Medium and short-term channel planform changes on the Rivers Tay and Tummel, Scotland

Winterbottom, S. J.

doi:10.1016/s0169-555x(00)00007-6

Cited by 195 publications

(129 citation statements)

References 16 publications

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“…Highland rivers exhibit a great variety of channel patterns, including braided and meandering alluvial channels, bedrock-constricted reaches, mountain torrents and steep headwater streams (Werritty & Hoey, 2003). Most trunk valleys are occupied by wandering gravel-bed rivers (Figure 21), characterized by a meandering planform research has been carried out on changes in alluvial channel patterns within the past few centuries or decades, and how such changes relate to climate, land-use change, river management and flood events (Werritty & Ferguson, 1980;Ferguson & Werritty, 1983;Werritty, 1984;Maizels, 1988;McEwen & Werritty, 1988;McEwen, 1989McEwen, , 1994Ferguson & Ashworth, 1990;Winterbottom, 2000;Werritty & Leys, 2001). However, recent reviews highlight the dearth of information regarding the longer-term Holocene evolution of alluvial landforms (McEwen, 1997;Werritty & McEwen, 1997).…”

Section: Holocene Alluvial Historymentioning

confidence: 99%

After the Ice: Holocene Geomorphic Activity in the Scottish Highlands

Ballantyne

2008

Scottish Geographical Journal

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A rich variety of processes have modified the glacial landscape of the Scottish Highlands since the last glaciers disappeared 11,500 years ago. Many of these processes can be described as paraglacial (glacially-conditioned): retreat of glacier ice has resulted in exposure of metastable sediment sources (rock slopes, drift-mantled slopes and valley-floor glacigenic deposits) that have been reworked over a range of timescales. Much of the reworked sediment has been deposited in paraglacial sediment stores (talus accumulations, debris cones, alluvial fans, valley fills, river terraces and deltas). The trajectory of paraglacial sediment transfer can be approximated by an exhaustion model. A corollary of this model is that all sediment stores eventually undergo a change from net accumulation to net erosion, reflecting the non-renewable nature of sediment sources. This concept helps to explain why most talus accumulations, debris cones and alluvial fans in the Highlands are now relict, and why many floodplains appear to have experienced an initial period of aggradation followed by later river incision and terrace development. Since deglaciation, rock slopes have experienced paraglacial stress release due to differential deglacial unloading. Many rock slopes have remained stable or experienced gradual adjustment through intermittent rockfall. At over 600 sites, however, large-scale rock-slope failure has occurred, either in the form of catastrophic failure with complete or arrested debris runout, or as major slope deformations. Modification of drift-mantled slopes has been dominated by rainstorm-generated debris flows activity, which have stripped sediment from slopes and redeposited it in debris cones. Radiocarbon dating of buried organic horizons shows that debris flows have occurred intermittently throughout the Holocene. Snow avalanches have played only a localized role in paraglacial sediment transfer. The Holocene alluvial history of the Highlands is poorly understood. Some alluvial fans formed during a few exceptional flood events, and there is evidence that postglacial floodplain aggradation peaked in the late Holocene and was succeeded by floodplain incision and terrace development, possibly reflecting upstream reduction in paraglacial sediment supply. Other processes have operated independently of glacial conditioning. The effects of wind action are dominant in the coastal zone, forming dunefields through aeolian reworking of beach sand, and on plateaux in the form of deflation surfaces and sand sheets. Extensive erosion of plateau-top sands and aeolisols occurred in the period AD 1550-1700, a period of exceptional storminess. Small-scale periglacial processes have also been active on high ground throughout the Holocene, including granular weathering of exposed rock surfaces, the development of small-scale frost-sorted patterned ground on unvegetated terrain, and slow downslope movement of solifluction sheets, solifluction lobes and ploughing boulders.

