Showing papers on "Shore published in 1983"

Ecological and regional zoogeography of the marine benthic fauna of Chile: Report no. 49 of the Lund University Chile Expedition 1948–49

Abstract: The zoogeographic analysis is based on 240 species of 13 taxa, mainly the many new records from the ‘Lund University Chile Expedition 1948-49’. The purpose has been to find out whether or not the new data confirm earlier conceptions of zoogeographic regions and borders in Chilean waters. The climatic conditions at the shore and the hydrography are described. The Chilean archipelago differs from the area north thereof both in topography, climate, and hydrography. The direction and extension of the currents and the small differences in salinity and also in temperature along the shore favour a wide distribution. Except for brackish-water areas in the archipelago the salinity is high. The sea off Chile is colder than at the same latitudes in other oceans, except for southern Chile, where the sea is a little warmer than normal. The local annual range in temperature is small. The vertical and horizontal distributions of the species are illustrated in tables and maps. There are few wide-spread and endemic specie...

The Sea Shore Ecology of Hong Kong

Abstract: This book reviews the factors creating and maintaining Hong Kong's living shore, and describes the wide range of plants and animals found within the intertidal boundaries of the shore. A full range from exposure to shelter is to be found, from communities of the sheer rock faces, beaten by the storm waves of the South China Sea, to the denizens of mudflats in high shelter at the heads of harbours and inlets.

Journal of Waterway, Port, Coastal, and Ocean Engineering

Abstract: The Journal of Waterway, Port, Coastal, and Ocean Engineering presents information regarding the engineering aspects of dredging, floods, ice, pollution, sediment transport, and tidal wave action that affect shorelines, waterways, and harbors. The development and operation of ports, harbors, and offshore facilities, as well as deep ocean engineering and shore protection and enhancement, are also covered. Other topics include the regulation and stabilization of rivers and the economics of beach nourishment.

Numerical Simulation of the Airflow over Lake Michigan for a Major Lake-Effect Snow Event

Abstract: A mesoscale model is used to simulate the airflow over Lake Michigan for the major lake-effect snowstorm of 10 December 1977. This storm was characterized by a land breeze circulation and a narrow shore-parallel radar reflectivity band. The model successfully simulated the major atmospheric circulation features including a mesoscale low pressure center and a land breeze front. The model also captured the general character of the observed precipitation pattern which was typified by a narrow band of heavy precipitation along the eastern shore of Lake Michigan. Further simulations were made to examine the effects of latent heat release, lake surface temperature distribution and model grid resolution upon the simulation. Latent heat release was found to have an important effect in strengthening convection. However, the basic land-breeze circulation was found to develop for the simulated conditions even without latent beating. For a given mean lake-land temperature difference, details of the lake surf...

Community Structure of Intertidal Sandy Beaches in New South Wales, Australia

Abstract: Sand beaches comprise approximately 60% of the intertidal shoreline of New South Wales. However, there are no published accounts of the sandy beach fauna in New South Wales, or for that matter, for any sandy beaches in Australia. The shoreline, particularly in the vicinity of Sydney, is exposed to a heavier wave regime than that of most other coasts throughout the world (Short, Wright 1981, Wright 1976, Wright et al. 1979). Hence the infauna of exposed sandy beaches inhabit an especially rigorous physical environment.

Shore-level changes in South Norway during the last 13000 years, traced by biostratigraphical methods and radiometric datings

Abstract: Hafsten, U 1983 Shore-level changes in South Norway during the last 13,000 years, traced by biostratigraphical methods and radiometric datings Norsk geogr Tidsskr Vol 37, 63–79 Oslo ISSN 0029-1951 This article presents the status as regards shoreline research in Norway at the end of UNESCO's International Geological Correlation Program (IGCP) Curves intended to reflect the general course of the shore-level displacement since the last glaciation are presented for 15 different regions along the coast of South Norway The curves, which all have been converted to an equal time scale and also to an equal scale of depth, demonstrate clearly the great differences in Late and post-Weichselian shore-level changes from one region to another along the coast of South Norway As a result of differential uplift the marine isobases generally become situated lower from the central part toward the outer coast regions The highest marine levels recorded drop from 220m in the Oslo area, in early Preboreal time, an

The estuarine character of the Gulf of Nicoya, an embayment on the Pacific coast of Central America

