either case, traction carpets as a bed load overlying the erosive boundary at the base of flow are required. Although some descriptions have reported SPLs forming antidune bedform-like structures and the association of SPLs with structureless massive deposits have not been clearly explained. In this study, we suggest a novel model of SPL formation by repetition of basal erosion and resurgence to high-sedimentation rates, based on detail examinations of SPLs both showing bedform-like structures and lateral extents of hundreds of meters. SPLs were investigated in the Mio-Pliocene Kiyosumi Formation in central Japan and the Miocene Aoshima Formation in southwest Japan. In a turbidite in the Kiyosumi Formation, SPLs show three mound-like structures, suggesting antidune bedforms with wavelengths of about 6 to 7 m. On the upcurrent flanks, SPLs show lenticular cross laminations or pinching out of units; those units do not show clear inverse grading. Rip-up mud clasts and relatively high-angle imbrications are also observed. On the other hand, SPLs on the downcurrent flanks show relatively clear inverse grading and transition downcurrent into a massive structureless bed. In the Aoshima Formation, SPLs with ca. 1 cm unit thickness continue approximately 50 m along a palaeocurrent direction without changes in thickness. These SPLs gradually transition upward into a massive structureless unit. From the observations described above, in addition to

  6. A multi-nuclide approach to quantify long-term erosion rates and exposure history through multiple glacial-interglacial cycles

    Strunk, Astrid; Larsen, Nicolaj Krog; Knudsen, Mads Faurschou;

    possible to resolve the complex pattern of exposure history under a fluctuating ice sheet. In this study, we quantify long-term erosion rates along with durations of multiple exposure periods in West Greenland by applying a novel Markov Chain Monte Carlo (MCMC) inversion approach to existing 10Be and 26Al....... The new MCMC approach allows us to constrain the most likely landscape history based on comparisons between simulated and measured cosmogenic nuclide concentrations. It is a fundamental assumption of the model that the exposure history at the site/location can be divided into two distinct regimes: i...... simulates numerous different landscape scenarios based on these four parameters and zooms in on the most plausible combination of model parameters. We apply the MCMC-model to the concentrations of 10Be and 26Al measured in previously published studies from Upernavik, Uummannaq and Sisimiut and quantify...

  7. Efficiency of erosion mitigation strategies in reducing sediment-loading rates from unpaved road networks into coral reef-bearing waters of the Eastern Caribbean

    Ramos-Scharron, Carlos; Gray, Sarah; Sears, Whitney


    Erosion from unpaved road networks represents a critical source of stress affecting the coral reef systems of the U.S. Virgin Islands in the Northeastern Caribbean. Combined community- and government-driven efforts to reduce sediment contributions from unpaved roads in the island of St. John have consisted in improving road drainage design, paving selected road segments, and constructing sediment retention structures. Here we describe empirical evidence attesting to the efficacy of these mitigation efforts. Road drainage improvements reduced sediment production rates to about a third of pre-treatment levels. Road-segment scale erosion rates following paving ranged from 5-30% of pre-treatment levels, depending on road slope and road grading frequency. A 616-m3 sediment retention pond proved to contain 86 Mg of sediment annually and about 94% of the runoff generated from a 12 ha sub-catchment with an unpaved road density of 19 km km-2. Watershed-scale modeling evaluations suggested that the combination of these three treatments within the 13-km2 Coral Bay watershed resulted in the reduction of annual sediment delivery rates from 445 Mg yr-1 to 327 Mg yr-1. Cost-effectiveness analyses suggest that road drainage improvements and construction of the detention pond provided the greatest reductions in sediment delivery per total amount of funds spent. Even though paving is a proven erosion control method, the high costs involved made it a relatively cost-inefficient method. Marine sedimentation of terrigenous sediment (land-derived) was regularly monitored (every 26 days) at 15 near-shore and reef sites from 2008 to 2013 below the treated and undeveloped watersheds. Sediment composition (% terrigenous) determined by loss on ignition was multiplied by the total sediment accumulation rate in tube sediment traps to obtain terrigenous sediment accumulation rates (in mg cm-2 d-1). Mean terrigenous sediment accumulation rates were over 24 (near-shore) and 6 (reef) times greater

  8. Plio-Pleistocene paleo-erosion rates as a recorder of orographic barrier uplift in the NW-Argentine Andes (Humahuaca Basin)

    Pingel, Heiko; Schildgen, Taylor; Wittmann, Hella


    As an integral part of the Eastern Cordillera, the intermontane Humahuaca Basin in the NW Argentine Andes is located in transition between the arid and internally drained Puna Plateau to the west and the humid broken foreland to the east. In combination with moisture-bearing air masses sourced in the Atlantic Ocean and the Amazon Basin, the present-day topographic gradient of the eastern Andean margin comprises an efficient orographic barrier that results in a strong precipitation gradient, with rainfall of more than 2,000 mm/a along the eastern flanks and Mio-Pliocene by the growth of fault-bounded mountain ranges. This led to an increase in accommodation space and enabled the trapping of largely fluvial, late Miocene to Quaternary basin filling units. Subsequently, the basin was uplifted and internally deformed. Fossil records, sedimentologic evidence, and stable-isotopes (δD from volcanic glass) moreover imply that the re-routing of the fluvial network, an initial increase in precipitation, and, as the windward ranges attained threshold elevations to incoming moisture, reduced moisture availability by ca. 3 Ma, were all a consequence of the Mio-Pliocene uplift. In this study, we present first results of terrestrial cosmogenic nuclide-derived paleo-erosion rates from quartz-bearing fluvial sands and gravels of known stratigraphic age. In most cases, the age control is based on previously published U-Pb zircon data of intercalated volcanic ash deposits, but also utilizes new OSL and AMS14C ages. A reassessment of the sediment-accumulation history of the basin highlights important changes of the depositional system, apparently associated with the transformation from a humid foreland to a fluvially restricted and semi-arid intermontane basin. Similarly, our terrestrial cosmogenic nuclide-derived data indicate an order-of-magnitude decrease in erosion rates at ca. 3 Ma, which suggests a causal link between the onset of uplift-induced semi-arid conditions and

  9. Erosion sculptures

    Ristroph, Leif; Moore, M. N. J.; Childress, Stephen; Shelley, Michael; Zhang, Jun


    Erosion by flowing fluids carves the striking landscapes imprinted on the Earth and on the surfaces of our neighboring worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of clay bodies immersed in fast flowing water. Although commonly viewed as a smoothing process, we discover that erosion sculpts surprisingly sharp points and corners that persist as the body shrinks. These features result from a natural tendency to form surfaces that erode uniformly, and we argue that this principle may also apply to the more complex scenarios that occur in nature.

  10. Estimating rates of biologically driven coral reef framework production and erosion: a new census-based carbonate budget methodology and applications to the reefs of Bonaire

    Perry, C. T.; Edinger, E. N.; Kench, P. S.; Murphy, G. N.; Smithers, S. G.; Steneck, R. S.; Mumby, P. J.


    Census-based approaches can provide important measures of the ecological processes controlling reef carbonate production states. Here, we describe a rapid, non-destructive approach to carbonate budget assessments, termed ReefBudget that is census-based and which focuses on quantifying the relative contributions made by different biological carbonate producer/eroder groups to net reef framework carbonate production. The methodology is presently designed only for Caribbean sites, but has potential to be adapted for use in other regions. Rates are calculated using data on organism cover and abundance, combined with annual extension or production rate measures. Set against this are estimates of the rates at which bioeroding species of fish, urchins and internal substrate borers erode reef framework. Resultant data provide a measure of net rates of biologically driven carbonate production (kg CaCO3 m-2 year-1). These data have potential to be integrated into ecological assessments of reef state, to aid monitoring of temporal (same-site) changes in rates of biological carbonate production and to provide insights into the key ecological drivers of reef growth or erosion as a function of environmental change. Individual aspects of the budget methodology can also be used alongside other census approaches if deemed appropriate for specific study aims. Furthermore, the methodology spreadsheets are user-changeable, allowing local or new process/rate data to be integrated into calculations. Application of the methodology is considered at sites around Bonaire. Highest net rates of carbonate production, +9.52 to +2.30 kg CaCO3 m-2 year-1, were calculated at leeward sites, whilst lower rates, +0.98 to -0.98 kg CaCO3 m-2 year-1, were calculated at windward sites. Data are within the ranges calculated in previous budget studies and provide confidence in the production estimates the methodology generates.

  11. Rill erosion in natural and disturbed forests: 1. Measurements

    P. R. Robichaud; J. W. Wagenbrenner; R. E. Brown


    Rill erosion can be a large portion of the total erosion in disturbed forests, but measurements of the runoff and erosion at the rill scale are uncommon. Simulated rill erosion experiments were conducted in two forested areas in the northwestern United States on slopes ranging from 18 to 79%. We compared runoff rates, runoff velocities, and sediment flux rates from...

  12. Climate control on silicate weathering and physical erosion rates in young orogenic belts: Case study along a runoff gradient in Pacific and Amazonian Andean basins based on SNO-HYBAM Monitoring Program data

    Moquet, Jean-Sébastien; Guyot, Jean-Loup; Viers, Jérôme; Crave, Alain; Morera, Sergio; Rau, Pedro; Armijos, Elisa; Lagane, Christelle; Sven Lavado Casimiro, Waldo; Pombosa, Rodrigo; Fraizy, Pascal; Santini, William; Timouk, Franck; Vauchel, Philippe; Martinez, Jean-Michel


    At the global scale and on geological time scales, mechanical erosion and chemical weathering budgets are linked. Together, these processes contribute to the formation and the degradation of the Earth's critical zone and to the biogeochemical cycles of elements. In young orogenic belts, climate and tectonic subsidence control together the rate of these matter balance budget and their relationships. The climate gradient observed along the Andean basin in both the Pacific and the Atlantic slopes offers the opportunity to explore the role of the climate variability on the erosion and weathering budgets and on their reciprocal relationships. Based on the SNO-HYBAM Monitoring Program database (Geodynamical, hydrological and Biogeochemical control of erosion/weathering and material transport in the Amazon, Orinoco and Congo basins), we explore the relationship between climate, the lithology, silicate weathering rates and physical erosion rates along a runoff gradient in Andean basins of the Amazon River (13 gauging stations) and Pacific drainage rivers (5 gauging stations). No homogenous relationship between erosion rates (E) and chemical weathering rate (W) is observed over the monitored basins. Only the volcanic basins respond to a global relationship defined in the literature while the other basins budget may depend on anthropogenic interferences on erosion/sedimentation budget, a lithology dependence of the W-E relationship parameters or/and on the existence of a threshold in this relationship. The results presented here contribute to better understanding the role of mountains belt formation in the biogeochemical cycles and in particular in the long-term carbon cycle.Your presentation type preference.

  13. The use of straw mulch as a strategy to prevent extreme soil erosion rates in citrus orchard. A Rainfall simulation approach

    Cerdà, Artemi; Giménez-Morera, Antonio; Jordán, Antonio; Pereira, Paulo; Novara, Agata; García-Orenes, Fuensanta


    Not only the Sahel (Haregeweyn et al., 2013), the deforested land (Borelli et al., 2013) the chinese Plateau are affected by intense soil erosion rates (Zhao et al., 2013). Soil erosion affect agriculture land (Cerdà et al., 2009), and citrus orchards are being seeing as one of the crops with the highest erosion rates due to the managements that avoid the catch crops, weeds or litter. Example of the research carried out on citrus orchards is found in the Mediterranean (Cerdà and Jurgensen, 2008; 2009; Cerdà et al., 2009a; 2009b; Cerdà et al., 2011; 2012) and in China (Wu et al., 1997; Xu et al., 2010; Wang et al., 2011; Wu et al., 2011; Liu et al., 2011; Lü et al., 2011; Xu et al., 2012), and they confirm the non sustainable soil losses measured. The land management in citrus plantations results in soil degradation too (Lu et al., 1997; Lü et al., 2012; Xu et al., 2012). The use of cover crops to reduce the soil losses (Lavigne et al., 2012; Le Bellec et al., 2012) and the use of residues such as dried citrus peel has been found successful. There is a need to find new plants or residues to protect the soils on citrus orchards. Agriculture produces a high amount of residues. The pruning can contribute with a valuable source of nutrients and a good soil protection. The leaves of the trees, and some parts of the plants, once harvest can contribute to reduce the soil losses. Due to the mechanization of the agriculture, and the reduction of the draft animals (mainly horses, mules, donkeys and oxen) the straw is being a residue instead of a resource. The Valencia region is the largest producer of citrus in Europe, and the largest exporter in the world. This citrus production region is located in the eastern cost of Spain where we can find the rice production area of the l'Albufera Lagoon paddy fields, the third largest production region in Spain. This means, a rice production region surrounded by the huge citrus production region. There, the rice straw is not used

  14. Comparing global-scale topographic and climatic metrics to long-term erosion rates using ArcSwath, an efficient new ArcGIS tool for swath profile analysis

    Blomqvist, Niclas; Whipp, David


    The topography of the Earth's surface is the result of the interaction of tectonics, erosion and climate. Thus, topography should contain a record of these processes that can be extracted by topographic analysis. The question considered in this study is whether the spatial variations in erosion that have sculpted the modern topography are representative of the long-term erosion rates in mountainous regions. We compare long-term erosion rates derived from low-temperature thermochronometry to erosional proxies calculated from topographic and climatic data analysis. The study has been performed on a global scale including six orogens: The Himalaya, Andes, Taiwan, Olympic Mountains, Southern Alps in New Zealand and European Alps. The data was analyzed using a new swath profile analysis tool for ArcGIS called ArcSwath ( to determine the correlations between the long-term erosion rates and modern elevations, slope angles, relief in 2.5-km- and 5-km-diameter circles, erosion potential, normalized channel steepness index ksn, and annual rainfall. ArcSwath uses a Python script that has been incorporated into an ArcMap 10.2 add-in tool, extracting swath profiles in about ten seconds compared to earlier workflows that could take more than an hour. In ArcMap, UTM-projected point or raster files can be used for creating swath profiles. Point data are projected onto the swath and the statistical parameters (minimum, mean and maximum of the values across the swath) are calculated for the raster data. Both can be immediately plotted using the Python matplotlib library, or plotted externally using the csv-file that is produced by ArcSwath. When raster and point data are plotted together, it is easier to make comparisons and see correlations between the selected data. An unambiguous correlation between the topographic or climatic metrics and long-term erosion rates was not found. Fitting of linear regression lines to the topographic/ climatic metric

  15. Bentonite erosion. Final report

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))


    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.


    Juerg MERZ; Gopal NAKARMI; Pradeep M.DANGOL; Madhav P.DHAKAL; Bhawani S.DONGOL; Rolf WEINGARTNER


    Soil erosion is a hot topic in the foothills of Nepal and the entire Hindu Kush-Himalayan region. Particularly topsoil loss from water erosion is considered to be a big problem. As part of the project People and Resource Dynamics in Mountain Watersheds of the Hindu Kush-Himalayan region a number of erosion plots are monitored at an event resolution in two catchments of the Nepal middle mountains. On the basis of catchment wide sediment source mapping, surface erosion including gullying was determined to be the main erosive process in both catchments. In terms of importance as sediment source, surface erosion was likewise determined to be of major importance followed by streambank erosion and occasional landslides. In terms of topsoil loss through surface erosion degraded land produced the highest soil losses throughout the rainy season, followed by rainfed agricultural land, and finally only very small amounts of soil loss were observed on grassland. This is in general agreement with other soil erosion studies in the region. It was further observed that only a few large events are responsible for most of the annual soil loss. The event analysis also stressed the importance of rainfall amount and rainfall intensity for sediment mobilization. Particularly, the 30 minute maximum rainfall intensity, I30max, showed a good correlation with the soil loss that was nearly identical to that for the 10 minute maximum intensity, I10max, on one test catchment and was slightly better than that for I10max on the other test catchment. The importance of these rainfall parameters on degraded land is more pronounced due to the lack of vegetation cover and the subsequent lack of protection from the force of the rain drop splash. The antecedent precipitation conditions generally showed no correlation with the event soil loss from the plots.

  17. Validating and Improving Interrill Erosion Equations

    Zhang, Feng-Bao; Wang, Zhan-Li; Yang, Ming-Yi


    Existing interrill erosion equations based on mini-plot experiments have largely ignored the effects of slope length and plot size on interrill erosion rate. This paper describes a series of simulated rainfall experiments which were conducted according to a randomized factorial design for five slope lengths (0.4, 0.8, 1.2, 1.6, and 2 m) at a width of 0.4 m, five slope gradients (17%, 27%, 36%, 47%, and 58%), and five rainfall intensities (48, 62.4, 102, 149, and 170 mm h−1) to perform a systematic validation of existing interrill erosion equations based on mini-plots. The results indicated that the existing interrill erosion equations do not adequately describe the relationships between interrill erosion rate and its influencing factors with increasing slope length and rainfall intensity. Univariate analysis of variance showed that runoff rate, rainfall intensity, slope gradient, and slope length had significant effects on interrill erosion rate and that their interactions were significant at p = 0.01. An improved interrill erosion equation was constructed by analyzing the relationships of sediment concentration with rainfall intensity, slope length, and slope gradient. In the improved interrill erosion equation, the runoff rate and slope factor are the same as in the interrill erosion equation in the Water Erosion Prediction Project (WEPP), with the weight of rainfall intensity adjusted by an exponent of 0.22 and a slope length term added with an exponent of −0.25. Using experimental data from WEPP cropland soil field interrill erodibility experiments, it has been shown that the improved interrill erosion equation describes the relationship between interrill erosion rate and runoff rate, rainfall intensity, slope gradient, and slope length reasonably well and better than existing interrill erosion equations. PMID:24516624

  18. Quantification of debris-flow erosion rates by using high-resolution multitemporal terrestrial and airborne LiDAR data in the Kaunertal/Eastern Alps, Austria

    Neugirg, Fabian; Haas, Florian; Heckmann, Tobias; Hilger, Ludwig; Dusik, Jana-Marie; Becht, Michael


    Geomorphic processes in alpine high mountain areas show very high intensities. Not only high reliefs and steep slopes, but also the availability of recently exposed sediments in proglacial areas contribute to this fact. Furthermore the thawing and degradation of permafrost in high elevation zones trigger rock falls and debris flows in areas above and close to the glacier tongues, which provides for additional sediment input into the proglacial area. The work presented here is part of the interdisciplinary joint project PROSA (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) which deals with the quantification of the sediment budget of an alpine catchment, broken down by geomorphic process and accounting for glacial, fluvial and gravitative processes. The investigations are focused on the forefield of the Gepatschferner, Oetztal Alps, Austria which is overtowered by steep moraine slopes of the Little Ice Age glacial maximum. The rather poorly consolidated material of these moraine slopes leads to frequent occurrence of slope type debris flows. In order to quantify the activity of debris flows, high-resolution terrestrial laser scanning data of the lateral moraine slope of the Gepatschferner were acquired repeatedly from six different scanning positions. The resulting point clouds were used to derive high-resolution digital elevation models (DEMs) of the moraine slopes. Highly accurate co-registration of the multi-epoch LiDAR data was ensured by usage of permanently fixed reflectors on immobile bedrock faces within and next to the area investigated. For investigating larger debris flow events on the catchment scale, high-resolution multitemporal airborne LiDAR data were used to derive DEMs. Very accurate debris flow erosion and deposition rates can be obtained from DEMs of difference and a sediment budget can be calculated. A limit of detection threshold, based on the individual measuring errors of the device, was

  19. Estimation of root cohesion for desert shrub species in the Lower Colorado riparian ecosystem and its potential for streambank stabilization

    Adhikari, A. R.; Gautam, M. R.; Yu, Z.; Imada, S.; Acharya, K.


    Quantifying mechanical properties of native vegetation for streambank stability has remained a critical need of the Lower Colorado riparian revegetation effort. In the present study we estimated root cohesion for four representative native desert shrub species: Artiplex lentiformis (Torr.) S.Watson, Lycium andersonii A. Gray, Larrea tridentata (DC.) Coville, and Allenrolfea occidentalis (S.Watson) Kuntze to understand their suitability in streambank stabilization in the framework of a revegetation campaign. Field experiments were conducted to measure root length, root length density, root area ratio, and root tensile strength. Finally, the root cohesion values were assessed using a simple perpendicular model. Root area ratio estimates showed that on average plant roots occupy 0.46 % of the area under the crown of the selected species. The root tensile strength (Tr) was greatest for L. tridentata (62.23 MPa) followed by L. andersonii (53.53 MPa), A. lentiformis (49.17 MPa), and A. occidentalis (35.03 MPa).The root cohesion values could be used to rank the species according to their potential for shallow bank slope stabilization in riparian ecosystems of a desert environment. The maximum root cohesion in the present study was estimated for A. lentiformis (97.6kPa) followed by L. andersonii (89.3kPa), L. tridentata (35.6 kPa), and A. occidentalis (34.8 kPa). Root cohesion values were also estimated using Fiber bundle model (FBM) and compared to the perpendicular root model of Wu et al. (1979). The comparative root cohesion values for root diameter (> 0.5 mm) suggest that Wu's model estimates are greater than those of the FBM model by a reduction factor ranges between 0.35 and 0.56 for our studied species.

  20. Earthquake-induced soft-sediment deformations and seismically amplified erosion rates recorded in varved sediments of Köyceğiz Lake (SW Turkey)

    Avsar, Ulas


    Earthquake-triggered landslides amplify erosion rates in catchments, i.e. catchment response to seismic shocks (CR). In addition to historical eyewitness accounts of muddy rivers implying CRs after large earthquakes, several studies have quantitatively reported increased sediment concentrations in rivers after earthquakes. However, only a few paleolimnological studies could detect CRs within lacustrine sedimentary sequences as siliciclastic-enriched intercalations within background sedimentation. Since siliciclastic-enriched intercalations can easily be of non-seismic origin, their temporal correlation with nearby earthquakes is crucial to assign a seismic triggering mechanism. In most cases, either uncertainties in dating methods or the lack of recent seismic activity has prevented reliable temporal correlations, making the seismic origin of observed sedimentary events questionable. Here, we attempt to remove this question mark by presenting sedimentary traces of CRs in the 370-year-long varved sequence of Köyceğiz Lake (SW Turkey) that we compare with estimated peak ground acceleration (PGA) values of several nearby earthquakes. We find that earthquakes exceeding estimated PGA values of ca. 20 cm/s2 can induce soft-sediment deformations (SSD), while CRs seem only to be triggered by PGA levels higher than 70 cm/s2. In Köyceğiz Lake, CRs produce Cr- and Ni-enriched sedimentation due to the seismically mobilized soils derived from ultramafic rocks in the catchment. Given the varve chronology, the residence time of the seismically mobilized material in the catchment is determined to be 5 to 10 years.

  1. A sedimentary origin for intercrater plains north of the Hellas basin: Implications for climate conditions and erosion rates on early Mars

    Salese, Francesco; Ansan, Veronique; Mangold, Nicolas; Carter, John; Ody, Anouck; Poulet, Francois; Ori, Gian Gabriele


    Understanding the origin (volcanic or sedimentary) and timing of intercrater plains is crucial for deciphering the geological evolution of Mars. We have produced a detailed geological map of the intercrater plains north of the Hellas basin, based on images from the Mars Express High-Resolution Stereo Camera, the Mars Reconnaissance High-Resolution Imaging Science Experiment, and Context. Erosional windows and fresh impact craters provide a way of studying the lithology of intercrater plain units. They are composed predominantly of light-toned sedimentary rocks with subhorizontal bedding over a broad extent (greater than tens of kilometers), showing cross-bedding stratifications locally. The broad extent, geometry, and flat topography of these sediments favor a formation by aqueous processes (alluvial and lacustrine) rather than airfall (eolian and volcaniclastic). The Late Noachian ( 3.7 Ga) sedimentary plains are locally covered by dark-toned, rough-textured lava flows of Late Hesperian age ( 3.3 Ga). Fe/Mg phyllosilicates were detected within sedimentary rocks, whereas volcanic rocks contain pyroxene and lack signatures of alteration, in agreement with interpretations made from texture and morphology. In erosional windows, the superimposition of sedimentary rocks by younger volcanic flows enables the estimation of an erosion rate of 1000 nm yr-1 during the Hesperian period (3.3-3.7 Ga). Thus, our study shows that an intense sedimentary cycle occurred on the northern rim of the Hellas basin before and during the Late Noachian, leading to the formation of widespread sedimentary plains, which were then eroded, in agreement with a gradual change in the climatic conditions in this period, and later covered by volcanic flows.

  2. Erosion behavior and mechanism of boronised steels

    刘立; 凌国平; 刘涛; 郦剑


    Boronising of steels is a hardening process to get high surface hardness. The erosion resistance of boronised steels was researched with the use of four kinds of erodent, i.e. glass, alumina, quartz and silicon carbide. The erosion rate increases rapidly with erodent hardness and severe erosion occurs with high impacting angle range of hard particles. SEM analysis indicated that chipping is caused by repetitive impacting of glass and quartz, whereas by alumina and silicon carbide impacting, chipping, and that plastic flow take place simultaneously and the erosion rate reaches the peak value when the impacting angle is above 60°.

  3. Erosion behavior and mechanism of boronised steels

    刘立; 凌国平; 刘涛; 郦剑


    Boronising of steels is a hardening process to get high surfaoe hardness. The erosion resis-tance of boronised steels was researched with the use of four kinds of erodent, i.e. glass, alumina,quartz and silicon carbide. The erosion rate increases rapidly with erodent hardness and severe erosion occurs with high impacting angle range of hard particles. SEM analysis indicated that chipping is caused by repetitive impacting of glass and quartz, whereas b.y alumina and silicon carbide impacting, chipping,and that plastic flow .take place simultaneously and the erosion rate reaches the peak value when the impacting angle is above 60°.

  4. Tolerable soil erosion in Europe

    Verheijen, Frank; Jones, Bob; Rickson, Jane; Smith, Celina


    Soil loss by erosion has been identified as an important threat to soils in Europe* and is recognised as a contributing process to soil degradation and associated deterioration, or loss, of soil functioning. From a policy perspective, it is imperative to establish well-defined baseline values to evaluate soil erosion monitoring data against. For this purpose, accurate baseline values - i.e. tolerable soil loss - need to be differentiated at appropriate scales for monitoring and, ideally, should take soil functions and even changing environmental conditions into account. The concept of tolerable soil erosion has been interpreted in the scientific literature in two ways: i) maintaining the dynamic equilibrium of soil quantity, and ii) maintaining biomass production, at a location. The first interpretation ignores soil quality by focusing only on soil quantity. The second approach ignores many soil functions by focusing only on the biomass (particularly crop) production function of soil. Considering recognised soil functions, tolerable soil erosion may be defined as 'any mean annual cumulative (all erosion types combined) soil erosion rate at which a deterioration or loss of one or more soil functions does not occur'. Assumptions and problems of this definition will be discussed. Soil functions can generally be judged not to deteriorate as long as soil erosion does not exceed soil formation. At present, this assumption remains largely untested, but applying the precautionary principle appears to be a reasonable starting point. Considering soil formation rates by both weathering and dust deposition, it is estimated that for the majority of soil forming factors in most European situations, soil formation rates probably range from ca. 0.3 - 1.4 t ha-1 yr-1. Although the current agreement on these values seems relatively strong, how the variation within the range is spatially distributed across Europe and how this may be affected by climate, land use and land management

  5. Experiments on Erosion of Mud from the Danish Wadden Sea

    Johansen, C.; Larsen, Torben; Petersen, O.


    Experiments on erosion and consolidation of natural cohesive sediments from the harbour of Esbjerg located in the Danish Watten Sea were conducted using a rotating annular flume. The objective of the paper is to describe the erosion rate of deposited beds and relate the erosion rate...

  6. Physics of soil erosion at the microscale

    Philippe, Pierre; Cuéllar, Pablo; Brunier-Coulin, Florian; Luu, Li-Hua; Benahmed, Nadia; Bonelli, Stéphane; Delenne, Jean-Yves


    We focus here on the major and always topical issue of soil erosion by fluid flows, and more specifically on the determination of both a critical threshold for erosion occurrence and a kinetics that specifies the rate of eroded matter entrainment. A synthetic state-of-the-art is first proposed with a critical view on the most commonly used methods and erosion models. It is then discussed an alternative strategy, promoting the use of model materials that allow systematic parametric investigations with the purpose of first identifying more precisely the local mechanisms responsible for soil particle erosion and second ultimately quantifying both critical onsets and kinetics, possibly through existing or novel empirical erosion laws. Finally, we present and discuss several examples following this methodology, implemented either by means of experiments or numerical simulations, and coupling erosion tests in several particular hydrodynamical configurations with wisely selected mechanical tests.

  7. Comparative analyses of factors determining soil erosion rates based on network of Mediterranean monitored catchments for the innovative, adaptive and resilient agriculture of the future

    Smetanová, Anna; Le Bissonnais, Yves; Raclot, Damien; Perdo Nunes, João; Licciardello, Feliciana; Mathys, Nicolle; Latron, Jérôme; Rodríguez Caballero, Emilio; Le Bouteiller, Caroline; Klotz, Sébastien; Mekki, Insaf; Gallart, Francesc; Solé Benet, Albert; Pérez Gallego, Nuria; Andrieux, Patrick; Jantzi, Hugo; Moussa, Roger; Planchon, Olivier; Marisa Santos, Juliana


    In order to project the soil erosion response to climate change in the fragile Mediterranean region it is inevitable to understand its existing patterns. Soil erosion monitoring on a catchment scale enables to analyse temporal and spatial variability of soil erosion and sediment delivery, while the integrating study of different catchments is often undertaken to depicther the general patterns. In this study, eight small catchments (with area up to 1,32 km2), representative for the western part of the Mediterranean region (according to climate, bedrock, soils and main type of land use) were compared. These catchments, grouped in the R-OS Med Network were situated in France (3), Spain (2), Portugal (1), Italy (1) and Tunisia (1). The average precipitation ranged between 236 to 1303 mm·a-1 and mean annual sediment yield varied 7.5 to 6900 Mg·km-2·a-1. The complex databes was based on more than 120 years of hydrological and sediment data, with series between 3 and 29 years long. The variability of sediment data was described on annual and monthly basis. The relationship between the sediment yield and more than 35 factors influencing the sediment yield including the characteristics of climate, topography, rainfall, runoff, land use, vegetation and soil cover, connectivity and dominant geomorphic processes, was studied. The preliminary results confirmed the differences in rainfall, runoff and sediment response, and revealed both the similarities and differences in soil erosion responses of the catchments. They are further dependent on the variability of factors themselves, with important contribution of the state of soil properties, vegetation cover and land use. Anna Smetanová has received the support of the European Union, in the framework of the Marie-Curie FP7 COFUND People Programme, through the award of an AgreenSkills' fellowship (under grant agreement n° 267196)

  8. Saliva parameters and erosive wear in adolescents

    Zwier, N.; Huysmans, M.C.D.N.J.M.; Jager, D.H.J.; Ruben, J.; Bronkhorst, E.M.; Truin, G.J.


    The aim of this study was to investigate the relationship between several parameters of saliva and erosive wear in adolescents. (Un-)stimulated saliva was collected from 88 adolescents with erosion and 49 controls (age 16 ± 1 years). Flow rate, pH and buffer capacity were determined immediately.

  9. Saliva Parameters and Erosive Wear in Adolescents

    Zwier, N.; Huysmans, M. C. D. N. J. M.; Jager, D. H. J.; Ruben, J.; Bronkhorst, E. M.; Truin, G. J.


    The aim of this study was to investigate the relationship between several parameters of saliva and erosive wear in adolescents. (Un-)stimulated saliva was collected from 88 adolescents with erosion and 49 controls (age 16 +/- 1 years). Flow rate, pH and buffer capacity were determined immediately.

  10. The erosive potential of candy sprays

    Gambon, D.L.; Brand, H.S.; Nieuw Amerongen, A.V.


    Objective To determine the erosive potential of seven different commercially available candy sprays in vitro and in vivo. Material and methods The erosive potential was determined in vitro by measuring the pH and neutralisable acidity. The salivary pH and flow rate were measured in healthy volunteer

  11. Influence of austenization temperature on the erosion behavior of austempered ductile irons

    L.C.Chang; I.C.Hsui; L.H.Chen; S.T.Lui


    The erosion behavior of austempered ductile irons austenized at different temperatures was studied. The results indicate that the erosion rate well correlates with the mechanical properties. At high impact angles, increasing ductility and mechanical energy density results in decreasing erosion rate, whereas increasing hardness reduces the erosion rate at low impact angles.

  12. Soil erosion in Slovene Istria

    Matjaž Mikoš


    Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.


    C. Harrington; R. Kelly; K.T. Ebert


    Variations in erosion and deposition for the last fifty years (based on estimates from 137Cs profiles) on surfaces (Late Pleistocene to Late Holocene in age) making up the Fortymile Wash alluvial fan south of Yucca Mountain, is a function of surface age and of desert pavement development or absence. For purposes of comparing erosion and deposition, the surfaces can be examined as three groups: (1) Late Pleistocene surfaces possess areas of desert pavement development with thin Av or sandy A horizons, formed by the trapping capabilities of the pavements. These zones of deposition are complemented by coppice dune formation on similar parts of the surface. Areas on the surface where no pavement development has occurred are erosional in nature with 0.0 +/- 0.0 cm to 1.5 +/- 0.5 cm of erosion occurring primarily by winds blowing across the surface. Overall these surfaces may show either a small net depositional gain or small erosional loss. (2) Early Holocene surfaces have no well-developed desert pavements, but may have residual gravel deposits in small areas on the surfaces. These surfaces show the most consistent erosional surface areas on which it ranges from 1.0 +/-.01 cm to 2.0+/- .01 cm. Fewer depositional forms are found on this age of surface so there is probably a net loss of 1.5 cm across these surfaces. (3) The Late Holocene surfaces show the greatest variability in erosion and deposition. Overbank deposition during floods cover many edges of these surfaces and coppice dune formation also creates depositional features. Erosion rates are highly variable and range from 0.0 +/- 0.0 to a maximum of 2.0+/-.01. Erosion occurs because of the lack of protection of the surface. However, the common areas of deposition probably result in the surface having a small net depositional gain across these surfaces. Thus, the interchannel surfaces of the Fortymile Wash fan show a variety of erosional styles as well as areas of deposition. The fan, therefore, is a dynamic

  14. Emergency wind erosion control

    February through May is the critical time for wind erosion in Kansas, but wind erosion can happen any time when high winds occur on smooth, wide fields with low vegetation and poor soil structure. The most effective wind erosion control is to ensure a protective cover of residue or growing crop thro...

  15. Research on cohesive sediment erosion by flow: An overview


    Erosion of cohesive sediment by flow is a very complicated phenomenon occurring worldwide. Understanding and modeling of the erosion process are important for many issues such as the breaching of embankments, riverbank stability, siltation of harbors and navigation channels, service life of reservoirs, distribution of (heavy metal) pollutants and water quality problems. In the last few decades, numerous studies have been done on the erosion of cohesive sediment by flow. Nevertheless, the factors affecting the erosion resistance of cohesive sediment are still not fully understood and the knowledge of the physics of cohesive sediment erosion is in- adequate, as a result the mathematical modeling of this erosion is far from satis- factory. In this paper an overview of the studies on the erosion resistance, erosion threshold and the erosion rate of cohesive sediment by flow is presented. The outcomes achieved so far from the studies and the existing problems have been analyzed and summarized, based on which recommendations are proposed for future research.

