Erosion Rates

In a raised Pleistocene terrain, 2 km northwest of Santiniketan, West Bengal (23°41'50"N, 87°40'8"E), active gullying and escarpment retreat were initiated after excavation of an escape-channel in 1953. The area is partly capped by loosely aggregated laterite, probably developed in situ with additional contributions from upland sources. Hollow lateritic nodules and allochthonous petrified woods of genera Cynometroxylon, Milletioxylon and Palmoxylon are common in the region. An erosion survey between November, 1989 and February, 1993 has revealed that, in response to 4316 mm of rainfall, the average rates of gully extension, surface lowering and escarpment retreat were 16.1 cm/yr , 0.4 cm/yr and 21.7 cm/yr respectively in laterite capped areas and 33.9 cm/yr, 1.6 cm/yr and 40 cm/yr in non-lateritic areas. The landform units of the area can be classified according to their position in the cross-sectional profile. However, attainment of a mature badland topography has been successfully prevented by afforestation.

The article analyzes the contemporary processes of natural and human-induced shoreline dynamics between cape Kaliakra and cape Emine, Bulgarian Black Sea coastal zone. Main accent is put on the anthropogenic impact on beach morphodynamics, coastal erosion, sediment transport and accretion influenced by land use changes and technogenic load. The stages of recent landscape transformations since the beginning of the XX century are discussed chronologically. Assumptions are made with reference to existing relationships among coastal geomorphic processes, land use dynamics, levels of anthropogenization and coastal landscape change at the investigated area. - КиберЛенинка: https://cyberleninka.ru/article/n/recent-trends-in-state-of-landscapes-and-shoreline-dynamics-in-bulgarian-sector-of-the-black-sea

Quantifying denudation rates along orogenic systems is crucial to understand how tectonics and climate interact with each other to create topography. Long-term mean denudation rates estimated from geologic data in the Ambato range (Sierras Pampeanas) is 0.34 mm/yr. When compared with short-term denudation rates from other studies northward and southward along the Argentine South Central Andes foreland, our results are similar to those found in regions with higher mean annual precipitation. Here we utilize concentrations of 10 Be cosmogenic radionuclide (CRN) in river sediments from catchments along the eastern slope of the Ambato range to understand the relationship among short-term (10 2 e10 4 yrs) catchment-wide denudation rates and long-term denudation rates estimated from geologic data. CRN denudation rates range between ~0.038 and ~0.12 mm/yr. The relationship between geo-morphometric parameters (local relief, slope, hypsometric integral, and catchment mean channel steepness index, K sn) and CRN denudation rates shows linear behavior. The best correlation concerned K sn indicating a strong connection in the Ambato range between tectonics and denudation. When analyzed together with denudation rates from other studies northward and southward along the South Central Andes foreland, our results are similar to those found in more arid regions and suggest that bedrock strength variations should be contemplated in a regional analysis as well as climate.

The ∼900 km long Darling Scarp in Western Australia is one of the most prominent linear topographic features on Earth. Despite the presence of over-steepened reaches in all westerly flowing streams crossing the scarp, and significant seismic activity within 100 km of the scarp, there is no historical seismicity and no reported evidence for Quaternary tectonic displacements on the underlying Darling Fault. Consequently, it is unclear whether the scarp is a rapidly evolving landform responding to recent tectonic and/or climatic forcing or a more slowly evolving landform. In order to quantify late Quaternary rates of erosion and scarp relief processes, we obtained measurements of the cosmic-ray produced nuclide beryllium-10 (10Be) from outcropping bedrock surfaces along the scarp summit and face, in valley floors, and at stream knickpoints. Erosion rates of bedrock outcrops along the scarp summit surface range from 0·5 to 4·0 m Myr−1. These are in the same range as erosion rates of 2·1 to 3·6 m Myr−1 on the scarp face and similar to river incision rates of 2·6 to 11·0 m Myr−1 from valley floor bedrock straths, indicating that the Darling Scarp is a slowly eroding ‘steady state’ landform, without any significant contemporary relief production over the last several 100 kyr and possibly several million years. Knickpoint retreat rates determined from 10Be concentrations at the bases of two knickpoints on small streams incised into the scarp are 36 and 46 m Myr−1. If these erosion rates were sustained over longer timescales, then associated knickpoints may have initiated in the mid-Tertiary to early Neogene, consistent with early-mid Tertiary marginal uplift. Ongoing maintenance of stream disequilibrium longitudinal profiles is consistent with slow, regional base level lowering associated with recently proposed continental-scale tilting, as opposed to differential uplift along discrete faults. Cosmogenic 10Be analysis provides a useful tool for interpreting the palaeoseismic history of intraplate near-fault landforms over 105 to 106 years. Copyright © 2010 John Wiley & Sons, Ltd.

