scholarly journals Wave-Forced Dynamics at Microtidal River Mouths

2021 ◽  
Author(s):  
Maurizio Brocchini ◽  
Matteo Postacchini ◽  
Lorenzo Melito ◽  
Eleonora Perugini ◽  
Andrew J. Manning ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Morphological Evolution ◽  
River Mouth ◽  
Dynamic Environments ◽  
Sea Waves ◽  
Literature Evidence ◽  
Waves And Tides ◽  
Mouth Bars ◽  
River Mouths

Microtidal river mouths are dynamic environments that evolve as a consequence of many forcing actions. Under the hydrodynamic viewpoint, river currents, sea waves and tides strongly interact, and their interplay determines specific sediment transport and morphological patterns. Beyond literature evidence, information comes from field observations made at the Misa River study site, a microtidal river along the Adriatic Sea (Italy), object of a long-going monitoring. The river runs for 48 km in a watershed of 383 km2, providing a discharge of about 400 m3/s for return periods of 100 years. The overall hydrodynamics, sediment transport and morphological evolution at the estuary are analyzed with particular attention to specific issues like: the generation of vortical flows at the river mouth, the influence of various wave modes (infragravity to tidal) propagating upriver, the role of sediment flocculation, the generation and evolution of bed features (river-mouth bars and longitudinal nearshore bars). Numerical simulations are also used to clarify specific mechanisms of interest.

ROLE OF MOUTH PROCESSES IN THE DYNAMICS OF ACCUMULATIVE FORMS IN COASTAL ZONE OF BLACK SEA (WITHIN THE RUSSIAN SECTOR)

2018 ◽  
Author(s):  
М. Исупова ◽  
M. Isupova
Keyword(s):  
Black Sea ◽  
River Mouth ◽  
The Black Sea ◽  
Special Role ◽  
Coastal System ◽  
System A ◽  
Russian Sector ◽  
Mouth Bars ◽  
River Mouths

The processes in the river mouth areas play a special role in the formation and dynamics of coastal accumulative forms. The experience of Russian and foreign specialists on investigations of river mouths shows a modern intensification of sea impact on the river deltas in the world and enhance the abrasion of their delta coastlines. These processes show a trend of transformation of different mouths from the fluvial-dominated objects to the marine-dominated objects. A striking example of this process is the variability of the mouth fan, which has a complicated structure, and the mouth bars. In most cases, the structure of the mouth fan presents several successive layers. There are the following 1) abovewater and submarine sand layers; 2) layer of silty sediments of the sea slope of the mouth fan; 3) gently sloping layers of clay, component the foot of the mouth fan; 4) layer of shelf sand, not related to the formation of mouth fan. Each of these layers is characterized by a specific size and composition of sediments. Under intensification of abrasion of the mouth accumulative forms (accordance with the stage of this abrasion), the sediments significantly differed by composition, can be penetrate in the lithodynamic coastal system. A rather complex topography of the underwater slope rugged canyons is typical for the Russian coast of the Black Sea. Through these canyons, sediments, entering the river mouth area and playing an important role in the dynamics of coastal accumulative forms, can be delivered to the depths. These depths exclude of their return.

scholarly journals The Effect of Wave-Induced Current and Coastal Structure on Sediment Transport at the Zengwen River Mouth

2021 ◽  
Vol 9 (3) ◽  
pp. 333
Author(s):  
Chun-Hung Pao ◽  
Jia-Lin Chen ◽  
Shih-Feng Su ◽  
Yu-Ching Huang ◽  
Wen-Hsin Huang ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Finite Difference ◽  
Finite Volume ◽  
Morphological Evolution ◽  
River Mouth ◽  
Water Levels ◽  
Coastal Structures ◽  
Sea Bed ◽  
Residual Transport ◽  
Wave Induced

