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1.
《Coastal Engineering》2006,53(5-6):505-529
Texel inlet, the largest inlet in the Dutch Wadden Sea, has undergone drastic changes in the morphology of basin, ebb-tidal delta and adjacent coastlines after closure of a major part of its back-barrier basin. Despite intensive monitoring and analysis, present observation-based conceptual models lack the subtle physics necessary to explain the sand exchange between inlet, ebb-tidal delta and adjacent coastlines.Fundamental understanding of the inlet dynamics and evolution is obtained by integrating field and model data analysis. The state-of-the-art process-based model Delft3D Online Morphology has been used to generate synoptic data of high spatial and temporal resolution over the inlet domain. It is shown that the Delft3D Online Morphology model is capable of the quasi real-time simulation of the dominant flow and transport patterns over a 3-month period on the scale of the inlet. The high-resolution numerical model results prove to be a valuable tool in identifying the main transport patterns and mechanisms in the inlet domain. Qualitative transport patterns in Texel Inlet and its associated ebb-tidal delta are derived by integration of the observations and model results.The present ebb-tidal delta developments are best described as a second-stage self-organizing phase of redistribution and recirculation of sediments to obtain a natural dynamic equilibrium state, adapted to the changed configuration of the main-ebb channels. Sand is transported from the abandoned ebb-delta front (western margin of Noorderhaaks) and along the adjacent coastlines into the basin where it partly settles. Ebb-tidal currents redistribute sand back from the basin mainly onto the southern ebb-tidal delta shoals. Large gross transport rates, but small morphological changes, point to sediment recirculation. Sediment import into the basin results from net flood dominated transport due to tidal asymmetry, landward directed wind- and wave-driven flow, and larger flood transport capacities due to wave effects (e.g. enhanced bed shear stresses and stirring of sediment) that exceed the net ebb-dominated tidal residual transports.  相似文献   

2.
The Otzum ebb-tidal delta, located between Langeoog and Spiekeroog islands along the East Frisian barrier-island coast, southern North Sea, was investigated with respect to its morphological evolution, sediment distribution patterns and internal sedimentary structures. Bathymetric charts reveal that, over the last 50 years, the size of the Otzum ebb-tidal delta has slightly shrunk, while sediment has accreted on the ebb-delta lobe to the east of the main inlet channel (west of Spiekeroog). Swash bars superimposed on the eastern ebb-tidal shoal (Robben Plate) have migrated south or south-eastwards, i.e. towards the inlet throat. The main ebb-delta body is composed of fine quartz sand, whereas the superimposed swash bars and the inlet channel bed consist of medium-grained quartz sand containing high proportions of coarser bioclastic material. Internal sedimentary structures in short box-cores (up to 30 cm long) are dominated by flood-oriented cross-beds. Longer vibro-cores (up to 1.5 m long) show that, at depth, the sediment is dominated by storm-generated parallel (upper plane bed) laminations with intercalated shell layers and dune cross-bedding. The cross-bedded sands in both box-cores and vibro-cores from the ebb-delta shoal predominantly dip towards the south or southeast, indicating transport towards the inlet throat by the flood current. The observations demonstrate that, contrary to previous contentions, the sediments of the highly mobile swash bars do not bypass the inlet but are instead being continually recirculated by the combined action of tidal currents and waves. In this model, the cycle begins with both fine and medium sands, including shell hash, being transported seawards in the main ebb channel until they reach the shallow ebb-delta front. From here, the sediment is pushed onto the eastern ebb-delta shoal by the flood current assisted by waves, becoming strongly size-sorted in the process. The medium sands together with the shell hash are formed into swash bars which migrate along arcuate paths over a base of fine sand back to the main ebb channel located south of the ebb delta. By the same token, the fine sand between the swash bars is transported south-eastwards by the flood current in the form of small dunes until it cascades into the large flood channel located to the west of Spiekeroog. From here, the fine sand is fed back into the main ebb channel, thus completing the cycle. No evidence was found on the ebb delta for alongshore sediment bypassing.  相似文献   

