STUDY ON THE IMPROVEMENT EFFECT OF APPLICATION OF ALB FOR RIVER CHANNEL TOPOGRAPHY ON RIVER-BED VARIATION ANALYSIS

2018 ◽  
Vol 74 (2) ◽  
pp. I_465-I_474 ◽  
Author(s):  
Kaho YAMAGUCHI ◽  
Keisuke YOSHIDA ◽  
Shiro MAENO ◽  
Koji MANO ◽  
Ryosuke AKOH ◽  
...  
Keyword(s):  
River Channel ◽  
Variation Analysis ◽  
River Bed ◽  
Improvement Effect

scholarly journals Impacts of dam construction on river channel evolution: a case of Minjiang River in Southeastern China

2020 ◽  
Vol 383 ◽  
pp. 341-346
Author(s):  
Ying Yao ◽  
Wei Cui ◽  
Wen Wang ◽  
Fu-Min Ma ◽  
Ben-Yue Chen
Keyword(s):  
Storage Capacity ◽  
River Channel ◽  
Low Flow ◽  
Dam Construction ◽  
Upward Movement ◽  
Southeastern China ◽  
River Sand ◽  
Channel Evolution ◽  
Minjiang River ◽  
River Bed

Abstract. The Minjiang River is the largest river in Fujian Province. In 1993, the Shuikou Reservoir, which has an effective storage capacity of 700 million m3, was built at about 161 km above the estuary. The completion of the Shuikou Dam trapped most of the upstream sediment in the reservoir area, resulting in a drastic decrease in sediment in the lower reaches of the Minjiang River. The average annual sand load at the Zhuqi Station (about 45 km below the dam) was reduced about 2∕3 after the construction of the reservoir, from 7.42 to 2.55 million t by average, resulting in severe river bed downward cutting. At the same time, the demand for the sand in Minjiang River channel is increasing year by year. The amount of mined river sand is greater than the incoming sediment deposited in the river, which intensified the downcutting of the river bed. The downcutting leads to a continuous upward movement of the tide limit in the river channel especially in the low-flow season. Meanwhile, river embankments and river-related structures are damaged, and the navigation capacity of the Minjiang River is reduced. At present, the river bed of the lower Minjiang River is not yet stable, and the river regime is in a state of constant adjustment.

Recent Changes in the Teifi Estuary

1925 ◽  
Vol 62 (5) ◽  
pp. 223-223
Author(s):  
M. P. Latter
Keyword(s):  
Opposite Direction ◽  
High Tide ◽  
River Channel ◽  
East Side ◽  
The West ◽  
West Side ◽  
The North ◽  
River Bed ◽  
Main River ◽  
Sand Flats

Within the last 50 years the lower reaches of the Teifi from St. Dogmells to Cardigan Bar have undergone a complete change: the bed of the river formerly lay near the west side of the estuary as far as the Webley Arms, and this point in the river was then known as Pwll Cam (“the crooked pool”), as it was here that the river took a sharp bend describing an ogee curve by way of the spit to the east of the present sandbanks: this old river channel lay in clay, unlike the present shallow river bed on the east side of the estuary, and quite big vessels could float even at low tide in front of the Webley Arms, which is now a low stretch of mud banks covered at high tide. A wreck, which laid up over two or three tides, was the simple means of effecting this change in the river's course. Since then it has led to other comparatively rapid geological changes: the Manian-fâch stream, which has its source in the Pant-y-Groes plateau, used to flow almost direct into the Teifi, when in its old course; now, however, since the bed of the Teifi, on leaving the Battery Point, crosses over to the east side of the estuary, the whole of the estuary to the west has been silted up with sand and mud, and this has been accelerated by the formation of sand-banks right across the mouth of the bay: consequently the Manian-fâch stream, on emerging off the mainland, is now deflected to the S.E. and flows for about a mile approximately parallel to the main river, though in the opposite direction, before joining it nearby the Battery Point. The watershed of the roughly triangular strip of sand flats, seen at low tide, lies very close to the present river bed, so that practically all the water off this area at low tide drains first into the Manian-fâch, and thus describes nearly a complete circle twice daily. This instance is analogous to, but not quite homologous with, that of the Eiver Aide in Suffolk, the original mouth of which has been deflected more than 12 miles south by currents from the north.

scholarly journals Monitoring and prospects for conservation and rational use of the resources of the Eurasian beaver (Castor fiber Linnaeus, 1758) on the example of the Samara Region

2021 ◽  
Vol 10 (3) ◽  
pp. 19-24
Author(s):  
Vitaly Vasilievich Antipov ◽  
Mikhail Grigorevich Dvornikov
Keyword(s):  
Population Density ◽  
River Channel ◽  
Anthropogenic Load ◽  
Castor Fiber ◽  
Total Density ◽  
Buffer Zones ◽  
Eurasian Beaver ◽  
River Bed ◽  
Load Monitoring ◽  
Landscape Basis

