scholarly journals SHOALING WITH BYPASSING FOR CHANNELS AT TIDAL INLETS

1982 ◽  
Vol 1 (18) ◽  
pp. 91
Author(s):  
Cyril Galvin
Keyword(s):  
Tidal Inlet ◽  
Tidal Inlets ◽  
Littoral Drift ◽  
Systematic Method ◽  
Longshore Transport

A channel dredged at the mouth of a tidal inlet is subject to rapid shoaling because of longshore transport, but this shoaling is slower than would be computed from simple trapping of all the moving littoral drift. The reduction in shoaling rate is due to the bypassing of littoral drift which occurs simultaneously with shoaling. This report presents a systematic method for computing the rate of shoaling in channels subject to shoaling with bypassing. The method also permits estimates of the effect of the dredged channel on the downdrift beaches.

Stability of micro-tidal inlets along coastlines dominated by littoral drift

2017 ◽  
Vol 21 (6) ◽  
pp. 789-801 ◽  
Author(s):  
R. Senthilkumar ◽  
K. Murali ◽  
V. Sundar
Keyword(s):  
Tidal Inlets ◽  
Littoral Drift

Comparison of wave-and tide-dominated incised valleys: specific processes controlling systems tract architecture and reservoir geometry

2010 ◽  
Vol 181 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Hugues Fenies ◽  
Gilles Lericolais ◽  
Henry W. Posamentier
Keyword(s):  
Sea Level ◽  
Drainage Basin ◽  
Tidal Inlet ◽  
The South ◽  
Littoral Drift ◽  
Incised Valley ◽  
Valley Fill ◽  
Incised Valleys ◽  
Valley Fills ◽  
Sequence Boundaries

Abstract This paper presents a comparison between the system tract architecture and the reservoir geometries of the Gironde and Leyre (Arcachon) incised-valley fills, both located within the Bay of Biscay 100 km apart. This study, based on high resolution seismic lines acquired by Ifremer on the continental shelf and onshore core and well data, illustrates that some features of the Gironde and Leyre valleys fills are similar while some others are not. The architecture of both valley fills is characterized by fifth order depositional sequences (corresponding to an interval from 120000 yr B.P. to present day). Both valleys are filled predominantly with transgressive systems tract, with associated poorly developed lowstand and highstand systems tracts. Key stratigraphic surfaces punctuate the valley-fill architecture and comprise deeply eroding tidal ravinement surfaces merged with and enhancing, earlier formed, fluvial-related erosive sequence boundaries. These tidal ravinement surfaces can be undulatory in form and in most places mark the basal boundary of the incised valleys. In contrast, nearly horizontal wave ravinement surfaces cap the incised-valley fills, extending over the adjacent interfluves. The Gironde and Leyre (Arcachon) valley fills exhibit two main stratigraphic differences: 1) transgressive systems tract sand bodies are ribbon shaped within the Gironde and tabular shaped within the Leyre; 2) lowstand systems tract deposits, represented by fluvial sediments, are preserved within the Gironde but absent within the Leyre. In a wave- and tide-dominated environment, the geometry of the sandbodies within the transgressive systems tract is a function of the tidal ravinement processes, which characterizes the estuary inlet. Two categories of tidal ravinement processes can be distinguished here: “anchored tidal ravinement” and “sweeping tidal ravinement”. The Gironde estuary is characterized by an “anchored tidal ravinement”. The tidal inlet has remained largely in a fixed location; littoral drift has not shifted the tidal inlet to the south because it is constrained by resistive Eocene carbonates that define the margins of the Gironde incised valley. In contrast, the Leyre estuary is characterized by a “sweeping tidal ravinement”. The inlet has been shifted approximately 30 km to the south by the formation of a littoral drift associated spit. This extensive lateral shifting was made possible by the fact that the incised valley was cut into unconsolidated, easily eroded Pleistocene sands. Within a wave- and tide-dominated environment, the preservation potential of the lowstand systems tract is a function of the size of the fluvial drainage basin. During lowstand time, the erosive power of the fluvial discharge was much greater within the much larger Gironde valley, consequently the fluvial sequence boundary was cut much deeper in the Gironde valley than within the Leyre valley and, correspondingly, the thickness of the associated fluvial deposits was commensurately greater. In response, the lowstand systems tract was not preserved within the Leyre valley fill because the depth of tidal ravinement erosion formed during the sea-level rise and associated transgression was greater than that associated with fluvial incision generated during the sea-level fall.