3.
基于湛江湾口外海图地形资料,采用GIS与动力地貌分析的方法,研究了近50年来湛江湾口外落潮三角洲的冲淤变化特征,对湛江湾口外落潮三角洲的演变机制进行了探讨。湛江口外落潮三角洲体系包括口外东北浅滩、西南边滩及口门通道深槽。近50年来,东北浅滩东缘及滩顶出现了侵蚀后退,浅滩西缘和南缘呈淤积趋势,东北浅滩整体有西移南扩趋势;西南边滩有不同程度的侵蚀后退;口门通道深槽有所淤积。湛江湾口外落潮三角洲侵蚀与沿岸泥沙供给不足及人类活动影响有关,口门通道深槽淤积除与落潮三角洲侵蚀泥沙向西搬运有关外,还可能与湛江湾内围垦导致口门通道潮汐动力减弱有关。航道北侧东北浅滩变化对航道回淤的可能影响值得关注。  相似文献   

4.
A study of the East Frisian Islands has shown that the plan form of these islands can be explained by processes of inlet sediment bypassing. This island chain is located on a high wave energy, high tide range shoreline where the average deep-water significant wave height exceeds 1.0 m and the spring tidal range varies from 2.7 m at Juist to 2.9 m at Wangerooge. An abundant sediment supply and a strong eastward component of wave power (4.4 × 103 W m−1) have caused a persistent eastward growth of the barrier islands. The eastward extension of the barriers has been accommodated more by inlet narrowing, than by inlet migration.

It is estimated from morphological evidence that a minimum of 2.7 × 105 m3 of sand is delivered to the inlets each year via the easterly longshore transport system. Much of this sand ultimately bypasses the inlets in the form of large, migrating swash bars. The location where the swash bars attach to the beach is controlled by the amount of overlap of the ebb-tidal delta along the downdrift inlet shoreline. The configuration of the ebbtidal delta, in turn, is a function of inlet size and position of the main ebb channel. The swash bar welding process has caused preferential beach nourishment and historical shoreline progradation. Along the East Frisian Islands this process has produced barrier islands with humpbacked, bulbous updrift and bulbous downdrift shapes. The model of barrier island development presented in this paper not only explains well the configuration of the German barriers but also the morphology of barriers along many other mixed energy coasts.  相似文献   


5.
Morphodynamics of ebb-tidal deltas: a model approach   总被引：1，自引：0，他引：1  
The results of 2DH numerical models of the Frisian Inlet (located in the Dutch Wadden Sea) are discussed to gain further knowledge about the physical mechanisms causing the presence of both ebb-tidal deltas and of channels and shoals in tide-dominated inlet systems. A hydrodynamic model, extended with sediment transport formulations, was used to verify earlier conceptual models that deal with ebb-tidal delta characteristics. The model does not confirm their hypothesis concerning the observed spatial asymmetry of ebb-tidal deltas and suggests that long-term morphological simulations are needed to understand this aspect. Furthermore, the model indicates that the initial formation of the ebb-tidal delta is mainly due to convergence of the tidally averaged sediment flux related to residual currents, whilst the net sediment transport in the basin is mainly caused by tidal asymmetry. A second model (accounting for feedbacks between tidal motion and the erodible bottom) was used to simulate the long-term bathymetric evolution of the Frisian Inlet under fair weather conditions. This model reproduces the gross characteristics of the observed morphology: the presence of a double-inlet system with two distinct ebb-tidal deltas having different sizes and the presence of channels and shoals. The role of the ‘Engelsmanplaat’, a consolidated shoal in the middle of the Frisian Inlet, was not found to be crucial for the morphodynamic stability of this inlet system.  相似文献   