The mechanisms that control estuarine sediment transport are complicated due to the interaction between riverine flows, tidal currents, waves, and wave-driven currents. In the past decade, severe seabed erosion and shoreline retreat along the sandy coast of western Taiwan have raised concerns regarding the sustainability of coastal structures. In this study, ADCPs(Acoustic Doppler Current Profiler) and turbidity meters were deployed at the mouth of the Zengwen river to obtain the time series and the spatial distribution of flow velocities and turbidity during the base flow and flood conditions. A nearshore circulation model, SHORECIRC, has been adapted into a hybrid finite-difference/finite-volume, TVD (Total Variation Diminishing)-type scheme and coupled with the wave-spectrum model Simulating Waves Nearshore (SWAN). Conventional finite-difference schemes often produce unphysical oscillations when modeling coastal processes with abrupt bathymetric changes at river mouths. In contrast, the TVD-type finite volume scheme allows for robust treatment of discontinuities through the shock-capturing mechanism. The model reproduces water levels, waves, currents observed at the mouth of the Zengwen River reasonably well. The simulated residual sediment transport patterns demonstrate that the transport process at the river mouth is dominated by the interaction of the bathymetry and wave-induced currents when the riverine discharge was kept in reservoirs. The offshore residual transport causes erosion at the northern part of the river mouth, and the onshore residual transport causes accretion in the ebb tidal shoals around the center of the river mouth. The simulated morphological evolution displays significant changes on shallower deltas. The location with significant sea bed changes is consistent with the spot in which severe erosion occurred in recent years. Further analysis of morphological evolution is also discussed to identify the role of coastal structures, for example, the extension of the newly constructed groins near the river mouth.

scholarly journals Prediksi Transport Sedimen di Perairan Teluk Tahuna Kabupaten Kepulauan Sangihe

2020 ◽  
Vol 9 (3) ◽  
pp. 207-214
Author(s):  
Eunike Kumaseh ◽  
Yuliana Varala Tatontos ◽  
Costantein Imanuel Sarapil
Keyword(s):  
Sediment Transport ◽  
Sedimentation Rate ◽  
Sediment Trap ◽  
Research Method ◽  
Soil Mechanics ◽  
River Estuary ◽  
River Mouth ◽  
Measurement Results ◽  
River Mouths

ABSTRAK: Secara geografis, Teluk Tahuna diapit oleh 2 muara sungai yaitu Muara Sungai Tidore, yang dekat dengan Pelabuhan Nusantara Tahuna, dan Muara Sungai Towo’e. Hal ini memungkinkan terjadinya sedimentasi.Sehingga, perlu diketahui besarnya angkutan sedimen yang terjadi di perairan Teluk Tahuna.Metode penelitian yang digunakan yaitu membandingkan metode Engelund-Hansen dengan hasil pengukuran di lapangan. Pengambilan sedimen menggunakan sediment trap dan diukur selama 2 minggu sekali sebanyak 5 kali. Sedimen dibawa ke Laboratorium Mekanika Tanah untuk memperoleh ukuran diameter sedimen. Lokasi penelitian dibagi menjadi 3 stasiun, Stasiun 1 dekat muara sungai Tidore, Stasiun 2 pada bagian tengah perairan, dan Stasiun 3 dekat muara sungai Towoé. Hasil prediksi transport sedimen di Perairan Teluk Tahuna dengan metode Engelund-Hansen yaitu pada Stasiun 1 = 0,00000291(m3/m*s), Stasiun 2 = 0,00000697(m3/m*s), dan Stasiun 3 = 0,00000789(m3/m*s). Perhitungan transport sedimen yang paling tinggi adalah di Stasiun 3. Pengukuran laju sedimentasi yaitu pada Stasiun 1 sebesar 0,0000029 m3/hari, Stasiun 2 sebesar 0,0000053 m3/hari dan pada Stasiun 3 sebesar 0,0000072 m3/ hari. Rata – rata hasil pengukuran yang paling tinggi juga ada di Stasiun 3,yaitu dekat Muara Sungai Towoé. Hasil prediksi Metode Engelund-Hansen hampir sama dengan hasil pengukuran laju sedimen di lapangan. Metode Engelund-Hansen cocok digunakan untuk memprediksi transport sedimen di Perairan Teluk Tahuna. ABSTRACT: Geographically, Tahuna Bay has 2 river mouths, the Tidore river mouth, which is close to the Tahuna Harbor, and Towo'e river mouth. This allows sedimentation. So, it is necessary to know the calculation of sediment transport. The research method is comparing the Engelund-Hansen method with the results of measurements. Sediment rate measured by sediment trap and once in 2 weeks for 5 times. Sediments were taken to the Soil Mechanics Laboratory. The location was divided into 3 stations. The results of prediction of sediment transport in Tahuna Bay with the Engelund-Hansen method are Station 1  = 0,00000291 (m3/m*s), Station 2  = 0,00000697 (m3/m *s), and Station 3  = 0,00000789 (m3/m*s). The highest calculation of sediment transport is at Station 3. The average measurement of sedimentation rate at Station 1 of 0,0000029 m3/day, Station 2 of 0,0000053 m3/day and at Station 3 is 0,0000072 m3/day. The highest average measurement results are also at Station 3, which is near the Towoé River Estuary. The predicted results of the Engelund-Hansen Method are almost the same as those of the sediment rate measurements in the field. Engelund-Hansen Method can be used to predict the sediment transport in Tahuna bay.