  16. Interfacial Instability during Granular Erosion.

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre


    The complex interplay between the topography and the erosion and deposition phenomena is a key feature to model granular flows such as landslides. Here, we investigated the instability that develops during the erosion of a wet granular pile by a dry dense granular flow. The morphology and the propagation of the generated steps are analyzed in relation to the specific erosion mechanism. The selected flowing angle of the confined flow on a dry heap appears to play an important role both in the final state of the experiment, and for the shape of the structures. We show that the development of the instability is governed by the inertia of the flow through the Froude number. We model this instability and predict growth rates that are in agreement with the experiment results.

  17. Modeling Soil Erosion with the Aid of GIS

    WU Ping-li


    Soil erosion caused by water is an increasing global problem. In order to relieve this problem, several erosion models have been developed to measure the rate of erosion for soil conservation planning. This study takes Lee County, South Carolina, USA as an example to map soil erosion within ArcGIS environment by using the RUSLE with erosion indexes retrieved from DEM. This study proves that the integration of soil erosion models with GIS is a very simple but efficient tool for soil conservation.

  18. The effect of liquid film on liquid droplet impingement erosion

    Fujisawa, Nobuyuki, E-mail: [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Yamagata, Takayuki, E-mail: [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Saito, Kengo; Hayashi, Kanto [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan)


    Highlights: • Liquid droplet impingement erosion is studied experimentally using high-speed conical spray. • Erosion rate is increased with decreasing the liquid film thickness. • Erosion model is proposed considering the influence of liquid film thickness. -- Abstract: In the present paper, the pipe-wall thinning due to liquid droplet impingement erosion is studied experimentally by using a high-speed conical spray under the influences of liquid film on the target specimen. The size of the droplets considered is an order of tens of micrometers in diameter, which is the same order as those expected in the pipeline of nuclear/fossil power plants. In order to evaluate the erosion rate by the liquid droplet impingement under the influence of liquid film, the experiments are conducted by various combinations of the specimen diameters and the standoff distances of the spray from the nozzle. The experimental results show that the erosion depth increases linearly with the local flow volume, indicating the presence of terminal stage of erosion. The present results indicate that the erosion rate increases with decreasing the specimen diameter and increases slightly with increasing the standoff distance. This result combined with the theoretical consideration of the liquid film on the specimen leads to the conclusion that the erosion rate increases with decreasing the liquid film thickness, which supports the numerical result of liquid droplet impingement erosion in literature. Then, the erosion model for predicting the erosion rate by the liquid droplet impingement is proposed considering the influence of the liquid film.

  19. Dental erosion, summary.

    ten Cate, J M; Imfeld, T


    Although reports on dental erosion have always appeared in the dental literature, there is currently a growing interest among researchers and clinicians. Potential risk factors for dental erosion are changed lifestyle and eating patterns, with increased consumption of acidic foods and beverages. Various gastrointestinal and eating disorders expose the dentition to frequent contacts with very acidic gastric content, which may lead to erosion. Whether these factors indeed lead, on a population scale, to a higher prevalence and incidence of erosion is yet to be established. This article summarizes the different aspects of the prevalence, pathology, etiology, assessment, prevention and treatment of dental erosion, and concludes with recommendations for future research.

  20. Assessment of contemporary erosion/sedimentation rates trend within a small well-cultivated catchments using caesium-137 as a chronomarker (on the example of the Republic of Tatarstan, Russia)

    Sharifullin, Aidar; Gusarov, Artem; Gafurov, Artur; Golosov, Valentin


    extreme (storm) precipitation (>50 mm per a day). The influence of agricultural activity on the erosion and sedimentation changeability was insignificant, although some regional variation of crop rotation including an increase in the proportion of perennial grasses obviously caused the decline in soil losses during warm period of year. The similar trend of erosion/sedimentation rates due to mostly climate changes was identified for south-western sector of the East European Plain, but the more serious reduction of erosion rates is established for the Middle Volga region. Keywords: erosion, sedimentation, sediment, caesium-137, dry valley, small catchment, cultivated lands, Republic of Tatarstan, East European Plain.

  1. The Application of Erosive Burning to Propellant Charge Interior Ballistics

    ZHANG Hong-lin


    Erosive burning is a common burning phenomenon of the gunpowder with inner holes. The actual combustion law of the gunpowder with inner holes can be changed by erosive burning. Pressure difference between the inner and the outer of hole caused by loading density variation of the propellant charge makes erosive burning occur at inner holes during in-bore burning. The effect of erosive burning on burning speed of the propellant is studied by using the effects of flow rate, heat transfer and erosion of the combustion gas in inner holes on burning rate. The mathematic model of erosive burning of the propellant is established. The effects of the factors such as loading density, inner hole size and grain length on erosive burning and interior ballistic performance are analyzed .The method to improve the bore pressure for small charge mass and small firing range by erosive burning is proposed.

  2. Process identification of soil erosion in steep mountain regions

    N. Konz


    Full Text Available Mountainous soil erosion processes were investigated in the Urseren Valley (Central Switzerland by means of measurements and simulations. The quantification of soil erosion was performed on hill slope scale (2·20 m for three different land use types: hayfields, pastures with dwarf shrubs and pastures without dwarf shrubs with three replicates each. Erosion rates during growing season were measured with sediment traps between June 2006 and November 2007. Long-term soil erosion rates were estimated based on Cs- 137 redistribution. In addition, soil moisture and surface flow were recorded during the growing season in the field and compared to model output. We chose the WEPP model (Water Erosion Prediction Project to simulate soil erosion during the growing season. Model parameters were determined in the field (slope, plant species, fractional vegetation cover, initial saturation level, by laboratory analyses (grain size, organic matter and by literature study. The WEPP model simulates sheet erosion processes (interrill and splash erosion processes, please note that no rill erosion occurs at our sites. Model output resulted in considerable smaller values than the measured erosion rates with sediment traps for the same period. We attribute the differences to observed random gravity driven erosion of soil conglomerates. The Cs-137 measurements deliver substantially higher mean annual erosion rates, which are most likely connected to snow cover related processes such as snow gliding and avalanche activities.

  3. 10 CFR 960.4-2-5 - Erosion.


    ... 10 Energy 4 2010-01-01 2010-01-01 false Erosion. 960.4-2-5 Section 960.4-2-5 Energy DEPARTMENT OF... Postclosure Guidelines § 960.4-2-5 Erosion. (a) Qualifying condition. The site shall allow the underground... consider the climatic, tectonic, and geomorphic evidence of rates and patterns of erosion in the...

  4. Erosion--Corrosion

    Vyas, B.


    The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions.

  5. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix E. Missouri River Demonstration Projects. Volume 1.


    Peachleaf Willow Salix amygdaloides -. Cottonwood Populus deltoides Russian Olive Elaeagnus angustifolia Buffaloberry Shepherdia argentea In addition, 8,000... Elaeagnus angustifolia Buffaloberry Shepherdia argentea Red-Osier Dogwood Cornus stolonifera Golden Willow Salix alba vitelina Hackberry Celtis

  6. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix D. Ohio River Demonstration Projects.



  7. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix G. Demonstration Projects on Other Streams, Nationwide. Volume 2.


    Clermont County residents in the labor market are employed in Hamilton County. The employment structure of Clermont County in 1970 consisted of a high...percent of manufacturing (42 percent), wholesale and retail (17 percent), and 11 percent in services. The remaining market consists of a relatively...listed by either the state or the U.S. Department of Interior, but which is capable of generating special enthusiasm and concern among birdwatchers , are

  8. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix A. Literature Survey.


    Dyer, C. E., "Revetment--Stabilization of the Channel of the Rio Grande from Caballo Dam to Fort Quitman, New Mexico-Texas," Symposium on Channel...Stabilization of the Channel of the Rio Grande from Caballo Dam to Fort Quitman, New Mexico-Texas," Symposium on Channel Stabilization Problems, Technical

  9. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix C. Geotechnical Research.


    along the banks, secondary currents, freeze-thaw, and bed aggradation as eroded soil from upstream is deposited at the reach of the river under...reinforced headbox , fitted with a motorized aluminum headgate and turning vanes to direct the flow of the water (Figure C29), is mounted on the...does not take into account variations in tractive shear stress due to spiral (or helicoidal) flow, secondary currents, or flow separation in curved

  10. Exploring the relationship between gully erosion and rainfall erosivity

    Campo, Miguel; Casalí, Javier; Giménez, Rafael


    Rainfall erosivity plays and important role in gully erosion. However, there are few studies that explore this relationship. The main purpose of this work is to analyse the link between observed gully erosion rates and rainfall erosivity. However, in order to get a suitable and comparable set of daily rainfall erosivity data, we firstly evaluate the performance of several daily rainfall erosivity models to estimate the daily accumulated RUSLE EI30 index. One 300 ha watershed (El Cantalar) located in Navarre (Spain) was selected to carry out field studies. A meteorological station located 10 km appart from the experimental site provided daily precipitation records since 1930 to 2009 and also 10min records since 1991 to 2009. In this watershed a total of 35 gully headcuts developed in cohesive soil were monitored. Aerial photographic stereo-pairs covering the study area were used for the survey. These were taken in five different years and at different spatial scales each time: 1956 (1: 34,000), 1967 (1:17,500), 1982 (1:13,500), 2003 (1:20,000) and 2006 (1:2000). Manual restitution of photographs was carried out. 1m resolution DEMs were obtained by triangular interpolation (Triangular Irregular Network) and then used to characterize gully headcuts. Moreover, from the aerial photos and the DEMs, ortho-photographs with a final resolution of 0.40 m were created. The geocoding of the scenes had a Root Mean Square error of less than 0.5 m both in planimetry and altimetry. Furthermore, using the DEMs and the ortho-photographs, volumetric headcut retreat rates for each period were calculated as the product of the lineal retreat and a representative section of the headcut. Daily accumulated RUSLE EI30 index was calculated in a conventional way from records of precipitation every 10 minutes for the period 1991-2009; these results were used as reference data. In addition, for the same period, this index was estimated with daily precipitation records through several models

  11. Etiology and pathogenesis of dental erosion.

    Kanzow, Philipp; Wegehaupt, Florian J; Attin, Thomas; Wiegand, Annette


    The condition of dental erosion is defined as acid-related loss of tooth structure which does not involve microorganisms. Depending on the origin of the acid, extrinsic (usually caused by acids in food) and intrinsic (caused by endogenous acid) erosion can be distinguished. The presence and severity of erosive defects depend on various parameters such as nutrition, saliva, general diseases, and mechanical stress by abrasion and attrition. As an example, dietary habits which involve frequent intake of acidic food and beverages, occupational acid exposure, as well as certain drugs or diseases that affect saliva flow rate are accompanied by an increased risk of erosive dental hard tissue defects. By a thorough clinical examination and an accurate anamnesis, various erosion-related risk factors can be identified and strategies to reduce or eliminate these factors be identified.

  12. Rainfall erosivity in New Zealand

    Klik, Andreas; Haas, Kathrin; Dvorackova, Anna; Fuller, Ian


    Rainfall and its kinetic energy expressed by the rainfall erosivity is the main driver of soil erosion processes by water. The Rainfall-Runoff Erosivity Factor (R) of the Revised Universal Soil Loss Equation is one oft he most widely used parameters describing rainfall erosivity. This factor includes the cumulative effects of the many moderate-sized storms as well as the effects oft he occasional severe ones: R quantifies the effect of raindrop impact and reflects the amopunt and rate of runoff associated with the rain. New Zealand is geologically young and not comparable with any other country in the world. Inordinately high rainfall and strong prevailing winds are New Zealand's dominant climatic features. Annual rainfall up to 15000 mm, steep slopes, small catchments and earthquakes are the perfect basis for a high rate of natural and accelerated erosion. Due to the multifacted landscape of New Zealand its location as island between the Pacific and the Tasmanian Sea there is a high gradient in precipitation between North and South Island as well as between West and East Coast. The objective of this study was to determine the R-factor for the different climatic regions in New Zealand, in order to create a rainfall erosivity map. We used rainfall data (breakpoint data in 10-min intervals) from 34 gauging stations for the calcuation of the rainfall erosivity. 15 stations were located on the North Island and 19 stations on the South Island. From these stations, a total of 397 station years with 12710 rainstorms were analyzed. The kinetic energy for each rainfall event was calculated based on the equation by Brown and Foster (1987), using the breakpoint precipitation data for each storm. On average, a mean annual precipitation of 1357 mm was obtained from the 15 observed stations on the North Island. Rainfall distribution throughout the year is relatively even with 22-24% of annual rainfall occurring in spring , fall and winter and 31% in summer. On the South Island

  13. Erosion-corrosion; Erosionkorrosion

    Aghili, B


    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment 32 refs, 16 figs, tabs

  14. Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration

    E. M. Stacy; S. C. Hart; C. T. Hunsaker; D. W. Johnson; A. A. Berhe


    Lateral movement of organic matter (OM) due to erosion is now considered an important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet most published studies on the role of erosion focus on agricultural or grassland ecosystems. To date, little information is available on the rate and nature of OM eroded from forest ecosystems. We present annual...

  15. Definition of tolerable soil erosion values

    G. Sparovek


    Full Text Available Although the criteria for defining erosion tolerance are well established, the limits generally used are not consistent with natural, economical and technological conditions. Rates greater than soil formation can be accepted only until a minimum of soil depth is reached, provided that they are not associated with environmental hazard or productivity losses. A sequence of equations is presented to calculate erosion tolerance rates through time. The selection of equation parameters permits the definition of erosion tolerance rates in agreement with environmental, social and technical needs. The soil depth change that is related to irreversible soil degradation can be calculated. The definition of soil erosion tolerance according to these equations can be used as a guideline for sustainable land use planning and is compatible with expert systems.

  16. Sediment and Cavitation Erosion Studies through Dam Tunnels

    Muhammad Abid


    Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

  17. Paddys Run Streambank Stabilization Project at the Fernald Preserve, Harrison, OH

    Hooten, Gwendolyn [Dept. of Energy (DOE), Legacy Management; Hertel, Bill [Navarro Research and Engineering; Homer, John [Navarro Research and Engineering


    The Fernald Preserve is a former uranium-processing plant that underwent extensive remediation pursuant to CERCLA and is now managed by the US DOE Office of Legacy Management. While remediation of buildings and soil contamination was completed in 2006, aquifer remediation is ongoing. Paddys Run is a second-order stream that runs to the south along the western side of the Fernald Preserve. The Paddys Run watershed encompasses nearly 41 km2 (16 mi2), including most of the Fernald site. Field personnel conducting routine site inspections in March 2014 observed that Paddys Run was migrating east via bank erosion into the “Pit 3 Swale,” an area of known surface-water contamination. The soil there was certified pursuant to site regulatory agreements and meets all final remediation levels. However, weekly surface-water monitoring is conducted from two puddles within the swale area, when water that exceeds the final remediation levels is present. Paddys Run had migrated east approximately 4 m (13 ft) in 2 years and was approximately 29 m (95 ft) from the sample location. This rapid migration threatened existing conditions that allowed for continued monitoring of the swale area and also threatened Paddys Run water quality. Therefore, DOE and regulators determined that the east bank of Paddys Run required stabilization. This was accomplished with a design that included the following components: relocation of approximately 145 m (475 ft) of streambed 9 m (30 ft) west, installation of a rock toe along the east bank, installation of two cross-vane in-stream grade-control structures, stabilization of a portion of the east bank using soil encapsulated lifts, and regrading, seeding, and planting within remaining disturbed areas. In an effort to take advantage of low-flow conditions in Paddys Run, construction was initiated in September 2014. Weather delays and subsurface flow within the Paddys Run streambed resulted in an interim shutdown of the project area in December 2014

  18. Erosion Negril Beach

    Ten Ham, D.; Henrotte, J.; Kraaijeveld, R.; Milosevic, M.; Smit, P.


    The ongoing erosion of the Negril Beach has become worse the past decade. In most places along the coast line, the beach will be gone in approximately 10 years. This will result in a major decrease of incomes that are made by the local tourist sector. To prevent the erosion this study has been perfo

  19. Saliva and dental erosion

    BUZALAF, Marília Afonso Rabelo; HANNAS, Angélicas Reis; KATO, Melissa Thiemi


    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective This review discusses the role of salivary factors on the development of dental erosion. Material and Methods A search was undertaken on MEDLINE website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects. PMID:23138733

  20. Saliva and dental erosion

    Marília Afonso Rabelo Buzalaf


    Full Text Available Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  1. Erosion of soil organic carbon: implications for carbon sequestration

    Van Oost, Kristof; Van Hemelryck, Hendrik; Harden, Jennifer W.; McPherson, B.J.; Sundquist, E.T.


    Agricultural activities have substantially increased rates of soil erosion and deposition, and these processes have a significant impact on carbon (C) mineralization and burial. Here, we present a synthesis of erosion effects on carbon dynamics and discuss the implications of soil erosion for carbon sequestration strategies. We demonstrate that for a range of data-based parameters from the literature, soil erosion results in increased C storage onto land, an effect that is heterogeneous on the landscape and is variable on various timescales. We argue that the magnitude of the erosion term and soil carbon residence time, both strongly influenced by soil management, largely control the strength of the erosion-induced sink. In order to evaluate fully the effects of soil management strategies that promote carbon sequestration, a full carbon account must be made that considers the impact of erosion-enhanced disequilibrium between carbon inputs and decomposition, including effects on net primary productivity and decomposition rates.

  2. Numerical study of solid particle erosion in butterfly valve

    Liu, Bo; Zhao, Jiangang; Qian, Jianhua


    In the actual operation of butterfly valve, the butterfly valve is found severe erosion wear. A solid particle erosion analysis of butterfly valve based on the erosion theory is researched in this study. A CFD model has been built to simulate the flow erosion. Different parameters of butterfly valve including inlet velocity, particle mass fraction and solid particle diameter are separately analysed. The results show that erosion rate increase with the increase of inlet velocity, particle mass fraction and solid particle diameter. The peak erosion rate is up to 4.63E-5 (kg/m2/s) and erosion of valve disc mainly occurs around the upstream edge and the cylinder face.

  3. Erosion resistance of bionic functional surfaces inspired from desert scorpions.

    Zhiwu, Han; Junqiu, Zhang; Chao, Ge; Li, Wen; Ren, Luquan


    In this paper, a bionic method is presented to improve the erosion resistance of machine components. Desert scorpion (Androctonus australis) is a typical animal living in sandy deserts, and may face erosive action of blowing sand at a high speed. Based on the idea of bionics and biologic experimental techniques, the mechanisms of the sand erosion resistance of desert scorpion were investigated. Results showed that the desert scorpions used special microtextures such as bumps and grooves to construct the functional surfaces to achieve the erosion resistance. In order to understand the erosion resistance mechanisms of such functional surfaces, the combination of computational and experimental research were carried out in this paper. The Computational Fluid Dynamics (CFD) method was applied to predict the erosion performance of the bionic functional surfaces. The result demonstrated that the microtextured surfaces exhibited better erosion resistance than the smooth surfaces. The further erosion tests indicated that the groove surfaces exhibited better erosion performance at 30° injection angle. In order to determine the effect of the groove dimensions on the erosion resistance, regression analysis of orthogonal multinomials was also performed under a certain erosion condition, and the regression equation between the erosion rate and groove distance, width, and height was established.

  4. Calibrating thermal erosion models along an Arctic coastline

    Wobus, C. W.; Anderson, R. S.; Overeem, I.; Urban, F. E.; Clow, G. D.; Stanton, T. P.


    Coastal erosion rates of 20-30 meters per year have been documented along Alaska’s Beaufort Sea coastline, and a number of studies suggest that erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the role of climate change on coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on the potential magnitude of thermal erosion along a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where erosion rates have averaged 10-15 meters/year over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to directly observe erosion processes via time-lapse photography, while monitoring temperature, solar radiation and wind speed at the same time. These combined observations are used to calibrate models of thermal erosion. Our observations suggest that virtually all of the erosion in this setting can be explained as a purely thermal process. Coastal bluffs are first notched and then topple into the ocean, failing dominantly along ice wedges that serve as planes of weakness. Furthermore, the high ice content and the fine grain size of the coastal plain materials that comprise the bluffs appear to limit any strong negative feedback on erosion rates, since the sediments are readily dispersed on the shallow shelf. Although erosion driven purely by thermal processes may be unique to this particular coastal zone, these observations implicate a direct relationship between climatic warming and landscape change. Erosion of sandy coastlines in other parts of the NPR-A may also be ultimately controlled by thermal energy, once a thin veneer of clastic material is removed by wave action from



    Traditionally gully erosion has been identified with the dissection of the landscape in agricultural settings but it is also recognized as a prevalent erosion feature in earthen dam auxiliary spillways and embankments. Flows through earthen spillways and over dam embankments, due to large rainfall events, have the potential to erode and breach the dam or spillway and result in catastrophic releases from the reservoir. The gully erosion process in an earthen spillway or on an embankment can be characterized by stages of initiation, development, and migration of a headcut. A headcut is defined as a near vertical drop at the upstream end of a gully. The rate of headcut migration is important in determining the breach potential of an earthen spillway and dam embankment. A research program is being conducted to examine the gully erosion processes of earthen dam auxiliary spillways and embankments. This paper describes: 1) the unique test facilities constructed to examine the dominant factors affecting the erosion of earthen spillways and embankments; 2) the observations of the erosion processes and results to date; and 3) the predictive relationships that have been developed for dam gully erosion research at the ARS Hydraulic Engineering Research Unit laboratory in Stillwater, OK.

  6. Soft drinks and in vitro dental erosion.

    Gravelle, Brent L; Hagen Ii, Ted W; Mayhew, Susan L; Crumpton, Brooks; Sanders, Tyler; Horne, Victoria


    The purpose of this investigation was to determine to what extent the in vitro exposure of healthy teeth to various commonly consumed carbonated soft drinks may precipitate dental erosion. Forty-two healthy, extracted, previously unerupted human molars were weighed prior to, during, and after suspension in various sugared and diet or zero-calorie carbonated beverages for 20 days; the specimens were stored at room temperature while being stirred at 275 rpm. The percentage decrease in tooth weight from before to after exposure represented the weight loss due to enamel erosion; values in the experimental groups varied from 3.22% to 44.52% after 20 days' exposure. Data were subjected to analysis of variance and post hoc Scheffe testing at a level of α = 0.05. Nonsugared drinks (diet and zero-calorie) as a whole were more erosive than sugared beverages. A significant positive correlation was found between the amount of titratable acid and percentage of tooth erosion, while a significant negative correlation was revealed between the beverage pH and percentage of tooth erosion. No significant correlations were found between calcium or phosphate ion concentrations and the amount of erosion. It appears that enamel erosion is dependent on not only the beverage flow rate, pH, and amount of titratable acid, but also whether the soft drink is of the diet or zero-calorie variety, which reflects the type of artificial sweetener present.

  7. Polyanhydride degradation and erosion.

    Göpferich, A; Tessmar, J


    It was the intention of this paper to give a survey on the degradation and erosion of polyanhydrides. Due to the multitude of polymers that have been synthesized in this class of material in recent years, it was not possible to discuss all polyanhydrides that have gained in significance based on their application. It was rather the intention to provide a broad picture on polyanhydride degradation and erosion based on the knowledge that we have from those polymers that have been intensively investigated. To reach this goal this review contains several sections. First, the foundation for an understanding of the nomenclature are laid by defining degradation and erosion which was deemed necessary because many different definitions exist in the current literature. Next, the properties of major classes of anhydrides are reviewed and the impact of geometry on degradation and erosion is discussed. A complicated issue is the control of drug release from degradable polymers. Therefore, the aspect of erosion-controlled release and drug stability inside polyanhydrides are discussed. Towards the end of the paper models are briefly reviewed that describe the erosion of polyanhydrides. Empirical models as well as Monte-Carlo-based approaches are described. Finally it is outlined how theoretical models can help to answer the question why polyanhydrides are surface eroding. A look at the microstructure and the results from these models lead to the conclusion that polyanhydrides are surface eroding due to their fast degradation. However they switch to bulk erosion once the device dimensions drop below a critical limit.

  8. Erosive burning of solid propellants

    King, Merrill K.


    Presented here is a review of the experimental and modeling work concerning erosive burning of solid propellants (augmentation of burning rate by flow of product gases across a burning surface). A brief introduction describes the motor design problems caused by this phenomenon, particularly for low port/throat area ratio motors and nozzleless motors. Various experimental techniques for measuring crossflow sensitivity of solid propellant burning rates are described, with the conclusion that accurate simulation of the flow, including upstream flow development, in actual motors is important since the degree of erosive burning depends not only on local mean crossflow velocity and propellant nature, but also upon this upstream development. In the modeling area, a brief review of simplified models and correlating equations is presented, followed by a description of more complex numerical analysis models. Both composite and double-base propellant models are reviewed. A second generation composite model is shown to give good agreement with data obtained in a series of tests in which composite propellant composition and heterogeneity (particle size distribution) were systematically varied. Finally, the use of numerical models for the development of erosive burning correlations is described, and a brief discussion of scaling is presented.

  9. Soil Erosion Threatens Food Production

    Michael Burgess


    Full Text Available Since humans worldwide obtain more than 99.7% of their food (calories from the land and less than 0.3% from the oceans and aquatic ecosystems, preserving cropland and maintaining soil fertility should be of the highest importance to human welfare. Soil erosion is one of the most serious threats facing world food production. Each year about 10 million ha of cropland are lost due to soil erosion, thus reducing the cropland available for world food production. The loss of cropland is a serious problem because the World Health Organization and the Food and Agricultural Organization report that two-thirds of the world population is malnourished. Overall, soil is being lost from agricultural areas 10 to 40 times faster than the rate of soil formation imperiling humanity’s food security.

  10. Sets resilient to erosion

    Pegden, Wesley


    The erosion of a set in Euclidean space by a radius r>0 is the subset of X consisting of points at distance >/-r from the complement of X. A set is resilient to erosion if it is similar to its erosion by some positive radius. We give a somewhat surprising characterization of resilient sets, consisting in one part of simple geometric constraints on convex resilient sets, and, in another, a correspondence between nonconvex resilient sets and scale-invariant (e.g., 'exact fractal') sets.

  11. Fluvial erosion on Mars: Implications for paleoclimatic change

    Gulick, Virginia C.; Baker, Victor R.


    Fluvial erosion on Mars has been nonuniform in both time and space. Viking orbiter images reveal a variety of different aged terrains exhibiting widely different degrees of erosion. Based on our terrestrial analog studies, rates of fluvial erosion associated with the formation of many of the valleys on Mars is probably on the order of hundreds of meters per million years, while rates of erosion associated with the formation of the outflow channels probably ranged from tens to hundreds of meters in several weeks to months. However, estimated rates of erosion of the Martian surface at the Viking Lander sites are extremely low, on the order of 1 micron/yr or less. At most this would result in a meter of material removed per million years, and it is unlikely that such an erosion rate would be able to produce the degree of geomorphic work required to form the fluvial features present elsewhere on the surface. In addition, single terrain units are not eroded uniformly by fluvial processes. Instead fluvial valleys, particularly in the cratered highlands, typically are situated in clusters surrounded by vast expanses of uneroded surfaces of the same apparent lithologic, structural, and hydrological setting. Clearly throughout its geologic history, Mars has experienced a nonuniformity in erosion rates. By estimating the amount of fluvial erosion on dissected terrains and by studying the spatial distribution of those locations which have experienced above normal erosion rates, it should be possible to place further constraints on Mars' paleoclimatic history.

  12. Soil erosion evolution and spatial correlation analysis in a typical karst geomorphology using RUSLE with GIS

    Zeng, Cheng; Wang, Shijie; Bai, Xiaoyong; Li, Yangbing; Tian, Yichao; Li, Yue; Wu, Luhua; Luo, Guangjie


    Although some scholars have studied soil erosion in karst landforms, analyses of the spatial and temporal evolution of soil erosion and correlation analyses with spatial elements have been insufficient. The lack of research has led to an inaccurate assessment of environmental effects, especially in the mountainous area of Wuling in China. Soil erosion and rocky desertification in this area influence the survival and sustainability of a population of 0.22 billion people. This paper analyzes the spatiotemporal evolution of soil erosion and explores its relationship with rocky desertification using GIS technology and the revised universal soil loss equation (RUSLE). Furthermore, this paper analyzes the relationship between soil erosion and major natural elements in southern China. The results are as follows: (1) from 2000 to 2013, the proportion of the area experiencing micro-erosion and mild erosion was at increasing risk in contrast to areas where moderate and high erosion are decreasing. The area changes in this time sequence reflect moderate to high levels of erosion tending to convert into micro-erosion and mild erosion. (2) The soil erosion area on the slope, at 15-35°, accounted for 60.59 % of the total erosion area, and the corresponding soil erosion accounted for 40.44 %. (3) The annual erosion rate in the karst region decreased much faster than in the non-karst region. Soil erosion in all of the rock outcrop areas indicates an improving trend, and dynamic changes in soil erosion significantly differ among the various lithological distribution belts. (4) The soil erosion rate decreased in the rocky desertification regions, to below moderate levels, but increased in the severe rocky desertification areas. The temporal and spatial variations in soil erosion gradually decreased in the study area. Differences in the spatial distribution between lithology and rocky desertification induced extensive soil loss. As rocky desertification became worse, the erosion

  13. Time-Dependent Erosion of Ion Optics

    Wirz, Richard E.; Anderson, John R.; Katz, Ira; Goebel, Dan M.


    The accurate prediction of thruster life requires time-dependent erosion estimates for the ion optics assembly. Such information is critical to end-of-life mechanisms such as electron backstreaming. CEX2D was recently modified to handle time-dependent erosion, double ions, and multiple throttle conditions in a single run. The modified code is called "CEX2D-t". Comparisons of CEX2D-t results with LDT and ELT post-tests results show good agreement for both screen and accel grid erosion including important erosion features such as chamfering of the downstream end of the accel grid and reduced rate of accel grid aperture enlargement with time.

  14. Erosion dynamics of a wet granular medium.

    Lefebvre, Gautier; Jop, Pierre


    Liquid may give strong cohesion properties to a granular medium, and confer a solidlike behavior. We study the erosion of a fixed circular aggregate of wet granular matter subjected to a flow of dry grains inside a half-filled rotating drum. During the rotation, the dry grains flow around the fixed obstacle. We show that its diameter decreases linearly with time for low liquid content, as wet grains are pulled out of the aggregate. This erosion phenomenon is governed by the properties of the liquids. The erosion rate decreases exponentially with the surface tension while it depends on the viscosity to the power -1. We propose a model based on the force fluctuations arising inside the flow, explaining both dependencies: The capillary force acts as a threshold and the viscosity controls the erosion time scale. We also provide experiments using different flowing grains, confirming our model.

  15. Bank erosion events and processes in the Upper Severn basin

    D. M. Lawler


    Full Text Available This paper examines river bank retreat rates, individual erosion events, and the processes that drive them in the Upper Severn basin, mid-Wales, UK. Traditional erosion pin networks were used to deliver information on patterns of downstream change in erosion rates. In addition, the novel automatic Photo-Electronic Erosion Pin (PEEP monitoring system was deployed to generate near-continuous data on the temporal distribution of bank erosion and accretion: this allowed focus on the magnitude and timing of individual erosional and depositional events in relation to specific flow episodes. Erosion dynamics data from throughout the Upper Severn basin are combined with detailed information on bank material properties and spatial change in channel hydraulics derived from direct field survey, to assess the relationships between flow properties and bank erosion rates. Results show that bank erosion rates generally increase downstream, but relate more strongly to discharge than to reach-mean shear stress, which peaks near the basin head. Downstream changes in erosion mechanisms and boundary materials, across the upland/lowland transition (especially the degree of development of composite bank material profiles, are especially significant. Examples of sequences of bank erosion events show how the PEEP system can (a quantify the impact of individual, rather than aggregated, forcing events, (b reveal the full complexity of bank response to given driving agents, including delayed erosion events, and (c establish hypotheses of process-control in bank erosion systems. These findings have important implications for the way in which bank erosion problems are researched and managed. The complex responses demonstrated have special significance for the way in which bank processes and channel-margin sediment injections should be handled in river dynamics models.

  16. Erosion of Earthen Levees by Wave Action

    Ozeren, Y.; Wren, D. G.; Reba, M. L.


    Earthen levees of aquaculture and irrigation reservoirs in the United States often experience significant erosion due to wind-generated waves. Typically constructed using local soils, unprotected levees are subjected to rapid erosion and retreat due to wind generated waves and surface runoff. Only a limited amount of published work addresses the erosion rates for unprotected levees, and producers who rely on irrigation reservoirs need an economic basis for selecting a protection method for vulnerable levees. This, in turn, means that a relationship between wave energy and erosion of cohesive soils is needed. In this study, laboratory experiments were carried out in order to quantify wave induced levee erosion and retreat. A model erodible bank was packed using a soil consisting of approximately 14% sand, 73% silt, and 13% clay in a 20.6 m long 0.7 m wide and 1.2 m deep wave tank at the USDA-ARS, National Sedimentation Laboratory in Oxford MS. The geometry of the levee face was monitored by digital camera and the waves were measured by means of 6 capacitance wave staffs. Relationships were established between levee erosion, edge and retreat rates, and incident wave energy.

  17. Advances in Predicting Soil Erosion After Fire Using the Rangeland Hydrology and Erosion Model

    Al-Hamdan, Osama Z.; Pierson, Frederick B.; Nearing, Mark A.; Williams, C. Jason; Hernandez, Mariano; Boll, Jan; Nouwakpo, Sayjro; Weltz, Mark A.; Spaeth, Kenneth E.


    The magnitude of erosion from a hillslope is governed by the availability of sediment and connectivity of overland flow and erosion processes. For undisturbed conditions, sediment is mainly detached and transported by rainsplash and sheetflow (splash-sheet) processes in bare batches, but sediment generally only travels a short distance before deposition. On recently disturbed sites (e.g., after fire), bare ground is more extensive and runoff and erosion rates are higher relative to undisturbed conditions. Increased erosion following disturbance occurs largely due to a shift from splash-sheet to concentrated-flow-dominated processes. On long-disturbed sites (e.g., after woody plant encroachment), years of soil loss can limit sediment availability and soil erosion. In contrast, recently burned landscapes typically have ample sediment available and generate high erosion rates. This presentation highlights recent advancements in hillslope erosion prediction by the Rangeland Hydrology and Erosion Model (RHEM) that accommodate recently burned conditions. The RHEM tool is a process-based model that was developed specifically for predicting hillslope runoff and erosion on rangeland ecosystems. The advancements presented here include development of empirical equations to predict erodibility parameters for conditions in which erosion by concentrated flow processes is limited (by runoff or sediment availability) and an erodibility parameter for conditions in which erosion by concentrated flow processes is the dominant erosion mechanism and sediment is amply available (burned conditions). The data used for developing and evaluating the erodibility parameter equations were obtained from rainfall simulation databases maintained by the USDA-Agricultural Research Service. The data span undisturbed, long-disturbed, and recently burned conditions. For undisturbed and long-disturbed conditions, a regression analysis was applied to derive the relationship between splash

  18. Actinides, accelerators and erosion

    Fifield L. K.; Tims S.G.


    Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace...

  19. Measurement of erosion: Is it possible?

    Stroosnijder, L.


    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

  20. Measurement of erosion: Is it possible?

    Stroosnijder, L.


    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation re

  1. The Erosion of Frozen Argon by Swift Helium Ions

    Besenbacher, F.; Bøttiger, Jørgen; Graversen, O.


    The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore unequivo......The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore...

  2. Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

    Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.


    Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of

  3. Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

    Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo


    This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (catchment, the soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil.