The paper examines characteristics of the Eurasian beaver population (Castor fiber Linnaeus, 1758) on territories with different anthropogenic load. Monitoring the beaver population and habitat, including the landscape basis and natural zoning with the allocation of natural, natural-anthropogenic and anthropogenic territories as natural ecological systems allows you to manage and rationally use the resources of these animals. Previously there were mainly natural territories in the studied region, however with the growth of the human population and its economic activity their properties have changed. According to biotic criteria, geochemical circulation, significant (formerly natural) territories functionally already correspond to natural-anthropogenic and anthropogenic objects, since the supply of fodder, population density and density of animals have changed. According to natural zoning, taking into account the identified changes in the habitat of beavers (by biotic criteria), we have examined their territorial distribution as well as the number of settlements in various natural objects of the region. On the studied rivers the density of the beaver population in the channel decreases in the following order: natural territory natural-anthropogenic anthropogenic, but the indicator of private abundance (the density of animals on the territory where beavers live directly) and aggregation (crowding of individuals) increases. The population density of the river bed of the studied rivers by beavers on anthropogenic territories is from 0,9-3,7 individuals/km, which is lower than on natural and natural-anthropogenic territories, where this indicator is from 1,5 to 6 individuals/km. The length of the river bed, where beavers live directly, without taking into account significant buffer zones, varies in natural areas from 60 to 100%, which is more than in areas with anthropogenic load, where this indicator in the study area decreases to 40%. A decrease in the size of river channel sections suitable for beaver colonization leads to overcrowding (aggregation) of individuals. Compared with the total density of beaver population in the river channel 0,9-3,7 individuals/km of the channel (excluding the Kondurcha River - 6 individuals/km of the channel) the population density, locally, on anthropogenic and natural-anthropogenic territories increases to 4-7,5 individuals/km.

VI.—River Curves Round Alluvial Plains

1903 ◽  
Vol 10 (8) ◽  
pp. 350-354
Author(s):  
T. S. Ellis
Keyword(s):  
Suspended Matter ◽  
Water Channel ◽  
Alluvial Soil ◽  
River Channel ◽  
Alluvial Plain ◽  
River Bed ◽  
Straight Line ◽  
Tributary Stream ◽  
Adjoining Area ◽  
Lake Bottom

In the Geological Magazine for October, 1902, Dr. Callaway mentions the explanation of these curves that I gave in a paper printed twenty-one years ago. His quotation should be read with the immediate context—”These [the tributary streams] keep open a channel into which the larger stream falls.” This is the essence of my argument.Professor Phillips and Sir A. Geikie have remarked that an alluvial plain in the course of a river may be regarded as an old lake-bottom, now drained; the lake-like appearance being renewed in times of flood. Let us suppose ABCB (Fig. 1) to represent such an area with a river flowing through it in a straight line, and, on one side, a tributary stream, or, to use a shorter and more expressive term, an affluent, coming in at an angle. Such a condition, if it existed, would not continue even in consolidated alluvial soil; it is still less likely to have existed in the soft mud when the area was first drained. A succession of floods would certainly wash away the bank where the affluent, coming through it, had caused a break in its continuity. By this the river-bed opposite the affluent would be expanded beyond its requirements when at low water. At every flood the whole of the bed of the river and the adjoining area of land will be covered with water, the ordinary river channel being effaced. From this water suspended matter falls and forms a deposit, visible after the flood has subsided, but in greater quantity on the banks by the sides of the low-water channel than on the adjoining land.

scholarly journals Improvement of the method of combined plans for the analysis of channel re-formations of a water body on the example of the oka river section

2021 ◽  
Vol 2131 (3) ◽  
pp. 032076
Author(s):  
M Matugin ◽  
D Miltsin ◽  
M Reshetnikov ◽  
A Mazgaleva
Keyword(s):  
Water Body ◽  
Vertical Channel ◽  
River Channel ◽  
Qualitative Assessment ◽  
Channel Processes ◽  
Channel Deformations ◽  
Channel Changes ◽  
River Bed ◽  
The Stability ◽  
Vertical Deformations

Abstract The article discusses the ways of improving the method of combined plans for a water body channel reformations analysis on the example of a section of the Oka River. The main disadvantages of the existing classical approach to the analysis of channel processes through the channel surveys separate isobaths’combination are highlighted. A new approach to combining digital models of the river bed relief obtained from the hydrographic surveys results is proposed. Two directions of surface comparison are shown for the subsequent analysis of channel processes. For a qualitative assessment of channel changes, it is proposed to construct a new surface of vertical deformations and visualize it in color gradation or using lines of equal vertical deformations. For a quantitative assessment of channel processes, the use of a cartogram of vertical channel deformations is considered, and the numerical parameters for assessing the stability of the river channel are introduced. For the considered section of the Oka river channel, the main indicators of channel processes were obtained and analyzed using the proposed updated method. Separately, the calculation of the most optimal grid size was performed when constructing a cartogram of vertical channel deformations.