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Section: Holocene Alluvial Historymentioning

confidence: 99%

After the Ice: Holocene Geomorphic Activity in the Scottish Highlands

Ballantyne

2008

Scottish Geographical Journal

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“…2b allows channel bed changes -which in the case of rivers have been reported to be of importance in short periods (Winterbottom, 2000) -to also be discussed This fact should be significant for the water exchange between the two lobes as it depends on the relative direction of different sections of the channel and the relevant winds.…”

Section: Discussionmentioning

confidence: 99%

Geodynamical processes in the channel connecting the two lobes of the Large Aral Sea

Roget

Zavialov

Khan

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract.Reasons for the existence of the channel connecting the two lobes of the present Large Aral Sea are discussed. In situ measurements in 2005 show that differences between the measured depths and those contained in the available digital bathymetry of the lake are considerably different at the channel (7.5±0.9 m, at nine measurement stations along it) and at the northern part of the eastern lobe (1.6±0.3 m, at six stations from the western to the eastern shore). Differences in the misfits observed in the two zones are discussed and thought to be a consequence of the variation of the transversal area of the channel as it enters the eastern lobe, which would affect the flow velocity and thus the strength of the erosion process at the bottom. Field data together with satellite images have been used to modify an original digital bathymetry of the lake and have been implemented into a 3-D hydrodynamical model. A numerical simulation shows that a wind of 12 m/s blowing from the east (112 • ) generates velocities of up to 45 cm/s in the channel, allowing denser water from the eastern lobe (salinity: 132 g/kg) to flow about 38 km towards the fresher western lobe (salinity: 98 g/kg) in one day. The effect of the inflow on the vertical structure of the western lobe is also illustrated. Although nowadays the channel will be soon a thing of the past, in a more general context, the Aral Sea is presented as an example showing that geomorphologic and geophysical processes, along with hydrological and atmospheric processes, must be taken into account for short-term predictions.

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“…In this studied river reach, the upper section of the Bayangaole-Sanhuhekou subreach presents a typical braided river pattern. Although the limit of vegetation could be an important indicator of channel boundary (e.g., Gurnell 1997;Winterbottom 2000;Richard et al 2005;Yao et al 2013;, it is seldom distributed in the study river reach, in particular along the margins of the Wulanbuhe and Kubuqi deserts.…”

Section: Methodsmentioning

confidence: 99%

Spatial and temporal variations of channel lateral migration rates in the Inner Mongolian reach of the upper Yellow River

Ran

Yan

2016

Environ Earth Sci

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Channel variations of the Inner Mongolian reach in the upper Yellow River are very complicated because of diversity of channel patterns, intense changes in water and sediment, and enhanced human activities in the last decades. It is important to examine the channel migration rates in this river reach. Based on channel planform changes at 236 digital channel cross-sections, the present study estimated the channel migration rates in terms of mid-channel line shift at the digital channel cross-sections during the periods 1975-1990, 1990-2000, 2000-2006, 2006-2010, and 2010-2011. The results show that the average channel migration rate for the whole river reach is 5.0, 7.9, -5.9, 8.6, and -1.0 m -1 in the five different periods, respectively. In both directions to the right and to the left, the highest channel migration rate was always observed in the meandering channels, while the lowest channel migration rate was in the whole Inner Mongolian reach except the Sanhuhekou-Zhaojunfen (S-Z) sub-reach. The temporal variation of channel migration rate was mainly controlled by changing sediment concentration in river flow, while the spatial variation along the straight, braided, and meandering channel reaches was largely affected by material differences of channel banks as reflected by different channel patterns. With the highest average lateral migration rate to the left bank, the meandering channel reach is extremely vulnerable to lateral migration and needs to be protected with engineering practices, because a large population and wide farmland are located on its left floodplain.

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Medium and short-term channel planform changes on the Rivers Tay and Tummel, Scotland

Cited by 195 publications

References 16 publications

After the Ice: Holocene Geomorphic Activity in the Scottish Highlands

After the Ice: Holocene Geomorphic Activity in the Scottish Highlands

Geodynamical processes in the channel connecting the two lobes of the Large Aral Sea

Spatial and temporal variations of channel lateral migration rates in the Inner Mongolian reach of the upper Yellow River

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