scholarly journals Exchange Mechanism of the Suspended Sediment at the Mouth of Hangzhou Bay under Coastline Changes

2021 ◽  
Vol 233 ◽  
pp. 03035
Author(s):  
Zhuzhu Yu ◽  
Zhiguo He ◽  
Li Li ◽  
Taoyan Ye ◽  
Yuezhang Xia
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Exchange Mechanism ◽  
Hangzhou Bay ◽  
The South ◽  
Topographic Data ◽  
The North ◽  
Water And Sediment ◽  
Open Sea ◽  
Inflowing Water

Based on FVCOM hydrodynamic numerical model and coastline topographic data in 2013, a three-dimensional numerical model of fine sediment transport in Hangzhou Bay has been established to explore the water and sediment exchange mechanism between Hangzhou Bay and the open sea at different typical sections. The results of validation with measured and satellite retrieved data show that the model can well simulate the process of water and sediment movement in Hangzhou Bay. Compared with the calculation results of the coastline topographic data of Hangzhou Bay in 1974 and 2020, the influence mechanism of shoreline change on the water and sediment exchange mechanism between Hangzhou Bay and the open sea has been studied. The results show that the sediment transport inside and outside the Hangzhou Bay is generally in the pattern of north-inflow and south-discharge. Compared with the coastline in 1974, the sediment transport from Yangshan port in the north of Hangzhou Bay and Zhoushan Islands in the middle of Hangzhou Bay increases when the coastline is pushed into the bay in 2020, while the outward sediment transport from Jintang Channel in the South decreases. The overall trend features that the sediment transport into the bay increases, with the bay mouth silting. In the three sections extending from Hangzhou Bay to the open sea, the inflowing water and sediment of the horizontal section on the north side is decreasing, while the discharged sediment from the south side and the inflowing water and discharged sediment from the vertical section at the east side are increasing.

scholarly journals Transport Mechanism of Suspended Sediments and Migration Trends of Sediments in the Central Hangzhou Bay

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2189
Author(s):  
Zekun Song ◽  
Weiyong Shi ◽  
Junbiao Zhang ◽  
Hao Hu ◽  
Feng Zhang ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Hangzhou Bay ◽  
The South ◽  
Transport Mode ◽  
Tidal Pumping ◽  
The North

Based on the 2013 field survey data of hydrology, suspended sediments and bottom sediments in the Central Hangzhou Bay, this paper explores the dynamic mechanism of suspended sediments in Hangzhou Bay by employing material flux decomposition. Meanwhile, the migration trends of bed sediments are also investigated by analyzing grain size trends. The results show that during an ebb or flood tide, the hydrograph of suspended sediment concentration of Hangzhou Bay is dominated by an M shape (bimodal), which is attributed primarily to the generation of a soft mud layer and a separate fluid mud layer. Laterally, the distribution of suspended sediment concentration is high in the south and low in the north. From a macroscopic perspective, the net sediment transport in the study area displays a “north-landward and south-seaward” trend, presenting a “C”-shaped transport mode. That is, the sediments are transported from the bay mouth to the bay head on the north side and from the bay head to the bay mouth on the south side. The sediment transports by advection and tidal pumping are predominant, while the sediment transport by vertical circulation makes little contribution to the total sediment transport. Moreover, the sediment transport in the center of the reach area is dominated by advection, whereas that near both sides of the banks is controlled by tidal pumping. The asymmetry of the tides, i.e., flood-dominance in the north and ebb-dominance in the south, is the primary cause of the dynamic mechanism for the overall “C”-shaped transport mode in Hangzhou Bay. Additionally, coupled with the narrow-head wide-mouth geomorphology, Hangzhou Bay remains evolving by south shore silting and north shore scouring.

