Effects of grid scale and resulting initial bed disturbance differences on the evolution of braided rivers

2021 ◽  
Author(s):  
Changjin Wang ◽  
Peng Hu
Keyword(s):  
Numerical Model ◽  
Dominant Role ◽  
Morphological Characteristics ◽  
Statistical Characteristics ◽  
Morphological Description ◽  
Average Height ◽  
Braided Rivers ◽  
Average Area ◽  
Braiding Index ◽  
Scale Difference

<p>Physics-based models have been increasingly developed in recent years and applied to simulate the braiding process and evolution of channel units in braided rivers. Braided rivers are the river network system characterized by the staggered distribution of bars and channels. In the numerical calculation, the grid scale affects the behavior process and morphological description of braided rivers. In this paper, a 2D numerical model is used to simulate the evolution of the braided rivers where the transport of load bed sediment plays a dominant role. In the natural scale braided rivers evolution modeling, the difference of the braided rivers' morphological characteristics under different grid scales is discussed, and the influence of different distribution of topographic disturbance caused by grid scale difference on the morphological characteristics of braided rivers is discussed. The study shows that the grid scale does not affect the description of braided rivers evolution process, and braided rivers evolve in the same way regardless of grid scale (within a reasonable range). However, the statistical characteristics of braided rivers are greatly affected by the grid scale. The braiding index increases as the grid scale decreases, but when the grid scale decreases to a certain extent (20m in this paper), the braiding index no longer increases. The number and average height of bars in braided rivers increase with the decrease of grid scale, and the average area of bar near riverbed also increases with the decrease of grid scale, but the average area of bar near water surface does not change with the change of grid scale. In general, the higher the grid resolution is, the more similar the bar morphology in the numerical model is to that in natural rivers. In addition, the different distribution of topographic disturbance caused by the grid scale difference has an influence on the braiding intensity and the bar morphology of the braided rivers, but the influence degree is much smaller than that caused by the grid scale difference.</p>

Découverte d’une nouvelle population de Rhithrogena delphinensis Sowa & Degrange, 1987, dans le massif des Arves, et compléments à la description de la larve (Ephemeroptera, Heptageniidae)

2021 ◽  
Vol 126 (4) ◽  
pp. 401-420
Author(s):  
Bertrand Launay ◽  
Julien Barnasson ◽  
Juliette Becquet ◽  
Michel Brulin ◽  
Sophie Cauvy-Fraunie ◽  
...  
Keyword(s):  
Drainage Basin ◽  
Morphological Characteristics ◽  
Western Alps ◽  
Coi Gene ◽  
Morphological Description ◽  
Base Pairs ◽  
Northern Flank ◽  
Ecological Requirements ◽  
First Time ◽  
Existing Data

Discovery of a new population of Rhithrogena delphinensis Sowa & Degrange, 1987, in the Arves Massif, and additions to the morphological description of the larva (Ephemeroptera, Heptageniidae). Rhithrogena delphinensis, described originally on the basis of four larvae from the Western Alps, south of the Arves Massif and from the northern flank of the Ecrins Massif, had not been captured again since 1986. Here, we report the discovery of a new population from river Arvan, whose drainage basin is located between the Grandes Rousses Massif and the northern flank of the Arves Massif. This newly discovered population seems abundant in numbers, and reveals the particular ecological requirements of the species as well as its dependence on glacier fed or nival streams. The morphological characteristics of the larvae are described in detail, and illustrated by photographs. The variability of some of the proposed identification criteria is discussed, and a key to the identification of the Rhithrogena species from the alpestris group of the Western Alps, to which R. delphinensis belongs, is provided. Finally, a portion of 658 base pairs of the COI gene of R. delphinensis is sequenced for the first time and compared to already existing data on the alpestris group in the Western Alps.