  4. Impact of tillage erosion on water erosion in a hilly landscape.

    Wang, Y; Zhang, J H; Zhang, Z H; Jia, L Z


    Little has been known of the interaction between tillage erosion and water erosion, while the two erosion processes was independently studied. Can tillage-induced soil redistribution lead to exaggerated (or retarded) runoff flow and sediment concentrations in steeply sloping fields? A series of simulated tillage and artificial rainfall events were applied to rectangular runoff plots (2m×8m) with a slope of 15° to examine the impacts of tillage erosion intensities on water erosion in the Yangtze Three Gorges Reservoir Area, China. Mean flow velocity, effective/critical shear stress, and soil erodibility factor K were calculated to analyze the differences in hydrodynamic characteristics induced by tillage. Our experimental results suggest that mean runoff rates were 2.26, 1.19, and 0.65Lmin(-1) and that mean soil detachment rates were 1.53, 1.01, and 0.61gm(-2)min(-1) during the 70-min simulated rainfall events for 52-, 31-, and 10-year tillage, respectively. A significant difference (Perosion increases soil erodibility and delivers the soil for water erosion in sloping fields, accelerating water erosion.

  5. SOTER-Based Soil Water Erosion Simulation in Hainan Island



    The actual and potential water erosion rates of soils with different land covers in Hainan Island, China,were estimated based on the universal soil loss equation (USLE) and a 1:200 000 Soils and Terrain Digital Database (SOTER) database, from which soil water erosion factors could be extracted. 92.8% of the whole island had a current erosion rate of lower than 500 t km-2 a-1. Soil erosion risk was considered to be high because of its abundant rainfall. Without vegetation cover, the potential soil erosion rate would be extremely high and 90.8% of the island would have a soil erosion rate higher than 2 500 t km-2 a-1. Relative erosion vulnerability of different soil zones, landform types, and lithological regions of the island was compared by introducing a relative erosion hazard parameter α. Cambosols developed from siltstone and mudstone in low hill regions were pinpointed as soils with the highest erosion risk in the island.

  6. 10-daily soil erosion modelling over sub-Saharan Africa.

    Symeonakis, Elias; Drake, Nick


    Soil erosion is considered to be one of the greatest environmental problems of sub-Saharan Africa. This paper investigates the advantages and disadvantages of modelling soil erosion at the continental scale and suggests an operational methodology for mapping and quantifying 10-daily water runoff and soil erosion over this scale using remote sensing data in a geographical information system framework. An attempt is made to compare the estimates of this study with general data on the severity of soil erosion over Africa and with measured rates of soil loss at different locations over the continent. The results show that the measured and estimated rates of erosion are in some areas very similar and in general within the same order of magnitude. The importance and the potential of using the soil erosion estimates with simple models and easily accessible free data for various continental-scale environmental applications are also demonstrated.

  7. Density Development During Erosion Experiments of Cohesive Sediments

    Johansen, Claus; Larsen, Torben


    The density development during erosion experiments was investigated. The calculation of the erosion rate requires the knowledge of the density profile with respect to the consolidation time(Parchure, 1984). At present, the basic assumption in the calculations is that the density profile is achieved...... from consolidation experiments conducted with the same consolidation period (Malta, 1986; Metha and Partheniades, 1979). Furthermore, the density is assumed constant throughout the erosion experiment. Therefore, experiments were conducted in order to investigate this assumption. Kaolinite was used...

  8. Density Development During Erosion Experiments of Cohesive Sediments

    Johansen, Claus; Larsen, Torben


    The density development during erosion experiments was investigated. The calculation of the erosion rate requires the knowledge of the density profile with respect to the consolidation time(Parchure, 1984). At present, the basic assumption in the calculations is that the density profile is achieved...... from consolidation experiments conducted with the same consolidation period (Malta, 1986; Metha and Partheniades, 1979). Furthermore, the density is assumed constant throughout the erosion experiment. Therefore, experiments were conducted in order to investigate this assumption. Kaolinite was used...

  9. Coastal Erosion Control Methods

    Greene, V.


    Coastal erosion is bad because the ecosystem there will be washed away and the animals could drown or be displaced and have to adapt to a new ecosystem that they are not prepared for. I'm interested in this problem because if there aren't beaches when I grow up I won't be able to do the things I would really like to do. I would like to be a marine biologist. Secondly, I don't want to see beach houses washed away. I would like to see people live in harmony with their environment. So, to study ways in which to preserve beaches I will make and use models that test different erosion controls. Two different ideas for erosion control I tested are using seaweed or a rock berm. I think the rock berm will work better than the model of seaweed because the seaweed is under water and the waves can carry the sand over the seaweed, and the rock berm will work better because the rocks will help break the waves up before they reach the shore and the waves can not carry the sand over the rocks that are above the water. To investigate this I got a container to use to model the Gulf of Mexico coastline. I performed several test runs using sand and water in the container to mimic the beach and waves from the Gulf of Mexico hitting the shoreline. I did three trials for the control (no erosion control), seaweed and a rock berm. Rock berms are a border of a raised area of rock. The model for seaweed that I used was plastic shopping bags cut into strips and glued to the bottom of my container to mimic seaweed. My results were that the control had the most erosion which ranged from 2.75 - 3 inches over 3 trials. The seaweed was a little better than the control but was very variable and ranged from 1.5 - 3 inches over 3 trials. The rock berm worked the best out of all at controlling erosion with erosion ranging from 1.5 - 2 inches. My hypothesis was correct because the rock berm did best to control erosion compared to the control which had no erosion control and the model with seaweed.

  10. Lateral erosion in an experimental bedrock channel: The influence of bed roughness on erosion by bed load impacts

    Fuller, Theodore K.; Gran, Karen B.; Sklar, Leonard S.; Paola, Chris


    Physical experiments were conducted to evaluate the efficacy of bed load particle impacts as a mechanism of lateral bedrock erosion. In addition, we explored how changes in channel bed roughness, as would occur during development of an alluvial cover, influence rates of lateral erosion. Experimental channels were constructed to have erodible walls and a nonerodible bed using different mixtures of sand and cement. Bed roughness was varied along the length of the channel by embedding sediment particles of different size in the channel bed mixture. Lateral wall erosion from clear-water flow was negligible. Lateral erosion during periods in which bed load was supplied to the channel removed as much as 3% of the initial wetted cross-sectional area. The vertical distribution of erosion was limited to the base of the channel wall, producing channels with undercut banks. The addition of roughness elements to an otherwise smooth bed caused rates of lateral erosion to increase by as much as a factor of 7 during periods of bed load supply. However, a minimum roughness element diameter of approximately half the median bed load particle diameter was required before a substantial increase in erosion was observed. Beyond this minimum threshold size, further increases in the relative size of roughness elements did not substantially change the rate of wall erosion despite changes in total boundary shear stress. The deflection of saltating bed load particles into the channel wall by fixed roughness elements is hypothesized to be the driver of the observed increase in lateral erosion rates.

  11. Quantifying modern and ancient drainage basin erosion with detrital thermochronology

    Ehlers, T. A.; Stock, G. M.; Rahl, J. M.; Farley, K. A.; van der Pluijm, B. A.


    Studies of drainage basin erosion and landform evolution are often limited by not knowing where sediment is sourced from and how erosion rates vary over different time scales. Detrital thermochronometer cooling ages collected from modern river sediments and basin deposits provide a promising tool to address these problems. We present two applications of detrital thermochronology to quantify: (1) spatial variations in erosion using modern river sediments; and (2) temporal variations in erosion calculated using syntectonic sedimentary deposits. In our first application, the elevation dependence of detrital apatite (U-Th)/He (AHe) ages is used to track the elevations where sediment is produced from bedrock. The ages are measured in river sediments from the mouth of two catchments in the Sierra Nevada, California, and used as sediment tracers to quantify spatial variations in erosion. We measured ~54 AHe single grain ages from each catchment. Measured AHe age probability density functions (PDFs) were compared with predicted PDFs, calculated by convolving catchment hypsometry with bedrock age-elevation relationships. Statistical comparison of the PDFs evaluates the spatial distribution of erosion in the catchments. Predicted and observed PDFs are statistically identical for the nonglaciated Inyo Creek catchment, indicating uniform erosion. However, a statistically significant lack of older ages is observed in the recently deglaciated Lone Pine catchment, suggesting sediment is derived from the lower half of the catchment; possibly due to sediment storage at higher elevations and/or enhanced erosion at intermediate elevations. Second, we evaluate the ability of detrital thermochronology to record transients in drainage basin erosion on million year time scales. A transient 1D thermal model is used to predict cooling ages in a syntectonic stratigraphic section where sediment is sourced from a region with temporally variable erosion. In simulations with transient erosion

  12. Modelling erosion on a daily basis

    Pikha Shrestha, Dhruba; Jetten, Victor


    Effect of soil erosion causing negative impact on ecosystem services and food security is well known. To assess annual erosion rates various empirical models have been extensively used in all the climatic regions. While these models are simple to operate and do not require lot of input data, the effect of extreme rain is not taken into account in the annual estimations. For analysing the effects of extreme rain the event- based models become handy. These models can simulate detail erosional processes including particle detachment, transportation and deposition of sediments during a storm. But they are not applicable for estimating annual erosion rates. Moreover storm event data may not be available everywhere which prohibits their extensive use. In this paper we describe a method by adapting the revised MMF model to assess erosion on daily basis so that the effects of extreme rains are taken into account. We couple it to a simple surface soil moisture balance on a daily basis and include estimation of daily vegetation cover changes. Annual soil loss is calculated by adding daily erosion rates. We compare the obtained results with that obtained from applying the revised MMF model in a case study in the Mamora plateau in northwest Morocco which is affected by severe gully formation. The results show clearly the effects of exceptional rain in erosional processes which cannot be captured in an annual model.

  13. Sand transport, erosion and granular electrification

    Merrison, J.P.


    The transport of granular materials by wind has a major impact on our environment through sand/soil erosion and the generation and transport of atmospheric dust aerosols. Terrestrially the transport of dust involves billions of tons of material every year, influencing the global climate and impac......The transport of granular materials by wind has a major impact on our environment through sand/soil erosion and the generation and transport of atmospheric dust aerosols. Terrestrially the transport of dust involves billions of tons of material every year, influencing the global climate...... can affect grain transport through the generation of intense electric fields and processes of electrostatic assembly. Importantly the transport of sand is characterized by saltation, which is known to be an active process for erosion and therefore a source for dust and sand formation. Using novel...... erosion simulation techniques the link between grain transport rates and erosion rates has been quantified. Furthermore this can be linked to production rates for dust and has been associated with chemical and mineral alteration through a process of mechanical activation of fractured surfaces. This work...

  14. Solid particle erosion of polymers and composites

    Friedrich, K.; Almajid, A. A.


    After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

  15. Concentrated flow erosion processes under planned fire

    Langhans, Christoph; Noske, Phil; Van Der Sant, Rene; Lane, Patrick; Sheridan, Gary


    The role of wildfire in accelerating erosion rates for a certain period after fire has been well documented. Much less information is available on the erosion rates and processes after planned fires that typically burn at much lower intensity. Observational evidence, and some studies in southern and southeastern Australia suggest that erosion after planned fire can be significant if rainfall intensities exceed critical intensities and durations. Understanding erosion processes and rates under these event conditions is of critical importance for planning of burn locations away from critical human assets such as water supplies and infrastructure. We conducted concentrated flow experiments with the purpose to understand what critical conditions are required for significant erosion to occur on planned burn hillslopes. Concentrated flow runon was applied on pre-wetted, unbounded plots of 10 m at rates of 0.5, 1, 1.5 and 2 L/s, with three replicates for each rates applied at 1m distance of each other. The experiments were carried out at three sites within one burn perimeter with different burn severities ranging from low to high, with two replicates at each site. Runon was applied until an apparent steady state in runoff was reached at the lower plot boundary, which was typically between 0.7 and 2.5 minutes. The experiments were filmed and erosion depth was measured by survey methods at 1m intervals. Soil surface properties, including potential sediment trapping objects were measured and surveyed near the plots. We found that fire severity increased plot scale average erosion depth significantly even as experiments were typically much shorter on the high severity plots. Unit stream power was a good predictor for average erosion depth. Uncontrolled for variations in soil surface properties explained process behaviour: finer, ash rich surface material was much less likely to be trapped by fallen, charred branches and litter than coarser, ash-depleted material. Furthermore

  16. Laboratory simulation of water-resources conservation by means of the layout of a series of ponds along a streambank

    Jean, Jiin-Shuh; Hung, Chao-Chi

    The purpose of this research is to describe a water-storage method that is more reliable than reservoirs, and to study the efficacy of interception and storage of surface runoff in ponds. In this method, a series of ponds is laid out along a streambank so that interception of surface runoff can be increased and more water can be stored in the wet season for use in the dry season. The simulated results show that the structure of a pond, vegetation and the extent of land development, topographic slope, and the degree to which a pond penetrates an aquifer affect the efficacy of interception and storage of surface runoff in ponds. Résumé Le but de ce travail est de décrire une méthode de stockage d'eau qui soit plus sure que les réservoirs, et d'étudier l'efficacité de l'interception et du stockage d'eau de ruissellement dans des bassins. Dans cette méthode, une série de bassins est disposée le long d'une berge de rivière de façon à ce que l'interception de l'écoulement de surface puisse être accrue et que plus d'eau puisse être stockée pendant la saison humide pour être utilisée en saison sèche. Les résultats de la simulation montrent que l'efficacité de l'interception et du stockage du ruissellement dans les bassins sont déterminés par la structure du bassin, la végétation et l'importance du développement agricole, la pente des versants et le degré de pénétration du bassin dans la nappe. Resumen El objetivo de este trabajo es describir un método de almacenamiento de agua que ofrece mayor garantía que los embalses, así como estudiar la eficacia de la intercepción y almacenamiento de la escorrentía superficial en pequeñas lagunas artificiales. Este método consiste en crear una serie de lagunas a lo largo de las riberas de un torrente, de manera que intercepción de la escorrentía superficial se pueda incrementar y se almacene más agua en la época húmeda para su utilización en la época seca. Los resultados simulados muestran

  17. Assessment of croplands dynamics in the river basins of the different landscape zones of the Russian plain for the last 30 years as factor of soil erosion rate trend

    Ivanov, Maxim; Zalyaliev, Rinal; Efimov, Kirill; Kondrat'eva, Alina; Kinyashova, Anastasiya; Ionova, Yuliya


    After the collapse of the USSR in the period of transition from a state-controlled economy to a market-driven economy, there have been significant changes in land use. Information about changes in the structure of agricultural land is very important to assess the ecological condition of the territories. In this study was evaluated the changes of croplands in areas of the European territory of Russia located in different climate, landscape and geomorphological conditions. Mapping of the croplands in the territory of 9 river basins for the two time slices (the middle of the 1980s, and the present-day period 2013-2015) was carried out by visual interpretation of multi-seasonal images Landsat 5 and Landsat 8. We are using mapping technique realized in the CORINE Land Cover 2000 project (CLC2000), adjusted for the regional features and purposes of our study. Using vector layers, obtained as a result of digitization, the areas of croplands in the analyzed periods have been calculated and changes occurred in 30 years was evaluated. Croplands is the dominant category of land use in almost all regions, and it is in the range of 40-65% in 2015. The decrease of croplands area was established for the all studied river basins. The largest decrease of croplands (37.7%) is observed in the Izh river basin located in the forest landscape zone. Significantly smaller reduction of croplands (10%) observed in the basins belonging to the forest-steppe landscape zone. In the basins, located in the steppe zone of the reduction of croplands is in the range 10-20%. Land use changes are a powerful factor determining the rate of erosion and sedimentation and some other exogenic processes. However, for the evaluation of these rates is important to determine whether the decrease of cropland due to the abandonment the more steep slope, which are less suitable for traditional cultivation. For this aim, steepness of slopes was analyzed for the each river basin. Slope rasters for the studied river

  18. Dynamics of soil organic carbon and microbial biomass carbon in relation to water erosion and tillage erosion.

    Xiaojun, Nie; Jianhui, Zhang; Zhengan, Su


    Dynamics of soil organic carbon (SOC) are associated with soil erosion, yet there is a shortage of research concerning the relationship between soil erosion, SOC, and especially microbial biomass carbon (MBC). In this paper, we selected two typical slope landscapes including gentle and steep slopes from the Sichuan Basin, China, and used the (137)Cs technique to determine the effects of water erosion and tillage erosion on the dynamics of SOC and MBC. Soil samples for the determination of (137)Cs, SOC, MBC and soil particle-size fractions were collected on two types of contrasting hillslopes. (137)Cs data revealed that soil loss occurred at upper slope positions of the two landscapes and soil accumulation at the lower slope positions. Soil erosion rates as well as distribution patterns of the erosion is the major process of soil redistribution in the gentle slope landscape, while tillage erosion acts as the dominant process of soil redistribution in the steep slope landscape. In gentle slope landscapes, both SOC and MBC contents increased downslope and these distribution patterns were closely linked to soil redistribution rates. In steep slope landscapes, only SOC contents increased downslope, dependent on soil redistribution. It is noticeable that MBC/SOC ratios were significantly lower in gentle slope landscapes than in steep slope landscapes, implying that water erosion has a negative effect on the microbial biomass compared with tillage erosion. It is suggested that MBC dynamics are closely associated with soil redistribution by water erosion but independent of that by tillage erosion, while SOC dynamics are influenced by soil redistribution by both water erosion and tillage erosion.

  19. Dynamics of Soil Organic Carbon and Microbial Biomass Carbon in Relation to Water Erosion and Tillage Erosion

    Xiaojun, Nie; Jianhui, Zhang; Zhengan, Su


    Dynamics of soil organic carbon (SOC) are associated with soil erosion, yet there is a shortage of research concerning the relationship between soil erosion, SOC, and especially microbial biomass carbon (MBC). In this paper, we selected two typical slope landscapes including gentle and steep slopes from the Sichuan Basin, China, and used the 137Cs technique to determine the effects of water erosion and tillage erosion on the dynamics of SOC and MBC. Soil samples for the determination of 137Cs, SOC, MBC and soil particle-size fractions were collected on two types of contrasting hillslopes. 137Cs data revealed that soil loss occurred at upper slope positions of the two landscapes and soil accumulation at the lower slope positions. Soil erosion rates as well as distribution patterns of the erosion is the major process of soil redistribution in the gentle slope landscape, while tillage erosion acts as the dominant process of soil redistribution in the steep slope landscape. In gentle slope landscapes, both SOC and MBC contents increased downslope and these distribution patterns were closely linked to soil redistribution rates. In steep slope landscapes, only SOC contents increased downslope, dependent on soil redistribution. It is noticeable that MBC/SOC ratios were significantly lower in gentle slope landscapes than in steep slope landscapes, implying that water erosion has a negative effect on the microbial biomass compared with tillage erosion. It is suggested that MBC dynamics are closely associated with soil redistribution by water erosion but independent of that by tillage erosion, while SOC dynamics are influenced by soil redistribution by both water erosion and tillage erosion. PMID:23717530

  20. Can control of soil erosion mitigate water pollution by sediments?

    Rickson, R J


    The detrimental impact of sediment and associated pollutants on water quality is widely acknowledged, with many watercourses in the UK failing to meet the standard of 'good ecological status'. Catchment sediment budgets show that hill slope erosion processes can be significant sources of waterborne sediment, with rates of erosion likely to increase given predicted future weather patterns. However, linking on-site erosion rates with off-site impacts is complicated because of the limited data on soil erosion rates in the UK and the dynamic nature of the source-pathway-receptor continuum over space and time. Even so, soil erosion control measures are designed to reduce sediment production (source) and mobilisation/transport (pathway) on hill slopes, with consequent mitigation of pollution incidents in watercourses (receptors). The purpose of this paper is to review the scientific evidence of the effectiveness of erosion control measures used in the UK to reduce sediment loads of hill slope origin in watercourses. Although over 73 soil erosion mitigation measures have been identified from the literature, empirical data on erosion control effectiveness are limited. Baseline comparisons for the 18 measures where data do exist reveal erosion control effectiveness is highly variable over time and between study locations. Given the limitations of the evidence base in terms of geographical coverage and duration of monitoring, performance of the different measures cannot be extrapolated to other areas. This uncertainty in effectiveness has implications for implementing erosion/sediment risk reduction policies, where quantified targets are stipulated, as is the case in the EU Freshwater Fish and draft Soil Framework Directives. Also, demonstrating technical effectiveness of erosion control measures alone will not encourage uptake by land managers: quantifying the costs and benefits of adopting erosion mitigation is equally important, but these are uncertain and difficult to

  1. Cavitation erosion of NiAl

    Akhtar, A. [Powertech Labs. Inc., Surrey, British Columbia (Canada)]|[Univ. of British Columbia (Canada). Metals and Materials Engineering Dept.; Salvi, R. [Univ. of British Columbia (Canada). Metals and Materials Engineering Dept.; Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.


    Vibratory cavitation erosion tests were carried out on as-cast NiAl intermetallic compounds containing 46.5 to 62.1 at. pct Ni. The erosion rate decreased with increasing nickel content by over two orders of magnitude, from a high of 16.4 to 0.11 mg{center_dot}h{sup {minus}1}. These low erosion rates exhibited by the nickel-rich alloys containing 58 and 62.1 at. pct Ni, the interruptions in their mass loss with time, and the unusual effects associated with surface finish and intensity of cavitation were found to be associated with the stress-induced martensitic transformation. Alloys containing 58 to 62 at. pct Ni have the potential for use as materials for the cavitation protection of hydraulic machinery.

  2. Stellar Wind Erosion of Protoplanetary Discs

    Schnepf, Neesha R; Romanova, Marina


    An analytic model is developed for the erosion of protoplanetary gas discs by high velocity magnetized stellar winds. The winds are centrifugally driven from the surface of rapidly rotating, strongly magnetized young stars. The presence of the magnetic field in the wind leads to Reynolds numbers sufficiently large to cause a strongly turbulent wind/disk boundary layer which entrains and carries away the disc gas. The model uses the conservation of mass and momentum in the turbulent boundary layer. The time-scale for significant erosion depends on the disc accretion speed, accretion rate and on the wind mass loss rate. The time-scale is estimated to be ~2E6 yr. The stellar wind erosion may act in conjunction with photo-evaporation of the discs.

  3. Beryllium-7 measurements of wind erosion on sloping fields in the wind-water erosion crisscross region on the Chinese Loess Plateau.

    Zhang, Jiaqiong; Yang, Mingyi; Deng, Xinxin; Liu, Zhang; Zhang, Fengbao; Zhou, Weiying


    Soil erosion is complex in the wind-water erosion crisscross region of the Chinese Loess Plateau, as interleaving of wind and water erosion occurs on both temporal and spatial scales. It is difficult to distinguish wind erosion from the total erosion in previous studies due to the untraceable of aeolian particles and the limitation of feasible methods and techniques. This study used beryllium-7 measurements to study wind erosion in the wind-water erosion crisscross region on the Chinese Loess Plateau arms to delineate wind erosion distribution, to analyze its implication to erosive winds and surface microrelief, and to determine correlations between erosion rates and slope gradients. Results obtained using beryllium-7 measurements based on observation plots were verified with saltating particle collection method, and were also verified on a field scale. Results indicated that the effective resultant erosion wind was from northward, which was proved by the eight-directional distributed saltating particles. The microrelief of the ground surface contributed to the formation of high or low erosion centers. Wind erosion rates increased with a linear (R(2)≥0.95) or exponential (R(2)≥0.83) fitting increase in the slope gradients as reported in previous studies. Compared to wind erosion on field scale, both the plots and fields exhibited similar distribution patterns in wind erosion isolines. We also determined that the wind erosion rate for two fields estimated, based on equations developed from plot scale was acceptable. This study validates the feasibility of beryllium-7 measurements for soil-wind erosion field experiments and the potential to expand this approach to real field conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Clinical studies of dental erosion and erosive wear

    Huysmans, M.C.D.N.J.M; Chew, H.P; Ellwood, R.P


    We define erosion as a partial demineralisation of enamel or dentine by intrinsic or extrinsic acids and erosive tooth wear as the accelerated loss of dental hard tissue through the combined effect...

  5. Solid particle erosion and viscoelastic properties of thermoplastic polyurethanes

    G. Arena


    Full Text Available The wear resistance of several thermoplastic polyurethanes (TPUs having different chemical nature and micronscale arrangement of the hard and soft segments has been investigated by means of erosion and abrasion tests. The goal was correlating the erosion performances of the materials to their macroscopic mechanical properties. Unlike conventional tests, such as hardness and tensile measurements, viscoelastic analysis proved to be a valuable tool to study the erosion resistance of TPUs. In particular, a strict correlation was found between the erosion rate and the high-frequency (~107 Hz loss modulus. The latter reflects the actual ability of TPU to dissipate the impact energy of the erodent particles.

  6. Gastroesophageal Reflux is Not Associated with Dental Erosion in Children

    Wild, Yvette K.; Heyman, Melvin B.; Vittinghoff, Eric; Dalal, Deepal H.; Wojcicki, Janet M.; Clark, Ann L.; Rechmann, Beate; Rechmann, Peter


    Background & Aims Dental erosion is a complication of gastroesophageal reflux (GER) in adults; in children, it is not clear if GER has a role in dental pathologic conditions. Dietary intake, oral hygiene, high bacterial load, and decreased salivary flow might contribute independently to GER development or dental erosion, but their potential involvement in dental erosion from GER is not understood. We investigated the prevalence of dental erosion among children with and without GER symptoms, and whether salivary flow rate or bacterial load contribute to location-specific dental erosion. Methods We performed a cross-sectional study of 59 children (ages 9–17 y) with symptoms of GER and 20 asymptomatic children (controls); all completed a questionnaire on dietary exposure. Permanent teeth were examined for erosion into dentin, erosion locations, and affected surfaces. The dentist was not aware of GER status, nor was the gastroenterologist aware of dental status. Stimulated salivary flow was measured and salivary bacterial load was calculated for total bacteria, Streptococcus mutans and Lactobacilli. Results Controlling for age, dietary intake, and oral hygiene, there was no association between GER symptoms and dental erosion, by tooth location or affected surface. Salivary flow did not correlate with GER symptoms or erosion. Erosion location and surface were independent of total bacteria and levels of Streptococcus mutans and Lactobacilli. Conclusions Location-specific dental erosion is not associated with GER, salivary flow, or bacterial load. Prospective studies are required to determine the pathogenesis of GER-associated dental erosion and the relationship between dental caries to GER and dental erosion. PMID:21820389

  7. Erosion wear behaviour and mechanism of abradable seal coating



    The erosion wear behaviour and mechanism of several middle temperature seal coatings were investigated by a CMS-100 self-made vacuum sand erosion machine. The results show that the relationship between the erosion mass loss and the erosion time is linear, the coatings hold a maximum erosion rate at 60° impact angle, and the relationship between the erosion rate and the impact speed is an exponential function. The speed exponent increases with the increase of the impact angle. At 90° impact, indentations and extruded lips were generated on the coating surface subjected to impact. With repetitive impact by the abrasive particles, the extruded lips were work-hardened and peeled off, while flattened metal phase grains were impacted repeatedly, loosed and debonded. At 30° impact, the erosion wear of the coating is characterized by micro-cutting, plowing and tunneling via pores and non-metal phase. The model of the erosion mechanism is advanced on the basis of the above-mentioned erosion wear behaviour.

  8. Gas-solid Erosion on Bionic Configuration Surface

    HAN Zhiwu; ZHANG Junqiu; GE Chao; JIANG Jialian; REN Luquan


    A three levels orthogonal table- L9(34) was used, namely, impact angle, rotating speed, erodent size, and surface configuration were considered. The three bionic surface configurations are pit, groove, and ring. The experimental results indicate the experiment factors affecting erosive rate are, in their sequence of contribution, erodent size, impact angle, configuration, and rotating speed; the erosive rate increased with increase in rotating speed, erodent size; the erosion resistance of the sample with ring structure is higher than that of the other two samples. Based on this result, regression orthogonal experiment was carried out to select the optimal erosion resistance condition with respect to the ring bionic surface configuration. Regression equations between erosive rate and experimental factors of ring surface configurations were obtained.


    Chih Ted YANG


    @@ The river systems observed today is the cumulative result of surface, rill, and gully erosion, and sediment transport, scour, and deposition. The divisions of approach between these two related areas are man-made, and are not based on sound science. Most of the erosion studies are done by geologists and agricultural engineers who are concerned of the surface, rill, and gully erosion and the loss of agricultural land productivity. Hydraulic engineers are more interested in the study of sediment transport, scour, and deposition, and their impacts on river engineering and hydraulic structures in rivers and reservoirs. Erosion studies are often based on empirical relationships or field data to determinate the annual sediment yield from a watershed. On the other hand, hydraulic engineers focus their attention on solving equations based on assumed initial and boundary conditions with a time scale of days, hours, or seconds. Both approaches have their complementary strengths and weaknesses. It is important to provide a forum for specialists in both areas to communicate, exchange ideas, and learn from each other.

  10. Erosion of dust aggregates

    Seizinger, Alexander; Kley, Wilhelm


    Aims: The aim of this work is to gain a deeper insight into how much different aggregate types are affected by erosion. Especially, it is important to study the influence of the velocity of the impacting projectiles. We also want to provide models for dust growth in protoplanetary disks with simple recipes to account for erosion effects. Methods: To study the erosion of dust aggregates we employed a molecular dynamics approach that features a detailed micro-physical model of the interaction of spherical grains. For the first time, the model has been extended by introducing a new visco-elastic damping force which requires a proper calibration. Afterwards, different sample generation methods were used to cover a wide range of aggregate types. Results: The visco-elastic damping force introduced in this work turns out to be crucial to reproduce results obtained from laboratory experiments. After proper calibration, we find that erosion occurs for impact velocities of 5 m/s and above. Though fractal aggregates as ...

  11. Dune erosion above revetments

    Van Thiel de Vries, J.S.M.


    In a situation with a narrow dune, the dune base can be protected with a revetment to reduce dune erosion during extreme events. To quantify the effects of a revetment on storm impact, the functionality of the numerical storm impact model XBeach (Roelvink et al., 2009) is extended to account for the

  12. A stochastic formulation for erosion of cohesive sediments

    Van Prooijen, B.C.; Winterwerp, J.C.


    The linear formulation for erosion E = M(τb−τc), often applied in engineering applications, has two properties, which do not always comply with field and laboratory observations, they are as follows: (1) The erosion rate is zero below the critical bed shear stress τc and increases linearly with bed

  13. Erosive wear of selected materials for fossil energy applications

    Adler, Thomas A.; Rawers, James C.; Tylczak, Joseph H.; Hawk, Jeffrey A.


    A number of materials have been evaluated to determine their erosion resistance for fossil energy applications. This is part of a larger program to study wear and corrosion at Albany Research Center. This paper will present the results for some of these materials, including FeAl, FeAl cermets, WC-Co cemented carbides, Si3N4-MoSi2, Si3N4, Stellite 6B, white cast irons and 440C steel. Trends in erosion rates due to material properties and erosive conditions will be presented. FeAl cermets performed well compared to the WC-Co cemented carbides. The interparticle spacing of the WC-Co cemented carbides correlated with the erosion rate. The erosion rate of the WC-Co cemented carbides decreased as the interparticle spacing decreased. It is important to realize that erosion resistance is not an intrinsic material property, but is a system response. A change in the wear environment can significantly alter the relative rankings of materials with respect to their wear rate. For example, at relatively low velocities, the carbides in the white cast irons are more erosion resistant than the matrix, while at higher velocities the matrix is more erosion resistant.

  14. Erosion processes and prediction in NW U.S. forests

    W. J. Elliot; P. R. Robichaud; R. B. Foltz


    The greatest amounts of forest erosion usually follow infrequent wildfires. Sediment from these fires is gradually routed through the stream system. The forest road network is usually the second greatest source of sediment, generating sediment annually. Erosion rates associated with timber harvest, biomass removal, and prescribed fire are generally minimal with current...

  15. A Simplified Analytical Modeling of the Hole Erosion Test

    Mohammed Bezzazi


    Full Text Available Problem statement: Internal erosion occurs in soils containing fine particles under the action of high pressure gradients that could result from water discharge. This phenomenon can yield in its final stage to the formation of piping which constitutes a real threat for hydraulics infrastructures as it can precipitate their entire rupture in very short time. In order to mitigate this insidious hazard, it is important to characterize piping dynamics. In this context, the Hole Erosion Test was introduced to assess the erosive features of soils by means of two parameters, the erosion rate and the critical shear stress indicating the beginning of erosion. Modeling this test can enable to understand more comprehensibly the piping phenomenology. Approach: A simplified analytical modeling of the Hole Erosion Test was considered in this study. A closed form solution of erosion taking place during piping was derived without resorting to the habitual cumbersome developments that are needed to achieve complete solution of the rational equations describing this highly coupled problem. This was achieved by assuming formal analogy between the erosive shear stress and the friction shear that develops at a cylindrical piping wall under an axial viscous flow. The flow was assumed to be uniform along the tube. Results: A closed form analytical formula describing erosion dynamics associated to piping was derived. Theoretical predictions were compared with experimental results and the simplified model was found to predict accurately the increase of flow rate that results from piping erosion. Conclusion/Recommendations: The one-dimensional modeling that was proposed for the Hole Erosion Test under strong simplifying assumptions was found to yield the same features as those obtained in the literature by using other approaches. It gives furthermore the dynamics as function of the fluid regime existing inside the tube. In order to get further insight

  16. Reply to comment by J.L. Díaz-Hernández and R. Julià on “Quaternary landscape evolution and erosion rates for an intramontane Neogene basin (Guadix-Baza basin, SE Spain)”

    Pérez-Peña, José Vicente; Azañón, José Miguel; Azor, Antonio; Sánchez-Almazo, Isabel María; Tuccimei, Paola; Della Seta, Marta; Soligo, Michele


    We demonstrate that the age of 43 ka obtained for the topmost calcrete layer in the Guadix-Baza remains the only reliable numerical dating of the flat geomorphic surface that marks the end of the sedimentation in the basin. Consequently, the late Pleistocene to Holocene erosion rates derived from the incision of the present-day drainage network into the flat geomorphic surface remain valid. The calcrete radiometric ages reported by Díaz-Hernández and Julià (2012) in their comment are untenable due to the contamination with detrital 230Th (not corrected with the applied U/Th technique) and the possible mix of textural elements with different ages (older inherited grains and newly formed grains). Díaz-Hernández and Julià also quote U/Th ages for travertine terraces formed later than the calcrete layer. These ages lack internal consistency probably due to systematic contamination and/or weathering of the samples. The archaeological ages reported by Díaz-Hernández and Julià are subjected to great uncertainties, but independently of the age assumed as most realistic, they are completely compatible with the age of 43 ka that we obtained for the topmost calcrete layer in the Guadix-Baza basin.

  17. Climatic controls on the pace of glacier erosion

    Koppes, Michele; Hallet, Bernard; Rignot, Eric; Mouginot, Jeremie; Wellner, Julia; Love, Katherine


    Mountain ranges worldwide have undergone large-scale modification due the erosive action of ice, yet the mechanisms that control the timing of this modification and the rate by which ice erodes remain poorly understood. Available data report a wide range of erosion rates from individual ice masses over varying timescales, suggesting that modern erosion rates exceed orogenic rates by 2-3 orders of magnitude. These modern rates are presumed to be due to dynamic acceleration of the ice masses during deglaciation and retreat. Recent numerical models have focused on replicating the processes that produce the geomorphic signatures of glacial landscapes. Central to these models is a simple quantitative index that relates erosion rate to ice dynamics and to climate. To provide such an index, we examined explicitly the factors controlling modern glacier erosion rates across climatic regimes. Holding tectonic history, bedrock lithology and glacier hypsometries relatively constant across a latitudinal transect from Patagonia to the Antarctic Peninsula, we find that modern, basin-averaged erosion rates vary by three orders of magnitude, from 1->10 mm yr-1 for temperate tidewater glaciers to 0.01-ELA, in accord with theory. The general relationship between ice dynamics and erosion suggests that the erosion rate scales non-linearly with basal sliding speed, with an exponent n ≈ 2-2.62. Notably, erosion rates decrease by over two orders of magnitude between temperate and polar glaciers with similar ice discharge rates. The difference in erosion rates between temperate and colder glaciers of similar shape and size is primarily related to the abundance of meltwater accessing the bed. Since all glaciers worldwide have experienced colder than current climatic conditions, the 100-fold decrease in long-term relative to modern erosion rates may in part reflect the temporal averaging of warm and cold-based conditions over the lifecycle of these glaciers. Higher temperatures and

  18. Severe Environmental Corrosion Erosion Facility

    Federal Laboratory Consortium — NETL’s Severe Environment Corrosion Erosion Facility in Albany, OR, allows researchers to safely examine the performance of materials in highly corrosive or erosive...