Study Impact on Water and Sediment from Nansha Harbor

2014 ◽  
Vol 1065-1069 ◽  
pp. 634-637
Author(s):  
Jie He ◽  
Jing Chen
Keyword(s):  
Numerical Model ◽  
Suspended Sediment ◽  
The South ◽  
The North ◽  
Water And Sediment ◽  
Harbor Area

The construction of a series of docks in Nansha harbor would lead to the increase of the sediment silting in harbor basin, and the forecast for the amount of the sediment silting is a necessary work to do. The numerical model through verification shows that the source of suspended sediment is from the south of the harbor area, the thickness of sediment silting along the harbor has the characteristic ‘low in the north and high in the south’, and the sediment silting in phase IandII basin will be declined after construction. Those characteristics will be a good suggestion for us to design the planned harbor.

scholarly journals Numerical Investigation of Hydrodynamics and Cohesive Sediment Transport in Cua Lo and Cua Hoi Estuaries, Vietnam

2021 ◽  
Vol 9 (11) ◽  
pp. 1258
Author(s):  
Viet Thanh Nguyen ◽  
Minh Tuan Vu ◽  
Chi Zhang
Keyword(s):  
Sediment Transport ◽  
Great Influence ◽  
Wave Model ◽  
Sediment Concentration ◽  
Wave Climate ◽  
Cohesive Sediment ◽  
Wave Direction ◽  
The South ◽  
The North ◽  
Cohesive Sediment Transport

Two-dimensional models of large spatial domain including Cua Lo and Cua Hoi estuaries in Nghe An province, Vietnam, were established, calibrated, and verified with the observed data of tidal level, wave height, wave period, wave direction, and suspended sediment concentration. The model was then applied to investigate the hydrodynamics, cohesive sediment transport, and the morphodynamics feedbacks between two estuaries. Results reveal opposite patterns of nearshore currents affected by monsoons, which flow from the north to the south during the northeast (NE) monsoon and from the south to the north during the southeast (SE) monsoon. The spectral wave model results indicate that wave climate is the main control of the sediment transport in the study area. In the NE monsoon, sediment from Cua Lo port transported to the south generates the sand bar in the northern bank of the Cua Hoi estuary, while sediment from Cua Hoi cannot be carried to the Cua Lo estuary due to the presence of Hon Ngu Island and Lan Chau headland. As a result, the longshore sediment transport from the Cua Hoi estuary to the Cua Lo estuary is reduced and interrupted. The growth and degradation of the sand bars at the Cua Hoi estuary have a great influence on the stability of the navigation channel to Ben Thuy port as well as flood drainage of Lam River.

scholarly journals Modeling of Sediment Transport Using Wave Height action in Fialaka Marina

2021 ◽  
Vol 958 (1) ◽  
pp. 012023
Author(s):  
K Al-Salem ◽  
A Al-Rashed
Keyword(s):  
Sediment Transport ◽  
Spring Tide ◽  
Arabian Gulf ◽  
Coarse Sand ◽  
Point Of View ◽  
The South ◽  
Plan View ◽  
The North ◽  
Failaka Island ◽  
Southern Half

Abstract Failaka Island is the second-largest and one of the most important islands of Kuwait from the point of view of tourism located in the north Arabian Gulf. It has a marina constructed in 1979 and managed by the Ministry of Communication (MOC) and a tourism enterprise, and is widely used for its ferry landing facility. The coastal waters around Failaka are turbid and current velocities tend to be as high as ~0.5 m/s during spring tide. The marina basin, with axial plan view dimensions of about 285 m by 260 m experiences shoaling of naturally flocculated fine (cohesive) sediment and coarse sand in the entrance channel and more generally in the southern half of the basin. A particularly noteworthy zone of heavy and visible shoaling is along the inner side of the south breakwater close to the entrance. The marina at Failaka Island is suffering from siltation and sediment deposing issues. This study was carried out numerically to assess the annual sedimentation, sediment direction, and longshore current from locations around the existing marina to help in a suggestion of the solutions to reduce the siltation and sediment deposing based on sediments transport direction on marina entrance. A newly developed numerical solution for annual longshore sediments transport was used to estimate the total sediment transport and its direction. The study shows that the annual sediment transport directions which affect the Fialaka marina entrance are coming from the south to north due to wave action.

scholarly journals Impacts of Massive Sediment Input on the Channel Geometry Adjustment of Alluvial Rivers: Revisiting the North Fork Toutle River Case

