Wave erosion of a massive artificial coastal landslide
California ; Coastal dynamics ; Coastal environment ; Coastal erosion ; Earthquake ; Fault ; Landslide ; Model ; Tide ; United States of America ; Wave
The Lone Tree landslide is located on the coast north of San Francisco, California, and is unusual in that it is positioned within the San Andreas fault zone. The focus of this paper is on the development of a model to analyse the frequency of wave
attack in terms of tide levels and wave conditions. A beach consisting of cobbles and boulders formed at the toe of the debris, offering partial protection and reducing the rate of continued erosion.
Bypassing of sand over sand waves and through a sand wave field in the central region of the Southern North Sea in Tide-influenced sedimentary environments and facies.
A sand wave field lies uncomfortably in the middle of a slightly undulating, current swept lag gravel pavement between Sandettie and South Falls banks in the central region of the Southern Bight of the Southern North Sea. - (L'A.).
Beobachtungen von atmosphärischen Schwerewellen mit einem Schwerewellen-Messnets. (Observations of atmospheric gravity waves with a gravity waves measuring network)
A stationary measuring network for atmospheric gravity waves in the lower atmosphere is described. It is located at Juliusruh (Rügen/GDR) and consists of three sensor stations with data telemetry and primery data processing by microprocessor
Beach erosion and accretion on the Palisadoes, south-east Jamaica, is a diurnal phenomenon, caused by changes in wave form in response to the local sea-land breeze regime. Sea breezes generate destructive wave forms which remove sediment from
the foreshore. These waves decay when the land breeze operates, and sediment is returned to the foreshore by constructive wave action. For this area, meteorological data are a satisfactory substitute for wave data in prediction of short-term beach erosion
Nearshore circulation over transverse bar and rip morphology with oblique wave forcing
Coastal dynamics ; Coastal environment ; Florida ; North Atlantic Ocean ; Ocean circulation ; Sea current ; Surfing ; United States of America ; Wave
A combination of in-situ current meters and surf zone drifters are used to characterize the nearshore circulation over a transverse bar and rip morphology at Pensacola Beach, Florida in the presence of relatively low energy oblique waves. Current
speeds vary in response to the relative wave height ratio (Hs/h), which defines the degree and extent of breaking over the shoal. In the absence of wave breaking the nearshore circulation was dominated by an alongshore current driven by the oblique waves
. As waves begin to break across the shoal, the nearshore circulation is characterized by a meandering alongshore current. As conditions became more dissipative, the meandering current is replaced by an unsteady rip circulation that moves offshore between
the shoals before turning alongshore in the direction of wave advance outside the surf zone. While the currents had a low velocity and would not pose a significant hazard to the average swimmer, the results of this study suggest that the transverse bar
and rip morphology is sufficient to create an alongshore variation in wave dissipation that forces alongshore meandering and low-energy rip circulation systems under oblique wave forcing.
Field observations of wave refraction and propagation pathways on coral reef platforms
Hydrodynamics ; Indian Ocean ; Maldives ; Marine hydrology ; Reef ; Shore platform ; Space time ; Wave
Field experiments were conducted to investigate the refraction and propagation of ocean waves across 2 coral reef platforms in the Maldives, central Indian Ocean. Seven pressure sensors were deployed on each reef to quantify temporal and spatial
variations in wave characteristics across the platform surfaces. Directional wave properties were calculated from high frequency wave and current records obtained at 2 locations on each reef and corroborate theoretically predicted propagation pathways derived
from an analytical wave refraction model. Results demonstrate that reef geometry critically controls the refraction and propagation behaviour of incident swell across the reef structures. Furthermore, wave focussing has been identified as a major
mechanism controlling the transformation of wave energy across the reefs. Results provide the first field-based validation of wave refraction and convergence on coral reefs and have significant implications for sedimentation processes and the formation
Sediments and water fluxes in a muddy coastline : interplay between waves and tidal channel hydrodynamics
Coastal dynamics ; Coastal environment ; Intertidal zone ; Louisiana ; Sediment transport ; Storm wave ; Tidal creek ; United States of America ; Wave ; Wind
measurements were integrated with measurements of wave activity in the bay at the mouth of the channel, thus allowing the quantification of feedbacks between waves and sediment fluxes. Results indicate that the sediment concentration in the channel is directly
related to the wave height in the adjacent bay during flood and high slack water, whereas the concentration during ebb depends on local channel velocity.
A sandy beach in the south of Portugal (Faro beach, Ria Formosa) was surveyed from the dune crest seaward to 15 m depth 20 times over a period of 26 months. Wave time-series between surveys were analysed to obtain relationships between wave height
and vertical profile variations and to define wave thresholds for important morphological changes. Results show that the active zone of the profile lies between 5 m above and 10.4 m below mean sea level. Based on the pattern of vertical variability, the AA
. divided the profile into 4 cross-shore sectors and calculated thresholds for significant wave height generating important morphological changes in each sector.
Wave structures and turbulent features of the winter airflow in southern Wyoming in Interpretation of windflow characteristics from Eolian landforms.