6.
《Marine Geology》2006,225(1-4):23-44
The morphodynamics of inlets and ebb-tidal deltas reflect the interaction between wave and tidal current-driven sediment transport and significantly influence the behaviour of adjacent shorelines. Studies of inlet morphodynamics have tended to focus on sand-dominated coastlines and reference to gravel-dominated or ‘gravel-rich’ inlets is rare. This work characterises and conceptualises the morphodynamics of a meso-tidal sand–gravel inlet at the mouth of the Deben estuary, southeast England. Behaviour of the inlet and ebb-tidal delta over the last 200 yr is analysed with respect to planform configuration and bathymetry. The estuary inlet is historically dynamic, with ebb-tidal shoals exhibiting broadly cyclic behaviour on a 10 to 30 yr timescale. Quantification of inlet parameters for the most recent cycle (1981–2003) indicate an average ebb delta volume of 1 × 106 m3 and inlet cross-sectional area of 775 m2. Bypassing volumes provide a direct indicator of annual longshore sediment transport rate over this most recent cycle of 30–40 × 103 m3 yr− 1. Short-term increases in total ebb-tidal delta volume are linked to annual variability in the north to northeasterly wind climate. The sediment bypassing mechanism operating in the Deben inlet is comparable to the ‘ebb delta breaching’ model of FitzGerald [FitzGerald, D.M., 1988. Shoreline erosional–depositional processes associated with tidal inlets, in: Aubrey, D.G., Weishar, L. (Ed.), Hydrodynamics and Sediment Dynamics of Tidal Inlets. Springer-Verlag Inc., New York, pp. 186–225.], although the scales and rates of change exhibited are notably different to sand-dominated systems. A systematic review of empirical models of sand-dominated inlet and ebb-tidal delta morphodynamics (e.g. those of [O'Brien, M.P., 1931. Estuary tidal prisms related to entrance areas. Civil Engineering, 1, 738–739.; Walton, T.L., and Adams, W.D., 1976. Capacity of inlet outer bars to store sand. Proceedings of 15th Coastal Engineering Conference, 1919–1937.; Gaudiano, D.J., Kana, T.W., 2001. Shoal bypassing in mixed energy inlets: geomorphic variables and empirical predictions for nine South Carolina inlets. J. Coast. Res., 17, (2), 280–291.]) shows the Deben system to be significantly smaller yet characterised by a longer bypassing cycle than would be expected for its tidal prism. This is attributed to its coarse-grained sedimentology and the lower efficiency of sediment transporting processes.  相似文献   

7.
Indian River Inlet is located at roughly the mid-point of the Atlantic coast of Delaware and connects the ocean to two Delaware inland bays. Jetties constructed in 1940 have maintained the inlet for navigation purposes but have also acted as a barrier to net northerly alongshore sediment transport causing downdrift erosion. A mobile, land-based bypassing system was initiated in 1990 in an effort to counteract this erosion. Beach profile data from 1985 (pre-bypassing) until 2008 are used to investigate the effect of the sand bypassing system on beaches adjacent to the inlet. The downdrift beach experienced horizontal shoreline erosion between 10 and 60 m during the pre-bypassing period but accreted 10–20 m during the bypassing period. The mean shoreline location on the updrift beach during bypassing is 10–20 m landward (erosion) of its position during the pre-bypassing period. Empirical orthogonal function (EOF) amplitudes from analyses performed on mean-removed elevation surfaces during the periods of highest bypassed volume (average of 83% of design rate) showed that the influence of the bypassing system on the downdrift beach extends to about 1500 m of the inlet. An EOF analysis showed that different morphologic responses were evident following the initiation of bypass operations. Temporal variations of shoreline and beach morphology were correlated to the temporal variations in bypassing rates on the downdrift beach only. The downdrift beach response was greatest near the inlet for larger bypassing volumes. Correlation in these instances occurred with a roughly 1-year time lag suggesting that the beach quickly redistributes the bypassed sand. EOF amplitude and shoreline response are weakly correlated to bypassed volumes when the system bypassed smaller volumes (average of 56% of design rate) of sand suggesting that there is a minimum bypassing rate, regardless of yearly variability, below which the effect on the downdrift beach is obscured.  相似文献   

8.
Todd L. Walton  Jr. 《Coastal Engineering》2005,52(12):1127-1132
Bypassing of the coastal sediment at inlets is required to prevent downdrift erosion or the filling in of navigation channels. When coastal structures such as jetties or terminal groins are placed along the inlet boundaries, bypassing is reduced but not eliminated. Bypassing solutions such as Pelnard-Considere (1956) [Pelnard-Considere, R., 1956. Essai de Theorie de l'Evolution des Forms de Rivages en Plage de Sable et de Galets, Fourth Journess de l'Hydralique, les energies de la Mer, Question III, Rapport No. 1, pp. 289–298.] are known although the effect of existing background erosion on such bypassing is not so well known. The occurrence of existing erosion due to offshore sand loss complicates the bypassing situation. The following note reviews existing analytical bypassing solutions and presents a solution and nomograms for solving a bypassed amount when existing erosion occurs along a shoreline and the sand which bypasses the updrift structure is assumed to reach the downdrift shoreline without being trapped in shoals or inlet channel.  相似文献   