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2802
Author(s):  
Xiaofan Wang ◽  
Xudong Ma ◽  
Xingnian Liu
Keyword(s):  
Sediment Transport ◽  
Hydraulic Geometry ◽  
Medium Term ◽  
Channel Geometry ◽  
Channel Adjustment ◽  
The North ◽  
Water And Sediment ◽  
North Fork ◽  
Sediment Input ◽  
Downstream Hydraulic Geometry

In this study, the impacts of massive sediment input on channel geometry adjustment were analyzed across decades based on the downstream hydraulic geometry. Massive amounts of field data and evolution models showed that the alternation of degradation and aggradation in short-to-medium-term channel adjustment is common in evolving rivers. This phenomenon has always been challenging in research; most existing studies have focused on unidirectional adjustment in short-term channel adjustment. A few studies have considered the alternation of degradation and aggradation in short-to-medium-term channel adjustment, presuming that this phenomenon is caused by water and sediment changes. However, we found that the alternations also occurred under stable water and sediment transport in the North Fork Toutle River, southwestern Washington, USA. This adjustment across decades was analyzed by downstream hydraulic geometry in this study. It was concluded that the river consumes surplus energy to reach the optimal cross section through this short-to-medium-term adjustment under stable water and sediment transport. The objective of channel adjustment is minimal energy loss.

scholarly journals Microfacies Architecture and Stratigraphic Development of the Yamama Formation, Southern Iraq

2019 ◽  
Vol 60 (5) ◽  
pp. 1115-1128
Author(s):  
Taisir Ghanem Zaki Al Mafraji ◽  
Aiad Ali Hussien Al-Zaidy
Keyword(s):  
Depositional Environment ◽  
The South ◽  
Third Order ◽  
The North ◽  
Open Sea ◽  
Sulaiy Formation ◽  
Maximum Flooding Surface ◽  
Cretaceous Period ◽  
Petrographic Study ◽  
Southern Iraq

The Yamama Formation belongs to the late Berriasian-Aptian succession, which was deposited during the Lower Cretaceous period within the main shallow marine depositional environment. Petrographic study and microfacies analysis enabled the recognition of six main microfacies for three association facies. These are the Semi-restricted, Shallow open marine and Shoal environments. The study succession represents deposition of three third order cycles, these cycles where deposited during successive episodes of relative sea level rises and still stand. The presence of shoal association facies (oolitic packstone microfaces) between the Sulaiy and Yamama formations refer to continue the deposition during the same stage, and may suggest the end of Sulaiy Formation was maximum flooding surface (mfs). The first stage started with occurrence of the shallow open marine association facies underlain by semi-restricted association and then shoal association facies. There are three cycles of this sequence consistently in the south of the study area, so that it continues to the lower part of the Ratawi Formation to be the upper contact of the Yamama Formation of a conformable and continuous in sedimentation To the north of the study area (near of Rf-1 and  Hf-5 wells) the shoal association was only shown once at the bottom of the Yamama Formation and these cycles to became unclear.  This suggest that the paleo-high was developed to the south of studied area, while the open sea was characterized the northern part.

scholarly journals The genetic structure of Norway

2020 ◽  
Author(s):  
Morten Mattingsdal ◽  
S. Sunna Ebenesersdóttir ◽  
Kristjan H. S. Moore ◽  
Ole A. Andreassen ◽  
Thomas F. Hansen ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Maritime History ◽  
The South ◽  
Effective Population ◽  
The North ◽  
Open Sea ◽  
Norwegian Population ◽  
Northern Border ◽  
Single Marker ◽  
Fixation Indices

AbstractThe aim of the present study was to describe the genetic structure of the Norwegian population using genotypes from 6369 unrelated individuals with detailed information about places of residence. Using standard single marker- and haplotype-based approaches, we report evidence of two regions with distinctive patterns of genetic variation, one in the far northeast, and another in the south of Norway, as indicated by fixation indices, haplotype sharing, homozygosity and effective population size. We detect and quantify a component of Uralic Sami ancestry that is enriched in the North. On a finer scale, we find that rates of migration have been affected by topography like mountain ridges. In the broader Scandinavian context, we detect elevated relatedness between the mid- and northern border areas towards Sweden. The main finding of this study is that despite Norway’s long maritime history and as a former Danish territory, the region closest to mainland Europe in the south appears to have been the most isolated region in Norway, highlighting the open sea as a barrier to gene flow.