Saline water intrusion adjacent to the Fraser River, Richmond, British Columbia

2001 ◽  
Vol 38 (1) ◽  
pp. 67-82 ◽  
Author(s):  
Laurie Neilson-Welch ◽  
Leslie Smith
Keyword(s):  
Dynamic Equilibrium ◽  
Saline Water ◽  
Salt Water ◽  
Ground Surface ◽  
River Channel ◽  
Low Flow ◽  
Salt Water Intrusion ◽  
Fraser River ◽  
Water Intrusion ◽  
River Bed

During periods of average to low flow in the Fraser River, seawater from Georgia Strait migrates with a rising tide up the river channel, reaching distances up to 16 km from the river's outlet to the ocean. This relatively dense water infiltrates through the river bed and circulates as a stable wedge of saline water within permeable deltaic deposits adjacent to the river. At the Kidd2 site in Richmond, the wedge extends approximately 500 m inland from the river. The top of the transition zone between fresh and saline water is 10 m below ground surface. The bottom of the saline wedge is located at the contact with underlying low-permeability delta slope deposits, resulting in a wedge with a vertical extent of approximately 10 m. Maximum salinity values observed in the wedge (16–17 parts per thousand) reflect the time-averaged response to density-driven flow under a complex sequence of daily and seasonal variations in salinity within the Fraser River and mixing with fresh river water that may enter the aquifer during the summer freshet. Under the assumption of dynamic equilibrium, simulation of the saline wedge at the Kidd2 site suggests (1) the effective, long-term average salinity at the base of the river channel is approximately 19 parts per thousand; (2) the velocity of groundwater, directed inland in the central portion of the wedge, is in the range from 0.5 to 6 m/year; and (3) fresh water in the confined deltaic sands moves from inland areas toward the Fraser River under a hydraulic gradient of approximately 3 × 10–4.Key words: salt water intrusion, deltaic sediments, modeling.

scholarly journals Adapting of bridges at mining area to the lowered bed of rivers

2019 ◽  
Vol 106 ◽  
pp. 01001
Author(s):  
Piotr Bętkowski
Keyword(s):  
Water Table ◽  
Urban Areas ◽  
Mining Area ◽  
River Channel ◽  
Technical Problems ◽  
Ground Pressure ◽  
River Bed ◽  
The Stability ◽  
Existing Bridges ◽  
Technical Solutions

This article describes technical problems concerning bridges, dangers that arise when the bottom of the river bed is lowered during the liquidation of the floodplains. These floodplains arise as a result of terrain subsidence caused by mining exploitation. In urban areas with developed building and road infrastructure, bayous can cause significant social and material damages. One of manners of the floodplain liquidation or long-lasting lowering the water table is lowering the bottom of river channel on the leakage from bayou. Lowering the river channel can concern the section of few kilometres even long. Lowering the riverbed by dredging or considerable deepening generally does not cause important problems. Significant technical problems are generated by bridge objects. In the case of bridges, it is necessary to ensure the stability of bridgeheads, protect foundations from washing away and undermining. It is necessary to design channel reinforcement so that significant horizontal forces do not occur due to removing the part of the soil-ground from the riverbed (lack of passive ground pressure). Several technical solutions of adapting existing bridges to the lowered river bed for different structures are described.

scholarly journals Two-Dimensional Numerical Simulation Study on Bed-Load Transport in the Fluctuating Backwater Area: A Case-Study Reservoir in China

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1425 ◽  
Author(s):  
Ming Luo ◽  
Heli Yu ◽  
Er Huang ◽  
Rui Ding ◽  
Xin Lu
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Water Level ◽  
River Channel ◽  
Bed Load ◽  
Two Dimensional ◽  
River Bed ◽  
Random Events ◽  
Load Transport ◽  
Bed Load Transport

Numerical modeling of sedimentation and erosion in reservoirs is an active field of reservoir research. However, simulation of the bed-load transport phenomena has rarely been applied to other water bodies, in particular, the fluctuating backwater area. This is because the complex morphological processes interacting between hydrodynamics and sediment transport are generally challenging to accurately predict. Most researchers assert that the shape of a river channel is mainly determined by the upstream water and sediment, and the physical boundary conditions of the river channel, rather than random events. In this study, the refinement and application of a two-dimensional shallow-water and bed-load transport model to the fluctuating backwater area is described. The model employs the finite volume method of the Godunov scheme and equilibrium sediment transport equations. The model was verified using experimental data produced by a scaled physical model, and the results indicated that the numerical model is believable. The numerical model was then applied to actual reservoir operations, including reservoir storage, reservoir drawdown, and the continuous flood process, to predict the morphology of reservoir sedimentation and sediment transport rates, and the changes in bed level in the fluctuating backwater area. It was found that the location and morphology of sedimentation affected by the downstream water level result in random evolution of the river bed, and bed-load sedimentation is moved from upstream to downstream as the slope of the longitudinal section of the river bed is reduced. Moreover, the research shows that the river channel sedimentation morphology is changed by the change water level of the downstream reach, causing the dislocation of the beach and channel and random events that will affect the river, which is of certain reference value for waterway regulation.

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