  19. Effect of carbides on erosion resistance of 23-8-N steel

    Aniruddha A Gadhikar; Ashok Sharma; D B Goel; C P Sharma


    Microstructure is one of the most important parameters influencing erosion behaviour of materials. The role of carbides in the matrix is very complicated in controlling the erosion rate of the materials. Conflicting results have been reported in the literature about the effect of carbides on erosion resistance. Carbides are of great importance especially as obstacles against the penetration of erosive particles into the material surface. However, they are susceptible to cracking and causing matrix decohesion which may increase the overall erosion rate. In 23-8-N nitronic steel, carbides present in the form of bands are observed to accelerate the erosion rate. Coarse carbides cause depletion of carbon in the austenite matrix which adversely affects the strain hardening tendency thus causing deterioration in erosion resistance of the bulk material. The dissolution of carbides in the austenitic matrix after solution annealing is observed to improve the erosion resistance of 23-8-N nitronic steel.

  20. Recent Developments in Understanding Wind Driven Erosion

    Merrison, J. P.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.; Rasmussen, K. R.


    The wind driven transport of granular material is an important environmental/climatic factor on Earth and even more so on Mars. Several related aspects of Aeolian activity are presently being studied in the laboratory. These include simulating wind driven erosion in the laboratory and the study of mineral change due to mechanical activation as well as quantifying erosion rates. The generation of electric fields and the effects of these electric fields on grain transport is also being investigated using environmental wind tunnel simulators.

  1. Relationships Between Intensity Gradation and Evolution of Soil Erosion: A Case Study of Changting in Fujian Province, China

    LIN Chen; ZHOU Sheng-Lu; WU Shao-Hua; LIAO Fu-Qiang


    Soil erosion gradation is a robust and objective quantitative indicator of soil erosion intensity.Recent applications of soil erosion gradation have focused on monitoring soil erosion with models or simulation of soil erosion through gradation trends.However,soil erosion simulation accuracy is generally being reduced due to the rare consideration of the relationship between soil erosion gradation and erosion evolution.In this study,we investigated different soil erosion intensity grades to demonstrate their sensitivity to types and rates of erosion.Specifically,the objective was to define the relationship between soil erosion gradation and soil erosion evolution in Changting,an undeveloped area in Fujian Province,China,for four time intervals (1975,1990,1999,and 2006).The time series of erosion gradation were developed by modeling analysis with integration of several erosion indicators,and the relationships between the erosion grades and evolution types and rates were quantified.Comparison of the collapsing forces with natural and restoring forces based on human activity demonstrated that there existed an obvious spatial uncertainty in the erosion evolution types,both positive and negative succession coexisted,and the evolution rates were mostly influenced by the force of policy orientation.The impacts of these driving forces were eventually reflected in the erosion intensity gradation and erosion evolution.The correlation between the negative succession rate and erosion intensity gradation was weak and showed a poor contribution to the average succession rate,while the negative correlation between the positive succession rate and erosion intensity gradation would be increasingly clear as time passed.

  2. The influence of material hardness on liquid droplet impingement erosion

    Fujisawa, Nobuyuki, E-mail: [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Yamagata, Takayuki, E-mail: [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Takano, Shotaro; Saito, Kengo [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Morita, Ryo; Fujiwara, Kazutoshi; Inada, Fumio [Central Research Institute of Electric Power Industry, 2-11-1, Iwatokita, Komae, Tokyo 201-8511 (Japan)


    Highlights: • Liquid droplet impingement erosion is studied for various metal materials. • Average power dependency on droplet velocity is found as 7. • Power dependency on Vickers hardness is found as −4.5. • An empirical formula is constructed for erosion rates of metal materials. • Predicted erosion rate is well correlated with experiment within a factor of 1.5. - Abstract: This paper describes the experimental study on the liquid droplet impingement erosion of metal materials to understand the influence of material hardness on the erosion rate. The experiment is carried out using a water spray jet apparatus with a condition of relatively thin liquid film thickness. The metal materials tested are pure aluminum, aluminum alloy, brass, mild steel, carbon steel and stainless steel. The liquid droplets considered are 30 ± 5 μm in volume average diameter of water, which is the same order of droplet diameter in the actual pipeline in nuclear/fossil power plants. In order to understand the influence of material hardness on the liquid droplet impingement erosion, the scanning electron microscope (SEM) observation on the eroded surface and the measurement of erosion rate are carried out in the terminal stage of erosion. The experimental results indicate that the erosion rates are expressed by the droplet velocity, volume flux, Vickers hardness and the liquid film thickness, which are fundamentals of the liquid droplet impingement erosion. The empirical formula shows that the power index for droplet velocity dependency is found to be 7 with a scattering from 5 to 9 depending on the materials, while the power index for Vickers hardness dependency is found as −4.5.

  3. Research on cohesive sediment erosion by flow: An overview

    ZHU YongHui; LU dinYou; LIAO HongZhi; WANG diaSheng; FAN BeiLin; YAO ShiMing


    Erosion of cohesive sediment by flow is a very complicated phenomenon occurring worldwide. Understanding and modeling of the erosion process are important for many issues such as the breaching of embankments, riverbank stability, siltation of harbors and navigation channels, service life of reservoirs, distribution of (heavy metal) pollutants and water quality problems. In the last few decades, numerous studies have been done on the erosion of cohesive sediment by flow. Nevertheless, the factors affecting the erosion resistance of cohesive sediment are still not fully understood and the knowledge of the physics of cohesive sediment erosion is in-adequate, as a result the mathematical modeling of this erosion is far from saris-factory. In this paper an overview of the studies on the erosion resistance, erosion threshold and the erosion rate of cohesive sediment by flow is presented. The outcomes achieved so far from the studies and the existing problems have been analyzed and summarized, based on which recommendations are proposed for future research.

  4. Actinides, accelerators and erosion

    Tims, S. G.; Fifield, L. K.


    Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium), and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  5. Actinides, accelerators and erosion

    Fifield L.K.


    Full Text Available Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium, and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  6. Estimating Sediment Yield on Disturbed Rangeland Using the Rangeland Hydrology and Erosion Model (RHEM)

    The Rangeland Hydrology and Erosion Model (RHEM) is an event-based model that estimates runoff, erosion, and sediment delivery rates and volumes at the spatial scale of the hillslope and the temporal scale of a single rainfall event. It represents erosion processes on normal rangeland, as well as, r...

  7. Modeling of Erosion on Jelateng Watershed Using USLE Method, Associated with an Illegal Mining Activities (PETI)

    Ananda, I. N.; Aswari, F. V.; Narmaningrum, D. A.; Nugraha, A. S. A.; Asidiqi, M. A. A.; Setiawan, Y.


    The Indonesian archipelago has abundant mineral resources, and it causes many mining activities. Mineral resource is natural based resource which cannot be renewable. An abandon mining pit makes a hole in land surface and it increase the erosion severity level on the rainy season. This erosion would brought sediment to the sea, and it causes damage the ecosystem of the coastal. Erosion modeling in Jelateng watershed performed temporally using remote sensing image data, which consist of LANDSAT-5 (1995), and LANDsAt-8 (2015), and supported by field data as well. The parameters for modeling of erosion through rasterization process as input from erosion USLE models to IDRISI software. The results shown that in 1995, the majority of the area has a low level of erosion. The low erosion rate is less than 183.67 tons/hectare/year and high erosion rate is 408.34 up to 633 tons/hectare/year. Compare with in 2015, erosion models shown that erosion is most prevalent on the upstream area of Jelateng watershed, with low erosion rate is less than 432.2 tons/hectare/year and high erosion rate is 615.64 up to 1448.31 tons/hectare/year.

  8. Improving Soil Erosion Prevention in Greece with New Tools

    G. N. Zaimes


    Full Text Available Unsustainable anthropogenic activities such as agriculture and urbanization have caused excessive erosion rates that exceed soil formation rates. The Mediterranean region has and continues to experience severe erosion because of the inappropriate agricultural management, overgrazing, deforestation, wildfires, land abandonment, intense road construction and other construction activities. The forecasted increase of intensive rainfall events and prolonged drought periods due to climate change, will enhance surface runoff and sediment transport capacity. The objective of this study was to develop new tools to help land managers mitigate erosion in the country of Greece. One of the tools was a new sensor (ASEMS that is based on the physical properties of ultrasound to detect erosion locally with great accuracy (1 mm, while simultaneously measuring precipitation, soil moisture, and soil and air temperature. The other tool was the development of the Soil Erosion Integrated Information System (SE-I2S that enables land managers through a series of questions to understand if they are facing erosion problems and what type of erosion. This tool can be applied to large areas. Overall, both new tools are user friendly and help land managers mitigate soil erosion cost-effectively.

  9. Uso do césio-137 para avaliar taxas de erosão em cultura de soja, café e pastagem Use of cesium-137 to assess soil erosion rates under soybean, coffee and pasture

    A. C. Andrello


    Full Text Available Utilizou-se o césio-137 para avaliar as taxas de perda ou ganho de solo numa microbacia com diferentes culturas, situada no município de Cambe (PR, a 23º16' Sul e 51º17' Oeste. Foi utilizada uma equação teórica que considera a perda ou ganho de solo num ponto diretamente proporcional à redistribuição de césio-137. Uma amostragem em transectos foi efetuada com o objetivo de avaliar a redistribuição de solo dentro da microbacia. Um ponto em mata nativa na microbacia foi amostrado para estimar a quantidade de césio-137 depositado na região pela precipitação radioativa. Os pontos amostrados em área de pastagem apresentaram, em sua maioria, perda de solo. Os pontos amostrados em área de cafeeiro não apresentaram perda nem ganho de solo. Os pontos amostrados em área de soja, em sistema convencional de preparo de solo, apresentaram perda de solo.The methodology cesium-137 was used to assess soil erosion and deposition rates in a small watershed with varied crops, at 23º16' S and 51º17' W, in a district of Cambé, Paraná State, Brazil. A theoretical equation which considers soil loss or gain directly proportional to the cesium-137 redistribution was utilized in this study. In the watershed, soil redistribution was assessed by transect sampling, and the regional input of cesium-137 by radioactive rainfall determined based on samples from a point in the native forest. Most sampled pasture points presented soil loss, as well as the points in the soybean area under conventional tillage, while in the coffee crop there was neither soil loss nor gain.

  10. Effect of Vegetation Changes on Soil Erosion on the Loess Plateau

    ZHENG Fen-Li


    Vegetation is one of the key factors affecting soil erosion on the Loess Plateau. The effects of vegetation destruction and vegetation restoration on soil erosion were quantified using data from long-term field runoff plots established on the eastern slope of the Ziwuling secondary forest region, China and a field survey. The results showed that before the secondary vegetation restoration period (before about 1866-1872), soil erosion in the Ziwuling region of the Loess Plateau was similar to the current erosion conditions in neighboring regions, where the soil erosion rate now is 8 000 to 10 000t km-2 year-1. After the secondary vegetation restoration, soil erosion was very low; influences of rainfall and slope gradient on soil erosion were small; the vegetation effect on soil erosion was predominant; shallow gully and gully erosion ceased; and sediment deposition occurred in shallow gully and gully channels. In modern times when human activities destroyed secondary forests, soil erosion increased markedly, and erosion rates in the deforested lands reached 10 000 to24 000 t km-2 year-1, which was 797 to 1682 times greater than those in the forested land prior to deforestation. Rainfall intensity and landform greatly affected the soil erosion process after deforestation. These results showed that accelerated erosion caused by vegetation destruction played a key role in soil degradation and eco-environmental deterioration in deforested regions.

  11. Application of Remote Sensing and Participatory Soil Erosion Assessment Approach for Soil Erosion Mapping in a Watershed

    Krishna Prasad BHANDARI


    Full Text Available This research addresses the problem of soil erosion in the Phewa watershed, Pokhara, Nepal, through remote sensing application of the Revised Universal Soil Loss Equation (RUSLE model, and Participatory Geographic Information System (PGIS based Erosion Damage Assessment (EDA. Acceleration of soil erosion is due to anthropogenic factors, such as construction of roads without conservation, intensive agriculture, and socio-economic activities. The aim of the study is to identify the major causes of soil erosion by application of remote sensing; RUSLE and PGIS based EDA for soil erosion reduction management. The methodologies employed include structured questionnaires, focus groups, stakeholders’ sketches, and application of remote sensing and GIS on RUSLE model. The RUSLE model results indicate that the rate of soil erosion in the Phewa watershed varies from 0 to 206.78 t/ha/yr, and the mean annual rate of soil loss was 14.71 t/ha/yr in 2010. The PGIS based EDA resulted in different classes of severity (stable, slight, moderate, severe, very severe which were similar to the quantified results of RUSLE, except for the dense forest class in Land Use and Land Cover (LULC. Erosion-prone maps were developed through PGIS based EDA by stakeholders and use of the RUSLE model. Maps showed that the soil erosion risk areas were similar on both maps. The stakeholders’ sketched map, with knowledge gained from PGIS based EDA, RS and GIS technology for their conservation practices, could help to reduce soil erosion. The study identifies that the major issues are soil and agriculture management practices, and concludes that there is a link between RS and GIS and the estimated erosion by the RUSLE model. Thus, the RS and GIS techniques and PGIS based EDA approach can benefit stakeholders in applying better measures for soil erosion management.

  12. Influence of chemical and materials in the rate of erosion corrosion. Modelling the cycle chemistry and materials characterization measurements on CN Cofrentes; Influencia de la quimica y materiales en la tasa de erosion corrosion. Modelizacion de la quimica del ciclo y medidas de caracterizacion de materiales en C. N. Cofrentes

    Paule Ramos, A.; Sanchez-Zapata, J. D.


    The chemical cycle and the type of material are some of the factors that have great influence on the phenomenon of erosion-corrosion. The paper present the modeling of chemistry through the software cycle strategies COMSY and materials characterization measures undertaken in order to more effectively control this phenomenon in CN Cofrentes.

  13. Bedload transport controls bedrock erosion under sediment-starved conditions

    Beer, A. R.; Turowski, J. M.


    Fluvial bedrock incision constrains the pace of mountainous landscape evolution. Bedrock erosion processes have been described with incision models that are widely applied in river-reach and catchment-scale studies. However, so far no linked field data set at the process scale had been published that permits the assessment of model plausibility and accuracy. Here, we evaluate the predictive power of various incision models using independent data on hydraulics, bedload transport and erosion recorded on an artificial bedrock slab installed in a steep bedrock stream section for a single bedload transport event. The influence of transported bedload on the erosion rate (the "tools effect") is shown to be dominant, while other sediment effects are of minor importance. Hence, a simple temporally distributed incision model, in which erosion rate is proportional to bedload transport rate, is proposed for transient local studies under detachment-limited conditions. This model can be site-calibrated with temporally lumped bedload and erosion data and its applicability can be assessed by visual inspection of the study site. For the event at hand, basic discharge-based models, such as derivatives of the stream power model family, are adequate to reproduce the overall trend of the observed erosion rate. This may be relevant for long-term studies of landscape evolution without specific interest in transient local behavior. However, it remains to be seen whether the same model calibration can reliably predict erosion in future events.

  14. Erosion and redeposition processes of molybdenum with oblique incidence of magnetic field

    Kojima, Masahiro; Ido, Yasuhiro; Ezumi, Naomichi; Ohno, Noriyasu; Takamura, Shuichi [Nagoya Univ. (Japan)


    Erosion and redeposition processes have been investigated using a linear plasma device and a Monte Carlo simulation code. Argon plasmas were irradiated on a molybdenum substrate with an oblique incidence of magnetic field. The erosion distributions depending on the direction of magnetic field are clearly observed. Numerical code analysis gives a qualitative explanation for the erosion profiles by considering the effect of prompt redeposition of high Z material. However, we have still quantitative differences for their erosion and redeposition rates. (author)

  15. Geophysical monitoring of coastal erosion and cliff retreat of ...


    figures were determined for sediment erosion and accretion, the rate of .... system where a GPS antenna height is used to define the shape of shore .... east with the beach composition grading from a more rocky undulose substrate to the sandy.

  16. Extent of Cropland and Related Soil Erosion Risk in Rwanda

    Fidele Karamage


    Full Text Available Land conversion to cropland is one of the major causes of severe soil erosion in Africa. This study assesses the current cropland extent and the related soil erosion risk in Rwanda, a country that experienced the most rapid population growth and cropland expansion in Africa over the last decade. The land cover land use (LCLU map of Rwanda in 2015 was developed using Landsat-8 imagery. Based on the obtained LCLU map and the spatial datasets of precipitation, soil properties and elevation, the soil erosion rate of Rwanda was assessed at 30-m spatial resolution, using the Revised Universal Soil Loss Equation (RUSLE model. According to the results, the mean soil erosion rate was 250 t·ha−1·a−1 over the entire country, with a total soil loss rate of approximately 595 million tons per year. The mean soil erosion rate over cropland, which occupied 56% of the national land area, was estimated at 421 t·ha−1·a−1 and was responsible for about 95% of the national soil loss. About 24% of the croplands in Rwanda had a soil erosion rate larger than 300 t·ha−1·a−1, indicating their unsuitability for cultivation. With a mean soil erosion rate of 1642 t·ha−1·a−1, these unsuitable croplands were responsible for 90% of the national soil loss. Most of the unsuitable croplands are distributed in the Congo Nile Ridge, Volcanic Range mountain areas in the west and the Buberuka highlands in the north, regions characterized by steep slopes (>30% and strong rainfall. Soil conservation practices, such as the terracing cultivation method, are paramount to preserve the soil. According to our assessment, terracing alone could reduce the mean cropland soil erosion rate and the national soil loss by 79% and 75%, respectively. After terracing, only a small proportion of 7.6% of the current croplands would still be exposed to extreme soil erosion with a rate >300 t·ha−1·a−1. These irremediable cropland areas should be returned to mountain forest to

  17. Modeling sunspot and starspot decay by turbulent erosion

    Litvinenko, Yuri E


    Disintegration of sunspots (and starspots) by fluxtube erosion, originally proposed by Simon and Leighton, is considered. A moving boundary problem is formulated for a nonlinear diffusion equation that describes the sunspot magnetic field profile. Explicit expressions for the sunspot decay rate and lifetime by turbulent erosion are derived analytically and verified numerically. A parabolic decay law for the sunspot area is obtained. For moderate sunspot magnetic field strengths, the predicted decay rate agrees with the results obtained by Petrovay and Moreno-Insertis. The new analytical and numerical solutions significantly improve the quantitative description of sunspot and starspot decay by turbulent erosion.

  18. Bentonite erosion. Laboratory studies

    Jansson, Mats (Div. of Nuclear Chemistry, Royal Inst. of Technology, Stockholm (Sweden), School of Chemical Science and Engineering)


    This report covers the laboratory studies that have been performed at Nuclear Chemistry, KTH in the project 'Bentonite Erosion'. Many of the experiments in this report were performed to support the work of the modelling group and were often relatively simple. One of the experiment series was performed to see the impact of gravity and concentration of mono- and di-valent cations. A clay suspension was prepared in a test tube. A net was placed in contact with the suspension, the test tube was filled with solutions of different concentrations and the system was left overnight to settle. The tube was then turned upside down and the behaviour was visually observed. Either the clay suspension fell through the net or stayed on top. By using this method surprisingly sharp determinations of the Critical Coagulation (Flocculation) Concentration (CCC/CFC) could be made. The CCC/CFC of Ca2+ was for sodium montmorillonite determined to be between 1 and 2 mM. An artificial fracture was manufactured in order to simulate the real case scenario. The set-up was two Plexiglas slabs separated by 1 mm thick spacers with a bentonite container at one side of the fracture. Water was pumped with a very low flow rate perpendicular to bentonite container and the water exiting the fracture was sampled and analyzed for colloid content. The bentonite used was treated in different ways. In the first experiment a relatively montmorillonite rich clay was used while in the second bentonite where only the readily soluble minerals had been removed was used. Since Plexiglas was used it was possible to visually observe the bentonite dispersing into the fracture. After the compacted bentonite (1,000 kg/m3) had been water saturated the clay had expanded some 12 mm out into the fracture. As the experiment progressed the clay expanded more out into the fracture and seemed to fractionate in two different phases with less material in the outmost phase. A dark rim which was later analyzed to contain

  19. Demonstrating usefulness of real-time monitoring at streambank wells coupled with active streamgages - Pilot studies in Wyoming, Montana, and Mississippi

    Eddy-Miller, Cheryl A.; Constantz, Jim; Wheeler, Jerrod D.; Caldwell, Rodney R.; Barlow, Jeannie R.B.


    Groundwater and surface water in many cases are considered separate resources, but there is growing recognition of a need to treat them as a single resource. For example, groundwater inflow during low streamflow is vitally important to the health of a stream for many reasons, including buffering temperature, providing good quality water to the stream, and maintaining flow for aquatic organisms. The U.S. Geological Survey (USGS) has measured stream stage and flow at thousands of locations since 1889 and has the ability to distribute the information to the public within hours of collection, but collecting shallow groundwater data at co-located measuring sites is a new concept. Recently developed techniques using heat as a tracer to quantify groundwater and surface-water exchanges have shown the value of coupling these resources to increase the understanding of the water resources of an area. In 2009, the USGS Office of Groundwater began a pilot study to examine the feasibility and utility of widespread use of real-time groundwater monitoring at streambank wells coupled with real-time surface-water monitoring at active streamgages to assist in understanding the exchange of groundwater and surface water in a cost effective manner.

  20. Erosive Burning Study Utilizing Ultrasonic Measurement Techniques

    Furfaro, James A.


    A 6-segment subscale motor was developed to generate a range of internal environments from which multiple propellants could be characterized for erosive burning. The motor test bed was designed to provide a high Mach number, high mass flux environment. Propellant regression rates were monitored for each segment utilizing ultrasonic measurement techniques. These data were obtained for three propellants RSRM, ETM- 03, and Castor@ IVA, which span two propellant types, PBAN (polybutadiene acrylonitrile) and HTPB (hydroxyl terminated polybutadiene). The characterization of these propellants indicates a remarkably similar erosive burning response to the induced flow environment. Propellant burnrates for each type had a conventional response with respect to pressure up to a bulk flow velocity threshold. Each propellant, however, had a unique threshold at which it would experience an increase in observed propellant burn rate. Above the observed threshold each propellant again demonstrated a similar enhanced burn rate response corresponding to the local flow environment.

  1. A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion ?

    Pasini G.


    Full Text Available In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in1968, antigravitative erosion (= erosione antigravitativa, coined in 1966 and antigravitational erosion (wrong English translation ofthe Italian term erosione antigravitativa, utilized later on. The term paragenesis should be abandoned because of the priority of theterm erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand,the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the termsgravitation and gravity have in Physics. Therefore, to designate the phenomenon of the “ascending erosion” there would be nothingleft but the term antigravitative erosion.The antigravitative erosion process and its recognizability are illustrated.Examples of caves with evident antigravitative erosion phenomena, developed in different karstifiable rocks and in several partsof the world, are given.It is recalled that the antigravitative erosion is a phenomenon well-known since 1942 and widely proven and supported, and that it isrelatively easy – in many cases - to recognize the antigravitative origin of karstic passages.It is stressed that the antigravitative erosion is an important phenomenon, exclusive of the karstic caves and unique in nature.

  2. Identification of soil erosion risk areas for conservation planning in different states of India.

    Sharda, V N; Mandal, Debashis; Ojasvi, P R


    Assessment of soil erosion risks, especially in the developing countries, is a challenging task mainly due to non-availability or insufficiency of relevant data. In this paper, the soil erosion risks have been estimated by integrating the spatial data on potential erosion rates and soil loss tolerance limits for conservation planning at state level in India. The erosion risk classes have been prioritized based upon the difference between the prevailing erosion rates and the permissible erosion limits. The analysis revealed that about 50% of total geographical area (TGA) of India, falling in five priority erosion risk classes, requires different intensity of conservation measures though about 91% area suffers from potential erosion rates varying from 40 t ha(-1) yr(-1). Statewise analysis indicated that Andhra Pradesh, Maharashtra and Rajasthan share about 75% of total area under priority Class 1 (6.4 M ha) though they account for only 19.4% of the total area (36.2 M ha) under very severe potential erosion rate category (> 40 t ha(-1)yr(-1)). It was observed that about 75% of total geographical area (TGA) in the states of Bihar, Gujarat, Haryana, Kerala and Punjab does not require any specific soil conservation measure as the potential erosion rates are well within the tolerance limits. The developed methodology can be successfully employed for prioritization of erosion risk areas at watershed, region or country level.

  3. Bank erosion along the dam-regulated lower Roanoke River, North Carolina

    Hupp, C.R.; Schenk, E.R.; Richter, J.M.; Peet, Robert K.; Townsend, Phil A.


    Dam construction and its impact on downstream fluvial processes may substantially alter ambient bank stability and erosion. Three high dams (completed between 1953 and 1963) were built along the Piedmont portion of the Roanoke River, North Carolina; just downstream the lower part of the river flows across largely unconsolidated Coastal Plain deposits. To document bank erosion rates along the lower Roanoke River, >700 bank-erosion pins were installed along 66 bank transects. Additionally, discrete measurements of channel bathymetry, turbidity, and presence or absence of mass wasting were documented along the entire study reach (153 km). A bank-erosion- floodplain-deposition sediment budget was estimated for the lower river. Bank toe erosion related to consistently high low-flow stages may play a large role in increased mid- and upper-bank erosion. Present bank-erosion rates are relatively high and are greatest along the middle reaches (mean 63 mm/yr) and on lower parts of the bank on all reaches. Erosion rates were likely higher along upstream reaches than present erosion rates, such that erosion-rate maxima have since migrated downstream. Mass wasting and turbidity also peak along the middle reaches; floodplain sedimentation systematically increases downstream in the study reach. The lower Roanoke River isnet depositional (on floodplain) with a surplus of ??2,800,000 m3yr. Results suggest that unmeasured erosion, particularly mass wasting, may partly explain this surplus and should be part of sediment budgets downstream of dams. ?? 2009 The Geological Society of America.

  4. Effect of erodent particles on the erosion of metal specimens

    Razzaque, M. Mahbubur; Alam, M. Khorshed; Khan, M. Ishak


    This paper presents the experimental results of the measurement of erosion rate of carbon steel specimens in sand water slurry system in a slurry pot tester. Sylhet sand has been sieved to get three sizes of erodent particles; namely, less than 250 micron, 250 to 590 micron and 590 to 1190 micron. Experiments are done with three sand concentrations (10%, 15% and 20%). The rate of erosion of the carbon steel specimens is measured as the loss of weight per unit surface area per unit time under the dynamic action of solid particles. The eroded surfaces of the specimens are examined using Scanning Electron Microscopy (SEM) to visualize the impact of the slurry of various conditions. It is seen that irrespective of the particle size the rate of erosion increases with the increase of slurry concentration. This increment of erosion rate at high concentration is high for large particles. High erosion rate is observed in case of large sand particles. In case of small and fine particles erosion rate is small because of low impact energy as well as the wastage of energy to overcome the hindrance of the finer particles before striking on the specimen surface.

  5. Soil erosion in Iran: Issues and solutions

    Hamidreza Sadeghi, Seyed; Cerdà, Artemi


    Iran currently faces many soil erosion-related problems (see citations below). These issues are resulted from some inherent characteristic and anthropogenic triggering forces. Nowadays, the latter plays more important rule to accelerate the erosion with further emphasis on soil erosion-prone arid and semi arid regions of the country. This contribution attempts to identify and describe the existing main reasons behind accelerated soil erosion in Iran. Appropriate solutions viz. structural and non-structural approaches will be then advised to combat or minimise the problems. Iran can be used as a pilot research site to understand the soil erosion processes in semiarid, arid and mountainous terrain and our research will review the scientific literature and will give an insight of the soil erosion rates in the main factors of the soil erosion in Iran. Key words: Anthropogenic Erosion, Land Degradation; Sediment Management; Sediment Problems Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7-ENV-2013- supported this research. References Aghili Nategh, N., Hemmat, A., & Sadeghi, M. (2014). Assessing confined and semi-confined compression curves of highly calcareous remolded soil amended with farmyard manure. Journal of Terramechanics, 53, 75-82. Arekhi, S., Bolourani, A. D., Shabani, A., Fathizad, H., Ahamdy-Asbchin, S. 2012. Mapping Soil Erosion and Sediment Yield Susceptibility using RUSLE, Remote Sensing and GIS (Case study: Cham Gardalan Watershed, Iran). Advances in Environmental Biology, 6(1), 109-124. Arekhi, S., Shabani, A., Rostamizad, G. 2012. Application of the modified universal soil loss equation (MUSLE) in prediction of sediment yield (Case study: Kengir Watershed, Iran). Arabian Journal of Geosciences, 5(6), 1259-1267.Sadeghi, S. H., Moosavi, V., Karami, A., Behnia, N. 2012. Soil erosion assessment and prioritization of affecting factors at plot

  6. Estimating overland flow erosion capacity using unit stream power

    Hui-Ming SHIH; Chih Ted YANG


    Soil erosion caused by water flow is a complex problem.Both empirical and physically based approaches were used for the estimation of surface erosion rates.Their applications are mainly limited to experimental areas or laboratory studies.The maximum sediment concentration overland flow can carry is not considered in most of the existing surface erosion models.The lack of erosion capacity limitation may cause over estimations of sediment concentration.A correlation analysis is used in this study to determine significant factors that impact surface erosion capacity.The result shows that the unit stream power is the most dominant factor for overland flow erosion which is consistent with experimental data.A bounded regression formula is used to reflect the limits that sediment concentration cannot be less than zero nor greater than a maximum value.The coefficients used in the model are calibrated using published laboratory data.The computed results agree with laboratory data very well.A one dimensional overland flow diffusive wave model is used in conjunction with the developed soil erosion equation to simulate field experimental results.This study concludes that the non-linear regression method using unit stream power as the dominant factor performs well for estimating overland flow erosion capacity.

  7. Monitoring Riverbank Erosion in Mountain Catchments Using Terrestrial Laser Scanning

    Laura Longoni


    Full Text Available Sediment yield is a key factor in river basins management due to the various and adverse consequences that erosion and sediment transport in rivers may have on the environment. Although various contributions can be found in the literature about sediment yield modeling and bank erosion monitoring, the link between weather conditions, river flow rate and bank erosion remains scarcely known. Thus, a basin scale assessment of sediment yield due to riverbank erosion is an objective hard to be reached. In order to enhance the current knowledge in this field, a monitoring method based on high resolution 3D model reconstruction of riverbanks, surveyed by multi-temporal terrestrial laser scanning, was applied to four banks in Val Tartano, Northern Italy. Six data acquisitions over one year were taken, with the aim to better understand the erosion processes and their triggering factors by means of more frequent observations compared to usual annual campaigns. The objective of the research is to address three key questions concerning bank erosion: “how” erosion happens, “when” during the year and “how much” sediment is eroded. The method proved to be effective and able to measure both eroded and deposited volume in the surveyed area. Finally an attempt to extrapolate basin scale volume for bank erosion is presented.

  8. Future climate variability impacts on potential erosion and soil organic carbon in European croplands

    M. van der Velde


    Full Text Available We investigate the impact of future climate variability on the potential vulnerability of soils to erosion and the consequences for soil organic carbon (SOC in European croplands. Soil erosion is an important carbon flux not characterized in Earth System Models. We use a~European implementation of EPIC, driven by reference climate data (CNTRL, and climate data with reduced variability (REDVAR. Whether erosion regimes will change across European cropland depends on the spatial conjunction of expected changes in climate variability and physiographic conditions conducive to erosion. We isolated the effect of erosion by performing simulations with and without erosion. Median CNTRL and REDVAR erosion rates equalled 14.4 and 9.1 ton ha−1, and 19.1 and 9.7, for 1981–2010 and 2071–2100, respectively. The total amount of carbon lost from European cropland due to erosion was estimated at 769 Tg C for 1981–2010 (from a total storage of 6197 Tg C without erosion under CNTRL climate. Climate trend impacts reduce the European cropland SOC stock by 578 Tg C without – and by 683 Tg C with erosion, from 1981 to 2100. Climate variability compounds these impacts and decreases the stock by an estimated 170 Tg without erosion and by 314 Tg C with erosion, by the end of the century. Future climate variability and erosion will thus compound impacts on SOC stocks arising from gradual climate change alone.

  9. Storms, channel changes, and a sediment budget for an urban-suburban stream, Difficult Run, Virginia, USA

    Gellis, Allen; Myers, Michael; Noe, Gregory; Hupp, Cliff R.; Shenk, Edward; Myers, Luke


    Determining erosion and deposition rates in urban-suburban settings and how these processes are affected by large storms is important to understanding geomorphic processes in these landscapes. Sediment yields in the suburban and urban Upper Difficult Run are among the highest ever recorded in the Chesapeake Bay watershed, ranging from 161 to 376 Mg/km2/y. Erosion and deposition of streambanks, channel bed, and bars and deposition of floodplains were monitored between 1 March 2010 and 18 January 2013 in Upper Difficult Run, Virginia, USA. We documented the effects of two large storms, Tropical Storm Lee (September 2011), a 100-year event, and Super Storm Sandy (October 2012) a 5-year event, on channel erosion and deposition. Variability in erosion and deposition rates for all geomorphic features, temporally and spatially, are important conclusions of this study. Tropical Storm Lee was an erosive event, where erosion occurred on 82% of all streambanks and where 88% of streambanks that were aggrading before Tropical Storm Lee became erosional. Statistical analysis indicated that drainage area explains linear changes (cm/y) in eroding streambanks and that channel top width explains cross-sectional area changes (cm2/y) in eroding streambanks and floodplain deposition (mm/y). A quasi-sediment budget constructed for the study period using the streambanks, channel bed, channel bars, and floodplain measurements underestimated the measured suspended-sediment load by 61% (2130 Mg/y). Underestimation of the sediment load may be caused by measurement errors and to contributions from upland sediment sources, which were not measured but estimated at 36% of the gross input of sediment. Eroding streambanks contributed 42% of the gross input of sediment and accounted for 70% of the measured suspended-sediment load. Similar to other urban watersheds, the large percentage of impervious area in Difficult Run and direct runoff of precipitation leads to increased streamflow and

  10. Storms, channel changes, and a sediment budget for an urban-suburban stream, Difficult Run, Virginia, USA

    Gellis, A. C.; Myers, M. K.; Noe, G. B.; Hupp, C. R.; Schenk, E. R.; Myers, L.


