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River action and control
Published in F.G. Bell, Geological Hazards, 1999
Deposition occurs where turbulence is at a minimum or where the region of turbulence is near the surface of a river. For example, lateral accretion occurs with deposition of a point bar on the inside of a meander bend. A point bar grows as the meander moves downstream or new ones are built as the river changes course during or after floods. Old meander scars can often be seen on flood plains (Figure 6.5a). The combination of point bar and filled slough results in what is called ridge and swale topography. The ridges are composed of sand bars, and the swales are the depressions, which are subsequently filled with silt and clay.
Channel migration characteristics of the Yamuna River from 1954 to 2015 in the vicinity of Agra, India: A case study using remote sensing and GIS
Published in International Journal of River Basin Management, 2019
P. Yunus Ali, Dou Jie, Armugha Khan, N. Sravanthi, Liaqat A. K. Rao, Chen Hao
The annual average rainfall for the basin varies between 400 mm to 2000 mm, mostly occur during the monsoon months of June to October. Yamuna River, for the majority of its extent is alluvial in nature, where the river itself has deposited the sediment. The major geomorphological features identified from the satellite’s imageries are the channel, meander scar, flood plain, paleochannels, upland surface, and salt-encrusted areas. Sinha et al. (2005) observed that the uplift and following erosion in Himalayan catchment resulted in enormous sediment yield in the rivers. Floodplains are also well developed in the downstream reaches on both sides of Yamuna. The manifestation of the geomorphic diversity in the Indo-Gangetic Plains by Sinha et al. (2005) and others based on stream power and sediment supply are marked by degradational topography with badland development, shallow, aggrading channels with frequent avulsions and extensive flooding. As a result of constant river reworking, the river has built point bars, and meandering bends along its course (Figure 1). For the majority of river course, a corridor that extends beyond its current channel boundaries is visible. The size of such corridor reflects the rates of lateral shift, or migration, that are characteristic of an alluvial river. At portions, the migration is relatively slow because of low stream energy, whereas some segments migrate very rapidly where stream energy and sediment loads are relatively high.