Yellow River's water and sediment discharge decreasing steadily

Eos ◽  
1998 ◽  
Vol 79 (48) ◽  
pp. 589-592 ◽  
Author(s):  
Z. S. Yang ◽  
J. D. Milliman ◽  
J. Galler ◽  
J. P. Liu ◽  
X. G. Sun
Keyword(s):  
Sediment Discharge ◽  
Water And Sediment

Postglacial geomorphic development of the Dinosaur Provincial Park badlands, Alberta

1987 ◽  
Vol 24 (1) ◽  
pp. 135-146 ◽  
Author(s):  
Rorke B. Bryan ◽  
Ian A. Campbell ◽  
Aaron Yair
Keyword(s):  
Red Deer ◽  
Experimental Studies ◽  
Sediment Discharge ◽  
Erosion Rates ◽  
Water And Sediment ◽  
Provincial Park ◽  
Geomorphic Processes ◽  
Aeolian Sands

Experimental studies concerning current geomorphic processes and erosion rates in the badlands of Dinosaur Provincial Park, Alberta, have not explained the unusual extent of badland development or prominent nonstructural near-horizontal surfaces that occur in the park. Two of these surfaces result from spillway development associated with Wisconsin deglaciation, and the extent of badland development is associated with major spillway concentration and exposure of highly erodible Cretaceous strata. A third surface is associated with erosion caused by locally generated runoff. All surfaces are blanketed with aeolian sands and silts deposited around 5500 BP, which profoundly affected the hydrology of the area and water and sediment discharge from the badlands to the Red Deer River. Subsequent stripping of the aeolian cover by streams, along with piping and tunnel erosion, has reexposed vulnerable Cretaceous strata and restored the high erosion rates now observed in these badlands.

scholarly journals Seasonal logging, process response, and geomorphic work

2013 ◽  
Vol 1 (1) ◽  
pp. 311-335 ◽  
Author(s):  
C. H. Mohr ◽  
A. Zimmermann ◽  
O. Korup ◽  
A. Iroumé ◽  
T. Francke ◽  
...  
Keyword(s):  
Quantile Regression ◽  
Overland Flow ◽  
Timber Harvest ◽  
Dry Season ◽  
Sediment Flux ◽  
Slope Instability ◽  
High Temporal Resolution ◽  
Sediment Discharge ◽  
Dimensional Parameter ◽  
Water And Sediment

Abstract. Deforestation is a prominent anthropogenic cause of erosive overland flow and slope instability, boosting rates of soil erosion and concomitant sediment flux. Conventional methods of gauging or estimating post-logging sediment flux focus on annual timescales, but potentially overlook important geomorphic responses on shorter time scales immediately following timber harvest. Sediments fluxes are commonly estimated from linear regression of intermittent measurements of water and sediment discharge using sediment rating curves (SRCs). However, these often unsatisfactorily reproduce non-linear effects such as discharge-load hystereses. We resolve such important dynamics from non-parametric Quantile Regression Forests (QRF) of high-frequency (3 min) measurements of stream discharge and sediment concentrations in similar-sized (~ 0.1 km2) forested Chilean catchments that were logged during either the rainy or the dry season. The method of QRF builds on the Random Forest (RF) algorithm, and combines quantile regression with repeated random sub-sampling of both cases and predictors. The algorithm belongs to the family of decision-tree classifiers, which allow quantifying relevant predictors in high-dimensional parameter space. We find that, where no logging occurred, ~ 80% of the total sediment load was transported during rare but high magnitude runoff events during only 5% of the monitoring period. The variability of sediment flux of these rare events spans four orders of magnitude. In particular dry-season logging dampened the role of these rare, extreme sediment-transport events by increasing load efficiency during more moderate events. We show that QRFs outperforms traditional SRCs in terms of accurately simulating short-term dynamics of sediment flux, and conclude that QRF may reliably support forest management recommendations by providing robust simulations of post-logging response of water and sediment discharge at high temporal resolution.