To gain a better understanding of the global application of soil erosion prediction models, we comprehensively reviewed relevant peer-reviewed research literature on soil-erosion modelling published between 1994 and 2017. We aimed to identify (i) the processes and models most frequently addressed in the literature, (ii) the regions within which models are primarily applied, (iii) the regions which remain unaddressed and why, and (iv) how frequently studies are conducted to validate/evaluate model outcomes relative to measured data. To perform this task, we combined the collective knowledge of 67 soil-erosion scientists from 25 countries. The resulting database, named ‘Global Applications of Soil Erosion Modelling Tracker (GASEMT)’, includes 3030 individual modelling records from 126 countries, encompassing all continents (except Antarctica). Out of the 8471 articles identified as potentially relevant, we reviewed 1697 appropriate articles and systematically evaluated and transferred 42 relevant attributes into the database. This GASEMT database provides comprehensive insights into the state-of-the-art of soil- erosion models and model applications worldwide. This database intends to support the upcoming country-based United Nations global soil-erosion assessment in addition to helping to inform soil erosion research priorities by building a foundation for future targeted, in-depth analyses. GASEMT is an open-source database available to the entire user-community to develop research, rectify errors, and make future expansions.

Tropical mountain areas may undergo rapid land degradation as demographic growth and intensified agriculture cause more people to migrate to fragile ecosystems. To assess the extent of the resulting damage, an erosion rate benchmark against which changes in erosion can be evaluated is required. Benchmarks reflecting natural erosion rates are usually not provided by conventional sediment fluxes, which are often biased due to modern land use change, and also miss large, episodic events within the measuring period.

To overcome this, we combined three independent assessment tools in the southern Ecuadorian Andes, an area that is severely affected by soil erosion. First, denudation rates from cosmogenic nuclides in river sediment average over time periods of 1–100 k.y. and establish a natural benchmark of only 150 ± 100 t km–2 yr–1. Second, we find that land use practices have increased modern sediment yields as derived from reservoir sedimentation rates, which average over periods of 10–100 yr to as much as 15 x 103 t km–2 yr–1. Third, our land cover analysis has shown us that vegetation cover exerts first-order control over present-day erosion rates at the catchment scale. Areas with high vegetation density erode at rates that are characteristically similar to those of the natural benchmark, regardless of whether the type of vegetation is native or anthropogenic.

Therefore, our data suggest that even in steep mountain environments sediment fluxes can slow to near their natural benchmark levels with suitable revegetation programs. A set of techniques is now in place to evaluate the effectiveness of erosion mitigation strategies.

Abstract Tropical mountain areas may undergo rapid land degradation as demographic growth and intensified agriculture cause more people to migrate to fragile ecosystems. To assess the extent of the resulting damage, an erosion rate benchmark against which changes in erosion can be evaluated is required. Benchmarks reflecting natural erosion rates are usually not provided by conventional sediment fluxes, which are often biased due to modern land use change, and also miss large, episodic events within the measuring ...