scholarly journals FORMATION AND EVOLUTION OF PARALLEL-BRAIDED CHANNEL REACHES

2020 ◽  
pp. 110-125
Author(s):  
Roman S. Chalov ◽  
◽  
Konstantin M. Berkovitch ◽  
Svetlana N. Ruleva ◽  
Aleksandr S. Zavadskiy ◽  
...  
Keyword(s):  
Anthropogenic Impacts ◽  
Water Discharge ◽  
Morphological Characteristics ◽  
Sediment Runoff ◽  
Channel Changes ◽  
Braided Channel ◽  
Determining Factors ◽  
Formation And Evolution ◽  
Large Width ◽  
Channel Control

The paper provides a comprehensive assessment of channel formation conditions and hydrological-morphological characteristics, and also considers the features of the channel changes regime of parallel-braided channel reaches, being the most complex and diverse in morphodynamics. The general condition for their development is a large width of channels (respectively, the maximum value of the criterion of the flow quasi-uniformity suggested by I.F. Karasev). In such channels, the flow is divided into two branches, between which, in the middle of the channel, occurs accumulation of sediments and formation of mid-channel bars and islands. At the same time, parallel-braided channels are the result of other channel types (non-meandering) development due to certain changes in determining factors: increased water content and sediment runoff, overgrowth of channel bars, as a result of which mid-channel bars turn into islands, and anthropogenic impacts on rivers. On sandy floodplain rivers, parallel-braided reaches are typical for low-stable and unstable channels in the absence of the directed influence from bedrock banks on the flow and when effective water discharge passes over the floodplain edge. The islands in such braided reaches are mostly small. On rivers with incised channels, they are either similar in morphology and the channel changes regime to wide floodplain unstable channels, differing from the latter in large islands with elongated shape, or form sculptural islands and are very stable. In any variety, parallel-braided channels are very individual in their channel changes regime and there are no universal channel control schemes for them.

scholarly journals MORPHOLOGICAL CHARACTERISTICS OF THE GIANH RIVER (FROM CO CANG TO CUA GIANH) IN RELATION TO THE EROSION AND ACCUMULATION

2019 ◽  
Vol 18 (4) ◽  
pp. 384-392
Author(s):  
Hai Nguyen Tien ◽  
Dang Vu Hai ◽  
Phuc La The ◽  
Ha Nguyen Thai
Keyword(s):  
River Flow ◽  
Dominant Role ◽  
Morphological Characteristics ◽  
Straight Channel ◽  
Meandering Channel ◽  
Braided Channel ◽  
River Bed ◽  
Erosion And Accretion ◽  
Channel Bar

On the basis of morphological characteristics and erosion - accumulation of sediment, it is possible to divide the stretch of the Gianh River from Co Cang to Cua Gianh (about 54km in length) into 3 sections as follows: Meandering channel (from Co Cang to Tien Xuan Isles): the length of the channel is 27.69km and the width of the channel is 80-250m. The channel is in the form of a meandering, narrow riverbed, flow plays a dominant role, deposition activities develop strongly at the convex side, while erosion occurs strongly in the concave side (cut side); Braided channel (from Tien Xuan Isles to Quang Phu): the length of the channel is 17.06km and the width of the channel is 800-2,200m. The channel is straight, the river bed is large and the depth of the river bed is 2-11m. Sedimentation occurs mainly at the bottom of the channel and creates bar in the middle of the channel; Straight channel (from Quang Phu to Cua Gianh): the length of the channel is 9.23km and the width of the channel is 800-1,000m. The channel is straight and the depth of the river bed is 8-12.5m. In addition to the role of river flow, it is strongly influenced by marine dynamics. The erosion and accretion activities occur mainly in estuaries. The results above show trend of river development: i) Meandering channel is the most vulnerable to changes for morphology of channel by erosion and accretion of sediment and can create 1-2 horseshoe pools by the river change line; ii) Braided channel mainly changes in the bottom of channel by the formation of channel bar; iii) Straight channel mainly changes in the estuary (the mouth of the river can be moved, enlarged or narrowed).

scholarly journals Channel processes of a small river heavily modified by human activities