9.
Modelled channel patterns in a schematized tidal inlet   总被引：1，自引：0，他引：1  
Tidal inlets in the Dutch Wadden Sea show typical morphological features, i.e. westward oriented main inlet channel and ebb-tidal delta. The objective of this study is to find the governing physical processes of these morphological features. The study uses a 2DH process-based morphodynamic model (Delft3D) on a schematized model domain, with dimensions similar to the Ameland inlet in the Dutch Wadden Sea.Starting from a flat bed the models are forced by tides only. Short-term simulations are made to explore the hydrodynamic characteristics and initial sedimentation and erosion patterns. Long-term morphodynamic simulations are employed to investigate the governing parameters of the main inlet channel and the ebb-tidal delta evolution. Sensitivity of the evolution is described in terms of initial inlet width (1.0 km and 3.5 km), direction and asymmetry of tidal forcing (M2, M4), transport formulations (Van Rijn, 1993; Engelund and Hansen, 1967) and relative position of the tidal basin with respect to the inlet (East (existing), Middle, and West).The results tend to produce morphological features typical to the Ameland inlet. The direction of tidal forcing is the main governing parameter to the present orientation of the main inlet channel and the ebb-tidal delta. The model results generally prove the conceptual hypotheses that describe the orientation of the main inlet channel and the ebb-tidal delta.  相似文献   

10.
A mathematical model of spit growth and barrier elongation adjacent to an inlet (of arbitrary width), supplied by sediment coming from longshore sediment transport, was developed based on the spit growth model proposed by Kraus (1999). The fundamental governing equation is the conservation equation for sand, where the width of the spit is assumed constant during growth. The portion of the longshore sediment transport feeding the spit has been estimated based on the ratio between the depth of the inlet channel and the depth of active longshore transport. Sediment transport from the channel due to the inlet flow, as well as other sinks of sand (e.g., dredging), are taken into account. Measured data on spit elongation at Fire Island Inlet, United States, and at Badreveln Spit, Sweden, were used to validate the model. The simulated results agree well with the measured data at both study sites, where spit growth at Fire Island was restricted by the inlet flow and the growth at Badreveln Spit was unrestricted. The model calculation for Fire Island Inlet indicates that the dredging to maintain channel navigation is the major reason for the stable period observed from 1954 to 1994 at the Fire Island barrier. The average annual net longshore transport rate at the eastern side of the Fire Island inlet obtained in this study was about 220,000 m3/yr, of which approximately 165,000 m3/yr (75% of the net longshore transport) is deposited in the inlet feeding the spit growth, whereas the remaining portion (25%) is bypassed downdrift through the ebb shoal complex.  相似文献   

11.
Analysis of four historical bathymetric surveys over a 132-year period has revealed significant changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of San Francisco Bay estuary. From 1873 to 2005 the San Francisco Bar vertically-eroded an average of 80 cm over a 125 km2 area, which equates to a total volume loss of 100 ± 52 million m3 of fine- to coarse-grained sand. Comparison of the surveys indicates the entire ebb-tidal delta contracted radially, with the crest moving landward an average of 1 km. Long-term erosion of the ebb-tidal delta is hypothesized to be due to a reduction in the tidal prism of San Francisco Bay and a decrease in coastal sediment supply, both as a result of anthropogenic activities. Prior research indicates that the tidal prism of the estuary was reduced by 9% from filling, diking, and sedimentation. Compilation of historical records dating back to 1900 reveals that a minimum of 200 million m3 of sediment has been permanently removed from the San Francisco Bay coastal system through dredging, aggregate mining, and borrow pit mining. Of this total, ∼54 million m3 of sand-sized or coarser sediment was removed from central San Francisco Bay. With grain sizes comparable to the ebb-tidal delta, and its direct connection to the bay mouth, removal of sediments from central San Francisco Bay may limit the sand supply to the delta and open coast beaches.  相似文献   

12.
Extensive vibracoring of both flood- and ebb-tidal deltas along the central Gulf Coast of the Florida peninsula reveals a strong overall similarity with subtle distinctions between flood and ebb varieties. Although the coast in question is microtidal, the inlets range from tide-dominated to distinctly wave-dominated. Both types of tidal deltas overlie a muddy sand interpreted to have been deposited in a back-barrier environment. The sharp contact at the base of the tidal delta sequence is typically overlain by a thin shell gravel layer. The ebb-tidal delta sequence is characterized by fine quartz sand with shell gravel in various concentrations; coarse and massive at the margins of the main ebb channel, and finer and imbricated at the marginal flood channels. The flood-tidal deltas are characterized by the same facies but with a small amount of mud. Shelly facies on the channels on flood deltas are not as well developed as on the ebb deltas. The combination of the stratigraphic sequence and the lithofacies make tidal deltas readily identifiable in the ancient record. The differences between flood and ebb varieties are subtle but consistent.  相似文献   