    Determining erosion and deposition rates in urban-suburban settings and how these processes are affected by large storms is important to understanding geomorphic processes in these landscapes. Sediment yields in the suburban and urban Upper Difficult Run are among the highest ever recorded in the Chesapeake Bay watershed, ranging from 161 to 376 Mg/km2/y. Erosion and deposition of streambanks, channel bed, and bars and deposition of floodplains were monitored between 1 March 2010 and 18 January 2013 in Upper Difficult Run, Virginia, USA. We documented the effects of two large storms, Tropical Storm Lee (September 2011), a 100-year event, and Super Storm Sandy (October 2012) a 5-year event, on channel erosion and deposition. Variability in erosion and deposition rates for all geomorphic features, temporally and spatially, are important conclusions of this study. Tropical Storm Lee was an erosive event, where erosion occurred on 82% of all streambanks and where 88% of streambanks that were aggrading before Tropical Storm Lee became erosional. Statistical analysis indicated that drainage area explains linear changes (cm/y) in eroding streambanks and that channel top width explains cross-sectional area changes (cm2/y) in eroding streambanks and floodplain deposition (mm/y). A quasi-sediment budget constructed for the study period using the streambanks, channel bed, channel bars, and floodplain measurements underestimated the measured suspended-sediment load by 61% (2130 Mg/y). Underestimation of the sediment load may be caused by measurement errors and to contributions from upland sediment sources, which were not measured but estimated at 36% of the gross input of sediment. Eroding streambanks contributed 42% of the gross input of sediment and accounted for 70% of the measured suspended-sediment load. Similar to other urban watersheds, the large percentage of impervious area in Difficult Run and direct runoff of precipitation leads to increased streamflow and

  11. The delicate balance between soil production and erosion, and its role on landscape evolution

    Dosseto, Anthony; Buss, Heather L; Suresh, P O


    The diversity in landscapes at the Earth’s surface is the result, amongst other things, of the balance (or imbalance) between soil production and erosion. While erosion rates are well constrained, it is only recently that we have been able to quantify rates of soil production. Uranium-series isotopes have been useful to provide such estimates independently of erosion rates. In this study, new U-series isotope are presented data from weathering profiles developed over andesitic parent rock in ...

  12. Simplified analytical modeling of the normal hole erosion test; Modelado analitico simplificado del ensayo normal de ersoion de tubo

    Khamlichi, A.; Bezzazi, M.; El Bakkali, L.; Jabbouri, A.; Kissi, B.; Yakhlef, F.; Parron Vera, M. A.; Rubio Cintas, M. D.; Castillo Lopez, O.


    The role erosion test was developed in order to study erosion phenomenon which occurs in cracks appearing in hydraulic infrastructures such as dams. This test enables describing experimentally the erosive characteristics of soils by means of an index which is called erosion rate and a critical tension which indicates the threshold of surface erosion initiation. The objective of this work is to five modelling of this experiment by means of a simplified analytical approach. The erosion law is derived by taking into account the flow regime. This law shows that the erosion occurring in the tube is controlled by a first order dynamics where only two parameters are involved: the characteristic's time linked to the erosion rate and the stress shear threshold for which erosion begins to develop. (Author) 5 refs.

  13. Thermal erosion of a permafrost coastline: Improving process-based models using time-lapse photography

    Wobus, C.; Anderson, R.; Overeem, I.; Matell, N.; Clow, G.; Urban, F.


    Coastal erosion rates locally exceeding 30 m y-1 have been documented along Alaska's Beaufort Sea coastline, and a number of studies suggest that these erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the specific processes that connect climate change to coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where coastal erosion rates have averaged 10-15 m y-1 over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to observe and quantify coastal erosion directly via time-lapse photography in combination with meteorological observations. Our observations indicate that the erosion of these bluffs is largely thermally driven, but that surface winds play a crucial role in exposing the frozen bluffs to the radiatively warmed seawater that drives melting of interstitial ice. To first order, erosion in this setting can be modeled using formulations developed to describe iceberg deterioration in the open ocean. These simple models provide a conceptual framework for evaluating how climate-induced changes in thermal and wave energy might influence future erosion rates in this setting.

  14. Does WEPP meet the specificity of soil erosion in steep mountain regions?

    N. Konz


    Full Text Available We chose the WEPP model (Water Erosion Prediction Project to describe soil erosion in the Urseren Valley (central Switzerland as it seems to be one of the most promising models for steep mountain environments. Crucial model parameters were determined in the field (slope, plant species, fractional vegetation cover, initial saturation level, by laboratory analyses (grain size, organic matter or by the WEPP manual (rill- and interrill erodibility, effective hydraulic conductivity, cation exchange capacity. The quantification of soil erosion was performed on hill slope scale for three different land use types: meadows, pastures with dwarf shrubs and pastures without dwarf shrubs. Erosion rates for the vegetation period were measured with sediment traps between June 2006 and November 2007. Long-term soil erosion rates were estimated by measuring Cs-137 redistribution, deposited after the Chernobyl accident. In addition to the erosion rates, soil moisture and surface flow was additionally measured during the vegetation period in the field and compared to model output. Short-term erosion rates are simulated well whereas long term erosion rates were underestimated by the model. Simulated soil moisture has a parallel development compared to measured data from April onwards but a converse dynamic in early spring (simulated increase and measured decrease in March and April. The discrepancy in soil water during springtime was explained by delayed simulated snow cover melting. The underestimation of simulated long term erosion rates is attributed to alpine processes other than overland flow and splash. Snow gliding processes might dominate erosion processes during winter time. We assume that these differences lead to the general simulated underestimation of erosion rates. Thus, forcing erosion processes which dominate erosion rates in mountainous regions have to be implemented to WEPP for a successful application in the future.

  15. Quantifying transient erosion of orogens with detrital thermochronology from syntectonic basin deposits

    Rahl, Jeffrey M.; Ehlers, Todd A.; van der Pluijm, Ben A.


    The evolution of an orogen is marked by phases of topographic growth, equilibrium, and decay. During these phases erosion rates vary in response to temporal and spatial changes in climate, topographic relief and slope, and deformation. Detrital thermochronometer cooling-age data collected from syntectonic basin deposits are a promising tool for quantifying erosion histories during orogenic evolution. Previous studies typically assume steady-state erosion for interpreting detrital data, although in many situations this assumption is not justified. Here we present a new numerical modeling approach that predicts thermochronometer cooling ages in a stratigraphic section where sediment is sourced from a region with a temporally variable erosion history. Multiple thermochronometer cooling ages are predicted at different stratigraphic horizons as a function of variable erosion histories, rock cooling rates in the hinterland, and thermophysical material properties and boundary conditions. The modeling approach provides the context for the interpretation of natural data, including geologically realistic situations with a temporally varying erosion rate. The results of three end-member hinterland erosion histories are explored: (1) steady-state erosion; (2) increasing erosion rate with time; and (3) decreasing erosion rate with time. Results indicate that for steady erosion rates between 0.2 and 1.0 mm/yr, up to 30 m.y. will pass following a change in erosion rate before the detrital ages have adjusted to reflect a new erosion regime. In simulations with transient erosion, the estimation of erosion rates from a detrital record using assumption of thermal steady-state will generally be in error, often by as much as - 25 to 100%. These results highlight that assumptions of steady erosion in mountain belts should be used with caution. Application of the model to thermochronometer cooling ages preserved in syntectonic sediments sourced from the Nanga Parbat region, Himalaya

  16. High temperature erosion testing in a gasifier environment

    Tylczak, Joseph H.; Rawers, James C.; Adler, Thomas A.


    The development of materials with the ability to operate in adverse conditions while resisting the effects of erosion and corrosion is essential to the future success of high efficiency power plants. Many next generation coal power plants are envisioned as combined cycle, with gasifiers used to produce both steam and syngas. The gasifier sections of these plants require materials of construction that are resistant to the effects of erosion from silica found in the gas streams and corrosion caused by a reducing atmosphere that may contain sulfur and chloride compounds. The Albany Research Center has developed a test apparatus designed to test the erosion-resistance of candidate materials under a range of environmental conditions, including those found in gasifiers. This Hostile Atmosphere Erosion Wear test apparatus (HAET) has been used to evaluate a group of high alloy candidate materials such as iron aluminide and Haynes HR 160, and compare them to a conventional 310 stainless steel. Erosion tests were conducted using 270μm silica abrasive, a typical impact velocities of 20 m/sec at temperatures up to 700°C in an atmosphere simulating gasifier conditions. The effects of erosion under these conditions on the surface scales that form are described. The total loss rate, loss rates due to erosion and corrosion for the test materials are compared.

  17. Erosion Resistance of CaO-Al2O3-SiO2 System Glass-Ceramics

    HE Feng; NIU Feng; LOU Guang-hui; DENG Zhi-guo


    The erosion resistance tests were used to research the erosion wear behavior of CaO-Al2O3-SiO2 system glass-ceramic. With the orthogonal test method, the factors that affect the erosion wear of CaO-Al2O3-SiO2 system glass-ceramic such as particles property, impact angle, impact time, size of particles were discussed.The results show that erosion rate rises along a straight line at the early period of erosion wear.With the impact time increased,the erosion rate deviates from original staight line,tendency of the erosion rate increases.With the size of paricle increased,it will have more kinetic energy,the erosion rate of the surface of glass-ceramics ploate rises.

  18. Water Impingement Erosion of Deep-Rolled Ti64

    Dina Ma


    Full Text Available In this work, the Liquid Impingement Erosion (LIE performances of deep-rolling (DR treated and non-treated Ti64 were investigated. Various erosion stages, from the incubation to the terminal erosion stages, could be observed. A full factorial design of experiments was used to study the effect of DR process parameters (Feed Rate, Spindle Velocity, Number of Passes, Pressure on the residual stress distribution, microhardness and surface roughness of the treated Ti64 specimens. The DR-treated Ti64 specimens exhibited improved surface microhardness, surface roughness, and large magnitude of compressive residual stresses, which were attributed to the amount of cold work induced by the DR process. Although DR improved the mechanical properties of the Ti64, the results showed that the treatment has little or no effect on the LIE performance of Ti64 but different damage modes were observed in these two cases. Evolution of the erosion stages was described based on water-hammer pressure, stress waves, radial wall jetting, and hydraulic penetration modes. The initial erosion stages were mainly influenced by water-hammer pressure and stress waves, whereas the intermediate erosion stages were influenced by the combination of the four modes together. The final erosion stages contain the four modes, however the erosion was greatly driven by the radial jetting and hydraulic penetration modes, where more material was removed. The failure mechanism of the final stages of the LIE test of both DR-treated and non-treated Ti64 was characterized as fatigue fracture. However, a brittle fracture behavior was observed in the initial and intermediate erosion stages of the DR-treated Ti64, whereas a ductile fracture behavior was observed in the non-treated Ti64. This was concluded from the micrographs of the LIE damage through different erosion stages.

  19. Hall Effect Thruster Plume Contamination and Erosion Study

    Jaworske, Donald A.


    The objective of the Hall effect thruster plume contamination and erosion study was to evaluate the impact of a xenon ion plume on various samples placed in the vicinity of a Hall effect thruster for a continuous 100 hour exposure. NASA Glenn Research Center was responsible for the pre- and post-test evaluation of three sample types placed around the thruster: solar cell cover glass, RTV silicone, and Kapton(R). Mass and profilometer), were used to identify the degree of deposition and/or erosion on the solar cell cover glass, RTV silicone, and Kapton@ samples. Transmittance, reflectance, solar absorptance, and room temperature emittance were used to identify the degree of performance degradation of the solar cell cover glass samples alone. Auger spectroscopy was used to identify the chemical constituents found on the surface of the exposed solar cell cover glass samples. Chemical analysis indicated some boron nitride contamination on the samples, from boron nitride insulators used in the body of the thruster. However, erosion outweighted contamination. All samples exhibited some degree of erosion. with the most erosion occurring near the centerline of the plume and the least occurring at the +/- 90 deg positions. For the solar cell cover glass samples, erosion progressed through the antireflective coating and into the microsheet glass itself. Erosion occurred in the solar cell cover glass, RTV silicone and Kapton(R) at different rates. All optical properties changed with the degree of erosion, with solar absorptance and room temperature emittance increasing with erosion. The transmittance of some samples decreased while the reflectance of some samples increased and others decreased. All results are consistent with an energetic plume of xenon ions serving as a source for erosion.

  20. Grazing incidence ion erosion in the presence of adsorbates

    Redinger, A; Michely, T [II. Physikalisches Institut, Universitaet zu Koeln, 50937 Koeln (Germany); Rosandi, Y; Urbassek, H M [Fachbereich Physik, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, 67663 Kaiserslautern (Germany)], E-mail:


    The effect of a background pressure of adsorbable species on sputtering and surface damage in grazing incidence ion erosion of Pt(111) is investigated by scanning tunneling microscopy and molecular dynamics simulations. The background pressure implies a partial surface coverage with adsorbates, which in turn causes an enhancement of the erosion rate by a factor of up to 40 compared to the clean case. Partial pressures of molecular oxygen and carbon monoxide were maintained during ion erosion with 5 keV Ar{sup +} for various grazing angles between 81 deg. and 87 deg. and temperatures ranging from 400 to 550 K.

  1. Dune erosion under climate change

    de Winter, R.C.|info:eu-repo/dai/nl/341476935


    This PhD-thesis investigated the effect of future climate change on dune erosion in the Netherlands. At present, dune erosion occurs under a combination of large storm surge and high waves, which are both generated by a storm event. Therefore to investigate the affect of future climate change on dun

  2. Nocturnal lagophthalmos and recurrent erosion.

    Sturrock, G. D.


    The symptoms and corneal changes caused by sleeping with one or both eyes open are described in 102 patients. The clinical picture is identical to that of the microform recurrent erosion. The close relationship between the micro- and macro-forms of recurrent corneal erosion suggests that the latter condition is also precipitated by nocturnal lagophthalmos. Images PMID:1268178

  3. Dune erosion under climate change

    de Winter, R.C.


    This PhD-thesis investigated the effect of future climate change on dune erosion in the Netherlands. At present, dune erosion occurs under a combination of large storm surge and high waves, which are both generated by a storm event. Therefore to investigate the affect of future climate change on dun

  4. Dune erosion during storm surges

    Van Thiel de Vries, J.S.M.


    Large parts of The Netherlands are protected from flooding by a narrow strip of sandy beaches and dunes. The aim of this thesis is to extend the existing knowledge of dune erosion during storm surges as it occurs along the Dutch coast. The thesis discusses: • A large scale dune erosion experiment to

  5. The erosive potential of lollipops

    Brand, H.S.; Gambon, D.L.; Paap, A.; Bulthuis, M.S.; Veerman, E.C.I.; Nieuw Amerongen, A.V.


    Aim: To determine the erosive potential of several commercially available lollipops and the protective effect of saliva. Methods: The erosive potential of lollipops was determined in vitro by measuring the pH and neutralisable acidity. Subsequently, 10 healthy volunteers tested different types of lo

  6. In situ estimation of erosion and deposition thresholds by Acoustic Doppler Velocimeter (ADV)

    Andersen, T.J.; Fredsøe, Jørgen; Pejrup, M.


    Field-based estimations of bed shear stress have been made using SonTek/YSI 10 MHz ADVs (Acoustic Doppler Velocimeter) at the Kongsmark mudflat, Danish Wadden Sea, in order to test if it was possible to estimate erosion and deposition thresholds in situ by use of unidirectional tidal and orbital...... (wave) currents. The results were promising and erosion thresholds were in the same range as those observed in EROMES erosion experiments carried out at the same site. Similarly, the short-term erosion rates which could be calculated matched closely those obtained with EROMES, and were in the same range...... as those published for a large annular flume (Sea Carousel) from another fine-grained site. This indicates that the erosion rates obtained with those two erosion-instruments are reasonable estimates of the actual erosion taking place under natural tidal current and waves. One advantage of the use of ADVs...

  7. A conceptual framework for shear flow-induced erosion of soft cohesive sediment beds

    Winterwerp, J. C.; van Kesteren, W. G. M.; van Prooijen, B.; Jacobs, W.


    This paper proposes a conceptual framework for erosion of cohesive sediment beds. We focus on cohesive beds, distinguishing between floc erosion, surface erosion, and mass erosion. By (our) definition, surface erosion is a drained soil mechanical process, whereas mass erosion occurs under undrained conditions. The eroding shear stress is modeled through a probability density function. This yields a continuous description of floc erosion and surface erosion as a function of mean bed shear stress. Furthermore, we assume a distribution for the bed strength. The mean values of the bed strength are derived from soil mechanical theory, assuming that the surface erosion rate is limited by the swelling rate from the undrained shear strength in the bed to its drained value at its surface. The rate of erosion then relates to the undrained shear strength of the soil, and its consolidation (swelling) coefficient. The critical shear stress for erosion is slightly larger than the true cohesion of the bed, i.e., the drained strength, and follows a power law relation with the plasticity index. The conceptual framework proposed herein has been validated against a limited number of experimental data, and has a series of advantages above other methods of direct measuring erodibility, as it is inexpensive and can be used to attain space-covering information on the sediment bed. Moreover, the use of bulk soil mechanical parameters accounts implicitly for the effects of organic material, though the role of, e.g., macrophytobenthos mats and/or bioturbation is difficult to capture a priori.

  8. Deterioration of Thermal Barrier Coated Turbine Blades by Erosion

    Rohan Swar


    Full Text Available A combined experimental and computational study was conducted to investigate the erosion of thermal barrier coated (TBC blade surfaces by alumina particles ingestion in a single-stage turbine. In the experimental investigation, tests were performed to determine the erosion rates and particle restitution characteristics under different impact conditions. The experimental results show that the erosion rates increase with increased impingement angle, impact velocity, and temperature. In the computational simulations, an Euler-Lagrangian two-stage approach is used in obtaining numerical solutions to the three-dimensional compressible Reynolds-Averaged Navier-Stokes equations and the particles equations of motion in each blade passage reference frame. User defined functions (UDFs were developed to represent experimentally based correlations for particle surface interaction models and TBC erosion rates models. UDFs were employed in the three-dimensional particle trajectory simulations to determine the particle rebound characteristics and TBC erosion rates on the blade surfaces. Computational results are presented in a commercial turbine and a NASA-designed automotive turbine. The similarities between the erosion patterns in the two turbines are discussed for uniform particle ingestion and for particle ingestion concentrated in the inner and outer 5% of the stator blade span to represent the flow cooling of the combustor liner.

  9. Erosion-Oxidation Response of Boiler Grade Steels: A Mathematical Investigation

    S. K. Das


    Full Text Available A ductile erosion model embodying the mechanisms of erosion involving cutting wear and repeated plastic deformation has been developed to predict erosion rates of boiler grade steels. The issue of erosion-oxidation interaction has also been addressed to further predict the mass loss resulted from this composite mechanism. A deterministic formalism for the kinetics of oxide-scale growth and a probabilistic approach to characterize the material loss are employed to describe simultaneous actions of high-temperature oxidation and mechanical erosion. The model predictions are in good agreement with the published data.


    ChenHuahui; ZhaoHuiyou; ShooHesheng; ZhaoShanzhon


    16Mn steel, 1Cr18Ni9 stainless steel, thermal sprayed Al2O3-TiO2 ceramic coating and nylonl010-5%Al2O3 coating were tested with an erosion-corrosion tester.The effects of pH values and slurry velocities on the erosion-corrosion behavior of the materials tested were determined. The erosion-corrosion behavior of the materials tested changes with pH values and presents different change tendencies. The erosion-corrosion rates of the materials are increased with slurry velocities. The erosion-corrosion mechanisms for the steels and the coatings are considerably different.

  11. Erosion of lithium coatings on TZM molybdenum and graphite during high-flux plasma bombardment

    Abrams, T.; Jaworski, M. A.; Kaita, R.; Stotler, D. P.; De Temmerman, G.; Morgan, T. W.; van den Berg, M. A.; van der Meiden, H. J.


    Abstract The rate at which Li films will erode under plasma bombardment in the NSTX-U divertor is currently unknown. It is important to characterize this erosion rate so that the coatings can be replenished before they are completely depleted. An empirical formula for the Li erosion rate as a

  12. An integrated assessment of soil erosion dynamics with special emphasis on gully erosion: Case studies from South Africa and Iran

    Maerker, Michael; Sommer, Christian; Zakerinejad, Reza; Cama, Elena


    Soil erosion by water is a significant problem in arid and semi arid areas of large parts of Iran. Water erosion is one of the most effective phenomena that leads to decreasing soil productivity and pollution of water resources. Especially in semiarid areas like in the Mazayjan watershed in the Southwestern Fars province as well as in the Mkomazi catchment in Kwa Zulu Natal, South Africa, gully erosion contributes to the sediment dynamics in a significant way. Consequently, the intention of this research is to identify the different types of soil erosion processes acting in the area with a stochastic approach and to assess the process dynamics in an integrative way. Therefore, we applied GIS, and satellite image analysis techniques to derive input information for the numeric models. For sheet and rill erosion the Unit Stream Power-based Erosion Deposition Model (USPED) was utilized. The spatial distribution of gully erosion was assessed using a statistical approach which used three variables (stream power index, slope, and flow accumulation) to predict the spatial distribution of gullies in the study area. The eroded gully volumes were estimated for a multiple years period by fieldwork and Google Earth high resolution images as well as with structure for motion algorithm. Finally, the gully retreat rates were integrated into the USPED model. The results show that the integration of the SPI approach to quantify gully erosion with the USPED model is a suitable method to qualitatively and quantitatively assess water erosion processes in data scarce areas. The application of GIS and stochastic model approaches to spatialize the USPED model input yield valuable results for the prediction of soil erosion in the test areas. The results of this research help to develop an appropriate management of soil and water resources in the study areas.

  13. Erosion characteristics and horizontal variability for small erosion depths in the Sacramento-San Joaquin River Delta, California, USA

    Schoellhamer, David H.; Manning, Andrew J.; Work, Paul


    Erodibility of cohesive sediment in the Sacramento-San Joaquin River Delta (Delta) was investigated with an erosion microcosm. Erosion depths in the Delta and in the microcosm were estimated to be about one floc diameter over a range of shear stresses and times comparable to half of a typical tidal cycle. Using the conventional assumption of horizontally homogeneous bed sediment, data from 27 of 34 microcosm experiments indicate that the erosion rate coefficient increased as eroded mass increased, contrary to theory. We believe that small erosion depths, erosion rate coefficient deviation from theory, and visual observation of horizontally varying biota and texture at the sediment surface indicate that erosion cannot solely be a function of depth but must also vary horizontally. We test this hypothesis by developing a simple numerical model that includes horizontal heterogeneity, use it to develop an artificial time series of suspended-sediment concentration (SSC) in an erosion microcosm, then analyze that time series assuming horizontal homogeneity. A shear vane was used to estimate that the horizontal standard deviation of critical shear stress was about 30% of the mean value at a site in the Delta. The numerical model of the erosion microcosm included a normal distribution of initial critical shear stress, a linear increase in critical shear stress with eroded mass, an exponential decrease of erosion rate coefficient with eroded mass, and a stepped increase in applied shear stress. The maximum SSC for each step increased gradually, thus confounding identification of a single well-defined critical shear stress as encountered with the empirical data. Analysis of the artificial SSC time series with the assumption of a homogeneous bed reproduced the original profile of critical shear stress, but the erosion rate coefficient increased with eroded mass, similar to the empirical data. Thus, the numerical experiment confirms the small-depth erosion hypothesis. A linear

  14. Using REE Tracers to Measure Sheet Erosion Changing to Rill Erosion

    宋炜; 刘普灵; 杨明义; 薛亚洲


    Rare earth element(REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different REE on different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amount increases with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4.3 and 5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amount. The new REE tracer method should be useful to future studying of erosion processes on slope lands.

  15. Viewpoint: Sustainability of pinon-juniper ecosystems - A unifying perspective of soil erosion thresholds

    Davenport, D.W.; Breshears, D.D.; Wilcox, B.P.; Allen, C.D.


    Many pinon-juniper ecosystem in the western U.S. are subject to accelerated erosion while others are undergoing little or no erosion. Controversy has developed over whether invading or encroaching pinon and juniper species are inherently harmful to rangeland ecosystems. We developed a conceptual model of soil erosion in pinon-jumper ecosystems that is consistent with both sides of the controversy and suggests that the diverse perspectives on this issue arise from threshold effects operating under very different site conditions. Soil erosion rate can be viewed as a function of (1) site erosion potential (SEP), determined by climate, geomorphology and soil erodibility; and (2) ground cover. Site erosion potential and cove act synergistically to determine soil erosion rates, as evident even from simple USLE predictions of erosion. In pinon-juniper ecosystem with high SEP, the erosion rate is highly sensitive to ground cover and can cross a threshold so that erosion increases dramatically in response to a small decrease in cover. The sensitivity of erosion rate to SEP and cover can be visualized as a cusp catastrophe surface on which changes may occur rapidly and irreversibly. The mechanisms associated with a rapid shift from low to high erosion rate can be illustrated using percolation theory to incorporate spatial, temporal, and scale-dependent patterns of water storage capacity on a hillslope. Percolation theory demonstrates how hillslope runoff can undergo a threshold response to a minor change in storage capacity. Our conceptual model suggests that pinion and juniper contribute to accelerated erosion only under a limited range of site conditions which, however, may exist over large areas.

  16. Determination of the Critical Erosion Threshold of Cohesive Sediments on Intertidal Mudflats Along the Dutch Wadden Sea Coast

    Houwing, E.-J.


    The bed shear strength on an intertidal mudflat bordering salt marshes along the Dutch Wadden Sea coast was determined by means of an in situ erosion flume (ISEF). Characteristic erosion patterns (type I- and type II-erosion) were observed for most measurements. The critical erosion threshold varied between 0·11-0·18 (Pa) for all measurements and erosion rates varied between 5×10 -5and 3×10 -3(kg m -2 s -1). No clear relationship was found between distinct parameters like bed density, moisture content or biological activity and the critical erosion threshold. A more pronounced effect of the erodability of the mudflat was found when the erosion rate was taken into account. Basically two clusters were distinguished. High mean peak erosion rates of the substratum were found at locations which were characterized by a low mud content of the substratum (below 20% mud by weight). In these situations bed load transport is expected to be the most important process which determined erosion of the bed and erosion of predominantly the sand fraction was found. At higher rates of the mud content (over 20% mud by weight) mean peak erosion rates decreased substantially (an order 6 to 10 times lower) and both erosion of the mud and sand fraction was found.

  17. Solid Particle Erosion response of fiber and particulate filled polymer based hybrid composites: A review

    Yogesh M


    Full Text Available The solid particle erosion behaviour of fiber and particulate filled polymer composites has been reviewed. An overview of the problem of solid particle erosion was given with respect to the processes and modes during erosion with focus on polymer matrix composites. The new aspects in the experimental studies of erosion of fiber and particulate filled polymer composites were emphasized in this paper. Various predictions and models proposed to describe the erosion rate were listed and their suitability was mentioned. Implementation of design of experiments and statistical techniques in analyzing the erosion behaviour of composites was discussed. Recent findings on erosion response of multi-component hybrid composites were also presented. Recommendations were given on how to solve some open questions related to the structureerosion resistance relationships for polymers and polymer based hybrid composites.

  18. Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites

    Jyoti R. Mohanty


    Full Text Available Solid particle erosion behavior of short date palm leaf (DPL fiber reinforced polyvinyl alcohol (PVA composite has been studied using silica sand particles (200 ± 50 μm as an erodent at different impingement angles (15–90° and impact velocities (48–109 m/s. The influence of fiber content (wt% of DPL fiber on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM to understand the erosion mechanism.

  19. [Gastric band erosion: Alternative management].

    Echaverry-Navarrete, Denis José; Maldonado-Vázquez, Angélica; Cortes-Romano, Pablo; Cabrera-Jardines, Ricardo; Mondragón-Pinzón, Erwin Eduardo; Castillo-González, Federico Armando


    Obesity is a public health problem, for which the prevalence has increased worldwide at an alarming rate, affecting 1.7 billion people in the world. To describe the technique employed in incomplete penetration of gastric band where endoscopic management and/or primary closure is not feasible. Laparoscopic removal of gastric band was performed in five patients with incomplete penetrance using Foley catheterization in the perforation site that could lead to the development of a gastro-cutaneous fistula. The cases presented include a leak that required surgical lavage with satisfactory outcome, and one patient developed stenosis 3 years after surgical management, which was resolved endoscopically. In all cases, the penetration site closed spontaneously. Gastric band erosion has been reported in 3.4% of cases. The reason for inserting a catheter is to create a controlled gastro-cutaneous fistula, allowing spontaneous closure. Various techniques have been described: the totally endoscopic, hybrid techniques (endoscopic/laparoscopic) and completely laparoscopic. A technique is described here that is useful and successful in cases where the above-described treatments are not viable. Copyright © 2015. Published by Masson Doyma México S.A.

  20. Study of Spatial and Temporal Processes of Soil Erosion on Sloping Land Using Rare Earth Elements As Tracers

    薛亚洲; 刘普灵; 杨明义; 琚彤军


    Rare earth elements(REE) were used to study the temporal and spatial processes of soil erosion from different depths and sections of a slope. Two simulated rainfall events were applied to a prepared plot with a slope of 22°. The total runoff and sediment yield were collected every minute during the rainfall events. During the first twenty minutes of the first rainfall event,the average rate of rill erosion and the accumulated sediment yield due to rill erosion was 0.5 and 0.3 times higher than for sheet erosion. During this time,most of the erosion occurred on the lower one third of the plot. After 20 min,rill erosion became the dominant process on the slope. The average acceleration in the rate of rill erosion,the rate of rill erosion and the accumulated sediment yield due to rill erosion were 42,6 and 4 times higher than that of sheet erosion,respectively. During the first 35 minutes of the second rainfall event,the average acceleration in the rate of rill erosion was 6~9 times higher than that of sheet erosion. Afterwards,the slope became nearly stable with little change in either rill or sheet erosion rates. Initially,most of the rill erosion occurred in the lower third of the slope but later the preexisting rillhead in the middle section of the slope became reactivated and erosion in this section of the slope increased rapidly. These results indicate that REE tracer technology is a valuable tool for quantifying spatial and temporal changes in erosion from a soil slope.


    ZHANG Yan; ZHANG Hong; PENG Bu-zhuo; YANG Hao


    Soil erosion on sloping field has led to a lot of environmental problems. In order to reveal the seriousnessof the damage of soil erosion on sloping fields 137Cs tracer method was used to estimate soil erosion rate. 137Cs referenceinventory of 2200Bq/m2 in Yixing, southern Jiangsu Province, was estimated and a model for estimating erosion of cultivat-ed soil was established in order to avoid overestimating soil erosion rates. Then based on the soil erosion rates and mea-sured soil physical and chemical properties, direct and indirect impacts of soil erosion on environment were further dis-cussed. Direct impacts of erosion on environment included on-site and off-site impacts. The on-site impacts were thatsoil layer became thin, soil structure was deteriorated and soil nutrients decreased. The off-site impacts were that waterbodies were polluted. The indirect impacts of soil erosion on environment were the increase of fertilizer application andenergy consumption, and change of adaptability of land uses. Although erosion intensity was not serious in the studyarea, its environmental impacts should not be ignored because of great soil nutrient loss and coarseness of soil particles.

  2. Soil erosion in developing countries: A politicoeconomic explanation

    Thapa, Gopal B.; Weber, Karl E.


    Soil erosion is accelerating in developing countries of Asia, Africa, and Latin America. It has threatened the livelihood of millions of peasants, for agriculture is their economic mainstay. A probe into the forces causing erosion reveals that the elite’s resolve to accumulate ever more wealth and to maintain, consolidate, or expand their sociopolitical power and the necessity of the poor to fulfill their requirements of food, fuelwood, and fodder are the two major factors accelerating soil erosion. Unless the vast masses of poor people are integrated into the national mainstream through the implementation of equitable and redistributive development policies, it is impossible to control the accelerating rate of soil erosion and thus to achieve the objective of sustainable development.

  3. Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility.

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi


    Dental erosion, and specifically its symptoms, has long been studied in Japan as an occupational dental disease. However, in recent years, few studies have investigated the development of this disease or labor hygiene management aimed at its prevention. As a result, interest in dental erosion is comparatively low, even among dental professionals. Our investigation at a lead storage battery factory in 1991 found that the work environmental sulfuric acid density was above the tolerable range (1.0mg/m(3)) and that longterm workers had dental erosion. Therefore, workers handling sulfuric acid were given an oral examination and rates of dental erosion by tooth type, rates of erosion by number of working years and rates of erosion by sulfuric acid density in the work environment investigated. Where dental erosion was diagnosed, degree of erosion was identified according to a diagnostic criterion. No development of dental erosion was detected in the maxillary teeth, and erosion was concentrated in the anterior mandibular teeth. Its prevalence was as high as 20%. Rates of dental erosion rose precipitously after 10 working years. The percentages of workers with dental erosion were 42.9% for 10-14 years, 57.1% for 15-19 years and 66.7% for over 20 years with 22.5% for total number of workers. The percentages of workers with dental erosion rose in proportion to work environmental sulfuric acid density: 17.9% at 0.5-1.0, 25.0% at 1.0-4.0 and 50.0% at 4.0-8.0mg/m(3). This suggests that it is necessary to evaluate not only years of exposure to sulfuric acid but also sulfuric acid density in the air in factory workers.

  4. Erosion-resistant composite material

    Finch, C.B.; Tennery, V.J.; Curlee, R.M.

    A highly erosion-resistant composite material is formed of chemical vapor-deposited titanium diboride on a sintered titanium diboride-nickel substrate. This material may be suitable for use in cutting tools, coal liquefaction systems, etc.

  5. Rill Erosion in Post Wildfire Forests after Salvage Logging

    Robichaud, Peter; Wagenbrenner, Joseph; Brown, Robert


    Despite the dominance of concentrated flow or rill erosion in the erosion processes especially in steep forest environments that have been affected by wildfire or management activities few studies have quantified these effects on rill erosion. This study quantified the effects of wildfire and post-fire timber salvage operations on rill runoff quantity, runoff velocity, and rill erosion. Simulated rill experiments were conducted at various sites in the Western US after wildfire and timber salvage operations. The onsite conditions consists of burned only, salvage logged, skid or snig trail, or skid trails with extra logging debris added. For each rill experiment, concentrated flow was applied at the top of the plot through an energy dissipater at five inflow rates for 12 min each. Runoff was sampled every 2 min and runoff volume and sediment concentration were determined for each sample. The runoff velocity was measured using a dyed calcium chloride solution and two conductivity probes placed a known distance apart. Runoff volume, runoff velocities, and sediment concentrations increased with increasing levels of disturbance. The burned only plots had lower runoff rates and sediment concentrations than any of the other disturbances. The salvage logged plots had greater responses than the burn only plots and the mitigation treatment had a marginal effect on runoff ratios, runoff velocities and sediment concentrations. These results suggest that additional disturbance after a wildfire can increase the erosional response and that proper erosion control mitigation may be an important consideration for post fire management to reduce onsite erosion.

  6. Erosion charcteristics of ductile iron with various matrix structures

    Shimizu, Kazumichi (Oita National Coll. of Technology (Japan)); Noguchi, Toru (Faculty of Engineering, Hokkaido Univ., Sapporo (Japan))


    Erosive wear tests were performed on austempered ductile iron (ADI), ferritic ductile iron (FDI) and pearlitic ductile iron (PDI) using a shot blast machine. Erosion damage was measured by the removed material volume at impact angles between 10 and 90 . The surface metal flow in vertical sections was also observed. The mechanism of erosive wear, the effect of impact angles, and differences in wear features of specimens were discussed. Experiment showed that, after an initial stage, the eroded volume increases almost linearly with blasting time in ADI, FDI and PDI. The erosion rate for ADI is about 1/10-1/25 of that for FDI and PDI. The surface hardness of eroded ADI specimens increased from the initial HV350 to HV700 after 600 s of blasting. The amount of retained austenite was measured as about 40% before the test, but decreased to about 3-5% by transformation of austenite to martensite, hardening the surface and lowering the erosion rate. It was shown that ADI has excellent erosion resistance and it is expected to find wide applications as a wear-resistant material. (orig.)

