scholarly journals Nearshore Waves and Littoral Drift Along a Micro-Tidal Wave-Dominated Coast Having Comparable Wind-Sea and Swell Energy

2020 ◽  
Vol 8 (1) ◽  
pp. 55
Author(s):  
Jesbin George ◽  
V. Sanil Kumar ◽  
R. Gowthaman ◽  
Jai Singh
Keyword(s):  
Sediment Transport ◽  
Wave Model ◽  
Model Data ◽  
Wave Direction ◽  
Littoral Drift ◽  
Relative Contribution ◽  
Wave Parameters ◽  
Longshore Sediment Transport ◽  
Wind Sea ◽  
Small Change

The nearshore wave characteristics and variations in littoral drift (longshore sediment transport; LST) are estimated based on different approaches for four years along the Vengurla coast, with comparable wind-sea and swell energy assessed. The waverider buoy-measured data at 15 m water depth is utilized as the input wave parameters along with the reanalysis model data, and the numerical wave model Delft-3D is used for estimating the nearshore wave parameters. The relative contribution of wind-seas and swells on LST rates are specifically examined. The clear prevalence of west-southwest waves implies the prevalence of south to north longshore sediment transport with net transport varying from 0.19–0.37 × 105 m3/yr. LST is strongly dependent on the breaker angle and a small change in the wave direction substantially alters the LST, and hence reanalysis/model data with coarse resolutions produce large errors (~38%) in the LST estimate. The annual gross LST rate based on integral wave parameters is only 58% considering the wind-seas and swells separately, since the wind-sea energy is comparable to swell energy, and the direction of these two systems differs significantly.

scholarly journals Global ship accidents and ocean swell-related sea states

2017 ◽  
Author(s):  
Zhiwei Zhang ◽  
Xiao-Ming Li
Keyword(s):  
Environmental Issues ◽  
Wave Model ◽  
Economic Losses ◽  
Model Data ◽  
Wave Direction ◽  
Sea State ◽  
Mean Wave Period ◽  
The Mean ◽  
Numerical Wave ◽  
Wind Sea

Abstract. With the increased frequency of shipping activities, navigation safety has become a major concern, especially when economic losses, human casualties and environmental issues are considered. As a contributing factor, sea state conditions play a significant role in shipping safety. However, the types of dangerous sea states that trigger serious shipping accidents are not well understood. To address this issue, we analyzed the sea state characteristics during ship accidents that occurred in poor weather or heavy seas based on a ten-year ship accident dataset. The sea state parameters, including the significant wave height, the mean wave period and the mean wave direction, obtained from numerical wave model data were analyzed for selected ship accidents. The results indicated that complex sea states with the co-occurrence of wind sea and swell conditions represent threats to sailing vessels, especially when these conditions include close wave periods and oblique wave directions.

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 Coastline changes in relation to longshore sediment transport and human impact, along the shoreline of Kato Achaia (NW Peloponnese, Greece)

2001 ◽  
Vol 2 (1) ◽  
pp. 5 ◽  
Author(s):  
S. POULOS ◽  
G. CHRONIS
Keyword(s):  
Sediment Transport ◽  
Human Activities ◽  
Dynamic Equilibrium ◽  
Littoral Drift ◽  
Coastal System ◽  
Longshore Sediment Transport ◽  
Longshore Drift ◽  
Management Plans ◽  
Natural Equilibrium ◽  
Oblique Approach

Coastal configuration depends upon the equilibrium between available sediment budget and prevailing nearshore wave and current conditions. Human activities often disturb this natural equilibrium by altering the sources of beach material and littoral drift pattern. In the coastal zone of NW Peloponnese, an essentially tideless environment, the oblique approach of wind-induced waves implies an overall longshore drift from east to west. On an annual basis, the potential longshore sediment transport rates at the different sections of the study area (Kato Achaia) is estimated to vary between 0.02 10-3 m3/s and 5 103 m3/s and to fluctuate seasonally. The construction of a port and the extraction of aggregates from the R. Peiros have changed significantly the pattern of sediment transport inducing dramatic changes on coastline configuration; thus, the part of the coastline west to the port had retreated as much as 70 m eliminating a touristic beach, while the entrance of the port was silted inhibiting navigation. Coastal engineering measures, such as modification of port-breakwaters and construction of groins have had only minimal contribution in beach recovery. Hence, coastal management plans should consider this dynamic equilibrium and protect the natural coastal system from the arbitrary human activities.

