Delineating lateral channel migration and risk zones of Ichamati River, West Bengal, India

2020 ◽  
Vol 244 ◽  
pp. 118740 ◽  
Author(s):  
Ismail Mondal ◽  
Sandeep Thakur ◽  
Jatisankar Bandyopadhyay
Keyword(s):  
West Bengal ◽  
Channel Migration ◽  
Lateral Channel ◽  
Risk Zones

scholarly journals Controls on the lateral channel‐migration rate of braided channel systems in coarse non‐cohesive sediment

2019 ◽  
Vol 44 (14) ◽  
pp. 2823-2836 ◽  
Author(s):  
Aaron Bufe ◽  
Jens M. Turowski ◽  
Douglas W. Burbank ◽  
Chris Paola ◽  
Andrew D. Wickert ◽  
...  
Keyword(s):  
Migration Rate ◽  
Cohesive Sediment ◽  
Channel Migration ◽  
Braided Channel ◽  
Lateral Channel ◽  
Channel Systems

Responses of Floods to Holocene Climatic Change in the Upper Mississippi Valley

1985 ◽  
Vol 23 (3) ◽  
pp. 287-300 ◽  
Author(s):  
James C. Knox
Keyword(s):  
Climatic Changes ◽  
Mississippi Valley ◽  
Channel Migration ◽  
Valley Bottom ◽  
Lateral Channel ◽  
History Of ◽  
And Storage ◽  
Recurrence Frequency ◽  
Large Floods

Dimensions of Holocene relict channels and sedimentological characteristics of point bars associated with these relict channels were used to reconstruct a Holocene history of long-term changes in magnitudes of 1.58-yr floods in Upper Mississippi Valley watersheds of southwestern Wisconsin. The reconstructed record of floods shows relatively large and persistent (nonrandom) departures from contemporary long-term average flood magnitudes. The flood history indicates climatic changes that are broadly similar to climatic changes indicated from fossil pollen in the same region. The Holocene floods ranged from about 10–15% larger to 20–30% smaller than contemporary floods of the same recurrence frequency. Large floods were characteristic between about 6000 – 4500 and 3000 – 2000 yr B.P., and during a brief interval after 1200 yr B.P. Small floods were common between about 8000 – 6500, 4500 – 3000, and 2000 – 1200 yr B.P. These fluvial responses were found to be closely associated with a long-term episodic mobility and storage of sediments in the Wisconsin watersheds. During periods of relatively large floods, relatively rapid lateral channel migration either reworked or removed extensive tracts of valley bottom alluvium. In contrast, during periods of relatively small floods, relatively slow lateral channel migration is apparent and the channel and floodplain system appear to have been relatively stable.

Controls on the lateral channel migration rate of braided alluvial channel systems

2020 ◽  
Author(s):  
Aaron Bufe ◽  
Jens Turowski ◽  
Douglas Burbank ◽  
Chris Paola ◽  
Andrew Wickert ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Migration Rate ◽  
External Boundary ◽  
Lateral Migration ◽  
Channel Migration ◽  
Channel System ◽  
Migration Rates ◽  
Lateral Channel ◽  
Channel Slope ◽  
Channel Systems

<p>Lateral movements of alluvial river channels control the extent and reworking rates of alluvial fans, floodplains, deltas, and alluvial sections of bedrock rivers. These lateral movements can occur by gradual channel migration or by sudden changes in channel position (avulsions). Whereas models exist for rates of river avulsion, we lack a detailed understanding of the rates of lateral channel migration on the scale of a channel belt. Here we develop, for the first time, an expression that describes the lateral migration rate of braided alluvial channels in non-cohesive sediment. On the basis of photographic and topographic data from laboratory experiments of braided channels performed under constant external boundary conditions, we first explore the impact of autogenic variations of the channel-system geometry (i.e., channel-bank heights, water depths, channel-system width, and channel slope) on channel-migration rates. In agreement with theoretical expectations, we find that, under such constant boundary conditions, lateral channel-migration rates scale inversely with the channel-bank height. Furthermore, when changes in channel-bank heights are accounted for, lateral migration rates appear independent of channel slope, channel-system width, and water depth. These constraints allow us to derive two dimensionally consistent expressions for lateral channel-migration rates under different boundary conditions. We find that migration rates are strongly sensitive to channel-bank heights and water discharges and more weakly sensitive to sediment discharges in braided equilibrium channel systems. In addition, the strong dependence of lateral migration rates on channel-bank heights implies that external perturbations (for example, perturbations of sediment and water discharges) that modulate the depth of channel incision and can indirectly affect lateral channel-migration rates.</p>