Data from airborne air-sensing probes reveal wave structures in the planetary boundary layer of the atmosphere in the wind corridor of south-central Wyoming. The airflow, which is nearly laminar throughout much of the region, responds in a series
of resonant lee waves when it encounters topographic obstacles. Gravity waves and turbulent mixing are associated with a downward transport of vertical momentum and occur in the region of accelerated windflow in the central Wyoming wind corridor. Kelvin
-Helmholtz waves are prevalent in the area of hydraulic jump at Windy Gap. Understanding of such waves and their controls is essential to siting of wind-energy systems in high-wind regions like the Wyoming wind corridor and in interpreting the mechanisms
Wave energy and clast transport in eastern Tasman Bay, New Zealand
Coastal dynamics ; Coastal environment ; Gravel ; New Zealand ; Sediment transport ; South Island ; South Pacific Ocean ; Wave ; Wind
The aim of this paper is to determine whether wave energy in Tasman Bay is sufficient to initiate clast transport along the gravel platforms. In this study, wind data form Nelson airport and measured wave data from Cable Bay and Mackay Bluff
are used in conjunction with 2 different mathematical models of clast transport. Values calculated from each of these models are compared with the present wind and wave environment of Tasman Bay. While the mathematical models can only provide approximations
because of differences in bathymetry and wave morphology, they will provide a calibrated scale of clast movement along eastern Tasman Bay.
Extreme wave events in the central Mediterranean : Geomorphic evidence of tsunami on the Maltese Islands
Boulder ; Coastal dynamics ; Coastal environment ; Historical period ; Malta ; Mediterranean Sea ; Model ; Remote sensing ; Satellite imagery ; Sea level ; Tsunami ; Wave
Field evidence from the Maltese Islands is presented of extreme wave activity in the central Mediterranean Sea. An extensive range of extreme wave signatures, both erosional and depositional, is here presented and indicates a wave attack from the NE
. Existing models of runup and boulder detachment imply that the extreme wave signatures lie beyond the capabilities of storm waves. These considerations, taken together with the range of evidence available, point toward tsunami as the agency responsible
, which is consistent with the evidence from Mediterranean marginal coasts opposed to the Maltese Islands. Evidence from existing boulder detachment, tsunami runup and wave velocity models suggests that tsunami with shoreline wave height of up to ~4 m
Field observations of infragravity waves and their behaviour on rock shore platforms
Cliff ; Coastal dynamics ; Coastal environment ; Coastal erosion ; New Zealand ; North Island ; Sea level ; Shore platform ; Wave
Infragravity wave (IGW) transformation was quantified from field measurements on 2 shore platforms on New Zealand's east coast (Oraka and Rothesay Bay). The observed increase in IGW height over the platform during both experiments is attributed
to shoaling. The proportional increase in IGW height shows a strong correlation to water level on each platform. The rate of shoaling of long period waves on the shallow, horizontal platforms increased at higher water levels resulting in a super elevation
in water level at the cliff toe during high tide. Results from this study show the first measurements of IGWs on shore platforms and identify long wave motion a significant process in a morphodynamic understanding of rock coast.
The dominance of dispersion in the evolution of bed material waves in gravel-bed rivers
This paper summarizes recent theoretical models, experiments and field studies that have been designed specifically to measure relative rates of dispersion and translation of bed material waves. In considering uniform channels only, and also
in disregarding exchanges of sediment between a channel and its floodplain, 2 factors influence wave behaviour : interactions between flow, wave topography and bed load transport; and relative particle sizes of input sediment and pre-existing bed material
. The results indicate that dispersion dominates the evolution of bed material waves in gravel-bed channels.
America's utopian experiments: communal havens from long-wave crises
Economic-geographic interpretation of the remarkable history of communally organized utopian settlements in America. Correlation of utopian surges with the fear and insecurity associated with down waves of Kondratiev cycles. Analyzes both
Observations of trapped waves in the atmosphere and ocean along the coast of southern Africa
The coastally trapped low pressure cell and associated shelf wave which travel eastward along the southern edge of the African continent are studied. Composite and case study analyses confirm a geographically anchored acceleration of the coastal low
Synoptical conditions and their influence on the formation of high waves along the rivers Varbitza and Yantra
This work elucidates the formation and specific features of high waves in two river basins in different climatic zones of Bulgaria. The typization of the synoptic material was made on the basis of 283 characteristic precipitation situations. - (SBV)
Waves and sandbar erosion in the Grand Canyon: applying coastal theory to a fluvial system
The purpose of this paper is to evaluate the relative importance of surface-gravity waves on sandbar stability in Grand Canyon, in contrast to unidirectional currents that are the primary focus of most fluvial studies. A second objective
Links between wave forcing, offshore islands and a macro-tidal headland-bound bay beach
Beach ; Coastal dynamics ; Coastal geomorphology ; Coastline ; Intertidal zone ; Island ; Model ; United Kingdom ; Wales ; Wave
Profiles were analysed in conjunction with wave climate to assess offshore island influences on an embayed beach at Tenby, Wales. Time series analyses showed medium and short-term beach oscillation, with volume exchanges between zones lagging by up
to 6 months. Modelled inshore breaking waves had less energy than offshore ones and the former behaved differently between the low and high tidal zones. Variations in wave direction from directly behind the islands resulted in reduced wave heights
and statistical analyses agreed with wave model results. These were correlated to morphological change and it was concluded that offshore islands change wave dynamics and modify the morphology of embayed beaches in their lee. Consequently, this work provides
Theoretical analysis of wave-induced gravel movements
Coastal environment ; Hydrodynamics ; Intertidal zone ; Model ; Sea level ; Sediment transport ; Wave
response to changing wave, tidal and sea-level conditions. An alternative is developed here in which frequency domain representations of a simplified set of process and response algorithms are presented, so that hydrodynamic, sediment dynamic