Continuous, diurnally fluctuating turbidity currents in Kluane Lake, Yukon Territory

2008 ◽  
Vol 45 (10) ◽  
pp. 1123-1138 ◽  
Author(s):  
Sarah Crookshanks ◽  
Robert Gilbert
Keyword(s):  
Suspended Sediment ◽  
River Mouth ◽  
Sediment Traps ◽  
Yukon Territory ◽  
Turbidity Currents ◽  
Paleoenvironmental Reconstruction ◽  
Sedimentary Processes ◽  
Sediment Distribution ◽  
Diurnal Range ◽  
Kluane Lake

Modern sedimentary processes were studied in Kluane Lake, Yukon Territory, to determine the spatial and temporal patterns of sediment distribution in a large, dynamic, glacier-fed lake. Data from a river monitoring station, moored instruments, sediment traps, and water-column profiles in the lake were used to document lacustrine sedimentary processes in 2006 and 2007. During the peak melt season, the suspended sediment concentration of Slims River is weakly dependent on river discharge and can reach up to 5 g L–1, although a diurnal range between 1 and 2 g L–1 is more commonly observed. The high suspended sediment load in the river generates continuous, diurnally fluctuating turbidity currents in Kluane Lake with maximum velocities up to 0.6 m s–1. During times of peak flow, variations in velocity can be traced to beyond 4 km from the river mouth. The vertical concentration profiles, mass accumulation rates, and suspended sediment loads show distinctive longitudinal variations; the highest rate of accumulation occurs ∼1 km from the point of inflow, which is concurrent with a distinct change in flow structure. Diurnal laminations are apparent in sediment traps close to the point of inflow and can be directly linked to variations in current velocity; however, these laminations do not occur consistently over space or time. These results suggest that long-term measurement records of lacustrine turbidity currents provide valuable insights regarding the multiple scales of environmental variability and have important implications for paleoenvironmental reconstruction using lacustrine sediments.

scholarly journals Spatial and temporal variations of sedimentation rate in the Timah Tasoh Water Reservoir, Perlis, Malaysia

2010 ◽  
Vol 42 (1) ◽  
pp. 127-138 ◽  
Author(s):  
Zullyadini Rahaman ◽  
Wan Ismail
Keyword(s):  
Suspended Sediment ◽  
Sedimentation Rate ◽  
River Mouth ◽  
Water Reservoir ◽  
Sediment Traps ◽  
Temporal Variations ◽  
Spatial And Temporal Variations ◽  
Sedimentation Rates ◽  
Wet Season ◽  
Monthly Average

Spatial and temporal variations of sedimentation rate in the Timah Tasoh Water Reservoir, Perlis, Malaysia Human activities such as logging, land conservation, road construction and other disturbances in watersheds will increase erosion rate and thus the amount of sediment transported into the river that reaches lakes, reservoirs and sea. Accelerated sedimentation rate in the reservoir can significantly reduce a reservoir's surface area, eliminating wetland area surrounding the reservoir and shallow the areas near the shore of the reservoir. A study of sedimentation rate in the Timah Tasoh water reservoir was carried out from May 2001 to April 2002 by means of sediment traps. The aim of this study is to determine the spatial and temporal pattern of sedimentation rates in the reservoir. The sediment traps were installed at five different locations in the reservoir and replaced every month. Gross sedimentation rates measured in the sediment traps vary from about an average of 1.4 kg/m2/month or 16.3 kg/m2/yr in the deepest part of the reservoir to about 79.2 kg/m2/yr (monthly average of 6.6 kg/m2/month) and 47.1 kg/m2/yr (monthly average of 3.9 kg/m2/month) near the inlet of the Pelarit River and the Tasoh River respectively. The sedimentation rate near the Pelarit River and the Tasoh River inflow is correlated with the water and suspended sediment discharge in the river, owing to its proximity to the rivers and the flooding effect, mainly during the wet season. The sedimentation rate decreases southward along the reservoir, as a result of increasing distance from the river mouth. The total suspended sediment load of the Upper Pelarit River and the Jarum River flowing into the reservoir is 11.4 × 103 ton/year and 5.41 × 103 ton//year respectively.