  7. Soil erosion in mountainous areas: how far can we go?

    Egli, Markus


    Erosion is the counter part of soil formation, is a natural process and cannot be completely impeded. With respect to soil protection, the term of tolerable soil erosion, having several definitions, has been created. Tolerable erosion is often equalled to soil formation or production. It is therefore crucial that we know the rates of soil formation when discussing sustainability of soil use and management. Natural rates of soil formation or production are determined by mineral weathering or transformation of parent material into soil, dust deposition and organic matter incorporation. In mountain areas where soil depth is a main limiting factor for soil productivity, the use and management of soils must consider how to preserve them from excessive depth loss and consequent degradation of their physical, chemical and biological properties. Even under natural conditions, landscape surfaces and soils are known to evolve in complex, non-linear ways over time. As a result, soil production and erosion change substantially with time. The fact that soil erosion and soil production processes are discontinuous over time is an aspect that is in most cases completely neglected. To conserve a given situation, tolerable values should take these dynamics into account. Measurements of long and short-term physical erosion rates, total denudation, weathering rates and soil production have recently become much more widely available through cosmogenic and fallout nuclide techniques. In addition to this, soil chronosequences deliver a precious insight into the temporal aspect of soil formation and production. Examples from mountainous and alpine areas demonstrate that soil production rates strongly vary as a function of time (with young soils and eroded surfaces having distinctly higher rates than old soils). Extensive erosion promotes rejuvenation of the surface and, therefore, accelerates chemical weathering and soil production - the resulting soil thickness will however be shallow

  8. Three Gorges Reservoir Area: soil erosion under natural condition vs. soil erosion under current land use

    Schönbrodt, Sarah; Behrens, Thorsten; Scholten, Thomas


    Xiangjiaba site (mean 640.1 t ha-1 a-1) the maximum soil erosion of 1,115.4 t ha-1 a-1 under natural conditions is negligible lower. Compared to these erosion rates the mean soil loss under current land use is considerably lower (Xiangxi Catchment: mean 161.5 t ha-1 a-1; Backwater area: mean 166.3 t ha-1 a-1; Quyuan: mean 211.2 t ha-1 a-1; Xiangjiaba: mean 158.6 t ha-1 a-1). However, soil loss of maximum 2,662.2 t ha-1 a-1 for Xiangxi Catchment, 2,397.9 t ha-1 a-1 for the backwater area, 1,689.9 t ha-1 a-1 for Quyuan site, and 957.1 t ha-1 a-1 for Xiangjiaba site are also potentially possible. According to the Chinese Soil Erosion Rate Standard (cf. Xu et al., 2008) almost 44 % of the area of the Xiangxi Catchment show extreme (> 80 t ha-1 a-1) soil erosion which mainly occur in the backwater area. Our results show that the Xiangxi Catchment is already highly prone to soil erosion under natural conditions. In places, the current land use in the mountainous relief of the Xiangxi Catchment still increases the potential soil erosion to an extreme high level. However, mean potential soil loss rates under current land use lie under those due to the natural disposition. This is due to the fact that the natural disposition to soil erosion does not consider the complete topography factor (LS factor), that effects the potential soil loss (R² = 0.77) by the human-influenced erosive slope length through farmland terraces. Moreover, our results indicate an urgent need of proper management and conservation decisions in order to reduce soil erosion against the background of a high land use dynamic in a region with low carrying capacity (Beattie, 2002). Literature Beattie, J. (2002): Dam Building, Dissent, And Development: The Emergence Of The Three Gorges Project. New Zealand Journal of Asian Studies, Vol. 4(1): 138-158. Behrens, T., Schmidt, K. and Scholten, T. (2008). An approach to remove uncertainties in nominal environmental covariates and soil class maps. In: Hartemink, A. E., Mc

  9. Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) data

    Price, Kevin P.


    Multispectral measurements collected by Landsat Thematic Mapper (TM) were correlated with field measurements, direct soil loss estimates, and Universal Soil Loss Equation (USLE) estimates to determine the sensitivity of TM data to varying degrees of soil erosion in pinyon-juniper woodland in central Utah. TM data were also evaluated as a predictor of the USLE Crop Management C factor for pinyon-juniper woodlands. TM spectral data were consistently better predictors of soil erosion factors than any combination of field factors. TM data were more sensitive to vegetation variations than the USLE C factor. USLE estimates showed low annual rates of erosion which varied little among the study sites. Direct measurements of rate of soil loss using the SEDIMENT (Soil Erosion DIrect measureMENT) technique, indicated high and varying rates of soil loss among the sites since tree establishment. Erosion estimates from the USLE and SEDIMENT methods suggest that erosion rates have been severe in the past, but because significant amounts of soil have already been eroded, and the surface is now armored by rock debris, present erosion rates are lower. Indicators of accelerated erosion were still present on all sites, however, suggesting that the USLE underestimated erosion within the study area.



    Although there is much evidence of intense soil erosion in cultivated areas of Navarre (Spain), scarce information currently is available regarding soil loss rates, the spatial and temporal distribution of erosion, and the factors controlling these processes. Rills and ephemeral gullies are frequently responsible for a high percentage of total soil erosion, and these features can be considered a good approximation for the minimum erosion rates. With the main purpose of determining the annual soil loss rates in cultivated areas of Central Navarre, a detailed assessment of rainfall and rill and gully erosion was made in 19 small watersheds cultivated with winter grains or vineyards. The study period spanned from 1995 to 2001. For cereal watersheds, soil losses were caused by only one or two rainfall events each year. High erosion rates were observed (0.20-11.50 kg/m2 per year). In vineyards, soil losses were caused by several rainfall events each year, occurring year round. High erosion rates were observed in these vineyards (0.33 y 16.19 kg/m2 per year). No erosion was observed in those cultivated watersheds with no-till practices. It can be concluded that rill and ephemeral gully erosion can be very significant in Mediterranean regions, and much more attention should be paid to the problem.

  11. Fractal Tectonics and Erosion

    Turcotte, Donald L.

    Tectonic processes build landforms that are subsequently destroyed by erosional processes. Landforms exhibit fractal statistics in a variety of ways; examples include (1) lengths of coast lines; (2) number-size statistics of lakes and islands; (3) spectral behavior of topography and bathymetry both globally and locally; and (4) branching statistics of drainage networks. Erosional processes are dominant in the development of many landforms on this planet, but similar fractal statistics are also applicable to the surface of Venus where minimal erosion has occurred. A number of dynamical systems models for landforms have been proposed, including (1) cellular automata; (2) diffusion limited aggregation; (3) self-avoiding percolation; and (4) advective-diffusion equations. The fractal statistics and validity of these models will be discussed. Earthquakes also exhibit fractal statistics. The frequency-magnitude statistics of earthquakes satisfy the fractal Gutenberg-Richter relation both globally and locally. Earthquakes are believed to be a classic example of self-organized criticality. One model for earthquakes utilizes interacting slider-blocks. These slider block models have been shown to behave chaotically and to exhibit self-organized criticality. The applicability of these models will be discussed and alternative approaches will be presented. Fragmentation has been demonstrated to produce fractal statistics in many cases. Comminution is one model for fragmentation that yields fractal statistics. It has been proposed that comminution is also responsible for much of the deformation in the earth's crust. The brittle disruption of the crust and the resulting earthquakes present an integrated problem with many fractal aspects.

  12. A method to detect soil carbon degradation during soil erosion

    F. Conen


    Full Text Available Soil erosion has been discussed intensively but controversial both as a significant source or a significant sink of atmospheric carbon possibly explaining the gap in the global carbon budget. One of the major points of discussion has been whether or not carbon is degraded and mineralized to CO2 during detachment, transport and deposition of soil material. By combining the caesium-137 (137Cs approach (quantification of erosion rates with stable carbon isotope signatures (process indicator of mixing versus degradation of carbon pools we were able to show that degradation of carbon occurs during soil erosion processes at the investigated mountain grasslands in the central Swiss Alps (Urseren Valley, Canton Uri. Transects from upland (erosion source to wetland soils (erosion sinks of sites affected by sheet and land slide erosion were sampled. Analysis of 137Cs yielded an input of 2 and 4.6 tha−1 yr−1 of soil material into the wetlands sites. Assuming no degradation of soil organic carbon during detachment and transport, carbon isotope signature of soil organic carbon in the wetlands could only be explained with an assumed 500–600 and 350–400 years of erosion input into the wetlands Laui and Spissen, respectively. The latter is highly unlikely with alpine peat growth rates indicating that the upper horizons might have an age between 7 and 200 years. While we do not conclude from our data that eroded soil organic carbon is generally degraded during detachment and transport, we propose this method to gain more information on process dynamics during soil erosion from oxic upland to anoxic wetland soils, sediments or water bodies.

  13. A method to detect soil carbon degradation during soil erosion

    C. Alewell


    Full Text Available Soil erosion has been discussed intensively but controversial both as a significant source or a significant sink of atmospheric carbon possibly explaining the gap in the global carbon budget. One of the major points of discussion has been whether or not carbon is degraded and mineralized to CO2 during detachment, transport and deposition of soil material. By combining the caesium-137 (137Cs approach (quantification of erosion rates with stable carbon isotope signatures (process indicator of mixing versus degradation of carbon pools we were able to show that degradation of carbon occurs during soil erosion processes at the investigated mountain grasslands in the central Swiss Alps (Urseren Valley, Canton Uri. Transects from upland (erosion source to wetland soils (erosion sinks of sites affected by sheet and land slide erosion were sampled. Analysis of 137Cs yielded an input of 2 and 2.6 t ha−1 yr−1 of soil material into the wetlands sites. Assuming no degradation of soil organic carbon during detachment and transport, carbon isotope signature of soil organic carbon in the wetlands could only be explained with an assumed 800 and 400 years of erosion input into the wetlands. The latter is highly unlikely with alpine peat growth rates indicating that the upper horizons might have an age between 7 and 200 years. While we do not conclude from our data that eroded soil organic carbon is generally degraded during detachment and transport, we propose this method to gain more information on process dynamics during soil erosion from oxic upland to anoxic wetland soils, sediments or water bodies.

  14. Modelling erosion and its interaction with soil organic carbon.

    Oyesiku-Blakemore, Joseph; Verrot, Lucile; Geris, Josie; Zhang, Ganlin; Peng, Xinhua; Hallett, Paul; Smith, Jo


    Water driven soil erosion removes and relocates a significant quantity of soil organic carbon. In China the quantity of carbon removed from the soil through water erosion has been reported to be 180+/-80 Mt y-1 (Yue et al., 2011). Being able to effectively model the movement of such a large quantity of carbon is important for the assessment of soil quality and carbon storage in the region and further afield. A large selection of erosion models are available and much work has been done on evaluating the performance of these in developed countries (Merritt et al., 2006). Fewer studies have evaluated the application of these models on soils in developing countries. Here we evaluate and compare the performance of two of these models, WEPP (Laflen et al., 1997) and RUSLE (Renard et al., 1991), for simulations of soil erosion and deposition at the slope scale on a Chinese Red Soil under cultivation using measurements taken at the site. We also describe work to dynamically couple the movement of carbon presented in WEPP to a model of soil organic matter and nutrient turnover, ECOSSE (Smith et al., 2010). This aims to improve simulations of both erosion and carbon cycling by using the simulated rates of erosion to alter the distribution of soil carbon, the depth of soil and the clay content across the slopes, changing the simulated rate of carbon turnover. This, in turn, affects the soil carbon available to be eroded in the next timestep, so improving estimates of carbon erosion. We compare the simulations of this coupled modelling approach with those of the unaltered ECOSSE and WEPP models to determine the importance of coupling erosion and turnover models on the simulation of carbon losses at catchment scale.

  15. Robotic weld overlay coatings for erosion control. Final technical progress report, July 1992--July 1995

    Levin, B.F.; DuPont, J.N.; Marder, A.R.


    The erosion behavior of weld overlay coatings has been studied. Eleven weld overlay alloys were deposited on 1018 steel substrates using the plasma arc welding process and erosion tested at 400{degrees}C at 90{degrees} and 30{degrees} particle impact angles. The microstructure of each coating was characterized before erosion testing. A relative ranking of the coatings erosion resistance was developed by determining the steady state erosion rates. Ultimet, Inconel-625, and 316L SS coatings showed the best erosion resistance at both impact angles. It was found that weld overlays that exhibit good abrasion resistance did not show good erosion resistance. Erosion tests were also performed for selected wrought materials with chemical composition similar to weld overlays. Eroded surfaces of the wrought and weld alloys were examined by Scanning Electron Microscopy (SEM). Microhardness tests were performed on the eroded samples below the erosion surface to determine size of the plastically deformed region. It was found that one group of coatings experienced significant plastic deformation as a result of erosion while the other did not. It was also established that, in the steady state erosion regime, the size of the plastically deformed region is constant.

  16. Wind erosion of soils burned by wildfire

    N. S. Wagenbrenner; M. J. Germino; B. K. Lamb; R. B. Foltz; P. R. Robichaud


    Wind erosion and aeolian transport processes are largely unstudied in the post-wildfire environment, but recent studies have shown that wind erosion can play a major role in burned landscapes. A wind erosion monitoring system was installed immediately following a wildfire in southeastern Idaho, USA to measure wind erosion from the burned area (Figure 1). This paper...

  17. Effects of cropping systems on water runoff, soil erosion and nutrient loss in the Moldavian Plateau, Romania

    Ailincai, C.; Jitareanu, G.; Bucur, D.; Ailincai, D.; Raus, L.; Filipov, F.


    The experiments carried out at the Podu-lloaiei Agricultural Research Sation, during 1986-2008, had the following objectives: the study of water runoff and soil losses, by erosion, in different crops; the annual rate of erosion process under the influence of anti-erosion protection of different crops; the influence of water runoff and soil erosion on losses of organic matter and mineral elements from soil. (Author) 7 refs.

  18. Uncertainty in soil carbon accounting due to unrecognized soil erosion.

    Sanderman, Jonathan; Chappell, Adrian


    The movement of soil organic carbon (SOC) during erosion and deposition events represents a major perturbation to the terrestrial carbon cycle. Despite the recognized impact soil redistribution can have on the carbon cycle, few major carbon accounting models currently allow for soil mass flux. Here, we modified a commonly used SOC model to include a soil redistribution term and then applied it to scenarios which explore the implications of unrecognized erosion and deposition for SOC accounting. We show that models that assume a static landscape may be calibrated incorrectly as erosion of SOC is hidden within the decay constants. This implicit inclusion of erosion then limits the predictive capacity of these models when applied to sites with different soil redistribution histories. Decay constants were found to be 15-50% slower when an erosion rate of 15 t soil ha(-1)  yr(-1) was explicitly included in the SOC model calibration. Static models cannot account for SOC change resulting from agricultural management practices focused on reducing erosion rates. Without accounting for soil redistribution, a soil sampling scheme which uses a fixed depth to support model development can create large errors in actual and relative changes in SOC stocks. When modest levels of erosion were ignored, the combined uncertainty in carbon sequestration rates was 0.3-1.0 t CO2  ha(-1)  yr(-1) . This range is similar to expected sequestration rates for many management options aimed at increasing SOC levels. It is evident from these analyses that explicit recognition of soil redistribution is critical to the success of a carbon monitoring or trading scheme which seeks to credit agricultural activities.

  19. Remote sensing and spatially distributed erosion models as a tool to really understand biocrust effects on soil erosion

    Rodriguez-Caballero, Emilio; Chamizo, Sonia; Román, Raul; Roncero, Beatriz; Weber, Bettina; Jetten, Victor; Cantón, Yolanda


    Since publication of the first Ecological Stides volume on biological soil crusts (biocrusts) in 2003, numerous studies have been conducted trying to understand the role of biocrusts in runoff generation and water erosion. Most of them considered these communities as one of the most important stabilizing factors dryland regions. However, these studies were concentrated only on patch or hillslope scales, and there is a lack of information on biocrust interactions with other surface components at catchment scale. Even on fine textured soils, where biocrusts increase water infiltration, they act as runoff source when compared to vegetation. Run-on from biocrusted areas may be harvested by downslope vegetation, but sometimes it may promote downslope erosion. Thus, to really understand the effect of biocrusts on soil erosion, studies on larger scales, preferably on a catchment scale are needed. For this we developed a new approach, based on field measurements and remote sensing techniques, to include biocrust effects in physically-based runoff and erosion modeling. Doing this we were able to analyze how runoff generated in biocrust areas is redistributed within the landscape and its effect on catchment water erosion. The Limburg Soil Erosion Model (LISEM) was used to parameterize and simulate the effects of biocrusts on soil erosion in a small badlands catchment, where biocrusts represent one of the main surface components. Biocrust stability and cohesion were measured in the field, their hydrological properties were obtained from runoff plots, and their cover and spatial distribution was estimated from a hyperspectral image by linear mixture analysis. Then, the model was run under different rainfall intensities and final runoff and erosion rates were compared with field data measured at the catchment outlet. Moreover, these results were compared with the hypothetical scenario in which biocrusts were removed, simulating human disturbances or climatic change effects on

  20. Erosion of a grooved surface caused by impact of particle-laden flow

    Jung, Sohyun; Yang, Eunjin; Kim, Ho-Young


    Solid erosion can be a life-limiting process for mechanical elements in erosive environments, thus it is of practical importance in many industries such as construction, mining, and coal conversion. Erosion caused by particle-laden flow occurs through diverse mechanisms, such as cutting, plastic deformation, brittle fracture, fatigue and melting, depending on particle velocity, total particle mass and impingement angle. Among a variety of attempts to lessen erosion, here we investigate the effectiveness of millimeter-sized grooves on the surface. By experimentally measuring the erosion rates of smooth and triangular-grooved surfaces under various impingement angles, we find that erosion can be significantly reduced within a finite range of impingement angles. We show that such erosion resistance is attributed to the swirls of air within grooves and the differences in erosive strength of normal and slanted impact. In particular, erosion is mitigated when we increase the effective area under normal impact causing plastic deformation and fracture while decreasing the area under slanted impact that cuts the surface to a large degree. Our quantitative model for the erosion rate of grooved surfaces considering the foregoing effects agrees with the measurement results.

  1. Extracting change information of land-use and soil-erosion based on RS & GIS technology

    LI Zhong-feng; LI You-cai


    Rapid land-use change has taken place in many arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. Land-use change and soil erosion dynamics were investigated by the combined use of remote sensing and geographic information systems (GIS). The objectives were to determine land-use transition rates and soil erosion change in Yulin prefecture over 15 years from 1986 to 2000. Significant changes in land-use and soil erosion occurred in the area over the study period. The results show the significant decrease in barren land mainly due to conversion to grassland. Agricultural land increased associated with conversions from grassland and barren land. The area of water erosion and wind erosion declined. The study demonstrates that the integration of satellite remote sensing and GIS is an effective approach for analyzing the direction, rate, and spatial pattern of land-use and soil erosion change.

  2. Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission

    Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry


    The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec.

  3. Soil Erosion as a stochastic process

    Casper, Markus C.


    corrected experimentally. To overcome this disadvantage of our actual models, soil erosion models are needed that are able to use stochastic directly variables and parameter distributions. There are only some minor approaches in this direction. The most advanced is the model "STOSEM" proposed by Sidorchuk in 2005. In this model, only a small part of the soil erosion processes is described, the aggregate detachment and the aggregate transport by flowing water. The concept is highly simplified, for example, many parameters are temporally invariant. Nevertheless, the main problem is that our existing measurements and experiments are not geared to provide stochastic parameters (e.g. as probability density functions); in the best case they deliver a statistical validation of the mean values. Again, we get effective parameters, spatially and temporally averaged. There is an urgent need for laboratory and field experiments on overland flow structure, raindrop effects and erosion rate, which deliver information on spatial and temporal structure of soil and surface properties and processes.

  4. Study of erosion characterization of carbon fiber reinforced composite material

    Debnath, Uttam Kumar; Chowdhury, Mohammad Asaduzzaman; Kowser, Md. Arefin; Mia, Md. Shahin


    Carbon fiber composite materials are widely used at different engineering and industrial applications there are good physical, mechanical, chemical properties and light weight. Erosion behavior of materials depends on various factors such as impact angle, particle velocity, particle size, particle shape, particle type, particle flux, temperature of the tested materials. Among these factors impact angle and particle velocity have been recognized as two parameters that noticeably influence the erosion rates of all tested materials. Irregular shaped sand (SiO2) particles of various sizes (200-300 µm, 400-500 µm, and 500-600 µm) were selected erosive element. Tested conditions such as impingement angles between 15 degree to 90 degree, impact velocities between 30-50 m/sec, and stand-off distances 15-25 mm at surrounding room temperature were maintained. The highest level of erosion of the tested composite is obtained at 60° impact angle, which signifies the semi-ductile behavior of this material. Erosion showed increasing trend with impact velocity and decreasing nature in relation to stand-off distance. Surface damage was analyzed using SEM to examine the nature of the erosive wear mechanism.

  5. Integration of transport concepts for risk assessment of pesticide erosion.

    Yang, Xiaomei; Van Der Zee, Sjoerd E A T M; Gai, Lingtong; Wesseling, Jan G; Ritsema, Coen J; Geissen, Violette


    Environmental contamination by agrochemicals has been a large problem for decades. Pesticides are transported in runoff and remain attached to eroded soil particles, posing a risk to water and soil quality and human health. We have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation.

  6. Solid particle erosion of plasma sprayed ceramic coatings

    Branco José Roberto Tavares


    Full Text Available Thermal spraying allows the production of overlay protective coatings of a great variety of materials, almost without limitations as to its components, phases and constituents on a range of substrates. Wear and corrosion resistant coatings account for significant utilization of thermal spray processes. Besides being a means to evaluate the coating tribological performance, erosion testing allows also an assessment of the coating toughness and adhesion. Nevertheless, the relationship between the erosion behavior of thermal sprayed coatings and its microstructural features is not satisfactorily understood yet. This paper examines room temperature solid particle erosion of zirconia and alumina-based ceramic coatings, with different levels of porosity and varying microstrucutre and mechanical properties. The erosion tests were carried out by a stream of alumina particles with an average size of 50 µm at 70 m/s, carried by an air jet with impingement angle 90°. The results indicate that current erosion models based on hardness alone cannot account for experimental results, and, that there is a strong relationship between the erosion rate and the porosity.

  7. Actions from landfast Ice on coastal Erosion Protection in the van Mijenfjord, Svalbard

    Østerås, Espen S.


    The geobag embankment constructed at Kapp Amsterdam is part of an ongoing research by SINTEF related to exploration of suitability for use of geobags for coastal erosion protection in the Arctic.Erosion rates in the Arctic are often high and the lack of proper local masses for erosion protection creates the need for alternative solutions.The actions on the embankment caused by the surrounding ice need to be mapped whereas theyc onstitute one of the important features related to Arctic environ...

  8. Management of Asymptomatic Erosive Esophagitis: An E-Mail Survey of Physician's Opinions

    Lim, Seong Woo; Lee, Jun Haeng; Kim, Jie-Hyun; Kim, Jeong Hwan; Kim, Heung Up; Jeon, Seong Woo


    Background/Aims The management of asymptomatic erosive esophagitis is controversial. We surveyed physicians' opinions on asymptomatic erosive esophagitis using e-mail. Methods All members of the Korean Society of Neurogastro-enterology and Motility were invited to answer the questionnaire on the treatment and follow-up of patients with asymptomatic erosive esophagitis by e-mail. Results A total of 73 members answered the questionnaire (response rate, 18%). As initial management, 41% of respon...




    Full Text Available Soil erosion is one of the main causes of degradation of large areas of agricultural land, causing great economic loss by removing fertile soil. The Universal Soil Loss Equation (USLE predicts the long term average annual rate of erosion on a field slope based on rainfall pattern, soil type, topography, crop system and management practices but does not however predict the soil loss resulting from gully erosion.

  10. ERMiT: Estimating Post-Fire Erosion in Probabilistic Terms

    Pierson, F. B.; Robichaud, P. R.; Elliot, W. J.; Hall, D. E.; Moffet, C. A.


    Mitigating the impact of post-wildfire runoff and erosion on life, property, and natural resources have cost the United States government tens of millions of dollars over the past decade. The decision of where, when, and how to apply the most effective mitigation treatments requires land managers to assess the risk of damaging runoff and erosion events occurring after a fire. The Erosion Risk Management Tool (ERMiT) is a web-based application that estimates erosion in probabilistic terms on burned and recovering forest, range, and chaparral lands. Unlike most erosion prediction models, ERMiT does not provide `average annual erosion rates;' rather, it provides a distribution of erosion rates with the likelihood of their occurrence. ERMiT combines rain event variability with spatial and temporal variabilities of hillslope burn severity, soil properties, and ground cover to estimate Water Erosion Prediction Project (WEPP) model input parameter values. Based on 20 to 40 individual WEPP runs, ERMiT produces a distribution of rain event erosion rates with a probability of occurrence for each of five post-fire years. Over the 5 years of modeled recovery, the occurrence probability of the less erodible soil parameters is increased and the occurrence probability of the more erodible soil parameters is decreased. In addition, the occurrence probabilities and the four spatial arrangements of burn severity (arrangements of overland flow elements (OFE's)), are shifted toward lower burn severity with each year of recovery. These yearly adjustments are based on field measurements made through post-fire recovery periods. ERMiT also provides rain event erosion rate distributions for hillslopes that have been treated with seeding, straw mulch, straw wattles and contour-felled log erosion barriers. Such output can help managers make erosion mitigation treatment decisions based on the probability of high sediment yields occurring, the value of resources at risk for damage, cost, and

  11. Urethral Stricture Outcomes After Artificial Urinary Sphincter Cuff Erosion: Results From a Multicenter Retrospective Analysis.

    Gross, Martin S; Broghammer, Joshua A; Kaufman, Melissa R; Milam, Douglas F; Brant, William O; Cleves, Mario A; Dum, Travis W; McClung, Christopher; Jones, LeRoy A; Brady, Jeffrey D; Pryor, Michael B; Henry, Gerard D


    To evaluate the influence of both repair type and degree of cuff erosion on postoperative urethral stricture rate. Sparse literature exists regarding patient outcomes after artificial urinary sphincter (AUS) cuff erosion. Surgeons from 6 high-volume male continence centers compiled a comprehensive database of post-erosion patients to examine outcomes. This retrospective multi-institution study included 80 patients treated for AUS cuff erosions. Seventy-eight patients had specific information regarding post-cuff erosion urethral strictures. Erosion patients were categorized into 1 of 3 repair types at the time of explant surgery: catheter only, single-layer capsule-to-capsule repair (urethrorrhaphy), and formal urethroplasty. Operative notes and available medical records were extensively reviewed to collect study data. Twenty-five of 78 patients manifested a urethral stricture after AUS cuff erosion (32%). More strictures occurred among patients who underwent urethrorrhaphy (40% vs 29% for catheter only and 14% for urethroplasty). Stricture rates did not vary significantly by repair type (P = .2). Strictures occurred significantly more frequently in patients with complete cuff erosions (58%) as compared to partial erosions (25%, P = .037). A trend was detected regarding increased percentage of erosion correlating with increased stricture rate, but this did not reach statistical significance (P = .057). Partially eroded patients were more likely to undergo urethrorrhaphy repair (60%, P = .002). Urethral stricture was more likely to occur after complete cuff erosion as opposed to partial erosion in this multicenter retrospective population. Repair type, whether catheter only, urethrorrhaphy, or formal urethroplasty, did not appear to influence postoperative stricture rate. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Relationships between slope erosion processes and aggregate stability of Ultisols from subtropical China during rainstorms

    Liu, Gang; Xiao, Hai; Liu, Puling


    Soil aggregates, being a key soil structural unit, influence several soil physical properties such as water infiltration, runoff and erosion. The relationship between soil aggregate stability and interrill and rill erodibility is unclear but critical to process-based erosion prediction models. One obvious reason is that it is hard to distinguish between interrill and rill-eroded sediment during the erosion process. This study was designed to partition interrill and rill erosion rates and relates them to the aggregate stability of Ultisols in subtropical China. Six kinds of rare earth element (REE) were applied as tracers mixed with two cultivated soils derived from the Quaternary red clay soil and the shale soil at six slope positions. Soil aggregate stability was determined by the Le Bissonnais (LB)-method. Simulated rainfall with three intensities (60, 90 and 120 mm/h) were applied to a soil plot (2.25 m long, 0.5 m wide, 0.2 m deep) at three slope gradients (10°, 20° and 30°) with duration of 30 min after runoff initiation. The results indicated that interrill and rill erosion increased with increasing rainfall intensity and slope gradient for both types of soil. Rill and interrill erosion rates of the shale soil were much higher than those of the Quaternary red clay soil. Rill erosion contribution enhanced with increasing rainfall intensity and slope gradient for both soils. Percentage of the downslope area erosion to total erosion was the largest, followed by the mid-slope area and then upslope area. Equations using an aggregate stability index As to replace the erodibility factor of interrill and rill erosion in the Water Erosion Prediction Project (WEPP) model were constructed after analyzing the relationships between estimated and measured rill and interrill erosion data. It was shown that these equations based on the stability index, As, have the potential to improve methods for assessing interrill and rill erosion erodibility synchronously for the

  13. CFD simulations of flow erosion and flow-induced deformation of needle valve: Effects of operation, structure and fluid parameters

    Zhu, Hongjun, E-mail: [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China); State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, Sichuan (China); Pan, Qian; Zhang, Wenli; Feng, Guang; Li, Xue [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, Sichuan (China)


    Highlights: • A combined FSI–CFD and DPM computational method is used to investigate flow erosion and deformation of needle valve. • The numerical model is validated with the comparison of measured and predicted erosion rate. • Effects of operation, structure and fluid parameters on flow erosion and flow-induced deformation are discussed. • Particle diameter has the most significant effect on flow erosion. • Inlet rate has the most obvious effect on flow-induced deformation. - Abstract: A three-dimensional fluid–structure interaction (FSI) computational model coupling with a combined continuum and discrete model has been used to predict the flow erosion rate and flow-induced deformation of needle valve. Comparisons with measured data demonstrate good agreement with the predictions of erosion rate. The flow field distribution of gas-particle flow and the erosion rate and deformation of valve core are captured under different operating and structural conditions with different fluid parameters. The effects of inlet velocity, valve opening and inlet valve channel size, particle concentration, particle diameter and particle phase components are discussed in detail. The results indicate that valve tip has the most severe erosion and deformation, and flow field, erosion rate and deformation of valve are all sensitive to inlet condition changes, structural changes and fluid properties changes. The effect of particle diameter on erosion is the most significant, while the influence of inlet rate on deformation is the greatest one.

  14. Assessment of soil erosion sensitivity and post-timber-harvesting erosion response in a mountain environment of Central Italy

    Borrelli, Pasquale; Schütt, Brigitta


    This study aimed to assess the effects of forest management on the occurrence of accelerated soil erosion by water. The study site is located in a mountainous area of the Italian Central Apennines. Here, forest harvesting is a widespread forestry activity and is mainly performed on the moderate to steep slopes of the highlands. Through modeling operations based on data on soil properties and direct monitoring of changes in the post-forest-harvesting soil surface level at the hillslope scale, we show that the observed site became prone to soil erosion after human intervention. Indeed, the measured mean soil erosion rate of 49 t ha- 1 yr- 1 for the harvested watershed is about 21 times higher than the rate measured in its neighboring undisturbed forested watershed (2.3 t ha- 1 yr- 1). The erosive response is greatly aggravated by exposing the just-harvested forest, with very limited herbaceous plant cover, to the aggressive attack of the heaviest annual rainfall without adopting any conservation practices. The erosivity of the storms during the first four months of field measurements was 1571 MJ mm h- 1 ha- 1 in total (i.e., from September to December 2008). At the end of the experiment (16 months), 18.8%, 26.1% and 55.1% of the erosion monitoring sites in the harvested watershed recorded variations equal or greater than 0-5, 5-10 and > 10 mm, respectively. This study also provides a quantification of Italian forestland surfaces with the same pedo-lithological characteristics exploited for wood supply. Within a period of ten years (2002-2011), about 9891 ha of coppice forest changes were identified and their potential soil erosion rates modeled.

  15. [Diagnosis, treatment and prophylaxis of acute ulcero-erosive gastroduodenal bleedings at cardiosurgical patients].

    Kazymov, I L; Kirilenko, A S; Faĭbushevic h, A G; Kurbanov, F S; Tarichko, Iu V


    Results of treatment of 495 patients who has undergone various cardiac operations with artificial circulation are analyzed. The complex program "Blood-free surgery" was used at 388 (78.4%) of them. Among the patients treated traditionally the acute gastroduodenal erosions and ulcers were diagnosed at 25.7% patients, the rate of gastroduodenal bleedings was 3.0%. Complex of prophylactic measures permits to reduce the rate of acute erosions and ulcers in 1.5 times (18.4%) and the rate of postoperative gastroduodenal bleedings--to 0.7%. Control of risk factors, timely diagnosis, complex prophylaxis and treatment of acute gastroduodenal erosions and ulcers are effective way to improvement of operations results at cardiosurgical patients. "Blood-free" program doesn't lead to increase of acute postoperative gastroduodenal erosions and ulcers rate. Endoscopic (including repeated) hemostasis at acute ulcero-erosive gastroduodenal bleedings is available method and permits to achieve the stable hemostasis.

  16. Mechanisms of erosion in miocene clays from the Tudela formation (Bardenas Reales, Navarra, Spain); Mecanismos de erosion en arcillas miocenas de la Formacion Tudela (Bardenas Reales, Navarra, Espana)

    Marin, C.; Desir, G.


    In Bardenas Reales area (located in the central-western part of the Ebro Depression) several erosion rates have been measured along the last years. The mean annual erosion rates are of 32 Tm/Ha/yr. Due to semiarid conditions, precipitation is irregularly distributed along the year with maximums on spring and autumn when the great erosion is produced. There are intensity and quality thresholds below which erosion does not take place. In Bardenas Reales some erosion processes act (mud slides and armoured mud balls among others). Mud slides are mobilised on spring when the sediment have reached its plastic limit and could slide due to heavy rains. Armored mud balls are produced by the enhancement of popcorn cracks that individualize clays cores which are rounded by water. The same kind of strong precipitation that mobilised mud slides is the responsible of armoured mud balls destruction because the conditions to its maintenance are very limited. (Author) 9 refs.

  17. Cover and Erosion Asymmetry in Saltation-Abrasion

    Stark, C. P.; Parker, G.


    Erosion in bedrock-floored rivers is both driven and limited by the amount of sediment transported along the bed. Some sediment boosts wear rates, whereas too much generates a protective cover. This phenomenon determines the shape of river channels in a variety of landscapes and limits how fast they evolve. Here we reevaluate data from a well-known bedrock wear experiment to throw new light on how the saltation-abrasion process. Instead of a symmetric form for erosion versus sediment flux relative to transport capacity, we find the erosion rate peak shifts towards lower sediment fluxes when blocking of oblique saltation trajectories is taken into account. The theoretical context for this reevaluation is a cover-saltation-abrasion model, based on queueing theory (QT), for bedload transport over a planar bedrock bed. The QT approach provides some clarity in the stochastic treatment of granular impacts and cover, and generates closed-form solutions for wear rate in terms of sediment flux and simplified saltation geometry. Applied to the Sklar & Dietrich (2001) experiments in a very small recirculating flume, the two-parameter QT model fits the observed relation between erosion rate and sediment load, infers sediment flux as a function of load, admits non-negligible wear rates for a mean sediment depth of one grain, i.e., for full cover on average, but also suggests that bedrock erosion is blocked at >=50% instantaneous cover. The QT model makes testable predictions for future laboratory experiments and highlights the need for specific improvements in more comprehensive treatments of bedrock erosion and cover.