Recent Evolution and Future Prediction of the Delta at the Yangtze River Mouth

2013 ◽  
Vol 353-356 ◽  
pp. 2699-2704 ◽  
Author(s):  
Ming Li ◽  
Yun Ping Yang ◽  
Yi Tian Li
Keyword(s):  
Mathematical Model ◽  
Yangtze River ◽  
River Mouth ◽  
Sediment Discharge ◽  
The Yangtze River ◽  
Discharge Data ◽  
One Dimensional ◽  
Water And Sediment ◽  
The Future ◽  
The One

In this study, an empirical curve describing the relation between erosion and deposition rate and water/sediment discharge was developed based on the recent evolution trend of the submerged delta at the Yangtze River Mouth, and the one-dimensional mathematical model for unsteady water-and sediment-transport was calibrated using the water and sediment discharge data after water impounding to predict the water and sediment discharge for the future 10 years and the future evolution of the submerged delta at the Yangtze River Mouth. The results showed that the 10 m and 20 m isobaths areas of the submerged delta changed with the water and sediment discharge from siltation to siltation slowing down to erosion. Siltation increased with large amount of rain received by the watershed during 1997-2000, while continuous retreat of erosion happened during 2000-2009. Using the one-dimensional mathematical model for river water and sediment calibrated and tested with data collected after impounding, the water and sediment discharges were calculated for Series 60 and 90, and its evolution in 2013-2022 was predicted for the delta. For Series 60, its 10 cm and 20 cm isobaths areas showed alternative scour and siltation, while the delta showed trends of erosion. For Series 90, its 10 m and 20 m isobaths showed substantial siltation in flood years. The water and sediment discharges since the Three Gorges Reservoirs was filled were lower than the calculated results for both Series 60 and 90. If the water and sediment discharges continue to decease, the delta will take an erosion trend.

scholarly journals Sediment load determines the shape of rivers

2021 ◽  
Vol 118 (49) ◽  
pp. e2111215118
Author(s):  
Predrag Popović ◽  
Olivier Devauchelle ◽  
Anaïs Abramian ◽  
Eric Lajeunesse
Keyword(s):  
Sediment Load ◽  
Sediment Flux ◽  
Sediment Discharge ◽  
Physically Based Model ◽  
Water And Sediment ◽  
Physically Based ◽  
Discharge Regime ◽  
Flux Profile ◽  
Large Discharge ◽  
Total Sediment

Understanding how rivers adjust to the sediment load they carry is critical to predicting the evolution of landscapes. Presently, however, no physically based model reliably captures the dependence of basic river properties, such as its shape or slope, on the discharge of sediment, even in the simple case of laboratory rivers. Here, we show how the balance between fluid stress and gravity acting on the sediment grains, along with cross-stream diffusion of sediment, determines the shape and sediment flux profile of laminar laboratory rivers that carry sediment as bedload. Using this model, which reliably reproduces the experiments without any tuning, we confirm the hypothesis, originally proposed by Parker [G. Parker, J. Fluid Mech. 89, 127–146 (1978)], that rivers are restricted to exist close to the threshold of sediment motion (within about 20%). This limit is set by the fluid–sediment interaction and is independent of the water and sediment load carried by the river. Thus, as the total sediment discharge increases, the intensity of sediment flux (sediment discharge per unit width) in a river saturates, and the river can transport more sediment only by widening. In this large discharge regime, the cross-stream diffusion of momentum in the flow permits sediment transport. Conversely, in the weak transport regime, the transported sediment concentrates around the river center without significantly altering the river shape. If this theory holds for natural rivers, the aspect ratio of a river could become a proxy for sediment discharge—a quantity notoriously difficult to measure in the field.

scholarly journals A comparative study of the flux and fate of the Mississippi and Yangtze river sediments

2015 ◽  
Vol 367 ◽  
pp. 312-319 ◽  
Author(s):  
K. Xu ◽  
S. L. Yang
Keyword(s):  
Anthropogenic Impacts ◽  
River Sediments ◽  
Large River ◽  
Sediment Discharge ◽  
Dispersal Patterns ◽  
Sediment Dispersal ◽  
River Deltas ◽  
Water And Sediment ◽  
Continental Shelves ◽  
Global Oceans

Abstract. Large rivers play a key role in delivering water and sediment into the global oceans. Large-river deltas and associated coastlines are important interfaces for material fluxes that have a global impact on marine processes. In this study, we compare water and sediment discharge from Mississippi and Yangtze rivers by assessing: (1) temporal variation under varying climatic and anthropogenic impacts, (2) delta response of the declining sediment discharge, and (3) deltaic lobe switching and Holocene sediment dispersal patterns on the adjacent continental shelves. Dam constructions have decreased both rivers’ sediment discharge significantly, leading to shoreline retreat along the coast. The sediment dispersal of the river-dominated Mississippi Delta is localized but for the tide-dominated Yangtze Delta is more diffuse and influenced by longshore currents. Sediment declines and relative sea level rises have led to coastal erosion, endangering the coasts of both rivers.

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