scholarly journals Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1568
Author(s):  
Vando J. C. Gomes ◽  
Nils E. Asp ◽  
Eduardo Siegle ◽  
José Diego Gomes ◽  
Ariane M. M. Silva ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Regional Climate ◽  
Strong Dependence ◽  
River Sediments ◽  
River Mouth ◽  
Sediment Supply ◽  
Amazon River ◽  
Sediment Delivery ◽  
Sediment Distribution ◽  
The World

In tide-dominated estuaries, maximum-turbidity zones (MTZs) are common and prominent features, characterized by a peak in suspended-sediment concentration (SSC) associated with estuarine processes. The Brazilian Amazon coast includes many estuaries, experiencing macrotidal conditions. MTZs are expected to occur and are crucial for sediment delivery to the longest continuous mangrove belt of the world. The area is under influence of the Amazon River plume (ARP), the main SSC source, as local rivers do not deliver substantial sediment supply. To assess the processes that allow the ARP to supply sediment to the estuaries and mangrove belt along the Amazon coast, the results from previous individual studies within five Amazon estuaries (Mocajuba, Taperaçu, Caeté, Urumajó and Gurupi) were compared with regards to SSC, salinity, morphology and tidal propagation. This comparison reinforces that these estuaries are subject to similar regional climate and tidal variations, but that their dynamics differ in terms of distance from the Amazon River mouth, importance of the local river sediment source, and morphology of the estuarine setting. The Urumajó, Caeté and Gurupi are hypersynchronous estuaries where perennial, classic MTZs are observed with SSC > 1 g·L−1. This type of estuary results in transport convergence and MTZ formation, which are suggested to be the main processes promoting mud accumulation in the Amazonian estuaries and therefore the main means of mud entrapment in the mangrove belt. The Mocajuba and the Taperaçu estuaries showed synchronous and hyposynchronous processes, respectively, and do not present classic MTZs. In these cases, the proximity to the ARP for the Mocajuba and highly connected tidal channels for the Taperaçu estuary, assure substantial mud supply into these estuaries. This study shows the strong dependence of the estuaries and mangrove belt on sediment supply from the ARP, helping to understand the fate of Amazon River sediments and providing insights into the mechanisms providing sediment to estuaries and mangroves around the world, especially under the influence of big rivers.

scholarly journals Modern sedimentary processes along the Doce river adjacent continental shelf

2015 ◽  
Vol 45 (4) ◽  
pp. 635-644 ◽  
Author(s):  
Valéria da Silva Quaresma ◽  
Geórgia Catabriga ◽  
Silvia Nossa Bourguignon ◽  
Estefânia Godinho ◽  
Alex Cardoso Bastos
Keyword(s):  
Continental Shelf ◽  
River Mouth ◽  
High Energy ◽  
Sediment Supply ◽  
Major Influence ◽  
Carbonate Content ◽  
Sedimentary Processes ◽  
Sediment Distribution ◽  
Shelf Sediment ◽  
Doce River

In areas of the continental shelf where sediment supply is greater than the sediment dispersion capacity, an extensive terrigenous deposits and consequently submerged deltas can be formed. The Eastern Brazilian shelf is characterized by the occurrence of river feed deltas in between starving coasts. Herein, modern sedimentary processes acting along the Doce river adjacent continental shelf are investigated. The main objective was to understand the shelf sediment distribution, recognizing distinct sedimentary patterns and the major influence of river sediment discharge in the formation of shelf deposits. The study used 98 surficial samples that were analyzed for grain size, composition and bulk density. Results revealed 3 distinct sectors: south - dominated by mud fraction with a recent deposition from riverine input until 30 m deep and from this depth bioclastic sands dominate; central north - sand mud dominated, been recognized as a bypass zone of resuspended sediment during high energy events; and north - relict sands with high carbonate content. The modern sedimentation processes along the Doce river continental shelf is dominated by distinct sedimentary regimes, showing a strong fluvial influence associated with wave/wind induced sediment dispersion and a carbonate regime along the outer shelf. These regimes seem to be controlled by the distance from the river mouth and bathymetric gradients.