Abstract: Hydrography and exchange processes in a tropical estuary, the Gulf of Nicoya, Costa Rica, are described from data collected in 1979 and 1980. The measurements and analyses were made in both the dry season and wet season and include temperature, salinity, and density at twenty locations in the gulf and currents (over a semi-diurnal tidal cycle) at five locations. These new results enlarge on the early study by Peterson (1958). Circulation in the lower gulf shows a marked east-west asymmetry due to the predominant runoff along its eastern shore from Rio Barranca and Tarcoles. The freshened surface water from the upper gulf combines with the runoff from these rivers and flows southward along the eastern side of the lower gulf. This flow is compensated by a northward flow of more saline water on the western side at all depths and on the eastern side along the bottom. The boundary between the southward and northward surface flow is marked by a strong salinity front in the rainy season. There is a rapid increase in tidal energy density toward the shoaling northern reaches of the lower gulf, between San Lucas Island and Puntarenas Peninsula. Enhanced mixing must accompany this increase, and direct measurements in the constriction between San Lucas and Puntaneras show that tidal mixing is dominant in transporting salt into the upper gulf against the freshwater runoff.

Food Web in the Surf Zone of an Exposed Sandy Beach along the Mid-Atlantic Coast of the United States

Abstract: To the casual observer it appears that the exposed sandy beach of temperate latitudes is, except for the conspicuous migrating shore birds, a rather desolate and abiotic region of the sea. We know, however, that this air-sandwater interface is also inhabited by less conspicuous shore-zone fishes and invertebrates. Each group is relatively well-known, has a low diversity and has evolved a variety of unique adaptations required for such an existence. Their interactions as parts of a distinct community, however, have been intensively studied in only a few parts of the world (e.g. in South Africa, McLachlan et al. 1981). The low diversity of the exposed beach is a factor which tends to simplify progress toward an understanding of the interactions, but the physical harshness of the region tends to impede collection of required biological information dealing with the fauna.

Continental shelf waves and their influence on the circulation around the Great Barrier Reef

Abstract: Winds and atmospheric pressure, sea level and water currents were measured at several locations over the continental shelf, both east and west of the Great Barrier Reef, between 14.5os. and 20oS., from June to November 1980. The dominant wind direction changed from westward over the Coral Sea to north- westward (roughly parallel to the shore) over the shelf. A strong non-tidal low-frequency signal in all sea- level and longshore current data was found, highly coherent from site to site and strongly correlated with the longshore wind component over the shelf, though not with the atmospheric pressure. A model of wind- driven barotropic shelf waves is used to explain a number of observations, such as the invariance of temporal fluctuations of longshore current with distance from shore, and the northward longshore propagation of oceanic disturbances at a speed equal to twice that of the first-mode barotropic free shelf wave, a speed one order of magnitude smaller than that of the wind system. The low-frequency current fluctuations resulted in large water displacements, up and down the coast. Low-frequency cross-shelf currents were much weaker and less coherent. Two upwelling mechanisms are internal tides and internal Kelvin waves coupled to the barotropic shelf waves.

Variability of current, temperature, and bottom pressure across the west Florida continental shelf, winter 1981–1982

Abstract: Observations are analyzed from four current meter moorings deployed on the broad continental shelf in the northeastern Gulf of Mexico from November 29, 1981, to February 8, 1982 (71 days). Consistent with recent modeling studies, the shelf circulation responds within an inertial period to the alternating up-and-down-coast synoptic scale wind forcing. Average response to a 0.5 dyn cm−2 alongshore wind stress (as measured at the coast) is ∼20 cm s−1 off Cedar Key and ∼40 cm s−1 in the north where the shelf narrows (off Cape San Bias). Lower layer currents veer counterclockwise with depth, as in a bottom Ekman layer (e-folding scale ∼8 m). The pressure field decays offshore (e-folding scale ∼160 km) and yields a geostrophic current in good agreement with the observed alongshelf flow. Cross-shelf and vertical variations of the tidal signals compare nicely with results from barotropic theory. Calculations indicate that most of the shoreward propagating tidal energy must be dissipated in depths of <20 m (within 50 km of shore).

A sediment budget for the Choptank River estuary in Maryland, U.S.A.