2020 ◽  
Vol 163 ◽  
pp. 06011
Author(s):  
Aleksandr Varenov ◽  
Anna Tarbeeva ◽  
Dmitriy Botavin ◽  
Nadezhda Mikhaylova ◽  
Leonid Turykin ◽  
...  
Keyword(s):  
Human Impact ◽  
Water Discharge ◽  
High Sensitivity ◽  
Bank Erosion ◽  
Small Rivers ◽  
Channel Processes ◽  
Channel Changes ◽  
Volga Upland ◽  
Local Residents ◽  
Special Approach

Widely-spread small rivers are very poorly studied in relation to channel processes. The influence of local factors, high sensitivity to human impact, close connection with basin processes, and relatively low rates of channel changes distinguish them from medium and large ones and make it necessary to form a special approach to studies. Based on collection of long-term maps and local residents’ interviews, we reconstructed the transformation of channels in the Kudma River basin (the Volga Upland) for the last 200 years. Based on the bank erosion monitoring during 2011-2019 the modern rates of channel changes were revealed. We found that significant human impact is associated with the artificial channels cutoffs and draining of ponds which led to channel incision of the Kudma and Ozerka Rivers in the middle reaches and the transformation of floodplain into terrace. Agriculture development caused siltation of the upper reaches of rivers. The rivers of the forested part of the basin experienced the least human changes. From 2011 to 2019 the maximum rates of bank erosion were found to be within range of 0.3 to 2.7 m/year and supposed to be driven by peak water discharge.

scholarly journals Morphology of the Kosi megafan channels

2014 ◽  
Vol 2 (2) ◽  
pp. 1023-1046 ◽  
Author(s):  
K. Gaurav ◽  
F. Métivier ◽  
O. Devauchelle ◽  
R. Sinha ◽  
H. Chauvet ◽  
...  
Keyword(s):  
Water Discharge ◽  
Morphological Characteristics ◽  
Acoustic Doppler Current Profiler ◽  
Sandy Sediment ◽  
Strongly Correlated ◽  
Data Set ◽  
Threshold Channel ◽  
Average Slope ◽  
Current Profiler ◽  
Channel Theory

Abstract. We study the morphology of streams flowing on the alluvial megafan of the Kosi River in north Bihar, India. All streams develop on a uniform sandy sediment and under a similar climate, allowing for statistically significant comparisons. Our data set includes both channels from the braid of the Kosi River and channels from isolated single-thread rivers. Using an Acoustic Doppler Current Profiler, we measure the width, depth and water discharge of the channels. Their average slope is also acquired with a kinematic GPS. These morphological characteristics are strongly correlated with the discharge. However, rescaling the data according to the threshold channel theory removes most of this dependency. The rescaled data suggest that the threads of the Kosi River braid are morphologically similar to isolated channels.

scholarly journals Sandstone body character, river styles, and geomorphology of the lower Eocene Willwood Formation, Bighorn Basin, Wyoming, USA

2021 ◽  
Author(s):  
Youwei WANG ◽  
Timothy Baars ◽  
Hiranya Sahoo ◽  
Joep Storms ◽  
Allard Martinius ◽  
...  
Keyword(s):  
Water Discharge ◽  
Bighorn Basin ◽  
Early Eocene ◽  
Average Width ◽  
Lower Eocene ◽  
Braided Rivers ◽  
Braided Channel ◽  
Facies Associations ◽  
Sinuous Channel ◽  
Willwood Formation

The lower Eocene Willwood Formation of the intermontane Bighorn Basin, Wyoming, USA, is an alluvial red bed succession with a sand content of ca. 20%-25%. The formation has been studied intensively for paleontology, paleoclimate, and sedimentary reconstruction. However, alluvial sandstone bodies and their corresponding river styles remain little characterized and documented. Here, efforts are made to study the characteristics and river styles of sandstone bodies through ca. 300 m of alluvial stratigraphy in the McCullough Peaks outcrop area based on the field data and a georeferenced 3-D photogrammetric model. Four channel facies associations are recognized, and they are ascribed to four river planform styles: distributary channel, massive trunk-shaped channel, braided channel, and sinuous channel, with the latter two styles being the more abundant. The channel sandstone bodies that show the character of sinuous rivers and those of braided rivers differ significantly in average thickness (6.1 m versus 9.0 m) and insignificantly in average width (on average 231 m) and paleoflow directions (on average N003). Braided-character dominated and sinuous-character dominated river styles are seen to alternate in the outcrop, while they show no spatial dependency in the 10 km2 study area. Bighorn Basin margins varied in the early Eocene, with differing tectonic, geological, and topographic characteristics. The observed mixture of river styles may be attributed to differential influences of axial and transverse river systems and/or climate change that controls water discharge and sediment load. An early Eocene geomorphologic reconstruction is constructed summarizing these new and earlier results.