scholarly journals TÁC ĐỘNG CỦA CÁC ĐIỀU KIỆN SÓNG ĐẾN ĐẶC ĐIỂM VẬN CHUYỂN BÙN CÁT VÀ BIẾN ĐỘNG ĐỊA HÌNH ĐÁY VÙNG CỬA SÔNG VEN BIỂN HẢI PHÒNG

2018 ◽  
Vol 18 (1) ◽  
pp. 10-26 ◽  
Author(s):  
Vu Duy Vinh ◽  
Tran Dinh Lan
Keyword(s):  
Sediment Transport ◽  
Coastal Area ◽  
Wave Climate ◽  
Model System ◽  
Climate Condition ◽  
Deposition Zone ◽  
Simulation Results ◽  
Set Up ◽  
River Mouths

The model system for the Hai Phong coastal area was set up based on the wave climate condition between 1992-2014 and the MORFAC (the morphological acceleration factor) method in the Delft3D model. The model results of more than 50 separate simulated scenarios show the role of each wave interval and direction on characteristics of sediment transport and morphological change in the studied area. In the case of without wave, sediments from the river settle and create deposition zone in river mouths. When the wave height increases, the erosion/deposition and sediment transport in the coastal zone increase. Due to the influence of the hydrodynamics and sediment transport, the erosion/deposition rate in the dry season is higher than that in the rainy season. The morphology strongly change in the depth less than 5 - 6 m with the rate of 20 - 50 mm/year. In the water zone of over 6 m, the morphology relatively stable and reflects an accretion trend with the rate of 10 - 20 mm/year. The simulation results also show an accretion trend in the Hai Phong coastal area. It may be a consequence of the decrease in the number of big typhoons impacted on this area in the last 20 years.

scholarly journals O-GlcNAcylation protein disruption by Thiamet G promotes changes on the GBM U87-MG cells secretome molecular signature

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Maria Cecilia Oliveira-Nunes ◽  
Glaucia Julião ◽  
Aline Menezes ◽  
Fernanda Mariath ◽  
John A. Hanover ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Critical Role ◽  
Molecular Signature ◽  
Label Free ◽  
Intercellular Signaling ◽  
Tumor Aggressiveness ◽  
Signaling Axis ◽  
Literature Evidence ◽  
Therapeutic Tools

AbstractGlioblastoma (GBM) is a grade IV glioma highly aggressive and refractory to the therapeutic approaches currently in use. O-GlcNAcylation plays a key role for tumor aggressiveness and progression in different types of cancer; however, experimental evidence of its involvement in GBM are still lacking. Here, we show that O-GlcNAcylation plays a critical role in maintaining the composition of the GBM secretome, whereas inhibition of OGA activity disrupts the intercellular signaling via microvesicles. Using a label-free quantitative proteomics methodology, we identified 51 proteins in the GBM secretome whose abundance was significantly altered by activity inhibition of O-GlcNAcase (iOGA). Among these proteins, we observed that proteins related to proteasome activity and to regulation of immune response in the tumor microenvironment were consistently downregulated in GBM cells upon iOGA. While the proteins IGFBP3, IL-6 and HSPA5 were downregulated in GBM iOGA cells, the protein SQSTM1/p62 was exclusively found in GBM cells under iOGA. These findings were in line with literature evidence on the role of p62/IL-6 signaling axis in suppressing tumor aggressiveness and our experimental evidence showing a decrease in radioresistance potential of these cells. Taken together, our findings provide evidence that OGA activity may regulate the p62 and IL-6 abundance in the GBM secretome. We propose that the assessment of tumor status from the main proteins present in its secretome may contribute to the advancement of diagnostic, prognostic and even therapeutic tools to approach this relevant malignancy.

Sign in / Sign up

Export Citation Format

Share Document