Abstract: A sediment budget for the Choptank River, one of the three largest estuaries on the eastern shore of Chesapeake Bay, was developed from measurements of sediment carried in upland runoff, shore erosion, sedimentation, and levels of suspended sediments in estuarine waters. Shore erosion was the major source of sediment (340 × 106 kg y−1), contributing seven times more sediment than upland runoff. Low relief, the rural character of the Coastal Plain drainage basin, and the susceptibility of poorly consolidated shoreline materials to erosion contributed to the dominance of shore erosion over runoff as a sediment source. Box modelling indicated a net annual flux (14–44 × 106 kg y−1) of sediment from the Choptank River to Chesapeake Bay. A mass balance estimate of sedimentation, calculated as the difference between total inputs and loss at the mouth of the estuary, (350 × 106 kg y−1) agreed well with an estimate based on 210Pb profiles (340 × 106 kg y−1) measured along the longitudinal axis of the estuary. Lead-210 sedimentation rates correspond to accumulation rates of 1·5–7·9 mm y−1.

Erosion of U.S. shorelines

Abstract: We have assembled data on the rate of change of the U.S. shorelines, including those of the Great Lakes. Obtained from geologists and engineers, our data base covers 1689 sites. The national average (unweighted) shoreline erosion rate is 0.40 m/yr. Along the Atlantic coast the average rate of recession is 0.8 m/yr; the Gulf coast is 1.8 m/yr; and the Pacific coast rate, including Alaska, is 0.005 m/yr. Statistics for Delaware Bay, Chesapeake Bay, and the Great Lakes are also summarized.

Tree ring indications of uplift at Icy Cape, Alaska, related to 1899 earthquakes

Abstract: Previous studies show that tree ring analysis can provide information about past major earthquakes. If occurrence of large, prehistoric seismic events and extent of areas affected by such events can be determined by analysis of old-aged trees, this information will be an important addition to the paleoseismological record. Two great earthquakes occurred in September 1899 on the southeastern coast of Alaska near Icy Cape, an area now included within the Yakataga seismic gap. Due to glacial coverage of Icy Bay and the scarcity of observers, any possible uplift at Icy Cape related to these earthquakes was unreported. In 1902 the presumed former shoreline trees at two sites, 2.4 km apart, show both an absolute increase in growth and an increase in growth relative to inland trees. The ages of the trees on the lowland seaward of the sample sites are all post-1899. If uplift occurred, a seaward shifting of the shoreline would improve the growth environment of trees growing on the former wave-beaten shoreline and former beach areas might be protected enough for initial afforestation. Other possible causes for tree growth and shoreline changes are considered; however, from the tree ring evidence, geomorphology, and reports of uplift in other parts of the region, it is the authors' interpretation that uplift occurred at Icy Cape related to the 1899 earthquakes. Subsequent accumulation of fluvial and littoral sediments has built out over and around the uplifted area, resulting in the present-day shoreline configuration. The methodologies used in this study have paleoseismological applications to other uplifted, forested, shoreline areas.

William Pitt’s Settlement at Black River on the Mosquito Shore: A Challenge to Spain in Central America, 1732-87

Abstract: URING the eighteenth century when William Pitt, Earl of Chatham, dominated English political life, a distant relative, also named William Pitt, established an unofficial English colony on the Mosquito Shore of what is now the Caribbean coastline of Honduras. It is unlikely that the two Pitts ever met. Nevertheless, had they done so, they would have discovered a common bond in their desire to undermine Spanish political and economic pretensions in America. Although the Mosquito Shore never attained official colonial status, by 1787 it contained approximately 2,600 British subjects scattered among a dozen small settlements on a 550-mile strip running east along the Honduran coast to Cape Gracias a Dios, and then south and east to Nicaragua's San Juan River. Together with Belize and Jamaica, the Shore formed an important triangular British power base, threatening the weakest link in Spain's New World empire. 1 The small town of Black River, founded by William Pitt in 1732 near Cape Cameron some 80 miles east of the Spanish frontier town of Trujillo, became the Shore's administrative center and a major, frustrating irritant to Spanish colonial administrators when, after 1740, Jamaican governors encouraged Pitt to develop his settlement into an entrep6t for contraband trade and a staging area for attacks on Spain's Central American possessions.