scholarly journals KARAKTERISTIK MORFOLOGI DAN FISIOLOGI BAKTERI ENDOFIT DAN RIZOBAKTERI DARI TANAMAN CENGKEH SEHAT

2021 ◽  
Vol 4 (1) ◽  
pp. 1-8
Author(s):  
Fina Dwimartina ◽  
Tri Joko ◽  
Triwidodo Arwiyanto
Keyword(s):  
Biological Control ◽  
Endophytic Bacteria ◽  
Host Plants ◽  
Morphological Characteristics ◽  
Plant Diseases ◽  
Bacterial Isolates ◽  
Biological Control Agents ◽  
Determining Factors ◽  
Symbiotic Mutualism ◽  
Bacillus Spp

One of the determining factors in disease control is the use of superior seeds which have good quality and quantity. The use of biological control agents that form a symbiotic mutualism in their host plants can be used as an effort to obtain quality clove seeds. Endophytic bacteria and rhizobacteria have been reported as potential biological control agents for many plant diseases because of their safety in humans and non-target organisms. The purpose of this study was to identify the physiological and morphological characteristics of endophytic and rhizobacterial isolates obtained from clove plants. A total of 46 endophytic bacterial isolates were isolated from healthy clove roots, stems, leaves and flowers. Also, 66 isolates were isolated from the soil around the rhizosphere area. Based on the results of the identification of physiological and morphological characteristics, it is evident that the endophytic and rhizobacterial bacteria tested have the same character as Bacillus spp.

Groundwater hydrogeochemical formation and evolution in a karst aquifer system affected by anthropogenic impacts

2019 ◽  
Vol 42 (9) ◽  
pp. 2609-2626 ◽  
Author(s):  
Xiancang Wu ◽  
Changsuo Li ◽  
Bin Sun ◽  
Fuqiang Geng ◽  
Shuai Gao ◽  
...  
Keyword(s):  
Anthropogenic Impacts ◽  
Karst Aquifer ◽  
Aquifer System ◽  
Karst Aquifer System ◽  
Formation And Evolution

scholarly journals Aspectos etnoecológicos e implicações para a conservação de Tursiops truncatus (Cetartiodactyla: Delphinidae) no Arquipélago das Cagarras, Rio de Janeiro, Brasil

2013 ◽  
Vol 13 ◽  
Author(s):  
Liliane Lodi ◽  
Camilah Antunes Zappes ◽  
Álvaro Samuel Guimarães dos Santos
Keyword(s):  
Tursiops Truncatus ◽  
Rio De Janeiro ◽  
Anthropogenic Impacts ◽  
Participant Observation ◽  
Bottlenose Dolphins ◽  
Morphological Characteristics ◽  
Small Scale ◽  
Common Bottlenose Dolphin ◽  
Significant Difference ◽  
The Common

The objectives of this study were to understand the ecological aspects of the common bottlenose dolphin (Tursiops truncatus) in the Cagarras Archipelago, Rio de Janeiro, Brazil, and possible anthropogenic impacts by comparing the knowledge of local small-scale fishermen (GA) and the regulars in the archipelago (GB). The data obtained were compared with those available in the literature to propose strategies for monitoring and preservation. Between August and December 2010, we applied the methods of participant observation, interviews-questionnaires and use of illustrative posters. Sixty-one interviews were conducted, from which 83.6% were selected by considering correct answers about the identification of the species on posters (morphological characteristics) and description of time of occurrence in the archipelago (July to December) as reported for the species in the literature. Regarding the seven questions analyzed statistically, a significant difference was found between the accounts of the two groups with respect to anthropic threats to T. truncatus. Gill-nets and the decrease of fishing resources were the main causes identified by the GA group whereas the GB group pointed to the disorganized use of space, pollution and predatory fishing as the factors that have threatened the common bottlenose dolphins. The use of ethnobiological data in conservation programs brings opportunities for the collaboration and participation of the community that is directly inserted into the ecosystem as well as a chance for locals to get involved in issues concerning the sustainability of the archipelago.