Tidal Inlet Protection Strategies for Oil Spill Response; Concepts, Testing, and Considerations

2014 ◽  
Vol 2014 (1) ◽  
pp. 287225
Author(s):  
Bradford Benggio ◽  
Kimberly Chesteen ◽  
Jason DeSantis ◽  
Richard Knudsen ◽  
John Slaughter
Keyword(s):  
Oil Spill ◽  
Oil Spills ◽  
Local Area ◽  
Tidal Inlet ◽  
South Florida ◽  
Environmental Resources ◽  
Tidal Inlets ◽  
Operational Strategies ◽  
Protection Strategies ◽  
Oil Spill Response

Coastal Area Contingency Plans (ACP) developed by local Area Committees are the consensus stakeholder documents that guide response actions to oil spills. Key to these ACPs are the Geographic Response Plans (GRPs) that identify specific areas and resources that are priorities for protection during spill response. Within the GRPs, the operational strategies to protect each priority are pre-identified and depicted on maps. One of the priorities contained within the GRPs are tidal inlets. They are the gateways to much of the most sensitive habitat and resources to protect in the event of an oil spill. To address protection of these important gateways, Tidal Inlet Protection Strategies (TIPS) for Oil Spill Response have been developed that are scientifically and operationally based. They are designed to protect the resources inside the inlet from oil that may enter from an offshore source. Tidal inlets, while among the most important areas to protect, are also some of the most difficult to effectively protect. This is due to strong currents created by flood and ebb tidal flows (which are often not fully known), associated bathymetry stability issues (shoaling), responder access, and sensitive resource concerns subject to impact from the oil as well as from response actions. The inlets, in addition to being so critical for the protection of environmental resources, are also typically very important gateways for commerce and other waterway use activities. The TIPS concept has been tested for several inlets over the years. Most recently, a class A inlet (highest degree of difficulty) strategy was tested in South Florida. This poster will present issues related to the value and importance of developing and testing TIPS, hurdles and difficulties to overcome when planning TIPS projects and tests, positive outcomes from an operational perspective as well as from benefits derived from education, coordination and management of expectations of government, industry, and the public when it comes to protection of environmental resources during a major oil spill. Finally, the poster will offer recommendations and issues for discussion that area committees should consider relative to TIPS and area contingency planning in general.

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.

scholarly journals EVALUATION OF OVERALL ENTRANCE STABILITY OF TIDAL ENTRANCES

1974 ◽  
Vol 1 (14) ◽  
pp. 91 ◽  
Author(s):  
P. Bruun ◽  
F. Gerritsen ◽  
N.P. Bhakta
Keyword(s):  
Sediment Transport ◽  
Spring Tide ◽  
Tidal Prism ◽  
Material Transport ◽  
Tidal Inlets ◽  
Littoral Drift ◽  
Overall Stability ◽  
The Mean ◽  
Two Parameters

This paper is written in continuation of earlier published material (2, 4, 5) dealing with stability of tidal inlets on littoral drift shores. The experience available at that time was responsible for the introduction of two parameters: .vmean max/ defined as the mean max. velocity in the gorge at spring tide and the K/M-tot ratio (tidal prism at spring tide divided by material transport to the entrance from the adjoining shores) as the most pertinent parameters for description of overall stability. A more detailed justification for this choice is given in this paper, based on computation of the relative sediment transport at various tidal phases. Examples of earlier date (4) and twelve new examples from India are given.

scholarly journals The Impact of Storm-Induced Breaches on Barrier Coast Systems Subject to Climate Change—A Stochastic Modelling Study