Large earthquakes, mean sea level, and tsunamis along the Pacific Coast of Mexico and Central America

Abstract: Along the Pacific Coast of Mexico and Central America, 26 local tsunamis have been reported during the period 1732 to 1973. Nine of these were caused by earthquakes with teleseismic hypocenters, all of which were located well inland. If these epicenters were correct, these earthquakes could not have generated tsunamis. Under the assumption that the true epicenters must have been located at the coast or off shore, it was estimated that teleseismic hypocenters in this area are mislocated by about 75 km toward the northeast, and 20 km toward greater depth. We propose that most teleseismic locations in this area are afflicted by this same error. The most likely cause for the mislocations are shorter than expected travel times for rays in the down-dip direction of the subducted lithospheric slab. These rays travel to North American stations which contribute strongly to hypocenter locations in Middle America. The annual mean sea level of 13 tide gauge stations along the Pacific coast of Mexico and Central America were examined for evidence of vertical crustal deformation changes that could have been associated with earthquakes along this coast. Only one coseismic change could be identified in the annual mean sea level data. It occurred at Acapulco, Mexico, during the 11 May ( M s = 7.0) and 19 May ( M s = 7.2) 1962 earthquakes. The crustal uplift was about 22 cm, estimated from the difference of the 10-yr sea level means before and after the events. By comparing annual mean with daily mean sea level data, it appears that about 23 per cent of the permanent uplift observed at Acapulco was due to aseismic slip or aftershocks in this area. If tide gauge data in this area are kept current, long-term precursory crustal movements might be detectable if they exceed several centimeters.

Contrasting Marginal Sediments of a Seasonally Flooded Saline Lake - Lake Eliza, South-Australia - Significance for Oil-Shale Genesis

Abstract: Lake Eliza is a hypersaline coastal lake in a region of winter rainfall and summer drought. Two areas of the lake margin exposed in summer were studied. The western protected shore is an area of fine carbonate sediments with high organic content. The eastern, exposed shore is an area of moderately sorted quartz-carbonate sand of lower organic content. The sediments of Lake Eliza are similar to some of those described from the Wilkins Peak Member of the Green River Formation, USA, and a comparison suggests that the lamosite oil shales of the type found in the Green River Formation may not have been deposited on a fresh to brackish lake floor as has been supposed.-from Authors

Shore stabilization with salt marsh vegetation

Abstract: : This report is published to provide engineers and scientists with guidelines on using coastal marsh vegetation as a shore erosion control measure in coastal regions of the United States. This erosion control alternatives is suitable for relatively sheltered shorelines such as those found on bays, sounds, and estuaries. For various reasons this alternative has not been found to be effective in the Great Lakes, Alaska, or Hawaii. Criteria are provided on (1) determining site suitability, (2) selecting plant materials, (3) planting procedures and specifications, (4) estimating project costs, and (5) assessing impact.

Development of mangrove forests from a geological perspective

Abstract: Mangrove swamps develop only where coastal physiography and energy conditions are favourable. They are most extensive where there is a low shore gradient, and occupy a broader belt on shorelines which have a large tidal range (Walsh, 1974). Sheltered habitats are essential for mangrove development, and on coasts which are exposed, mangroves are localised in the lee of other coastal landforms (Davies, 1972).

Beach Changes on Coasts with Different Wave Climates

Abstract: Seasonal and longer-term beach variability is quantified for seven U.S. beaches exposed to widely varying wave climates. One U.S. west coast location (southern California) and six U.S. east coast locations (from North Carolina to Massachusetts) form the basis of this study. Wave exposure varies from complete exposure to open ocean waves, to partly sheltered locations, and finally to nearly complete sheltering where locally-generated waves dominate. Beach response was documented with beach profiles distributed along each of the seven coastal locations, spanning a minimum of five years of observation. Frequency of measurement was at least once per month, with periods of more intense weekly sampling lasting for up to two years (southern California location). Wave climate was either measured directly or estimated from hindcast and/or compilations of ship observations. Consequently, wave information varies in detail from joint statistics of wave height, frequency, and direction, to compilations of local storm history (and hence inferred wave behaviour). Magnitude of annual beach variability ranged from 3.3 m3 per metre of beach to 0.2 m3 per metre of beach, with the greatest variability in regions exposed to open ocean waves (most severe wave climate) and the lowest variability along protected coasts (least severe wave climate). All open coast locations studied had a seasonal variability which accounted for at least 50% of the beach variability. Protected coastal locations had less pronounced seasonal signatures. These seasonal and aseasonal beach responses mirror corresponding seasonality (or lack thereof) in wave and storm climates. The study re-emphasizes the need for careful measurement or estimation of coastal wave climate to enable predictive modelling of shoreline behaviour, and discusses different analysis techniques for analyzing changes in beach profiles through time.