13.
曹妃甸老龙沟动力地貌体系及演化   总被引：3，自引：0，他引：3  
老龙沟为典型沙坝-泻湖型潮汐汊道,潮汐汊道地貌结构完整.老龙沟口门处潮流动力最强,发育-20m的深槽.口门内涨潮流三角洲上发育完整的多级水道体系.口门外落潮三角洲止于-11 m水深处.以突起的末端坝为地形标志,落潮主水道偏于落潮三角洲东侧发育,落潮三角洲西侧发育宽缓冲流平台.落潮主水道以落潮流为优势,冲流平台上潮流动力...  相似文献   

14.
A new numerical model was developed to simulate regional sediment transport and shoreline response in the vicinity of tidal inlets based on the one-line theory combined with the reservoir analogy approach for volumetric evolution of inlet shoals. Sand bypassing onshore and sheltering effects on wave action from the inlet bar and shoals were taken into account. The model was applied to unique field data from the south coast of Long Island, United States, including inlet opening and closure. The simulation area extended from Montauk Point to Fire Island Inlet, including Shinnecock and Moriches Inlets. A 20-year long time series of hindcast wave data at three stations along the coast were used as input data to the model. The capacity of the inlet shoals and bars to store sand was estimated based on measured cross-sectional areas of the inlets as well as on comprehensive bathymetric surveys of the areas around the inlet. Several types of sediment sources and sinks were represented, including beach fills, groin systems, jetty blocking, inlet bypassing, and flood shoal and ebb shoal feeding. The model simulations were validated against annual net longshore transport rates reported in the literature, measured shorelines, and recorded sediment volumes in the flood and ebb shoal complexes. Overall, the model simulations were in good agreement with the measured data.  相似文献   

15.
A large deficit in the coastal sediment budget, high rates of relative sea-level rise (~0.9 cm/year), and storm-induced current and wave erosion are forcing barrier shoreface retreat along the periphery of the Mississippi River delta plain. Additionally, conversion of interior wetlands to open water has increased the bay tidal prism, resulting in degradation of barrier islands due to inlet widening, formation of new inlets, and sediment sequestration at ebb-tidal deltas. Single-beam bathymetric surveys along a 165-km stretch of south-central Louisiana barrier coast, from Raccoon Point in Terrebonne Parish to Sandy Point in Plaquemines Parish, were conducted in 2006. These data, combined with historical bathymetry from three time periods (dating to the 1880s), provide a series of digital elevation models that were used to calculate sediment volumetric changes and determine long-term erosional-depositional trends. Dominant patterns during the 125-year period include (1) erosion of ~1.6 × 109 m3 from the shoreface, forcing up to 3 km of shoreface retreat, (2) sediment deposition in coastal bights and at ebb-tidal deltas, and (3) a combined increase in tidal inlet cross-sectional area from ~41,400 m2 to ~139,500 m2. Bathymetric and shoreline change datasets separated by shorter time periods (sub-annual) demonstrate that these long-term trends are driven by processes associated with major hurricane impacts, and that rates of shoreface erosion are an order of magnitude greater during active hurricane seasons compared to long-term trends.  相似文献   

16.
Morphodynamic Processes of Tidal Inlet and Ebb-Tidal Delta of Shuidong Bay   总被引：1，自引：0，他引：1  
Based on the observed data in 1982- 1985 at Shuidong Bay area, west Guangdong Province, the morphodynamic processes of tidal inlet and ebb-tidal delta in the barrier-lagoon system are presented, including the dynamic features of tides and in the tidal inlet, the regional dyanmics and longshore sediment transport in the ebb-tidal delta, the genesis of the entrance bar, the recent erosion and deposition in the ebb-tidal delta and so on. The paper attempts to answer two questions, i. e., the stability of the tidal inlet and the feasibility of dredging on the entrance bar for the course of Shuidong Harbour. The results show that the stability of the tidal inlet is ideal and that dredging action on the entrance bar may be successful if dredging is deep enough and the course position reasonable.  相似文献   