A FRACTAL SCALING LAW BETWEEN TORTUOSITY AND POROSITY IN POROUS MEDIA

Fractals ◽  
2020 ◽  
Vol 28 (02) ◽  
pp. 2050025
Author(s):  
PENG XU ◽  
LIPEI ZHANG ◽  
BINQI RAO ◽  
SHUXIA QIU ◽  
YUQING SHEN ◽  
...  
Keyword(s):  
Porous Media ◽  
Chemical Engineering ◽  
Oil And Gas ◽  
Scaling Law ◽  
Morphological Characteristics ◽  
Fractal Model ◽  
Statistical Characteristics ◽  
Scale Model ◽  
Reservoir Water ◽  
Flow Through

Hydraulic tortuosity is one of the key parameters for evaluating effective transport properties of natural and artificial porous media. A pore-scale model is developed for fluid flow through porous media based on fractal geometry, and a novel analytical tortuosity–porosity correlation is presented. Numerical simulations are also performed on two-dimensional Sierpinski carpet model. The proposed fractal model is validated by comparison with numerical results and available experimental data. Results show that hydraulic tortuosity depends on both statistical and morphological characteristics of porous media. The exponents for the scaling law between tortuosity and porosity depend on pore size distribution and tortuous fractal dimension. It has been found that hydraulic tortuosity indicates evident anisotropy for asymmetrical particle arrangements under the same statistical characteristics of porous media. The present work may be helpful to understand the transport mechanisms of porous materials and provide guidelines for the development of oil and gas reservoir, water resource and chemical engineering, etc.

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 Ichthyobodo salmonis sp. n. (Ichthyobodonidae, Kinetoplastida), an euryhaline ectoparasite infecting Atlantic salmon (Salmo salar L.)

Parasitology ◽  
2011 ◽  
Vol 138 (9) ◽  
pp. 1164-1175 ◽  
Author(s):  
TROND E. ISAKSEN ◽  
EGIL KARLSBAKK ◽  
KUNINORI WATANABE ◽  
ARE NYLUND
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Phylogenetic Analyses ◽  
Light And Electron Microscopy ◽  
Morphological Characteristics ◽  
Sensu Stricto ◽  
Ssu Rdna ◽  
Morphological Description ◽  
Rdna Sequences ◽  
Attachment Region

SUMMARYPhylogenetic analyses of SSU rDNA sequences have previously revealed the existence of 2 Ichthyobodo species able to infect Atlantic salmon (Salmo salar L.). Ichthyobodo necator sensu stricto (s.s.) is assumed to be a freshwater parasite, while a genetically distinct but undescribed species, Ichthyobodo sp. II sensu Todal et al. (2004) have been detected on Atlantic salmon in both fresh- and seawater. In the present study a morphological description of Ichthyobodo sp. II from the gills of salmon reared in fresh-, brackish- and seawater is presented, using both light- and electron microscopy. Comparative morphometry show that Ichthyobodo sp. II from both freshwater and seawater displays a different cell shape, and is significantly smaller than I. necator s.s. Also, ultrastructural characteristics distinguish these two species, notably differences in the attachment region and the presence of spine-like surface projections in Ichthyobodo sp. II. Based on both unique SSU rDNA sequences and morphological characteristics, we conclude that Ichthyobodo sp. II. represents a novel species for which we propose the name Ichthyobodo salmonis sp. n.

scholarly journals Study on the morphology of Mature ovarian follicles using Image Processing Toolbox

2020 ◽  
Author(s):  
LI-Feng Bao ◽  
Hui-Mei Li
Keyword(s):  
Image Processing ◽  
Retrospective Study ◽  
Reproductive Medicine ◽  
Morphological Characteristics ◽  
Clinical Value ◽  
Equivalent Circle Diameter ◽  
Average Area ◽  
Maximal Diameter ◽  
Measurement Software ◽  
Circle Diameter

Abstract Objective: This study aims to investigate the morphological characteristics of mature follicles with clinical value. Study Design:a retrospective studyMethods: The five morphological indexes of follicles in 72 natural ovulation cycles were measured. The shoot time of follicle photos was the day before ovulation. Measurement software was the MATLAB Image Processing Toolbox. Results: The measured average area, perimeter, equivalent circle diameter and roundness were 301.29 ± 8.52 mm2, 62.23 ± 6.82 mm, 20.21 ± 3.08 mm and 0.89 ± 0.05, respectively; and the maximal diameter was 23.12 ± 3.06 mm. Conclusion: Image Processing Toolbox is a simple and convenient measurement software. The standardization of the reference indexes of follicular morphology has an important clinical application value in reproductive medicine.Research Highlights and Graphical Abstract: In the present study, the morphological characteristics of these folliclesinclude the area, perimeter, maximal diameter, equivalent circle diameter and roundness were preliminarily studied using the related measurement software.