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

    Zhikun Ren


    Full Text Available 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.

  19. Estudo da erosão na microbacia do Ceveiro (Piracicaba, SP: I - Estimativa das taxas de perda de solo e estudo de sensibilidade dos fatores do modelo EUPS Erosion study in the Ceveiro Watershed (Piracicaba, SP.: I - Estimation o soil loss rates and sensitivity factor analysis of the USLE model

    Mara de Andrade Marinho Weill


    estimativas foi muito menor do que a do fator topográfico. A aplicação da EUPS permitiu estimar a expectativa de erosão do solo na área de estudo. O uso de geotecnologias e de métodos geoestatísticos de análise mostrou-se uma abordagem promissora nos estudos de erosão.Accelerated soil erosion is a serious global problem that degrades agriculture lands. Since erosion research is normally expensive and time-consuming, the use of models allows to estimate soil losses at locations and under conditions not represented directly in the research. The objective of this study was to estimate the soil erosion in an area intensively cultivated with sugarcane near the city of Piracicaba, São Paulo, contributing to diagnose the current land uses aimed at controlling erosion. The study was carried out based on a geographic information system using the universal soil loss equation (USLE to estimate erosion. A specific objective of the study was to analyze the influence of K (soil erodibility, LS (topography, C (crop use and management and P (erosion control practices factors in soil loss estimates. The results show an intense soil degradation process by accelerated erosion in nearly two-thirds of the studied area, mainly occupied by sugarcane. In these areas, the average estimated soil loss rate of 58 Mg ha-1 year-1 is equivalent to nearly four times the indicated average upper tolerance limit. In the remaining areas occupied by forest, riparian vegetation, afforestation and pasture, the estimated soil loss rates are low, around 2 Mg ha-1 year-1 , below the tolerance values. The model factor sensitivity analysis revealed that under the same weather condition (constant R factor, factors C and P (crop management and coverage and erosion control practices defined the magnitude of the soil losses, whether in units, tens or hundreds of Mg ha-1 year-1. For a same category of land use (factors C and P constant, the LS factor (topographic explained most of the observed variation. The

  20. Modeling fluvial erosion on regional to continental scales

    Howard, Alan D.; Dietrich, William E.; Seidl, Michele A.


    The fluvial system is a major concern in modeling landform evolution in response to tectonic deformation. Three stream bed types (bedrock, coarse-bed alluvial, and fine-bed alluvial) differ in factors controlling their occurrence and evolution and in appropriate modeling approaches. Spatial and temporal transitions among bed types occur in response to changes in sediment characteristics and tectonic deformation. Erosion in bedrock channels depends upon the ability to scour or pluck bed material; this detachment capacity is often a power function of drainage area and gradient. Exposure of bedrock in channel beds, due to rapid downcutting or resistant rock, slows the response of headwater catchments to downstream baselevel changes. Sediment routing through alluvial channels must account for supply from slope erosion, transport rates, abrasion, and sorting. In regional landform modeling, implicit rate laws must be developed for sediment production from erosion of sub-grid-scale slopes and small channels.




    Concentrated flow can cause gully formation on sloping lands and in riparian zones. Current practice for riparian gully erosion control involves blocking the gully with a structure comprised of an earthen embankment and a metal or plastic pipe. Measures involving native vegetation would be more attractive for habitat recovery and economic reasons. To test the hypothesis that switchgrass (Panicum virgatum L.) hedges planted at 0.5-m vertical intervals within a gully would control erosion,a series of hedges was established in four concentrated flow channels. Two of the channels were previously eroded trapezoidal channels cut into compacted fill in an outdoor laboratory. The other two channels were natural gullies located at the edge of floodplain fields adjacent to an incised stream.While vegetation was dormant, artificial runoff events were created in the two laboratory gullies and one of the natural gullies using synthetic trapezoidal-shaped hydrographs with peak discharge rates of approximately 0.03, 0.07, and 0.16 m3/s. During these tests flow depth, velocity, turbidity, and soil pore water pressures were monitored. The fourth gully was subjected to a series of natural runoff events over a five-month period with peaks up to 0.09 m3/s. Flow depths in all tests were generally < 0.3 m, and flow velocities varied spatially and exceeded 2.0 m/s at the steepest points of the gullies.Erosion rates were negligible for controlled flow experiments, but natural flows in the fourth gully resulted in 1 m of thalweg degradation, destroying the central portions of the grass hedges, most likely due to the highly erodible nature of the soils at this site. Geotechnical modeling of soil steps reinforced with switchgrass roots showed factors of safety > 1 for step heights < 0.5 m, but instability was indicated for step heights > 1 m, consistent with the experimental observations.

  2. Cavitation-erosion resistance of arc ion-plated (Ti, Cr) N coatings


    The cavitation-erosion behavior of (Ti,Cr)N multi-component coatings produced by arcion-plating on grey cast iron was studied by using an ultrasonic cavitation -erosion testing appara-tus and scanning electron microscopy. The test results indicated that surface roughness of thesubstrate, surface morphology of the coating, substrate bias voltage and the thickness of the coat-ing had certain influence on the erosion rate. Arc ion-plated (Ti,Cr)N multi-component coatingsshowed better cavitation -erosion resistance than single component coatings because of highermicrohardness and good adhesion.

  3. Plutonium as a tracer for soil erosion assessment in northeast China

    Xu, Yihong; Qiao, Jixin; Pan, Shaoming;


    Soil erosion is one of the most serious environmental and agricultural problems faced by human society. Assessing intensity is an important issue for controlling soil erosion and improving eco-environmental quality. The suitability of the application of plutonium (Pu) as a tracer for soil erosion...... assessment in northeast China was investigated by comparing with that of 137Cs. Here we build on preliminary work, in which we investigated the potential of Pu as a soil erosion tracer by sampling additional reference sites and potential erosive sites, along the Liaodong Bay region in northeast China, for Pu...... in cultivated land. The baseline inventories of 239+240Pu and 137Cs were 88.4 and 1688Bqm-2 respectively. Soil erosion rates estimated by 239+240Pu tracing method were consistent with those obtained by the 137Cs method, confirming that Pu is an effective tracer with a similar tracing behavior to that of 137Cs...

  4. Dynamics of Soil Erosion in Xingguo County, China,Determined Using Remote Sensing and GIS

    PAN Jian-Jun; ZHANG Tao-Lin; ZHAO Qi-Guo


    The spatial and temporal dynamics of soil erosion in Xingguo County, Jiangxi Province, China were studied using multi-period remote sensing images and GIS. The results indicated that the soil erosion status of the region has been improving, particularly since the 1980s, with the erosion rate showing an evident decline over the past 30 years. The improvement showed not only in the decline of eroded soil area, but also with the reduction in the extent of erosion. The extent of erosion mainly changed by one level, and the change primarily occurred with the severely or moderately eroded soil types. However, in general, soil erosion was still an overriding problem in the region with some areas becoming more serious, especially those with large quantities of granite.

  5. Erosion-corrosion interactions and their affect on marine and offshore components

    Wood, Robert JK [Surface Engineering and Tribology Group, School of Engineering Sciences, University of Southampton, SO17 1BJ (United Kingdom)


    The operation of modern fluid handling systems demands for low costs, reliability, longevity and no loss of fluid containment. All these can be achieved by minimising the material damage caused by the combined attack of solid particle or cavitation impingement and corrosion. This paper will cover the rationale behind the selection of erosion resistance surfaces for fluid handling equipment and highlight the complexities encountered when these surfaces are exposed to environments which contain sand particles or cavitation in a corrosive medium. The erosion and erosion-corrosion performance of a variety of coatings and bulk surfaces will be discussed using volume loss rate versus sand impact energy maps. Recent research into the erosion-corrosion of polymer coatings, PEO and HVOF aluminium and nickel aluminium bronze coatings will be reviewed. Electrochemical techniques designed to monitor the erosion-corrosion mechanisms and coating integrity will be presented and used to quantify the synergistic terms present when both erosion and corrosion act concurrently. (author)

  6. Standard test method for conducting erosion tests by solid particle impingement using gas jets

    American Society for Testing and Materials. Philadelphia


    1.1 This test method covers the determination of material loss by gas-entrained solid particle impingement erosion with jetnozzle type erosion equipment. This test method may be used in the laboratory to measure the solid particle erosion of different materials and has been used as a screening test for ranking solid particle erosion rates of materials in simulated service environments (1,2 ). Actual erosion service involves particle sizes, velocities, attack angles, environments, and so forth, that will vary over a wide range (3-5). Hence, any single laboratory test may not be sufficient to evaluate expected service performance. This test method describes one well characterized procedure for solid particle impingement erosion measurement for which interlaboratory test results are available. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determi...

  7. In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression Probe

    Polzin, Kurt; Korman, Valentin


    One potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster s operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. There are many different sensors and techniques that have been employed to quantify discharge channel erosion in Hall thrusters. Snapshots of the wear pattern can be obtained at regular shutdown intervals using laser profilometry. Many non-intrusive techniques of varying complexity and sensitivity have been employed to detect the time-varying presence of erosion products in the thruster plume. These include the use quartz crystal microbalances, emission spectroscopy, laser induced flourescence, and cavity ring-down spectroscopy. While these techniques can provide a very accurate picture of the level of eroded material in the thruster plume, it is more difficult to use them to determine the location from which the material was eroded. Furthermore, none of the methods cited provide a true in-situ measure of erosion at the channel surface while

  8. Spatial coincidence of rapid inferred erosion with young metamorphic massifs in the Himalayas

    Finlayson, David P.; Montgomery, David R.; Hallet, Bernard


    A spatially distributed rate-of-erosion index (EI) based on models of bedrock river incision documents a strong spatial correspondence between areas of high erosion potential and young metamorphic massifs as well as structural highs throughout the Himalayas. The EI is derived from slopes and drainage areas calculated from a hydrologically corrected digital elevation model (GTOPO30) combined with precipitation data (IIASA) to generate synthetic annual stream discharges. These variables drive three generalized process models to produce EI maps that, while differing in detail, provide an internally consistent, spatially continuous index of large-scale erosion rates. The large spatial variation in potential erosion rates in the Himalayas suggested by the EI patterns contrasts with the uniform convergence of the Indian subcontinent. If these EI gradients persist through time, they support the emerging view of a positive feedback between localized, rapid erosion and upward advection of lower crust.

  9. A Semi-Empirical Airborne Particle Erosion Model for Polyesteric Matrix Fiberglass Composites

    Valeriu DRAGAN


    Full Text Available The paper deals with the mathematical modeling of the airborne solid particle erosion rate of composite materials, in particular non-oriented fiberglass reinforced polyesteric matrices. Using the mathematical tool of non-linear regression, based on experimental data available in the state of the art, an algebraic equation has been determined to estimate the relative erosion rate of such composites. The formulation is tailored so that it relates to classical erosion models such as Finnie’s, Bitter’s or Tulsa angle dependent model which can be implemented into commercial computational fluid dynamics software. Although the implementation - per se - is not described herein, the model proposed can be useful in estimating the global effect of solid particle erosion on composite materials in this class. Further theoretical developments may add to the model the capacity to evaluate the erosion rate for a wider class of matrices as well as more types of weavings.

  10. Modeling Overland Erosion on Disturbed Rangeland

    Al-Hamdan, O. Z.; Hernandez, M.; Pierson, F. B.; Nearing, M.; Stone, J. J.; Williams, C. J.; Boll, J.; Weltz, M.


    The Rangeland Hydrology and Erosion Model (RHEM) is a new process-based model developed by the USDA-ARS primarily for undisturbed rangeland. Greater sediment detachment rates are usually generated by concentrated flow rather than by sheet flow. Disturbance on rangeland such as fire and tree encroachment can increase overland flow erosion rate by increasing the likelihood of concentrated flow formation on a more erodible surface. In this study, we made advancement to RHEM by developing a new version of the model to predict concentrated flow erosion rate from disturbed rangelands. The model was conceptualized based on observations and results of experimental studies on rangelands disturbed by fire and/or by tree encroachment. A logistic equation was used to partition overland flow into concentrated flow and sheet flow. The equation predicts the probability of overland flow to become concentrated based on slope angle, percentage bare soil, and flow discharge per unit width. Sediment detachment rate from concentrated flow was calculated using soil erodibility of the site and hydraulic parameters of the flow such as flow width and stream power. Soil detachment was assumed to start when concentrated flow starts (i.e. no threshold concept for initiating detachment was used). Width of concentrated flow was determined by flow discharge and slope using an equation which was developed specifically for rangeland. A dynamic erodibility concept was used where concentrated flow erodibility was set to be high at the beginning of the event and then decrease exponentially due to the reduction of availability of disturbance-source-sediment. Initial erodibility was estimated using an empirical parameterization equation as a function of readily available vegetation cover and surface soil texture data. Detachment rate from rain splash and sheet flow was determined by rainfall intensity and sheet flow discharge. A dynamic partial differential sediment continuity equation was used to


    Gorana Todorovic Rampazzo


    Full Text Available Different physical, chemical and biological processes influence the behaviour of organic contaminants in soils. A better understanding of the organic pollutant behaviour in soils would improve the environmental protection. One possible way for better attenuation of the risk of pollution in agriculture can be achieved through ta better-specified pesticide management based on the adaptation of the pesticide type and application rates to the specific environmental characteristics of the area of application. Nowadays, one of the actually most applied herbicide world wide is glyphosate. Glyphosate is highly water soluble and traces have been found in surface and groundwater systems. For a better understanding of the natural influence of erosion processes on glyphosate behaviour and dispersion under heavy rain conditions after application in the field, two erosion simulation experiments were conducted on two different locations in Austria with completely different soil types in September 2008. The results of the experiments showed that under normal practical conditions (e.g. no rainfall is expected immediatly after application, the potential adsorption capacity of the Kirchberg soil (Stagnic Cambisol, with about 16.000 ppm Fe-oxides is confirmed compared to the low adsorption Chernosem soil (about 8.000 ppm pedogenic Fe-oxides.  Considering the enormous difference in the run-off amounts between the two sites Pixendorf and Kirchberg soils it can be concluded how important the soil structural conditions and vegetation type and cover are for the risks of erosion and, as a consequence, pollution of neighbouring waters. In the rainfall experiments under comparable simulation conditions, the amount of run-off was about 10 times higher at Kirchberg, owing to its better infiltration rate, than at the Pixendorf site. Moreover, the total loss of glyphosate (NT+CT through run-off at the Kirchberg site was more than double that at Pixendorf, which confirms the

  12. Post-fire erosion and the effectiveness of emergency rehabilitation treatments over time

    Lee H. MacDonald; Peter R. Robichaud


    High-severity wildfires can increase runoff and erosion rates by one or more orders of magnitude, and these increases can threaten life and property as well as severely degrading water quality and aquatic ecosystems. Each year millions of dollars are spent on emergency postfire rehabilitation treatments to minimize flood runoff and soil erosion. Few data have been...

  13. Erosion processes and prediction with WEPP technology in forests in the Northwestern U.S.

    W. J. Elliot


    In the northwestern U.S., the greatest amounts of forest erosion usually follow infrequent wildfires. Sediment from these fires is gradually routed through the stream system. The forest road network is usually the second greatest source of sediment, generating sediment annually. Erosion rates associated with timber harvest, biomass removal, and prescribed fire are...

  14. Erosion by shallow concentrated flow - experimental model deconstruction

    Seeger, M.; Wirtz, S.; Ali, M.


    the sediment concentration. It is also shown that hydraulic parameters are not able to predict the combination of sediment detachment and transport. Moreover, the relationship between flowing water and sediment transport is shown to be complex, depending on the morphological evolution of the bed. The field experiments confirm these results, and also show that under variable conditions higher transport rates than those predicted by different model concepts are possible. Soil erosion by flowing water is much more complex than reflected in model concepts: they neither reflect the process variability nor the interaction between the different dynamic parameters of flow and soils. We conclude that mechanistic concepts, in which simple or composite predictors define the dynamics of soil erosion, can not succeed in soil erosion modelling.

  15. Assessment of mercury erosion by surface water in Wanshan mercury mining area.

    Dai, ZhiHui; Feng, Xinbin; Zhang, Chao; Shang, Lihai; Qiu, Guangle


    Soil erosion is a main cause of land degradation, and in its accelerated form is also one of the most serious ecological environmental problems. Moreover, there are few studies on migration of mercury (Hg) induced by soil erosion in seriously Hg-polluted districts. This paper selected Wanshan Hg mining area, SW China as the study area. Revised universal soil loss equation (RUSLE) and Geographic information system (GIS) methods were applied to calculate soil and Hg erosion and to classify soil erosion intensity. Our results show that the soil erosion rate can reach up to 600,884tkm(-2)yr(-1). Surfaces associated with very slight and extremely severe erosion include 76.6% of the entire land in Wanshan. Furthermore, the cumulative erosion rates in the area impacted by extremely severe erosion make up 90.5% of the total. On an annual basis, Hg surface erosion load was predicted to be 505kgyr(-1) and the corresponding mean migration flux of Hg was estimated to be 3.02kgkm(-2)yr(-1). The erosion loads of Hg resulting from farmland and meadow soil were 175 and 319kgyr(-1) respectively, which were enhanced compared to other landscape types due to the fact that they are generally located in the steep zones associated with significant reclamation. Contributing to establish a mass balance of Hg in Wanshan Hg mining area, this study supplies a dependable scientific basis for controlling soil and water erosion in the local ecosystems. Land use change is the most effective way for reducing Hg erosion load in Wanshan mining area. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. An experimental study on cavitation erosion-corrosion performance of ANSI 1020 and ANSI 4135 steel

    Wang, Leqin; Qiu, Ning [Institute of Process Equipment, Zhejiang University, Hangzhou (China); Hellmann, Dieter-Heinz [KSB Aktiengesellschaft, Frankenthal (Germany); Zhu, Xiaowen [Zhejiang Keer Pump Stock Co., Ltd, Whenzhou (China)


    Cavitation erosion is quite complex, containing corrosion-erosion interaction effect. High temperature oxidization may be aroused after bubble collapse, accompanied by hot gas contacting with the pump component surface. The analysis of the erosion pits can be an effective way to know the mechanism of cavitation erosion. In present paper, the cavitation erosion resistance of carbon steel (ANSI 1020) and alloy steel (ANSI 4135) were tested in an ultrasonic vibration apparatus. By using energy dispersive X-ray spectroscope and three dimensional laser microscope, the chemical composition around erosion pits and the oxidation film structure were analyzed. By using metallographic microscope and scanning electronic microscope, the metallographic structure of specimens (e.g., carbon steel and alloy steel), the nano structured iron oxide and corresponding influence on specimen's anti-erosion performance were discussed. Based on the comparison between the different tests performed in distilled water and tap water respectively, results can be obtained that erosion rate of carbon steel and alloy steel varies with the component of water which had close correlation to the oxidation effect. Erosion rate of alloy steel 4135 was much lower in distilled water compared to tap water while the difference of carbon steel 1020 was not that large. The remarkable different responses of these two materials had close relationship with oxidation effect. The oxidation effect transferred the original structure of alloy steel surface which had high anti-erosion capability, into newly generated iron oxide structure, which was preferentially to be attacked. The pumping of slightly corrosive fluids frequently leads to erosion-corrosion damage on impellers, and corrosion can further amplify the erosion process.

  17. Biogeochemistry: The soil carbon erosion paradox

    Sanderman, Jonathan; Berhe, Asmeret Asefaw


    Erosion is typically thought to degrade soil resources. However, the redistribution of soil carbon across the landscape, caused by erosion, can actually lead to a substantial sink for atmospheric CO2.

  18. Modelling soil carbon fate under erosion process in vineyard

    Novara, Agata; Scalenghe, Riccardo; Minacapilli, Mario; Maltese, Antonino; Capodici, Fulvio; Borgogno Mondino, Enrico; Gristina, Luciano


    Soil erosion processes in vineyards beyond water runoff and sediment transport have a strong effect on soil organic carbon loss (SOC) and redistribution along the slope. The variation of SOC across the landscape determines a difference in soil fertility and vine productivity. The aim of this research was to study erosion of a Mediterranean vineyard, develop an approach to estimate the SOC loss, correlate the vines vigor with sediment and carbon erosion. The study was carried out in a Sicilian (Italy) vineyard, planted in 2011. Along the slope, six pedons were studied by digging 6 pits up to 60cm depth. Soil was sampled in each pedon every 10cm and SOC was analyzed. Soil erosion, detachment and deposition areas were measured by pole height method. The vigor of vegetation was expressed in term of NDVI (Normalized difference Vegetation Index) derived from a satellite image (RapidEye) acquired at berry pre-veraison stage (July) and characterized by 5 spectral bands in the shortwave region, including a band in the red wavelength (R, 630-685 nm) and in the near infrared (NIR, 760-850 nm) . Results showed that soil erosion, sediments redistribution and SOC across the hill was strongly affected by topographic features, slope and curvature. The erosion rate was 46Mg ha-1 y-1 during the first 6 years since planting. The SOC redistribution was strongly correlated with the detachment or deposition area as highlighted by pole height measurements. The approach developed to estimate the SOC loss showed that during the whole study period the off-farm SOC amounts to 1.6Mg C ha-1. As highlighted by NDVI results, the plant vigor is strong correlated with SOC content and therefore, developing an accurate NDVI approach could be useful to detect the vineyard areas characterized by low fertility due to erosion process.

  19. Wind erosion and vegetation interactions in a desert ecosystem

    Hartman, L.; Epstein, H.; Li, J.; Okin, G.


    Desert grassland degradation is common in many arid environments and is related to increasing shrub coverage, declines in grass species and loss of soil nutrients. Wind erosion may contribute to this degradation by eroding surface soil and depleting soil nutrients. Areas downwind of wind eroded areas may also be affected because wind eroded soils can be trapped beneath shrub canopies, creating "islands of fertility," while grass species are likely abraded or buried by deposition. We have established a manipulative experiment on the Jornada Experimental Range in southern New Mexico in a predominantly grassland habitat (interspersed with some shrub cover) to examine interactions between wind erosion and vegetation structure and function in the Chihuahuan Desert. Each of three experimental blocks includes five 25x50m treatment plots with different levels of vegetation removed (100%, 75%, 50%, 25%, and 0% - control) to stimulate wind erosion. Dust flux and vegetation composition, coverage (lateral and fractional), and spatial distribution are being monitored on and immediately downwind of treated areas. Additionally, individual grasses and shrubs have been selected for monitoring of leaf-level photosynthesis rates on treated and downwind areas to determine impacts of erosion on plant physiology. Results indicate an exponential increase in dust flux with decreasing lateral coverage of vegetation. The spatial distribution of vegetation also appears to be an important factor influencing wind erosion rates. Specifically, there is a positive correlation between the average gap size (space between plants) and dust flux. Leaf level photosynthesis rates were higher for shrubs than grasses, and were lower for grasses downwind of the 100% removal areas compared to the controls. Additionally, a decrease in grass coverage downwind of treated areas suggests that community composition changes are occurring downwind from eroding areas. These results suggest a significant role for

  20. Impacts of shoreline erosion on coastal ecosystems in Songkhla Province

    Nipaporn Chusrinuan


    Full Text Available Songkhla Province is located on the eastern coast of the southern Thai Peninsula, bordering the Gulf of Thailand for approximately 107 km. Most of the basin’s foreshores have been extensively developed for housing, tourism and shrimp farming. The beaches are under deteriorating impacts, often causing sediment transport which leads to an unnaturally high erosion rate. This natural phenomenon is considered to be a critical problem in the coastal areas affected by the hazard of coastal infrastructure and reduced beach esthetics for recreation. In this study, shoreline changes were compared between 1975 and 2006 using aerial photographs and Landsat imageries using Geographic Information System (GIS. The results revealed that 18.5 km2 of the coastal areas were altered during the period. Of this, 17.3 km2 suffered erosion and 1.2 km2were subjected to accretion. The most significant changes occurred between 1975-2006. Shoreline erosion was found at Ban Paktrae, Ranot District, with an average erosion rate of 5.3 m/year, while accretion occurred at Laem Samila, MuangSongkhla District with an average accretion rate of 2.04 m/year. The occurrences of shoreline erosion have contributed to the degradation of coastal soil and water quality, destruction of beach and mangrove forests, loss of human settlements and livelihood.These processes have led to deterioration of the quality of life of the residents. Prevention and mitigation measures to lessen economic and social impacts due to shoreline erosion are discussed.

  1. Mechanics of Interrill Erosion with Wind-Driven Rain (WDR)

    This article provides an evaluation analysis for the performance of the interrill component of the Water Erosion Prediction Project (WEPP) model for Wind-Driven Rain (WDR) events. The interrill delivery rates (Di) were collected in the wind tunnel rainfall simulator facility of the International Cen...

  2. The Erosion of the Enlisted Force: A Study of Attrition


    with a high school diploma (32.5 percent). Homeschooling data indicates an attrition rate of 38.5 percent, or 7 percent less than those with a GED...enjoying robust economy; the number of veterans has declined and they are upset over benefit erosion; and Generation X does not trust large institutions

  3. Sediment contributions from floodplains and legacy sediments to Piedmont streams of Baltimore County, Maryland

    Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen


    Disparity between watershed erosion rates and downstream sediment delivery has remained an important theme in geomorphology for many decades, with the role of floodplains in sediment storage as a common focus. In the Piedmont Province of the eastern USA, upland deforestation and agricultural land use following European settlement led to accumulation of thick packages of overbank sediment in valley bottoms, commonly referred to as legacy deposits. Previous authors have argued that legacy deposits represent a potentially important source of modern sediment loads following remobilization by lateral migration and progressive channel widening. This paper seeks to quantify (1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, (2) proportions of streambank sediment derived from legacy deposits, and (3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont. We calculated measurable gross erosion and deposition rates within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 in Baltimore County, Maryland. We compared stream channel and floodplain morphology from lidar-based digital elevation data collected in 2005 with channel positions recorded on 1:2400 scale topographic maps from 1959-1961 in order to quantify 44-46 years of channel change. Sediment bulk density and particle size distributions were characterized from streambank and channel deposit samples and used for volume to mass conversions and for comparison with other sediment sources. Average annual lateral migration rates ranged from 0.04 to 0.19 m/y, which represented an annual migration of 2.5% (0.9-4.4%) channel width across all study segments, suggesting that channel dimensions may be used as reasonable predictors of bank erosion rates. Gross bank erosion rates varied from 43 to 310 Mg/km/y (median = 114) and were

  4. Soil erosion dynamics response to landscape pattern.

    Ouyang, Wei; Skidmore, Andrew K; Hao, Fanghua; Wang, Tiejun


    Simulating soil erosion variation with a temporal land use database reveals long-term fluctuations in landscape patterns, as well as priority needs for soil erosion conservation. The application of a multi-year land use database in support of a Soil Water Assessment Tool (SWAT) led to an accurate assessment, from 1977 to 2006, of erosion in the upper watershed of the Yellow River. At same time, the impacts of land use and landscape service features on soil erosion load were assessed. A series of supervised land use classifications of Landsat images characterized variations in land use and landscape patterns over three decades. The SWAT database was constructed with soil properties, climate and elevation data. Using water flow and sand density data as parameters, regional soil erosion load was simulated. A numerical statistical model was used to relate soil erosion to land use and landscape. The results indicated that decadal decrease of grassland areas did not pose a significant threat to soil erosion, while the continual increase of bare land, water area and farmland increased soil erosion. Regional landscape variation also had a strong relationship with erosion. Patch level landscape analyses demonstrated that larger water area led to more soil erosion. The patch correlation indicated that contagious grassland patches reduced soil erosion yield. The increased grassland patches led to more patch edges, in turn increasing the sediment transportation from the patch edges. The findings increase understanding of the temporal variation in soil erosion processes, which is the basis for preventing local pollution.

  5. Soil Erosion. LC Science Tracer Bullet.

    Buydos, John F., Comp.

    Soil erosion is the detachment and movement of topsoil or soil material from the upper part of the soil profile. It may occur in the form of rill, gully, sheet, or wind erosion. Agents of erosion may be water, wind, glacial ice, agricultural implements, machinery, and animals. Soil conservation measures require a thorough understanding of the…

  6. Soil Erosion Risk Assessment and Modelling

    Fister, Wolfgang; Kuhn, Nikolaus J.; Heckrath, Goswin


    Soil erosion is a phenomenon with relevance for many research topics in the geosciences. Consequently, PhD students with many different backgrounds are exposed to soil erosion related questions during their research. These students require a compact, but detailed introduction to erosion processes, the risks associated with erosion, but also tools to assess and study erosion related questions ranging from a simple risk assessment to effects of climate change on erosion-related effects on geochemistry on various scales. The PhD course on Soil Erosion Risk Assessment and Modelling offered by the University of Aarhus and conducted jointly with the University of Basel is aimed at graduate students with degrees in the geosciences and a PhD research topic with a link to soil erosion. The course offers a unique introduction to erosion processes, conventional risk assessment and field-truthing of results. This is achieved by combing lectures, mapping, erosion experiments, and GIS-based erosion modelling. A particular mark of the course design is the direct link between the results of each part of the course activities. This ensures the achievement of a holistic understanding of erosion in the environment as a key learning outcome.

  7. Cropping system effects on wind erosion potential

    Wind erosion of soil is a destructive process impacting crop productivity and human health and safety. The mechanics of wind erosion and soil properties that influence erosion are well understood. Less well-studied are the effects that cropping intensity has upon those soil properties. We collected ...

  8. Mapping monthly rainfall erosivity in Europe

    Ballabio, C; Meusburger, K; Klik, A


    Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and...

  9. Inhibition of erosive wear by fluoride varnish

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.


    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush abras

  10. Soil erosion in humid regions: a review

    Daniel J. Holz; Karl W.J. Williard; Pamela J. Edwards; Jon E. Schoonover


    Soil erosion has significant implications for land productivity and surface water quality, as sediment is the leading water pollutant worldwide. Here, erosion processes are defined. The dominant factors influencing soil erosion in humid areas are reviewed, with an emphasis on the roles of precipitation, soil moisture, soil porosity, slope steepness and length,...

  11. Inhibition of erosive wear by fluoride varnish

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.


    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush

  12. Predicting Postfire Hillslope Erosion with a Web-based Probabilistic Model

    Robichaud, P. R.; Elliot, W. J.; Pierson, F. B.; Hall, D. E.; Moffet, C. A.


    Modeling erosion after major disturbances, such as wildfire, has major challenges that need to be overcome. Fire-induced changes include increased erosion due to loss of the protective litter and duff, loss of soil water storage, and in some cases, creation of water repellent soil conditions. These conditions increase the potential for flooding, and sedimentation, which are of special concern to people who live and mange resources in the areas adjacent to burned areas. A web-based Erosion Risk Management Tool (ERMiT), has been developed to predict surface erosion from postfire hillslopes and to evaluate the potential effectiveness of various erosion mitigation practices. The model uses a probabilistic approach that incorporates variability in weather, soil properties, and burn severity for forests, rangeland, and chaparral hillslopes. The Water Erosion Prediction Project (WEPP) is the erosion prediction engine used in a Monte Carlo simulation mode to provide event-based erosion rate probabilities. The one-page custom interface is targeted for hydrologists and soil scientists. The interface allows users to select climate, soil texture, burn severity, and hillslope topography. For a given hillslope, the model uses a single 100-year run to obtain weather variability and then twenty 5- to 10-year runs to incorporate soil property, cover, and spatial burn severity variability. The output, in both tabular and graphical form, relates the probability of soil erosion exceeding a given amount in each of the first five years following the fire. Event statistics are provided to show the magnitude and rainfall intensity of the storms used to predict erosion rates. ERMiT also allows users to compare the effects of various mitigation treatments (mulches, seeding, and barrier treatments such as contour-felled logs or straw wattles) on the erosion rate probability. Data from rainfall simulation and concentrated flow (rill) techniques were used to parameterize ERMiT for these varied

  13. Forest harvesting influence on slope erosion in Baikal Basin Mountains

    Onuchin, A. A.; Borisov, A. N.; Burenina, T. A.


    Post-logging recovery of forest water protection and erosion prevention functions can occur different ways on slopes and in big river catchments. While erosion decreases several times during only three to five years after logging on slopes, as compared to its immediate post-logging rate, water silt load in big rivers can remain high for decades after forest logging in their catchments. Among other factors, this can be attributable to erosion of timber transportation roads and skidding trails, which become extremely eroded 10-15 years following forest logging. One should not underestimate a probable sediment load increase resulting from post-logging channel runoff changes. Disregarding this increase leads to contradictory conclusions about post-logging recovery of forest water protecting capability. Investigating this issue requires to clearly determine the type of the forest site of interest (a certain slope, an elementary or a complex catchments) and to consider the experience gained so far in estimating erosion rate changes depending on changing forest areas of continents. Therefore, hierarchical river catchments ranking should be recognized effective and useful for forest hydrology. This approach will allow systematizing the existing information and facilitating the development of fruitful analysis of water protection and erosion prevention functions of forest in areas of different ranks. This study used an approach that enabled a single-model description of the rate of soil erosion previously estimated by different models for areas of various ranks, from a micro slope to elementary catchments. An elementary catchments is defined as the smallest drainage area characterized by uniform surface, ground, and vegetation structures and having a single well-pronounced channel, with hydro network being practically absent. Using runoff slope length as the argument and introducing a dummy variable that describes specific investigation methodologies ensured high generality

  14. Transience and Glacial Erosion in South Central Alaska

    Valentino, J.; Spotila, J. A.; Owen, L. A.; Buscher, J.


    It is documented that a glacial presence in active orogenic belts undergoing rapid rock uplift will increase erosion rates often matching rates of rock uplift. Glacial erosion seems to have shaped the mass balance of numerous mountain ranges and tectonic settings, but the Kenai Peninsula and Chugach Mountains of south central Alaska do not conform to this pattern. The Kenai Peninsula is an uplifted forearc forming above the Aleutian subduction zone and the Chugach Mountains are the continuation of the orogenic belt around Prince William Sound. This mountain belt is comprised of accreted Mesozoic island arcs, which were sequentially metamorphosed from the cretaceous through the Tertiary. Geomorphic analysis and past studies, including Buscher et al. (2008) and Arkle et al. (2013), show that the Chugach Mountains and Kenai Peninsula are similar to the Saint Elias Mountains in the Yakutat collision zone with regards to topographic ruggedness. The region is dominated by alpine glaciers, ice fields, and extensive valley glaciers that are actively eroding the topography through headwall erosion and valley glacier down cutting. Despite this, there is a low background long term erosion rate of <0.1-0.2 mm/yr (Buscher et al, 2008). This suggests a transient landscape that has not yet fully adjusted to onset of erosive glacial conditions. Through the use of four dating techniques spanning different timescales, we aim to quantify erosion rates in the Kenai and Chugach Mountains. (U-TH)/He thermochronometry (106-7 yr), He/He thermochronometry (105-6 yr), OSL thermochronometry (105-6 yr), and 10Be and 36CL cosmogenic dating (103-4 yr), are being used in conjunction to test if short-term rates exceed long-term rates, thereby indicating a transient response to late Cenozoic glaciations. This analysis will also address how landscapes respond to the onset of glacial conditions and subsequent climate fluctuations. The history of exhumation and erosion will also characterize the role

  15. Erosion and sedimentation chronology of three watersheds in Maryland

    Segovia, A.V.; Foss, J.E.; Fanning, D.; Demas, G.