scholarly journals Effects of waves and currents on the siltation problem of Damietta harbour, Nile Delta coast, Egypt

2007 ◽  
Vol 8 (2) ◽  
pp. 33 ◽  
Author(s):  
ABO BAKER.I. ABO ZED
Keyword(s):  
Sediment Transport ◽  
Nile Delta ◽  
Monitoring Program ◽  
Wave Direction ◽  
Littoral Drift ◽  
Wave Refraction ◽  
The North ◽  
Dynamic Factors ◽  
Navigation Channel ◽  
Nile Delta Coast

This study evaluates the effect of prevailing dynamic factors on the sedimentation process in Damietta Harbour along the Nile delta coast of Egypt. The monitoring program spanned the period between 1978 and 1999 and included measurements of waves, currents and bathymetric profiles. The evaluation was based on determination of erosion and accretion rates, current regime, sediment transport, wave characteristics and wave refraction. Results revealed that the predominant wave direction from N-NW sector (86 %) throughout the year is responsible for generation of a longshore eastward current. Less frequent waves from the N-NE sector generate an opposing longshore westward current. The refraction pattern for the prevailing wave direction indicates that the harbour and its navigation channel are located within a divergence of wave orthogonal and in an accretion sediment sink area. The annual net rate of littoral drift on the western side of the harbour is about 1.43 * 105 m3 (accretion), while the annual net rate of littoral drift on the eastern side is about 2.54 * 105 m3 (erosion). Currents fluctuate tremendously in speed and direction, especially during the winter months. Hence, sediment transport takes place in offshore, eastward, and onshore directions. Progressive vector diagrams show that the largest near bottom offshore, onshore and easterly net drift occurs during summer, spring and winter respectively. The onshore sediment transport generated during spring and summer plays an important role in the redistribution of eroded sediments during the winter. The overall study of dynamic factors indicated that the harbour site is characterized by eastern, western, offshore and onshore sediment movements. Therefore, the north-south orientation of the navigation channel, with its depth greater than the surrounding area, interrupts sediment drift from different directions and reduces the current speed. Consequently, the sediments sink within the navigation channel from different directions. The sources of sediments contributing to the siltation process of the harbour and its navigation channels are mainly derived from the Rosetta promontory, Burullus beaches, Damietta promontory and from offshore and the dumping area.

scholarly journals Stability of a micro-tidal inlet using semi-numerical approach

2017 ◽  
Vol 8 (3) ◽  
pp. 113-125
Author(s):  
R Senthilkumar ◽  
K Murali ◽  
V Sundar
Keyword(s):  
East Coast ◽  
Wave Model ◽  
Numerical Approach ◽  
Wave Climate ◽  
Tidal Range ◽  
Tidal Inlets ◽  
Littoral Drift ◽  
East Coast Of India ◽  
Longshore Sediment Transport ◽  
The Stability

Tidal inlets get disconnected depending on the seasons due to the formation of sand bars near its mouth are termed as “seasonally open tidal inlets.” These inlets are usually small of width of about 100 m and occur in micro-tide (tidal range not exceeding 1 m). Since the east coast of India experiences a net littoral drift of up to about 0.8 Mm3/annum, which is one of the largest in magnitudes that needs to be considered in the analysis of modeling of the sand bar formation and the associated phenomena. Kondurpalem inlet situated along the South east coast of India is considered as a case study. A frequency domain wave model (STeady-state spectral WAVE) has been used to compute the nearshore wave climate. The wave-induced currents have been obtained, and the longshore sediment transport rate is obtained through empirical relations. The tidal prism is found from measured depth and tidal velocity by solving shallow water equations. The stability of the inlet is investigated by applying the criteria developed by Bruun (1986). The effect of a pair of training walls on maintaining the stability of the mouth is reassessed over the periods.