The Cnidia

1952 ◽  
Vol 47 ◽  
pp. 171-212 ◽  
Author(s):  
G. E. Bean ◽  
J. M. Cook
Keyword(s):  
Coastal Plains ◽  
The South ◽  
The West ◽  
Gentle Slope ◽  
The North ◽  
North Side ◽  
North Wind ◽  
Open Sea ◽  
Fertile Land

‘Their land lies towards the open sea—and this is the part which is called Triopion—but begins at the Bybassian Chersonese; and the whole of the Cnidia except for a little bit is surrounded by water, the part facing the north wind being bounded by the Ceramic Gulf, and that on the south by the sea towards Syme and Rhodes. This little bit, then, which is about five stades across, the Cnidians began to dig while Harpagus was conquering Ionia, with the intention of making their land an island. The whole of it was to lie inside; for where the Cnidian land terminates at the mainland, there is the isthmus which they began to dig’ (Hdt. I 174).The Cnidian peninsula measures 63 km. from base to tip. It consists of two mountain masses joined by an isthmus not much more than 2 km. broad. That on the east is rugged and almost uninhabited; but the greater western massif, though barren and sheer on the north side and at the west tip, has fertile land to offer in the small coastal plains of the south and especially in the valley which traverses the interior from Zeytincik to beyond Yaziköy, with its main outlet below Kumyer and a backdoor at Barkaz. A low ridge runs the length of the isthmus with a gentle slope towards the Gulf of Syme and an easy crossing from Reşadiye to the Ceramic Gulf at Körmen Limani.

Partial validation of a numerical model for tidal motion in the Tay Estuary

1987 ◽  
Vol 92 (3-4) ◽  
pp. 275-283
Author(s):  
D. J. Gunn ◽  
J. McManus ◽  
O. Yenigun
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Boundary Conditions ◽  
North Sea ◽  
Integral Method ◽  
The Road ◽  
Tidal Motion ◽  
The North ◽  
Open Sea ◽  
The North Sea

SynopsisIn a mathematical model of the Tay (Gunn & Yenigun 1987) based upon the Local Integral Method (Gunn & Yenigun 1985), tidal levels at the seaward boundaries and velocities at landward boundaries are used in setting boundary conditions, so that validation studies are mainly based upon changes in internal tidal levels, and comparison between computed and measured velocities within the modelled region. The comparisons of tidal levels within this estuary over a 5.0 m tide showed agreement with overall values from Buddon Ness to the rail bridge, but within the overall agreement there were significant differences in the immediate vicinity of the road bridge. Velocities predicted within the estuary have been compared with measurements provided by a number of surveys in the period from 1972-78. The agreement between experiment and prediction was good in the central and western regions of the model, but the comparison between measurement and prediction was less good near the eastern boundaries. The principal reason for poorer agreement in the east was the difficulty in setting boundary conditions at the open sea extremes of the model. The most satisfactory way of improving the model near the open sea boundaries would be to link the model for the Tay with a model for velocity and level in the North Sea.

A Sula-Ulúa Pottery Kiln

1941 ◽  
Vol 7 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Doris Stone ◽  
Conchita Turnbull
Keyword(s):  
River Valley ◽  
North Coast ◽  
The South ◽  
River Systems ◽  
The West ◽  
The North ◽  
Open Sea ◽  
Pottery Kiln ◽  
Semi Arid

On the western end of the north coast of Honduras, the outstanding river is the Ulúa, whose basin is formed by the plain of Sula. In the south, the gradually descending steps of the Cordilleras with the open avenues of the Ulúa on the west and her tributaries, the Lindo due south and the Comayagua at the east, bring contact to the wet valley of Sula from the semi-arid interior. Eastward lies the low margin of coast and the lagoons and river systems of the Pijol range. West and southwest is mountain land with an important river valley, the Chamelicon, which merges into the Sula plain. At the north is the open sea, bringing to this region varied influences from many and distant places.

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