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Characteristics of sediment movement and river-bed morphology at mountainous stream confluence region
Published in Silke Wieprecht, Stefan Haun, Karolin Weber, Markus Noack, Kristina Terheiden, River Sedimentation, 2016
X.K. Wang, E. Huang, X.N. Liu, X.F. Yan, H.F. Duan
Clockwise secondary currents can be clearly observed along cross sections, and the intensity reaches the peak at CS9. This can be attributed to gradual sinuous curve of mainstream and combination of sinuous curve of mainstream and flow separation in confluence. The secondary currents explain the behaviors of the sediment ridge accompanying the point bar on the flood plain (see Figure 3). The secondary currents are also believed to be the root cause of surface sediment sorting. The intensity of secondary currents compared to the primary flow is greatly lower so that only fine particles tend to be carried to the left bank side, which is in consistency with the result of bed surface sediment sorting (see Figure 6).
The Jalangi
Published in Balai Chandra Das, Sandipan Ghosh, Aznarul Islam, Suvendu Roy, Anthropogeomorphology of Bhagirathi-Hooghly River System in India, 2020
Balai Chandra Das, Soma Bhattacharya
The smaller the value of SmI is, the more intense the meander is. It was found that maximum SmI and minimum SmI were 0.89 and 0.03, respectively. Median SmI was 0.14. Therefore, 100% meanders have am > rc, and those are more sinuous than a regular sine curve. More than 50% meanders were acute meander (median SmI = 0.14). The average SmI was 0.22. Downstream variation in SmI shows no significant trend at all (Figure 12.12).
General geomorphometry, derivatives of altitude, and descriptive statistics
Published in Richard J. Chorley, Spatial Analysis in Geomorphology, 2019
Figure 2.8 shows that, given this smoothing, the correlation with skewness is good. It also shows that the lower r (the more sinuous the curve), the higher the skewness for an integral of 0.5, and the higher the integral for 0 skewness. This effect may be produced by curves which are generally symmetric, but about altitudes above 0.5. As Strahler suggests, the value of r for an empirical curve may be estimated by visual comparison with model curves. It is then possible to estimate skewness from the hypsometric integral and vice versa.
Trace fossils, algae, invertebrate remains and new U-Pb detrital zircon geochronology from the lower Cambrian Torneträsk Formation, northern Sweden
Published in GFF, 2021
Stephen McLoughlin, Vivi Vajda, Timothy P. Topper, James L. Crowley, Fan Liu, Ove Johansson, Christian B. Skovsted
The basal beds of the Torneträsk Formation rest non-conformably on weathered granitic to gneissic basement in the study area. At Luobákte, the base of the formation is characterized by a thin polymict conglomerate (Fig. 2A). Stodt et al. (2011) proposed that at least the basal part of this conglomerate was deposited during the mid-Ediacaran Gaskiers glaciation, although we found no evidence of glacigenic features in this deposit in the Torneträsk area. This bed is overlain by a succession(>6 m thick) of quartzose fine- to coarse-grained sandstones and conglomeratic lenses with few or no siltstone partings. These strata are collectively assigned to the informal “lower sandstone” interval. This unit is characterized by extensive high- to low-angle planar cross-bedding (Figs. 2B, 4A, C) with variable palaeocurrent orientations (Thelander 1982). Large-scale straight- to sinuous-crested asymmetrical ripples (Fig. 4B), smaller-scale symmetrical ripples, and inclined tabular packages of massive sandstone (Figs. 2B, 4C) are also represented. Thelander (1982, fig. 5) also recognized small-scale channel scours within the unit. Although Thelander (1982) inferred a fluvial setting for at least part of this unit, the sheet-like geometries of many beds, common low-angle bedforms, abundant current- and wave-rippled bedding surfaces, and scarcity of siltstone partings suggest a moderate- to high-energy shallow shoreface depositional setting for the “lower sandstone” interval.
Discharge and force distribution in a sinuous channel with vegetated floodplains during overbank flow
Published in Journal of Hydraulic Research, 2020
Pedro J.M. Moreta, Juan P. Martín-Vide
However, in those works only some features of the flow were investigated, i.e. water level, velocity and secondary flow. Bousmar, Omran, Atabay, and Knight (2009) showed a momentum analysis along a complete wave-length in a meandering channel, yet with the same roughness in floodplains and main channel. In the present paper, the overbank flow in a low sinuous channel with dense flexible vegetation in the floodplains is investigated along a meander wavelength. The aim of this paper is to assess the effect of floodplain roughness and flow depth on the discharge distribution between the main channel and floodplains and on the magnitude of the forces involved in the flow.
Geomorphic landscape design integrated with progressive mine restoration in clay quarries of Catalonia
Published in International Journal of Mining, Reclamation and Environment, 2021
José F. Martín Duque, María Tejedor, Cristina Martín Moreno, José M. Nicolau, Miguel A. Sanz Santos, Ramón Sánchez Donoso, José M. Gómez Díaz
From those inputs, we replicated the ‘A’ to ‘Aa+’ and ‘Cb’ fluvial channels type of the Rosgen morphological classification of rivers [30,31]. ‘A’ to ‘Aa+’ channels have a zig-zag pattern resulting from them flowing around ridges eroded into their valleys walls and they develop on gradients greater than 4%. The GeoFluv method associates these greater than 4% channels with this characteristic zig-zag pattern rather than the sinuous meander bends present in the lower gradient ‘Cb’ channel type. We fitted such fluvial channels and related hillslopes to the local hydrological, topographic and volumetric conditions of the clay quarries.