17.
《Coastal Engineering》1999,37(1):37-56
The seasonal closure of tidal inlets is a common and important coastal phenomena. However, studies which have been specifically geared to identify processes governing seasonal inlet closure are almost non-existent. Hence, this study was undertaken to gain insight into processes governing seasonal inlet closure. To determine the processes governing this phenomenon, Wilson Inlet, Western Australia, a typical seasonally open tidal inlet is taken as a case study. The study comprised of a field experiment over the summer of 1995, and a numerical modeling exercise employing a morphodynamic model. Results of the field study imply that longshore processes may not be the cause of inlet closure, but that onshore sediment transport due to persistent swell wave conditions in summer may govern seasonal closure of the inlet. Application of a morphodynamic model, which includes both cross-shore and longshore processes, to Wilson Inlet conclusively shows that seasonal closure of the inlet is due to onshore sediment transport under typical summer conditions. The effects of summer streamflow and storm events, which are not uncommon, are also examined using the morphodynamic model. The effect of both streamflow and storm events on the `open duration' of the inlet is shown to be dependent on the intensity and timing of the event.  相似文献   

18.
The paper presents investigations of wave climate, tidal inlet hydraulics, and sand sediment bypassing at the entrance to Westport Harbour, South Island, New Zealand. The results complement and extend those of studies of bar morphologies and sediment characteristics already published. Longshore transport of about 1 × 106 m3/year is directed in a net eastward fashion across the inlet because of an in‐built misalignment of the harbour training walls. Approximately 90% of the drift is bypassed, and has been since 1921, by deflection and splitting of the main sediment streams through the inner and outer bars and a transverse channel aoross the entrance. The outer bar appears to be the submarine, downdrift extension of Carters Breach and river load appears to contribute an order of magnitude less sediment to the complex than annual littoral drift. River sediments and littoral drift are mixed off the harbour and a declining proportion over time is recirculated to cause progradation of North Beach. The tidal compartment contributes little to scour of the entrance because of the predominance of bar bypassing. Contrary to the recommendations of several past studies, it is argued that improvements in navigation depths at West‐port are more likely to be obtained through modification of the littoral drift system than they are from tidal compartment enlargement.  相似文献   

19.
Three sediment transport studies using tracers were performed at Ancão Inlet (southern Portugal). The objectives of the experiments were to understand the sediment transport pathways and to determine their magnitudes on the updrift margin of an inlet. In order to apply the traditionally used Space Integration Methodology to the tracer experiments, adaptations were required. The study area was divided into four morphologically defined sectors and this was found to be a key factor for the applicability of tracers in a complex area. The four sectors are as follows: sector A is the straight part of the updrift beach; sector B is the upper area of the swash platform; sector C is the lower area of the swash platform; and sector D represents the inner parts of the inlet margin. The integrated analysis of all collected data (forcing mechanisms, tracer distribution and topographic evolution) led to the determination of the sediment pathways. A semi-quantitative conceptual model was developed in order to explain the sediment transport pathways and magnitudes that a known mass of sediment would follow after arriving at the swash platform. It was found that the areas with the largest sediment accumulation were sectors B and C, while almost no sediment was retained in sector D, which experienced significant erosion. According to the model, 53% of the initial mass of sediments remain in the system after two tidal cycles. It is hypothesised that sediment losses are caused by sediment transport towards the ebb delta and by sediment bypassing occurring from the ebb delta to the downdrift beach through swash bar processes. The herein defined conceptual model represents a useful tool that could be applied to other tidal inlets under similar conditions, facilitating sediment budget studies around tidal inlets.  相似文献   

20.
The ebb-tidal delta model of McBride and Moslow is the most comprehensive on the morphogenesis and distribution of shoreface ridges along the US Atlantic seaboard to date. This discussion evaluates the applicability of the above model to the southern North Sea barrier island coast. Results indicate that the characteristics of the North Sea shoreface-connected ridge sediments display a genetic relationship with those of the inlet ebb delta as implied by the ebb-tidal model. By contrast, ridge orientation is not well accounted for by lateral inlet migration and shoreline recession as suggested by the model. A possible reason for the aforementioned discrepancy is discussed.  相似文献   

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