scholarly journals Morphological description of the male genital organs of Pontoporia blainvillei (Gervais & d’Orbigny, 1844)

2020 ◽  
Author(s):  
Caroline Bizarre Randi ◽  
Lucas Guedes Spinelli ◽  
Renata de Britto Mari ◽  
Daniel de Souza Ramos Angrimani ◽  
Carolina Pacheco Bertozzi ◽  
...  
Keyword(s):  
Abdominal Cavity ◽  
Morphological Characteristics ◽  
Microscopic Analysis ◽  
Conservation Strategies ◽  
Morphological Description ◽  
Morphological Aspects ◽  
Pontoporia Blainvillei ◽  
Reproductive Apparatus ◽  
Sexually Mature ◽  
Male Genital

AbstractPontoporia blainvillei or Franciscana is a small cetacean endemic of South Atlantic Ocean and its highlighted as the most endangered species. Despite the necessity to development conservation strategies for Pontoporia blainvillei studies aiming to feature the reproductive biology and morphological characteristics of the genital organs are still scarce. In this context, the aim of this study was describe the morphological aspects of the genital organs of Pontoporia blainvillei. For this purpose, six male specimens of P. blainvillei stranded on the southeast region of Brazil, were used. Initially animals were measured, and the genital organs were collected, dissected and photodocumented. Then, fragments of all collected organs were submitted to microscopic analysis. The male genital organs of P. blainvillei showed similar results described for other cetaceans, such as, topography in abdominal cavity, presence of two testicles with epididymis, fibroelastic penis with sigmoid shape and presence of deferent duct. Moreover, a male uterus non-functional, two vestigial bones that support the penis, one retractor penis muscle and presence of associated muscles that support the entire reproductive apparatus were observed. However, some differences were present, such as, a simple cubic epithelium in the light of the epididymis, a small testicle even in sexually mature animals and absence of prostate, not previously observed in other cetaceans. Therefore, the animals analyzed showed similar features to other cetaceans, however some peculiarities were observed.

scholarly journals BULBOPHYLLUM ACEHENSE (ORCHIDACEAE), A NEW SPECIES OF SECTION BECCARIANA FROM ACEH, SUMATRA, INDONESIA

2020 ◽  
Vol 20 (1) ◽  
pp. 111
Author(s):  
Destario Metusala
Keyword(s):  
New Species ◽  
Morphological Characteristics ◽  
Flower Morphology ◽  
Morphological Description ◽  
Herbarium Specimens ◽  
Botanical Exploration ◽  
Aceh Province ◽  
Plant Habit ◽  
Highland Forests ◽  
A New Species

Abstract: Sumatra island has been considered as one of the diversity centers for Bulbophyllum species in Indonesia. During botanical exploration held in the mid of 2019, specimens of the genus Bulbophyllum (Orchidaceae) section Beccariana have been collected from highland forests in Aceh Province, Sumatra, Indonesia. Their flower morphology and plant habitus are relatively close to Bulbophyllum cornutum (Blume) Rchb.f. (section Beccariana). Therefore, the aim of this research is to compare the Bulbophyllum sp. from Aceh with closely resemble species in section Beccariana, also to describe and illustrate the morphological characteristics of this Bulbophyllum species from Aceh. Morphological description was carried out by characterizing the flowers and plant habit of the living plants, spirit materials, dried herbarium specimens and photographs. Morphological comparisons with other closely resemble Bulbophyllum species were carried out based on data from protologue, living plants, herbarium specimens and several taxonomic references. The result based on morphological comparisons has showed there were several distinct differences on their flower characteristics, especially on the labellum. Therefore, this Bulbophyllum sp. from Aceh is here described and illustrated as new species, namely Bulbophyllum acehense.Keywords: Bulbophyllum, Sumatra, Orchidaceae 

Towards validating a last generation, integrated wave-current-sediment numerical model in coastal regions using video measurements

2011 ◽  
Vol 40 (4) ◽  
Author(s):  
Sandro Carniel ◽  
Mauro Sclavo ◽  
Renata Archetti
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Dominant Role ◽  
Low Cost ◽  
Water Area ◽  
In Situ Data ◽  
Roms Model ◽  
Shallow Water Area ◽  
River Region ◽  
Alongshore Sediment Transport