Longshore sediment transport via littoral drift rose

2010 ◽  
Vol 37 (2-3) ◽  
pp. 228-235 ◽  
Author(s):  
Todd L. Walton ◽  
Robert G. Dean
Keyword(s):  
Sediment Transport ◽  
Littoral Drift ◽  
Longshore Sediment Transport

scholarly journals FIELD INVESTIGATION OF BEACH PROFILE CHANGES AND THE ANALYSIS USING EMPIRICAL EIGENFUNCTIONS

1982 ◽  
Vol 1 (18) ◽  
pp. 84
Author(s):  
Hiroshi Hashimoto ◽  
Takaaki Uda
Keyword(s):  
Sediment Transport ◽  
Time Lag ◽  
Field Investigation ◽  
Sand Transport ◽  
Wave Direction ◽  
Beach Profile ◽  
Sand Waves ◽  
Longshore Sediment Transport ◽  
Profile Changes ◽  
Incident Waves

In order to investigate the response of beach profiles to incident waves, computations by the empirical eigenfunction analysis proposed by Winant et al. are performed. The analysis of the data obtained at Ajigaura Beach over three years from 1976 to 1979 indicates that beach profile changes due to longshore and onshore-offshore sediment transport are separable by the empirical eigenfunction method. The beach profile changes due to longshore sediment transport has a time lag of 12 weeks with respect to the change of wave direction at Ajigaura Beach. It was found theoretically that this time lag was due to the sand waves propagating in the longshore direction. Regarding as onshore-offshore sand transport, the second eigenfunction is associated with the beach changes due to onshore-offshore sand transport caused by the change of wave height.

scholarly journals Dependence of Total Longshore Sediment Transport Rates on Incident Wave Parameters and Breaker Type

2009 ◽  
Vol 253 ◽  
pp. 675-683 ◽  
Author(s):  
Ernest R. Smith ◽  
Ping Wang ◽  
Bruce A. Ebersole ◽  
Jun Zhang
Keyword(s):  
Sediment Transport ◽  
Incident Wave ◽  
Wave Parameters ◽  
Longshore Sediment Transport

Sediment transport and shoreline shifts in response to climate change at the tidal inlets of Chilika, India

2018 ◽  
Vol 233 (1) ◽  
pp. 372-387 ◽  
Author(s):  
B Gopikrishna ◽  
MC Deo
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
Climate Model ◽  
Regional Climate ◽  
Shoreline Change ◽  
Tidal Inlets ◽  
Littoral Drift ◽  
The Past ◽  
Longshore Sediment Transport ◽  
Other Information

The shoreline adjoining Chilika Lake, situated along India’s east coast, has multiple tidal inlets which connect the lake with Bay of Bengal. The shoreline behavior near such inlets is generally studied with the help of a suitable numerical model. Such models are run on the basis of historical data of waves and other information. However, the waves in future may show different strength and pattern than the past as a result of the climate change induced by global warming. It is thus necessary that the model input should correspond to future or projected data of wind and waves. In this work, we have used the wind information from a state-of-the-art regional climate model, CORDEX RegCM-4, of future 25 years in order to run a shoreline evolution model and have derived the longshore sediment transport rate as well as the shoreline change rate around Chilika inlets. These future values are compared with corresponding ones of the past 25 years. It is found that at the given location, mean wind might go up by 20%, and this could raise the mean significant wave height strongly by 32%. The direction and frequency of occurrence of waves would also change, and this in turn will cause an increase in the net littoral drift by 41% and net accumulated drift over the entire cross-shore width by 84%. Interestingly, the present site where accretion was prevalent in the past may see erosion in future at the rate of about 1 m per year.

Sign in / Sign up

Export Citation Format

Share Document