Suspended sediment distribution and residual transport in the coastal ocean off the Ganges-Brahmaputra river mouth

1994 ◽  
Vol 120 (1-2) ◽  
pp. 41-61 ◽  
Author(s):  
Dilip K. Barua ◽  
Steven A. Kuehl ◽  
Richard L. Miller ◽  
Williard S. Moore
Keyword(s):  
Suspended Sediment ◽  
River Mouth ◽  
Coastal Ocean ◽  
Brahmaputra River ◽  
Sediment Distribution ◽  
Residual Transport ◽  
The Ganges

THE INITIAL RESULTS OF THE SUSPENDED SEDIMENT DYNAMICS DURING THE DRY SEASON IN THE HAU RIVER MOUTH AREA

2017 ◽  
Vol 17 (2) ◽  
Author(s):  
Nguyen Ngoc Tien ◽  
Dinh Van Uu ◽  
Nguyen Tho Sao ◽  
Do Huy Cuong ◽  
Nguyen Trung Thanh ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
River Mouth ◽  
Dry Season ◽  
Sediment Dynamics ◽  
Mouth Area ◽  
River Mouth Area ◽  
Initial Results

scholarly journals Watershed Suspended Sediment Supply and Potential Impacts of Dam Removals for an Estuary

2021 ◽  
Author(s):  
David K. Ralston ◽  
Brian Yellen ◽  
Jonathan D. Woodruff
Keyword(s):  
Suspended Sediment ◽  
River Estuary ◽  
Dam Removal ◽  
Hudson River ◽  
Sediment Traps ◽  
Sediment Supply ◽  
Watershed Area ◽  
Natural Lakes ◽  
Sediment Deposits ◽  
Dam Removals

AbstractObservations and modeling are used to assess potential impacts of sediment releases due to dam removals on the Hudson River estuary. Watershed sediment loads are calculated based on sediment-discharge rating curves for gauges covering 80% of the watershed area. The annual average sediment load to the estuary is 1.2 Mt, of which about 0.6 Mt comes from side tributaries. Sediment yield varies inversely with watershed area, with regional trends that are consistent with substrate erodibility. Geophysical and sedimentological surveys in seven subwatersheds of the Lower Hudson were conducted to estimate the mass and composition of sediment trapped behind dams. Impoundments were classified as (1) active sediment traps, (2) run-of-river sites not actively trapping sediment, and (3) dammed natural lakes and spring-fed ponds. Based on this categorization and impoundment attributes from a dam inventory database, the total mass of impounded sediment in the Lower Hudson watershed is estimated as 4.9 ± 1.9 Mt. This represents about 4 years of annual watershed supply, which is small compared with some individual dam removals and is not practically available given current dam removal rates. More than half of dams impound drainage areas less than 1 km2, and play little role in downstream sediment supply. In modeling of a simulated dam removal, suspended sediment in the estuary increases modestly near the source during discharge events, but otherwise effects on suspended sediment are minimal. Fine-grained sediment deposits broadly along the estuary and coarser sediment deposits near the source, with transport distance inversely related to settling velocity.

scholarly journals Suspended sediment distribution under varied currents in the largest river-connected lake of China

2017 ◽  
Vol 18 (3) ◽  
pp. 994-1004 ◽  
Author(s):  
Hua Wang ◽  
Yijun Zhao ◽  
Fengnian Zhou ◽  
Huaiyu Yan ◽  
Yanqing Deng ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Suspended Sediment ◽  
Flow Patterns ◽  
Field Investigation ◽  
Gravity Flow ◽  
Shear Stresses ◽  
Sediment Distribution ◽  
Back Flow ◽  
The North ◽  
Dry Seasons

Abstract Poyang Lake was selected as the research area. Based on laboratory experiment, field investigation and numerical simulation, the spatial distributions of suspended sediment (SS) under the gravity-flow, jacking-flow and back-flow patterns were quantitatively analysed. An annular flume experiment was conducted to determine the critical starting shear stresses of the sediments in the flood and dry seasons. By numerical experiment, the SS transport under different flow patterns was explored. Several results stand out. (1) The critical starting shear stresses of the sediments in the flood and dry seasons were 0.35 N·m−2 and 0.29 N·m−2, respectively. (2) Due to the strongest flow disturbance and scouring effect, SS under the gravity-flow pattern was characterized by the highest loads. The lowest SS was observed during the jacking-flow pattern, which could be attributed to the lowest water level gap between the lake and external rivers. The loads ranged from 0.053 kg·m−3 to 0.068 kg·m−3. (3) Under the back-flow pattern, SS in the north lake was evidently influenced by the Yangtze River, and the mean value was approximately 0.12 kg·m−3. With the gradually weakened back-flow impact, the SS load was decreased from the north to the middle of the lake.

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