AbstractThis paper presents the first steps in the implementation of a morphological numerical model to be applied in the Bevano River region, a shallow water area in the Adriatic Sea, with the aim of helping the identification and assessment of erosional patterns and bottom morphological modifications induced by severe marine storms. The numerical modeling, performed using a fully 3D coupled wave-current-sediment version of the ROMS model, has been complemented with in situ data analysis and observations: a first qualitative validation of the results was given by the analysis of images acquired via an ARGUS video station.Hydrodynamic modeling highlighted how shear bottom stresses and bottom currents fields were heavily influenced by severe storm situations, and had large effects on the morphology of shallow regions. The correlation between the wave-current induced bottom stresses and the resulting topography was investigated. Nearshore hydrodynamics modeling results demonstrated the dominant role played by alongshore sediment transport, with the magnitude of both cross- and along-shore wave-induced currents strongly depending on wave height and direction.We found a good qualitative conformity between the results of the numerical models applied during a “Bora” storm and the corresponding video observations; both techniques indicated the migration of the existing sandbar within the range of about 40 m seaward.Results show how integrated numerical open source tools, often used in oceanography, are becoming suitable for both preliminary investigations and for planning the effective littoral management, and how their calibration can be supported by the use of new low cost techniques, such as video measurements.

scholarly journals MORPHOLOGICAL CHARACTERISTICS AND NOMENCLATURE OF LEPTOSPIRA (SPIROCHÆTA) ICTEROHÆMORRHAGIÆ (INADA AND IDO)

1918 ◽  
Vol 27 (5) ◽  
pp. 575-592 ◽  
Author(s):  
Hideyo Noguchi
Keyword(s):  
Comparative Study ◽  
Causative Agent ◽  
New Genus ◽  
Morphological Characteristics ◽  
Systematic Position ◽  
The Body ◽  
Morphological Description ◽  
Caudal Portion ◽  
Destructive Action ◽  
Distinguishing Features

The present study deals with the morphology and systematic position of the causative agent of infectious jaundice. There are several features which are not found in any of the hitherto known genera of Spirochætoidea which led me to give this organism an independent generic name, Leptospira, denoting the peculiar minute elementary spirals running throughout the body. The absence of a definite terminal flagellum or any flagella, and the remarkable flexibility of the terminal or caudal portion of the organism are other distinguishing features. Unlike all other so called spirochetes the present organism resists the destructive action of 10 per cent saponin. A detailed comparative study of related genera, including Spirochæta, Saprospira, Cristispira, Spironema, and Treponema, has been given with the view of bringing out more strongly the contrast between them and the new genus. A study has been made to discover whether any differential features exist among the strains of Leptospira icterohæmorrhagiæ derived from the American, Japanese, and European sources, but none has been found. It is hoped that the creation of a new genus may facilitate a more exact morphological description than has hitherto been possible, due to the vague use of the term Spirochæta which indiscriminately covered at least six large genera of spiral organisms.

scholarly journals BEACH MORPHOLOGIES AT NOTSUKEZAKI SAND SPIT, JAPAN

2011 ◽  
Vol 1 (32) ◽  
pp. 48 ◽  
Author(s):  
Kentaro Hayashi ◽  
Koji Hayashimoto ◽  
Kazuki Yagisawa ◽  
Nobuhisa Kobayashi
Keyword(s):  
Numerical Model ◽  
Morphological Changes ◽  
Morphological Characteristics ◽  
Field Observations ◽  
Aerial Photos ◽  
Wave Hindcast ◽  
Beach Processes ◽  
Sand Spit ◽  
Term Field

Notsukezaki Sand Spit is the longest sand spit in Japan and the wave and morphological characteristics vary along the spit. The main purpose of this study is to investigate the morphological changes of the sand spit for long-term and mid-term field observations and aerial photos. The natural and morphological characteristics are investigated based on the field observations and aerial photos for a long-term period (decades). The regional sediment budget is estimated using the shoreline changes and the result of wave hindcast simulation for five years. Finally, the cross-shore beach processes are examined using the numerical model, CSHORE.

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