2020 ◽  
Vol 8 (4) ◽  
pp. 271 ◽  
Author(s):  
Koen R. G. Reef ◽  
Pieter C. Roos ◽  
Tessa E. Andringa ◽  
Ali Dastgheib ◽  
Suzanne J. M. H. Hulscher
Keyword(s):  
Nearest Neighbor ◽  
Morphological Evolution ◽  
Stochastic Modelling ◽  
Barrier Islands ◽  
Monte Carlo Analysis ◽  
Tidal Inlet ◽  
Degree Of Saturation ◽  
Tidal Inlets ◽  
The Creation ◽  
The Impact

Storms can have devastating impacts on barrier coasts causing coastal erosion, partial inundation, and possibly the breaching of barrier islands. The breaching of barrier islands provides a mechanism for the creation of new tidal inlets that connect the backbarrier basin (or lagoon) and the outer sea. As a new tidal inlet affects both the basin and the hydrodynamics of existing inlets, it is important to understand why an initial breach either closes or may evolve into a new tidal inlet. To this end, we performed a Monte Carlo analysis using an idealized model capable of simulating the long-term morphological evolution of multiple tidal inlets connected to a single backbarrier basin. To do so required the creation of a stochastic shell, as a new element around this existing barrier coast model. Our results demonstrate that barrier coast systems tend towards an equilibrium value for the number of inlets per kilometer of barrier coast and total inlet cross section. This even holds with the continuous stochastic forcing of storm-induced breaches. This finding implies that if a new breach opens in a coast that is already in equilibrium, existing inlets will shrink and may close if the new breach remains open. Furthermore, we find that climate-driven changes in storm frequency will modify the timescales in which barrier coasts reach their equilibrium state. Finally, we find that the distance between a new breach and its nearest neighbor is more important for its survival than the size of the breach or the degree of saturation of the barrier coast.

scholarly journals Analysis of Longshore Drift Patterns on the Littoral System of Nusa Dua Beach in Bali, Indonesia

2020 ◽  
Vol 8 (10) ◽  
pp. 749
Author(s):  
Anthony Harlly Sasono Putro ◽  
Jung Lyul Lee
Keyword(s):  
Erosion Rate ◽  
Satellite Image ◽  
Mass Conservation ◽  
Wave Direction ◽  
Littoral Drift ◽  
Longshore Transport ◽  
Beach Width ◽  
Longshore Drift ◽  
Reclamation Project ◽  
Tourism Attractions

Bali is one of the most popular tourist areas in Indonesia. With its coastline stretching 633 km, Bali has many beautiful beaches that have become world tourism attractions, thus making tourism the economic engine of Bali. The biggest priority of major tourism sites is maintaining sufficient beach width. However, based on a survey from Balai Wilayah Sungai (BWS) Bali Penida, Bali has suffered from a series of erosions along 215 km of its coastline, including Nusa Dua, in 2015. The location of the study area for this report is a 2.8 km stretch of coastline at Nusa Dua Beach. The erosion problem at Nusa Dua Beach was assessed by analyzing the longshore drift patterns. Simulations are required to assess this erosion problem, combined with the erosion rate and the simulated equilibrium shoreline for each sublittoral cell. To estimate the erosion rate, this study employed profile monitoring data of the beach obtained from 2003 to 2016. This advanced study was based on the mass conservation principle as a governing equation used to predict longshore drifts between sublittoral cells. The satellite image for every sublittoral cell was also used to check the equilibrium condition and estimate the predominant wave direction as the shoreline orientation. Nusa Dua Beach was found to suffer from the change of wave direction and the consequent generation of littoral drift after the reclamation project of Serangan Island located north of the Benoa strait. The correlation between the transportation of longshore sediments and the predominant wave direction indicates the effect of longshore drift in the system. The groin system also created a unique longshore transport pattern in the coastal area. The results obtained in this study can help manage the longshore drift system of Nusa Dua Beach and can be used to predict the beach area subject to erosion and deposition after every beach conservation project. Hence, a strategic plan for managing the shore target lines can be formulated.

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