scholarly journals Coarse-grained meandering distributive fluvial system of the basal Cedar Mountain Formation, U.S.A.

2021 ◽  
Vol 91 (11) ◽  
pp. 1188-1205
Author(s):  
Stephen P. Phillips ◽  
John A. Howell ◽  
Adrian J. Hartley ◽  
Magda Chmielewska
Keyword(s):  
Grain Size ◽  
Early Cretaceous ◽  
Foreland Basin ◽  
Fluvial System ◽  
Channel Migration ◽  
Fluvial Systems ◽  
Plan View ◽  
Cedar Mountain Formation ◽  
Lateral Channel ◽  
Net To Gross

ABSTRACT The analysis of downstream changes in ancient fluvial systems can better inform depositional models for foreland-basin systems. Herein we analyze the basal deposits of the Early Cretaceous Cedar Mountain Formation of Utah to better understand the variety of fluvial deposits present and to develop a depositional model for the Sevier foreland basin. We also evaluate the long-held interpretation of a braided origin for these deposits and document numerous examples of point-bar deposition in highly sinuous meandering rivers by analysis of large (20 to 60 km2) plan-view exposures. These plan-view exposures allow comparisons between planform and cross-sectional geometries. The study utilizes outcrop data, virtual outcrop models, and satellite imagery to develop a facies model and analyze the architecture of channel bodies in the Buckhorn Conglomerate and Poison Strip Sandstone of the Cedar Mountain Formation. We document downstream (west to east) decreases in lateral channel migration, sinuosity, channel amalgamation, grain size, and percent of fluvial channel facies (conglomerate and sandstone). Fluvial channel deposits occur arranged into larger stratal bodies: multistory–multilateral channel bodies that are dominantly composed of clast-supported conglomerate in the west to a mix of multistory, multilateral, and isolated channel bodies composed of matrix-supported conglomerate in the east. The median width of highly sinuous point bars is similar across the field area (344 m to 477 m), but the inclusion of narrower (median = 174 m), low-sinuosity bar elements in the east indicates an overall reduction in lateral channel migration and sinuosity downstream. Net-to-gross values range from 100% in much of the western outcrops to as low as 38% in the east. Paleocurrent analysis reveals a transverse (west to east) paleoflow for the study interval that merges with axial (south–north) paleoflow near the Utah–Colorado state line. We estimate 104 m3/s-scale discharge and 106 kilometer-scale drainage area for axial rivers based on paleohydraulic analysis which represents a significant part of the Early Cretaceous continental-scale drainage. The observed downstream trends in lateral channel migration, sinuosity, channel amalgamation, grain size, and net-to-gross for the basal Cedar Mountain Formation are consistent with expected trends for sinuous single-thread distributive fluvial systems and are similar to observed trends in the Jurassic Morrison Formation. Medial (Buckhorn Conglomerate) to distal (Poison Strip Sandstone) zones are preserved and span the forebulge to backbulge depozones of a foreland-basin system. Postulated deposits of the proximal distributive fluvial system have been removed during erosion of the foredeep depozone. The easternmost Poison Strip Sandstone and coeval Burro Canyon Formation represent deposits of an axial system at which western-sourced distributive fluvial systems end. Distributive fluvial systems dominate modern foreland basins, and this study suggests that they may constitute a significant proportion of ancient successions.

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