    Three small watersheds located in the Piedmont and Eastern Shore of Maryland were studied. The investigation included descriptions of residual and depositional soils. Buried soil horizons were dated by Carbon-14. In addition, phytoliths were studied to identify the vegetation contemporaneous with the deposition of soil levels. The presence of vertical successions of soil profiles indicate that rates of erosion and redeposition of soils varied in the last thousand years. Noticeable soil horizons were formed during long periods of slow erosion and little deposition, following short intervals of fast erosion and redeposition. Soil erosion was strong after the European contact, as a result of deforestation and intensive agricultural use of the land. The presence of corn phytoliths in this part of the section, the scarcity of grass phytolith and the presence of diatom tests in the soils of a closed depression suggest that erosion was caused by slash-burn methods of agriculture. Thus, the last two episodes of accumulation are ascribed to nonclimatic causes in contrast to previous episodes during the Holocene which were probably caused by climatic fluctuations.

  16. Numerical Analysis of Erosion Caused by Biomimetic Axial Fan Blade

    Jun-Qiu Zhang


    Full Text Available Damage caused by erosion has been reported in several industries for a wide range of situations. In the present work, a new method is presented to improve the erosion resistance of machine components by biomimetic method. A numerical investigation of solid particle erosion in the standard and biomimetic configuration blade of axial fan is presented. The analysis consists in the application of the discrete phase model, for modeling the solid particles flow, and the Eulerian conservation equations to the continuous phase. The numerical study employs computational fluid dynamics (CFD software, based on a finite volume method. User-defined function was used to define wear equation. Gas/solid flow axial fan was simulated to calculate the erosion rate of the particles on the fan blades and comparatively analyzed the erosive wear of the smooth surface, the groove-shaped, and convex hull-shaped biomimetic surface axial flow fan blade. The results show that the groove-shaped biomimetic blade antierosion ability is better than that of the other two fan blades. Thoroughly analyze of antierosion mechanism of the biomimetic blade from many factors including the flow velocity contours and flow path lines, impact velocity, impact angle, particle trajectories, and the number of collisions.

  17. Simulating river meandering processes using stochastic bank erosion coefficient

    Posner, Ari J.; Duan, Jennifer G.


    This study first compares the first order analytical solutions for flow field by Ikeda et. al. (1981) and Johanesson and Parker (1989b). Ikeda et. al.'s (1981) linear model of bank erosion was implemented to predict the rate of bank erosion in which the bank erosion coefficient is treated as a stochastic variable that varies with physical properties of the bank (e.g. cohesiveness, stratigraphy, vegetation density). The developed model was used to predict the evolution of meandering planforms. Then, the modeling results were analyzed and compared to the observed data. Because the migration of meandering channels consists of downstream translation, lateral expansion, and downstream or upstream rotations, several measures are formulated to determine which of the resulting planform is closest to the experimental measured one. Results from the deterministic model highly depend on the calibrated erosion coefficient. Because field measurements are always limited, the stochastic model yielded more realistic predictions of meandering planform evolutions. Because the coefficient of bank erosion is a random variable, the meandering planform evolution is a stochastic process that can only be accurately predicted by a stochastic model.

  18. Evaluating the Swelling, Erosion and Compaction Properties of Cellulose Ethers.

    Ghori, Muhammad U; Grover, Liam M; Asare-Addo, Kofi; Smith, Alan M; Conway, Barbara R


    Swelling, erosion, deformation and consolidation properties can affect the performance of cellulose ethers, the most commonly used matrix former in hydrophilic sustained tablet formulations. The present study was designed to comparatively evaluate the swelling, erosion, compression, compaction and relaxation properties of the cellulose ethers in a comprehensive study using standardised conditions. The interrelationship between various compressional models and the inherent deformation and consolidation properties of the polymers on the derived swelling and erosion parameters are consolidated. The impact of swelling (Kw) on erosion rates (KE) and the inter-relationship between Heckel and Kawakita plasticity constants was also investigated. It is evident from the findings that the increases in both substitution and polymer chain length led to higher Kw, but a lower KE; this was also true for all particle size fractions regardless of polymer grade. Smaller particle size and high substitution levels tend to increase the relative density of the matrix but reduce porosity, yield pressure (Py), Kawakita plasticity parameter (b(-1)) and elastic relaxation. Both KW vs KE (R(2) = 0.949-0.980) and Py vs b(-1) correlations (R(2) = 0.820-0.934) were reasonably linear with regards to increasing hydroxypropyl substitution and molecular size. Hence, it can be concluded that the combined knowledge of swelling and erosion kinetics in tandem with the in and out-of-die compression findings can be used to select a specific polymer grade and further to develop and optimise formulations for oral controlled drug delivery applications.

  19. The significance of the erosion-induced terrestrial carbonsink

    Berhe, A.A.; Harte, J.; Harden, J.W.; Torn, M.S.


    Estimating carbon (C) balance in erosional and depositionallandscapes is complicated by the effects of soil redistribution on bothnet primary productivity (NPP) and decomposition. Recent studies arecontradictory as to whether soil erosion does or does not constitute a Csink. Here we clarify the conceptual basis for how erosion can constitutea C sink. Specifically, the criterion for an erosional C sink is thatdynamic replacement of eroded C, and reduced decomposition rates indepositional sites, must together more than compensate for erosionallosses. This criterion is in fact met in many erosional settings, andthus erosion and deposition can make a net positive contribution to Csequestration. We show that, in a cultivated Mississippi watershed and acoastal California watershed, the magnitude of the erosion-induced C sinkis likely to be on the order of 1 percent of NPP and 16 percent of erodedC. Although soil erosion has serious environmental impacts, the annualerosion-induced C sink offsets up to 10 percent of the global fossil fuelemissions of carbon dioxide for 2005.

  20. Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration

    Stacy, E. M.; Hart, S. C.; Hunsaker, C. T.; Johnson, D. W.; Berhe, A. A.


    Lateral movement of organic matter (OM) due to erosion is now considered an important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet most published studies on the role of erosion focus on agricultural or grassland ecosystems. To date, little information is available on the rate and nature of OM eroded from forest ecosystems. We present annual sediment composition and yield, for water years 2005-2011, from eight catchments in the southern part of the Sierra Nevada, California. Sediment was compared to soil at three different landform positions from the source slopes to determine if there is selective transport of organic matter or different mineral particle size classes. Sediment export varied from 0.4 to 177 kg ha-1, while export of C in sediment was between 0.025 and 4.2 kg C ha-1 and export of N in sediment was between 0.001 and 0.04 kg N ha-1. Sediment yield and composition showed high interannual variation. In our study catchments, erosion laterally mobilized OM-rich litter material and topsoil, some of which enters streams owing to the catchment topography where steep slopes border stream channels. Annual lateral sediment export was positively and strongly correlated with stream discharge, while C and N concentrations were both negatively correlated with stream discharge; hence, C : N ratios were not strongly correlated to sediment yield. Our results suggest that stream discharge, more than sediment source, is a primary factor controlling the magnitude of C and N export from upland forest catchments. The OM-rich nature of eroded sediment raises important questions about the fate of the eroded OM. If a large fraction of the soil organic matter (SOM) eroded from forest ecosystems is lost during transport or after deposition, the contribution of forest ecosystems to the erosion-induced C sink is likely to be small (compared to croplands and grasslands).




    Sedimentation from soil erosion is a critical reservoir watershed management issue. Due to the difficulty of field investigations, empirical formulas are commonly used to estimate the soil erosion rate. However, these estimations are often far from accurate. An effective alternative to estimating soil erosion is to analyze the spatial variation of 137Cs inventory in the soil. 137Cs can be adsorbed by the soil and is widely assumed to change its distribution only when disturbed by rainfall and human activities. Thus, 137Cs distributed in soils can be a useful environmental tracer to estimate soil erosion. In this study, the net soil loss estimate is 108,346 t/yr and the gross erosion and net erosion rates are 10.1 and 9 t/ha yr respectively. The sediment delivery ratio is therefore estimated to be 0.9 based on the two erosion rates. Because of the steep hillsides in the watershed, only 10% of the sediment yield stayed in the deposition sites and 90% was transported to the river as the sediment output. Soil erosion estimates from spatial variations of the 137Cs activity in the Baishi river watershed showed satisfactory accuracy when compared to sediment yield data. Using soil 137Cs concentrations is therefore a feasible method for estimating soil loss or deposition in Taiwan. Data sampling, analysis and result of this approach are given in this paper.

  2. A comparison and measurement standardisation of four in situ devices for determining the erosion shear stress of intertidal sediments

    Tolhurst, T. J.; Black, K. S.; Paterson, D. M.; Mitchener, H. J.; Termaat, G. R.; Shayler, S. A.


    Predictive modelling of estuarine sediment erosion and transport requires a description of the erosional properties of the bed. The two main variables of interest are the critical erosion shear stress ( τcr) and the erosion rate ( ɛ). A number of different erosion devices exist to measure the erosion shear stress of intertidal sediments in situ. These devices apply different strategies to induce and measure erosion, and the area over which erosion is integrated varies greatly. In addition, the definition of erosion threshold differs between workers. This makes comparison of data collected from different devices very difficult. Four different types of erosion device, Microcosm system, In Situ Erosion Flume (ISEF), SedErode and cohesive strength meter (CSM) were used during the July 1997 EC INTRMUD Humber estuary (UK) field campaign. These devices were deployed simultaneously on the Skeffling intertidal mudflat to allow comparison of the data generated. This involved the comparison of suspended particulate matter (SPM) time series, the nature of the applied shear stress ( τo) and the area over which erosion was integrated. The initial goal was to develop a standard analysis procedure for comparison of stability measurements. The erosion threshold calculated from area normalised suspended particulate matter (SPM n) time series was relatively comparable between devices especially between the Microcosm and ISEF. However, device size and natural sediment spatial heterogeneity affected the results. The erosion rate varied by orders of magnitude between the different devices. This variation seemed to be due to the considerable differences in device deployment time. In conclusion, SPM data from different devices are broadly comparable, whilst erosion rates are only comparable if the shear stress steps are of the same duration.

  3. Ash particle erosion on steam boiler convective section

    Meuronen, V.


    , diameter loss and wall thickness loss measurements of the test sleeves were taken. Erosion wear as a function of flow conditions, tube material and tube construction was analysed by single-variable linear regression analysis. In developing the erosion wear calculation equations, multi-variable linear regression analysis was used. In the staggered tube bank, erosion wear had a maximum value in a tube row 2 and a local maximum in row 5. In rows 3, 4 and 6, the erosion rate was low. On the other hand, in the in-line tube bank the minimum erosion rate occurred in tube row 2 and in further rows the erosion had an increasing value, so that in a six row tube bank, the maximum value occurred in row 6. (orig.) 37 refs.

  4. Plant biodiversity effects in reducing fluvial erosion are limited to low species richness.

    Allen, Daniel C; Cardinale, Bradley J; Wynn-Thompson, Theresa


    It has been proposed that plant biodiversity may increase the erosion resistance of soils, yet direct evidence for any such relationship is lacking. We conducted a mesocosm experiment with eight species of riparian herbaceous plants, and found evidence that plant biodiversity significantly reduced fluvial erosion rates, with the eight-species polyculture decreasing erosion by 23% relative to monocultures. Species richness effects were largest at low levels of species richness, with little increase between four and eight species. Our results suggest that plant biodiversity reduced erosion rates indirectly through positive effects on root length and number of root tips, and that interactions between legumes and non-legumes were particularly important in producing biodiversity effects. Presumably, legumes increased root production of non-legumes by increasing soil nitrogen availability due to their ability to fix atmospheric nitrogen. Our data suggest that a restoration project using species from different functional groups might provide the best insurance to maintain long-term erosion resistance.

  5. The study on dynamic characteristics of soil erosion in Yuyao City of Zhejiang Province

    Zou, Yefeng; Zhang, Jinjuan; Li, Gang; Shen, Zhaowei; Lu, Fangchun; Zhou, Xijiong


    Taking Yuyao city as the study area, using GIS technology to establish a database of soil ero-sion. Based on the database, soil erosion in the study area was Evaluated and the dynamic variation of soil erosion intensity was analyzed. The results showed that during the past ten years from 2004-2014, the overall situation of soil erosion in Yuyao city had improved, and the total area of soil erosion decreased year by year, with an average annual reduction rate of 3.3199 km2/a. But high intensity erosion area increased due to mining, quarrying, road building caused by. And some area had the evil trend, however the area was not large. In the process of the dynamic transition of erosion, the weakening area of erosion mainly came from the transition of slightly eroded area to non-apparently eroded area. the exacerbating erosion area mainly came from the transition of non-apparently eroded area to the slightly and moderately eroded area.

  6. Dental erosion among South Brazilian adolescents: A 2.5-year longitudinal study.

    Brusius, C D; Alves, L S; Susin, C; Maltz, M


    This population-based longitudinal study investigated the incidence, progression and risk factors for dental erosion among South Brazilian adolescents. Eight hundred and one schoolchildren attending 42 public and private schools were clinically examined at 12 years of age; clinical examinations were repeated after 2.5 years (SD=0.3). After tooth cleaning and drying, permanent incisors and first molars were classified using the Basic Erosive Wear Examination (BEWE) scoring criteria. Questionnaires were used to collect data on socio-demographic characteristics, dietary habits, toothbrushing frequency and general health. Poisson regression analysis was used to assess the association between dental erosion incidence and explanatory variables, with adjusted incidence risk ratios (IRR) and 95% CI estimated. Among those who did not have dental erosion at baseline, 49 of 680 schoolchildren (7.1%; 95% CI=5.2-9.1) developed erosive lesions over the follow-up period. Among schoolchildren who had dental erosion at baseline, 31 of 121 (25.4%; 95% CI=17.6-33.3) had new or more severe lesions. Boys were more likely to develop dental erosion than girls (IRR=1.88; 95% CI=1.06-3.32). A moderate incidence of dental erosion was observed among South Brazilian adolescents, with boys being at higher risk. The high progression rate of 25% observed here is very concerning, and it should be taken in consideration when designing preventive strategies for dental erosion. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. How well does the Post-fire Erosion Risk Management Tool (ERMiT) really work?

    Robichaud, Peter; Elliot, William; Lewis, Sarah; Miller, Mary Ellen


    The decision of where, when, and how to apply the most effective postfire erosion mitigation treatments requires land managers to assess the risk of damaging runoff and erosion events occurring after a fire. The Erosion Risk Management Tool (ERMiT) was developed to assist post fire assessment teams identify high erosion risk areas and effectiveness of various mitigation treatments to reduce that risk. ERMiT is a web-based application that uses the Water Erosion Prediction Project (WEPP) technology to estimate erosion, in probabilistic terms, on burned and recovering forest, range, and chaparral lands with and without the application of mitigation treatments. User inputs are processed by ERMiT to combine rain event variability with spatial and temporal variabilities of hillslope burn severity and soil properties which are then used as WEPP inputs. Since 2007, the model has been used in making hundreds of land management decisions in the US and elsewhere. We use eight published field study sites in the Western US to compare ERMiT predictions to observed hillslope erosion rates. Most sites experience only a few rainfall events that produced runoff and sediment except for a California site with a Mediterranean climate. When hillslope erosion occurred, significant correlations occurred between the observed hillslope erosion and those predicted by ERMiT. Significant correlation occurred for most mitigation treatments as well as the five recovery years. These model validation results suggest reasonable estimates of probabilistic post-fire hillslope sediment delivery when compared to observation.

  8. Soil erosion and land degradation in the Highlands of Jordan

    Khresat, Saeb


    The Highlands of Jordan has a Mediterranean type of climate characterized by hot dry summers and cold wet winters. Unsustainable land use practices, recurrent droughts and climate change are the main causes of land degradation in the Highlands area of Jordan. Unsustainable land use practices include improper plowing, inappropriate rotations, inadequate or inexistent management of plant residues, overgrazing of natural vegetation, forest cutting, land fragmentation and over-pumping of groundwater. In addition, Jordan's rapid population growth (2.8% per year) is exerting considerable pressure upon its limited arable land through uncontrolled and random urbanization activities. Water erosion is the most widespread Land degradation type in the country. It greatly increases on slopes where the vegetation cover is (seasonally) reduced. It is further aggravated by a loss of soil structure and reduced infiltration rates. Wind erosion occurs most frequently in the arid and semi-arid portions of the southern Highlands, especially in areas with sandy or loamy soils. Rangeland degradation is the second most widespread land degradation type that is driven by overgrazing. The impact of overgrazing on the vegetation is evident from the excessive uprooting of the green matter (grass and bushes), leading to reduced seeding, reduced regeneration, and the consequent loss of plant cover which make the soil more susceptible to water and wind erosion. It is estimated that about 41 percent of Jordan's total land area is characterized as degraded of which 22 percent of the total land mass is classified as moderately degraded and agricultural productivity is greatly reduced. Observed aspects of land degradation include the recession of forest areas, high rate of erosion by water (formation of rills and gullies), expansion of urbanized area, reduction in soil organic matter and soil structure deterioration. Implementation of soil erosion control measures such as contour cultivation

  9. Splash erosion. A bibliometric Review

    Fernández Raga, M. B.


    Ellison (1944) developed the splash board as a system for measuring splash erosion that was both cheap and reliable. Bollinne (1975), Morgan (1978, 1981). Mutchler (1967) described another different type of splash detectors according to whether they were passive or could register data. In the study mentioned above these authors included bottles, funnels, glasses, photography, markers. After that several devices has been made up like the splash sampler (Leguedois et al., 2005), soil tray (Van Dijk et al., 2002), splash funnel (Terry, 1989) and several rain cups (Fernandez-Raga et al., 2010; Molina and Llinares, 1996; Torri et al., 1987). Splash erosion research has materialized in the form of a number of papers published in international journals. The database of bibliographic references employed has been one of the most prestigious ones: theWeb of Science (ISI). The search was carried out on January 27th 2012. Among the 3x10^8 scholarly documents included in the Science Citation Index Expanded (SCI-EXPANDED) 1899 to present , the searching engine located 439 containing the word "splash erosion*", where the asterisk acts as a wildcard for any letter or group of letters. Of these, 383 were classified as articles, 87 as proceeding papers, 5 as editorial material, 2 as notes and 1 as correction. These documents have been published in 163 different journals, although four are particularly recurrent: Earth surface processes and Landforms, Catena, Soil Science Society of America Journal and Hydrological processes, with 41, 35, 35 and 26 published documents respectively. A geographic analysis of these articles has been carried out in an attempt to determine in what parts of the world research projects were making use of splash erosion. The results are that anglo-saxon countries, as USA, England and Australia dominate, particularly USA, with 130 articles. China and Japan are large communities of researches too, and some Central European countries as Belgium, France Germany

  10. The Effects of Land Uses on Purplish Soil Erosion in Hilly Area of Sichuan Province, China

    LIU Gangcai; ZHANG Jianhui; TIAN Guanglong; WEI Chaofu


    In order to evaluate the soil erosion rate for different land uses and make recommendations on land-use alternatives for erosion control in hilly and mountain areas on a Purplish soil (Regosols in FAO taxonomy), experimental data were obtained from three continuously monitored sites located at Yanting,Nanbu and Pengxi of Sichuan province. The data showed that the rank of erosion rate is farmland >unfenced grassland > fenced grassland > forestland.The erosion rate of farmland was more than 3 times higher than that of forestland and fenced grassland,indicating that restricting human activity is crucial for over-erosion. The erodibility was higher at the initial period of rainy season for all the three types of land use. The erosion rates of fenced grassland and mature afforestation land were not proportional to rainfall intensity because these land uses changed impact energy of the rainfall. This research showed that restricting human activity, intensifying the management of initial period of rainy season, and increasing the cover rate of land surface are the three major measures for soil erosion prevention. It is recommended that farmers should cease cultivation on farmland at the top of hills and steep slope land return those lands back to grassland or forestland.

  11. Optimizing land use pattern to reduce soil erosion

    Reza Sokouti


    Full Text Available Soil erosion hazard is one of the main problems can affect ecological balance in watersheds. This study aimed to determine the optimal use of land to reduce erosion and increase the resident's income of Qushchi watershed in West Azerbaijan province, Iran. Income and expenses for the current land uses were calculated with field studies. Damages resulting from the soil erosion were estimated by soil depth equal to the specified land uses. For three different options including the current status of land uses without and with land management, and the standard status of land uses, multi-objective linear programming model was established by LINGO software. Then the optimization problem of the land use was solved by simplex method. Finally, the best option of land use was determined by comparing erosion rate and its cost in each scenario. Then the circumstances and the recommended conditions were compared. The results indicated that the current surface area of current land uses is not suitable to reduce erosion and increase income of residents and should change in the optimum conditions. At the optimum level, there should change horticulture area of 408 to 507 (ha, irrigated land area of 169 to 136 (ha and dry farming of 636 to 570 (ha, while conversion of rangeland area not indispensable. In addition, the results showed that in case of the optimization of land use, soil erosion and the profitability of the whole area will decrease 0.75% and increase 3.68%, respectively. In case of land management practices, soil erosion will decrease 42.27% and the profitability increase 21.39% while in the standard conditions, soil erosion will decrease 60.95% and profitability will increase 24.20%. The results of the sensitivity analysis showed that the changes in the horticulture and range land areas have the greatest impact on the increasing profitability and reducing soil erosion of Qushchi watershed. So, it is recommended using Education and Extension to promote

  12. Solid-particle erosion in the tube end of the tube sheet of a shell-and-tube heat exchanger

    Habib, M. A.; Badr, H. M.; Said, S. A. M.; Ben-Mansour, R.; Al-Anizi, S. S.


    Erosion is one of the major problems in many industrial processes, and in particular, in heat exchangers. The effects of flow velocity and sand particle size on the rate of erosion in a typical shell-and-tube heat exchanger were investigated numerically using the Lagrangian particle-tracking method. Erosion and penetration rates were obtained for sand particles of diameters ranging from 10 to 500 μm and for inlet flow velocities ranging from 0.197 to 2.95 m/s. A flow visualization experiment was conducted with the objective of verifying the accuracy of the continuous phase calculation procedure. Comparison with available experimental data of penetration rates was also conducted. These comparisons resulted in a good agreement. The results show that the location and number of eroded tubes depend mainly on the particle size and velocity magnitude at the header inlet. The rate of erosion depends exponentially on the velocity. The particle size shows negligible effect on the erosion rate at high velocity values and the large-size particles show less erosion rates compared to the small-size particles at low values of inlet flow velocities. The results indicated that the erosion and penetration rates are insignificant at the lower end of the velocity range. However, these rates were found to increase continuously with the increase of the inlet flow velocity for all particle sizes. The particle size creating the highest erosion rate was found to depend on the flow velocity range.

  13. MR imaging of erosions in interphalangeal joint osteoarthritis: is all osteoarthritis erosive?

    Grainger, A.J. [Leeds Teaching Hospitals, Department of Radiology, Leeds (United Kingdom); Musculoskeletal Centre, Chapel Allerton Hospital, Department of Radiology, Leeds (United Kingdom); Farrant, J.M.; O' Connor, P.J. [Leeds Teaching Hospitals, Department of Radiology, Leeds (United Kingdom); Tan, A.L.; Emery, P. [Leeds Teaching Hospitals and Leeds University, Department of Rheumatology, Leeds (United Kingdom); Tanner, S. [Leeds University, Department of Medical Physics, Leeds (United Kingdom); McGonagle, D. [Leeds Teaching Hospitals and Leeds University, Department of Rheumatology, Leeds (United Kingdom); Calderdale Royal Hospital, Halifax (United Kingdom)


    Erosive osteoarthritis is usually considered as an inflammatory subset of osteoarthritis (OA). However, an inflammatory component is now recognised in all subsets of OA, so this subgroup of erosive or inflammatory OA is more difficult to conceptualise. The aim of this study was to compare routine CR and MRI to investigate erosion numbers and morphology to determine whether hand OA in general is a more erosive disease than previously recognised. Fifteen patients with clinical (OA) of the small joints of the hand underwent MRI of one of the affected proximal interphalangeal (PIP) or distal interphalangeal (DIP) joints. Conventional radiographs (CR) of the hand were also obtained. The MR images were reviewed by two observers for the presence of central and marginal erosions. The site and morphology of any erosions was recorded. CR images of the same hand joint were scored independently for central and marginal erosions by the same observers. There was 100% agreement between the observers for scoring erosions on CR. Agreement for the MRI scores was also excellent (kappa = 0.84). MRI detected 37 erosions, of which only 9 were seen on CR. The increase in sensitivity using MRI was much greater for marginal erosions (1 detected on CR, 19 on MRI) than for central erosions (8 on CR, 18 on MRI). Using MRI 80% of joints examined showed 1 or more erosions compared with 40% using CR. If only marginal erosions were considered 80% of joints were still considered erosive by MRI criteria, but only 1 showed evidence of erosion on CR. Morphologically central erosions appeared to represent areas of subchondral collapse and pressure atrophy. In contrast, marginal erosions resembled those seen in inflammatory arthritides. Erosions, and particularly marginal erosions typical of those seen in inflammatory arthritis, are a more common feature of small joint OA than conventional radiographs have previously indicated. (orig.)

  14. The delicate balance between soil production and erosion, and its role on landscape evolution

    Dosseto, A., E-mail: [GeoQuEST Research Centre, School of Earth and Environmental Sciences, University of Wollongong. Wollongong, NSW (Australia); Buss, Heather [US Geological Survey. Menlo Park, CA (United States); Suresh, P.O. [Department of Environment and Geography, Macquarie University. North Ryde, NSW (Australia)


    Highlights: > The uranium-series isotope composition of regolith material can be used to determine the soil residence time. > Soil residence times up to 30 and 90 kyr are calculated for Frogs Hollow and Bisley, respectively. > Production rates are relatively similar for granitic and shale lithologies, but much higher over volcanic parent rock. > Soil production matches erosion in soil-mantled landscapes, demonstrating quantitatively that this type of landscape results from a balance between these two processes > Soil production is up to two orders of magnitude slower than erosion in cultivated areas. - Abstract: The diversity in landscapes at the Earth's surface is the result, amongst other things, of the balance (or imbalance) between soil production and erosion. While erosion rates are well constrained, it is only recently that we have been able to quantify rates of soil production. Uranium-series isotopes have been useful to provide such estimates independently of erosion rates. In this study, new U-series isotope are presented data from weathering profiles developed over andesitic parent rock in Puerto Rico, and granitic bedrock in southeastern Australia. The site in Australia is located on a highland plateau, neighbouring a retreating escarpment where soil production rates between 10 and 50 mm/kyr have been determined. The results show that production rates are invariant in these two regions of Australia with values between 15 and 25 mm/kyr for the new site. Andesitic soils show much faster rates, about 200 mm/kyr. Overall, soil production rates determined with U-series isotopes range between 10 and 200 mm/kyr. This is comparable to erosion rates in soil-mantled landscapes, but faster than erosion in cratonic areas and slower than in alpine regions and cultivated areas. This suggests that soil-mantled landscapes maintain soil because they can: there is a balance between production and erosion. Similarly, thick weathering profiles develop in cratonic areas

  15. When erosion ruins the chronology

    Wolters, Steffen; Enters, Dirk; Blume, Katharina; Lücke, Andreas


    Human land-use has considerably shaped the landscape of north-western Germany over the past millennia. Deforestation and agriculture created a predominantly open scenery preserved until today with only a few remnants of former landscape elements such as woodlands, peat bogs, heath lands and lakes. Here we present a multi-proxy approach including sedimentological and geochemical parameters (e. g. element concentrations and stable isotopes) as well as biological proxies (pollen, macro fossils and diatoms) combined with an archaeological site analysis to investigate the effects of prehistoric land-use on lake systems and their catchment areas with a special focus on changes of the water quality, e. g. eutrophication and acidification and its natural regeneration during phases of weaker land-use impact. The study reveals a millenia-long history of erosion processes caused by successive selective woodland clearances starting in Neolithic Times. The geochemical evidence of soil erosion is recorded by distinct peaks of the terrigenic elements K and Ti. However, due to (1) the low sensitivy of the XRF scanner for Si and (2) the prevalence of diatom related biogenic silicon XRF-scanning of highly organic lake sediments fails to reflect the actual sand input caused by erosion. Particularly single quartz grains are not detected in the organic sediment matrix. Therefore we make successful use of mineral grain analysis which previously has only been applied to record aeolian input in bogs. K and Ti concentrations are not correlated with the content of mineral grains which suggest two different erosion processes. Our efforts to construct robust age-depth relationships based on AMS 14C-dates of terrestrial plant macrofossils reveal a specific dating issue of northwest German lakes. Especially in younger sediments we observe 14C-dates which are on the one hand too old and on the other hand among themselves roughly contemporaneous. We explain this feature with the extensive bog


    Peiqing XIAO; Fenli ZHENG; Wenyi YAO


    Soil erosion at the hilly-gully region of the Loess Plateau has obvious vertical erosion zonation from watershed boundary to gully edge. Meanwhile, upslope runoff and sediment have a significant impact on the downslope erosion process. But due to the limits of research methods, there is not much data available to quantify the effects of upslope runoff and sediment on the downslope erosion process under different conditions. The objective of this study was to quantify the effects of upslope runoff and sediment on the downslope erosion process using a dual-box system with a 15° gradient consisting of a 2 m-long feeder box and a 5 m-long test box under different runoff rates and sediment concentrations in upslope runoff, rainfall intensities and soil surface conditions. The results showed that the sediment regime was detachment-transport dominant at steep hillslopes. The net sediment delivery S caused by upslope runoff was controlled by sediment concentration in upslope runoff, especially by interaction of the rainfall intensity, runoff rate, surface condition and dominant erosion process. The net sediment delivery S accounted for the total sediment delivery Sft at downslope 31.7% to 97.3% and 27.8 to 89.7% for both loose and compact surface treatments, respectively. Rainfall intensity, slope gradient, surface condition, and rill erosion development had important influences on the downslope erosion process.

  17. Soil erosion in sloping vineyards assessed by using botanical indicators and sediment collectors in the Ruwer-Mosel valley

    Rodrigo Comino, J.; Quiquerez, A.; Follain, S.; Raclot, D.; Bissonnais, Le Y.; Casalí, J.; Giménez, R.; Cerdà, A.; Keesstra, S.D.; Brevik, E.C.; Pereira, P.; Senciales, J.M.; Seeger, M.; Ruiz Sinoga, J.D.; Ries, J.B.


    Steep slopes, erodible soils, rill and ephemeral gullies, compaction due to wheel traffic and human trampling are common features in vineyards around the world and result in high soil erosion rates. However, little is known about seasonal and spatial variations of soil erosion rates due to factor

  18. Soil erosion in sloping vineyards assessed by using botanical indicators and sediment collectors in the Ruwer-Mosel valley

    Rodrigo Comino, J.; Quiquerez, A.; Follain, S.; Raclot, D.; Bissonnais, Le Y.; Casalí, J.; Giménez, R.; Cerda Bolinches, Artemio; Keesstra, S.D.; Brevik, E.C.; Pereira, P.; Senciales, J.M.; Seeger, M.; Ruiz Sinoga, J.D.; Ries, J.B.


    Steep slopes, erodible soils, rill and ephemeral gullies, compaction due to wheel traffic and human trampling are common features in vineyards around the world and result in high soil erosion rates. However, little is known about seasonal and spatial variations of soil erosion rates due to factors s

  19. Conventional and anti-erosion fluoride toothpastes: effect on enamel erosion and erosion-abrasion.

    Ganss, C; Lussi, A; Grunau, O; Klimek, J; Schlueter, N


    New toothpastes with anti-erosion claims are marketed, but little is known about their effectiveness. This study investigates these products in comparison with various conventional NaF toothpastes and tin-containing products with respect to their erosion protection/abrasion prevention properties. In experiment 1, samples were demineralised (10 days, 6 × 2 min/day; citric acid, pH 2.4), exposed to toothpaste slurries (2 × 2 min/day) and intermittently stored in a mineral salt solution. In experiment 2, samples were additionally brushed for 15 s during the slurry immersion time. Study products were 8 conventional NaF toothpastes (1,400-1,490 ppm F), 4 formulations with anti-erosion claims (2 F toothpastes: NaF + KNO(3) and NaF + hydroxyapatite; and 2 F-free toothpastes: zinc-carbonate-hydroxyapatite, and chitosan) and 2 Sn-containing products (toothpaste: 3,436 ppm Sn, 1,450 ppm F as SnF(2)/NaF; gel: 970 ppm F, 3,030 ppm Sn as SnF(2)). A mouth rinse (500 ppm F as AmF/NaF, 800 ppm Sn as SnCl(2)) was the positive control. Tissue loss was quantified profilometrically. In experiment 1, most NaF toothpastes and 1 F-free formulation reduced tissue loss significantly (between 19 and 42%); the Sn-containing formulations were the most effective (toothpaste and gel 55 and 78% reduction, respectively). In experiment 2, only 4 NaF toothpastes revealed significant effects compared to the F-free control (reduction between 29 and 37%); the F-free special preparations and the Sn toothpaste had no significant effect. The Sn gel (reduction 75%) revealed the best result. Conventional NaF toothpastes reduced the erosive tissue loss, but had limited efficacy regarding the prevention of brushing abrasion. The special formulations were not superior, or were even less effective.


    Chi-hua HUANG; Fenli ZHENG


    This paper highlights past efforts in developing erosion process concepts that lead to the development of the current process-based erosion prediction model, i.e., WEPP. Recent progress includes the development of a multiple-box system that can simulate hillslope hydrologic conditions. Laboratory procedures enable the quantification of near-surface hydrologic effects, i.e.,artesian seepage vs. drainage, on the soil erosion process and sediment regime, flow hydraulics, and sediment transport and deposition processes. These recent findings improve soil erosion science and provide new erosion control strategies that may have additional environmental benefits relative to the traditional erosion control practices. The paper also discusses the potential impacts of the erosion process on erosion model development and future research directions of soil erosion process research and model development.

  1. Coastal erosion dynamics on the permafrost-dominated Bykovsky Peninsula, north Siberia, 1951–2006

    Hugues Lantuit


    Full Text Available This study investigates the rate of erosion during the 1951–2006 period on the Bykovsky Peninsula, located north-east of the harbour town of Tiksi, north Siberia. Its coastline, which is characterized by the presence of ice-rich sediment (Ice Complex and the vicinity of the Lena River Delta, retreated at a mean rate of 0.59 m/yr between 1951 and 2006. Total erosion ranged from 434 m of erosion to 92 m of accretion during these 56 years and exhibited large variability (σ = 45.4. Ninety-seven percent of the rates observed were less than 2 m/yr and 81.6% were less than 1 m/yr. No significant trend in erosion could be recorded despite the study of five temporal subperiods within 1951–2006. Erosion modes and rates actually appear to be strongly dependant on the nature of the backshore material, erosion being stronger along low-lying coastal stretches affected by past or current thermokarst activity. The juxtaposition of wind records monitored at the town of Tiksi and erosion records yielded no significant relationship despite strong record amplitude for both data sets. We explain this poor relationship by the only rough incorporation of sea-ice cover in our storm extraction algorithm, the use of land-based wind records vs. offshore winds, the proximity of the peninsula to the Lena River Delta freshwater and sediment plume and the local topographical constraints on wave development.

  2. Formation and erosion of biogeomorphological structures: A model study on the tube-building polychaete

    Borsje, B.W.; Bouma, T.J.; Rabaut, M.; Herman, P.M.J.; Hulscher, S.J.M.H.; Borsje, B.W.; Herman, P.M.J.


    We study how organism traits and population densities of ecosystem engineering species, in combination withenvironmental factors, affect the formation and erosion rates of biogeomorphological structures, and focus on thewidely distributed marine tube-building polychaete Lanice conchilega, which live

  3. Sediment transport and erosion in the Fourchon area of Lafourche parish. [south Louisiana