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Origin and Formation of Organic and Inorganic Particles in Aquatic Systems
Published in Roger S. Wotton, The Biology of Particles in Aquatic Systems, 2020
G. Milton Ward, Amelia K. Ward, Cliff N. Dahm, Nicholas G. Aumen
A number of processes of significance for particle inputs to upland streams are those associated with the mass movement of soil and rock. Whether they operate seasonally or continuously, processes such as soil creep, slump/earthflow, and debris avalanches may be very important to sediment and organic matter budgets, particularly in geologically young terrains. In the Cascade Mountains of Oregon, soil creep has been shown to be an important source of inorganic matter to streams.11 Soil creep is the slow, downslope movement of the soil mantle under the force of gravity. Although difficult to quantify, creep occurs on all sloping soils, but may be quite slow, generally <1 cm year−1. Slump, or earthflow, is the slow, deep-seated downslope movement of soil, weathered bedrock, and perhaps fresh bedrock. Debris avalanches are the rapid, shallow mass movement of soil and weathered bedrock into a channel. Small debris slides may occur on the toe slopes of hills, but larger slides may be initiated further upslope, and typically occur following a period of high rainfall or a period of rain plus snowmelt. Debris avalanches are infrequent, episodic events, but when they do occur, they can have an enormous impact on particulate matter transfer that may be observed in the channel for decades, if not centuries. Natural debris avalanches are rather infrequent events, estimated by Swanson et al.11 to occur at a frequency of 0.008 year−1 in the H. J. Andrews Experimental Forest in Oregon, but more frequently in managed watersheds as the result of cultural practices associated with road failures and timbering.12
Some results of study of slow movements on the slopes of Russia
Published in Jan Rybář, Josef Stemberk, Peter Wagner, Landslides, 2018
Soil-creep is known to be the slow movement of the soil-ground masses on the slopes, occurring, as a rule, without visible cracks. For the first time the term “creep” was used by Davis (1962) in 1899 for the designation of slow movements on slopes. This term is used both for the designation of deep creep and for the superficial one. The second kind of slope deformations is considered in the article. A lot of Russian geomorphologists paid particular attention to the superficial soil-creep. The study of soil creep was made in various areas of Russia. This article is an attempt to generalize about the soil-creep study result in Russia.
Building movement: foundations
Published in Duncan Marshall, Derek Worthing, Roger Heath, Nigel Dann, Understanding Housing Defects, 2013
Duncan Marshall, Derek Worthing, Roger Heath, Nigel Dann
Landslips occur for a variety of reasons, e.g. on sloping ground with clay soils, there is a danger that the upper layers can slowly move downhill when they slide over lower layers. In many cases, susceptible soils or waste heaps can slip as a result of a prolonged period of rain, e.g. over the autumn and early winter of late 2012. It can often be recognised at the site investigation stage by the terraced appearance of the ground. Soil creep can occur in gradients as shallow as 1:10 and buildings with shallow foundations can obviously be damaged.
A new tree-ring-based index for the expression of spatial landslide activity and the assessment of landslide hazards
Published in Geomatics, Natural Hazards and Risk, 2021
On the basis of the abovementioned fact, the high SIt values can be interpreted as zones with continuous movements affecting a high proportion of all trees occupying the zone. On the contrary, a high concentration of disturbed trees and a high concentration of undisturbed trees in a specific zone indicates discontinuous slope movements, as evidenced by low SIt values. This slope behaviour can indicate the presence of soil creep movements instead of true slide movements (Fabiánová et al. 2021; Pawlik and Šamonil 2018; Saunders and Young 1983). Creep as a source of noise in chronologies of true slide movements was filtered (with some success) by artificial manipulations with It thresholds (Corona et al. 2014), avoiding tree sampling in unsuitable positions (Šilhán 2017), or considering the spatial pattern of disturbed trees (Fabiánová et al. 2021). Finding new SIt value behaviour opens new possibilities for filtering the effect of creep movements in the chronology of slide movements.