scholarly journals Linkages Between Sinuosity Index and Flood Sustainability: A Study of Morna River (Maharashtra), India

2021 ◽  
Vol 16 (2) ◽  
pp. 649-661
Author(s):  
Nilesh K. Susware ◽  
Jagdish B. Sapkale ◽  
Vinaya N. Susware ◽  
Shubham K. Gavhane
Keyword(s):  
Agricultural Land ◽  
Morphological Changes ◽  
Water Discharge ◽  
Research Work ◽  
Flood Management ◽  
River Channel ◽  
Flood Events ◽  
Sinuosity Index ◽  
Channel Changes ◽  
Stability And Instability

The morphological changes in the river channel over periods that occur due to the flood events, affected the sinuosity index of the river channel. The river characteristic like sinuosity also determines the intensity of flood in a channel. Recent flood losses have increased as a result of variability in rainfall; simultaneously such problems are coming up with sustainable development. The attempted research study has been carried out to evaluate and understand the river channel changes and bank stability of the Morna river in Maharashtra. The research work also identified the pattern/planform of the river. Morna river meets Warna river near the Mangle village. Most of the streams in the upper basin area are non-perennial. The occurrence of floods takes place due to seasonal rainfall. An index of Sinuosity was used to analyze variation in river courses, as well as identify stability and instability. Therefore, this may facilitate predicting probable riverbank erosion sites and also support sustainable flood management planning for these sites during forthcoming flood events. The sinuosity index of the Morna river ranges from 1.09 to 1.44. The sinuosity indexes for the Morna river and tributaries of its sub-basins/watersheds have been calculated using geospatial techniques. The disparities in sinuosity indexes of the Morna basin and sub-watersheds having a good correlation with slope of the river , fluvial processes, water discharge and hydraulic aspects of the river channel. Seasonal potential flood risk for the agricultural land may be found at the confluence of the Warna river and its tributary Morna river when it receives heavy rainfall in upstream.

Research on Characteristics of Sediment in Yichang-Wuhan Reach after Impoundment of the Three Gorges

2013 ◽  
Vol 405-408 ◽  
pp. 2250-2253
Author(s):  
Yan Hua Yang ◽  
Xiao Qiang Liu ◽  
Hong Qian Zhang
Keyword(s):  
Water Discharge ◽  
Test Method ◽  
Rank Test ◽  
Sediment Runoff ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
Reservoir Regulation ◽  
Change Trend ◽  
The Three Gorges Project

Reservoir regulation make conditions of sediment under the dam change greatly after impoundment of the Three Gorges Project. This paper analyzes change trend and abrupt change situation of incoming sediment and studies characteristics of new sediment of Yichang and Hankou Stations after impoundment of the Three Gorges with Mann-Kendall nonparametric rank test method. The result indicates that after operation of the Three Gorges Reservoir, annual sediment runoff changed suddenly and sediment runoff reduced sharply in Yichang and Hankou Stations; sediment entering the Yichang-Wuhan reach decreases substantially and it almost can be regarded as clean water discharge. Research shows unsaturated degree of the clear water released from reservoirs decreased after obtaining sediment along the river, so the sediment discharge would be partly recovered.

scholarly journals Osteological guide of songbirds from Central Europe

2015 ◽  
Vol 23 (2) ◽  
pp. 62-155 ◽  
Author(s):  
Jenő (Eugen) Kessler
Keyword(s):  
Central Europe ◽  
Measurement Data ◽  
Morphological Characteristics ◽  
Genus Level ◽  
Determining Factors ◽  
Method Of Measurement ◽  
Owl Pellets

Abstract The author provides an osteological guide to songbirds, based on 11 skeletal parts of 51 genera, at the genus level for ornithologists studying owl pellets, paleontologists and archaezoologists. The mandible, the coracoid bone, the scapula, the humerus, the ulna, the carpometacarp, the first phalanx bone of the second finger, the femur, the tibiotars, the tarsometatars and the claw bone are presented. The morphological characteristics and method of measurement of the examined skeletal parts and the photographs of the appropriate bones are illustrated on 52 plates and 17 figures. The measurement data are also provided in 11 size tables. For every discussed bone, 3-6 characteristics are chosen, and their codes consist of 3-6 letters. In case of overlaps, dimensions are the determining factors, and for the humerus and the ulna, the ensemble of the two bone end pairs can be used.

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