330 resultados para shores


Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The highly dynamic nature of some sandy shores with continuous morphological changes require the development of efficient and accurate methodological strategies for coastal hazard assessment and morphodynamic characterisation. During the past decades, the general methodological approach for the establishment of coastal monitoring programmes was based on photogrammetry or classical geodetic techniques. With the advent of new geodetic techniques, space-based and airborne-based, new methodologies were introduced in coastal monitoring programmes. This paper describes the development of a monitoring prototype that is based on the use of global positioning system (GPS). The prototype has a GPS multiantenna mounted on a fast surveying platform, a land vehicle appropriate for driving in the sand (four-wheel quad). This system was conceived to perform a network of shore profiles in sandy shores stretches (subaerial beach) that extend for several kilometres from which high-precision digital elevation models can be generated. An analysis of the accuracy and precision of some differential GPS kinematic methodologies is presented. The development of an adequate survey methodology is the first step in morphodynamic shore characterisation or in coastal hazard assessment. The sample method and the computational interpolation procedures are important steps for producing reliable three-dimensional surface maps that are real as possible. The quality of several interpolation methods used to generate grids was tested in areas where there were data gaps. The results obtained allow us to conclude that with the developed survey methodology, it is possible to Survey sandy shores stretches, under spatial scales of kilometers, with a vertical accuracy of greater than 0.10 m in the final digital elevation models.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Understanding and predicting patterns of distribution and abundance of marine resources is important for con- servation and management purposes in small-scale artisanal fisheries and industrial fisheries worldwide. The goose barnacle (Pollicipes pollicipes) is an important shellfish resource and its distribution is closely related to wave exposure at different spatial scales. We modelled the abundance (percent coverage) of P. pollicipes as a function of a simple wave exposure index based on fetch estimates from digitized coastlines at different spatial scales. The model accounted for 47.5% of the explained deviance and indicated that barnacle abundance increases non-linearly with wave exposure at both the smallest (metres) and largest (kilometres) spatial scales considered in this study. Distribution maps were predicted for the study region in SW Portugal. Our study suggests that the relationship between fetch-based exposure indices and P. pollicipes percent cover may be used as a simple tool for providing stakeholders with information on barnacle distribution patterns. This information may improve assessment of harvesting grounds and the dimension of exploitable areas, aiding management plans and support- ing decision making on conservation, harvesting pressure and surveillance strategies for this highly appreciated and socio- economically important marine resource.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Caspian Sea with its unique characteristics is a significant source to supply required heat and moisture for passing weather systems over the north of Iran. Investigation of heat and moisture fluxes in the region and their effects on these systems that could lead to floods and major financial and human losses is essential in weather forecasting. Nowadays by improvement of numerical weather and climate prediction models and the increasing need to more accurate forecasting of heavy rainfall, the evaluation and verification of these models has been become much more important. In this study we have used the WRF model as a research-practical one with many valuable characteristics and flexibilities. In this research, the effects of heat and moisture fluxes of Caspian Sea on the synoptic and dynamical structure of 20 selective systems associated with heavy rainfall in the southern shores of Caspian Sea are investigated. These systems are selected based on the rainfall data gathered by three local stations named: Rasht, Babolsar and Gorgan in different seasons during a five-year period (2005-2010) with maximum amount of rainfall through the 24 hours of a day. In addition to synoptic analyses of these systems, the WRF model with and without surface flues was run using the two nested grids with the horizontal resolutions of 12 and 36 km. The results show that there are good consistencies between the predicted distribution of rainfall field, time of beginning and end of rainfall by the model and the observations. But the model underestimates the amounts of rainfall and the maximum difference with the observation is about 69%. Also, no significant changes in the results are seen when the domain and the resolution of computations are changed. The other noticeable point is that the systems are severely weakened by removing heat and moisture fluxes and thereby the amounts of large scale rainfall are decreased up to 77% and the convective rainfalls tend to zero.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The decapod crustacean assemblages from unconsolidated seabed areas located near rocky shores in the Ubatuba region on the south-east coast of Brazil were analysed by investigating the abundance, richness, diversity and dominance of species. The relationships of the sediment and bottom-water temperature to total species abundance, richness and diversity were also evaluated. Monthly samples were taken from January 1998 through December 1999 at sites in Ubatumirim and Mar Virado. At each locality, three areas were defined as either 'exposed', 'sheltered' or 'island'. The highest species abundance was found in the sheltered area of Ubatumirim and the exposed area of Mar Virado, and during autumn. At Ubatumirim, the highest richness occurred in the exposed area and the highest diversity near the island. At Mar Virado, the highest richness and diversity were found near the island. Autumn and winter collections yielded the highest richness but the lowest diversity. The higher diversities, which were measured near the islands and during spring and summer, were consequences of the greater evenness of the data. The areas with the highest diversity also had the most heterogeneous sediment composition, thus reinforcing the hypothesis that areas with more complex substrata support more diverse faunas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Epilithic biofilm on rocky shores is regulated by physico-chemical and biological factors and is important as a source of food for benthic organisms. The influences of environmental and grazing pressure on spatial variability of biomass of biofilm were evaluated on shores on the north coast of São Paulo State (SE Brazil). A general trend of greater abundance of microalgae was observed lower on the shore, but neither of the environmental factors evaluated (wave exposure and shore level) showed consistent effects, and differences were found among specific shores or times (September 2007 and March 2008). The abundance of slow-moving grazers (limpets and littorinids) showed a negative correlation with chlorophyll a concentration on shores. However, experimental exclusion of these grazers failed to show consistent results at small spatial scales. Observations of divergent abundances of the isopod Ligia exotica and biomass of biofilm on isolated boulders on shores led to a short exclusion experiment, where the grazing pressure by L. exotica significantly decreased microalgal biomass. The result suggests that grazing activities of this fast-moving consumer probably mask the influence of slow-moving grazers at small spatial scales, while both have an additive effect at larger scales that masks environmental influences. This is the first evaluation of the impact of the fast-moving herbivore L. exotica on microalgal biomass on rocky shores and opens an interesting discussion about the role of these organisms in subtropical coastal environments.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Hydrodynamism is an environmental stressor on marine communities with effects on populations of intertidal organisms. Microphrys bicornutus is a crab species associated with secondary substrates on rocky shores and little is known about its population dynamics and its relation to the shore hydrodynamics. The aim of this study is to describe the population structure of Microphrys bicornutus on intertidal rocky shores from the north coast of the São Paulo State, Brazil, and the influence of wave exposure on the density of this decorator crab. There was a greater density of M. bicornutus on sheltered than on exposed rocky shores, which is probably due to the hydrodynamic influence on M. bicornutus populations on rocky shores: directly ( by the physical stress caused by wave impact) and indirectly ( by determining the dominance of the secondary substrate) acting on the density of these crabs. Our results also suggest a vertical distribution of juveniles and adults, where the juveniles might be more abundant on the infralittoral fringe and, thus, more influenced by hydrodynamism than adults in the infralittoral.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Sedentary consumers play an important role on populations of prey and, hence, their patterns of abundance, distribution and coexistence on shores are important to evaluate their potential influence on ecosystem dynamics. Here, we aimed to describe their spatio-temporal distribution and abundance in relation to wave exposure in the intertidal rocky shores of the south-west Atlantic to provide a basis for further understanding of ecological processes in this system. The abundance and composition of the functional groups of sessile organisms and sedentary consumers were taken by sampling the intertidal of sheltered and moderately exposed shores during a period of one year. The sublittoral fringe of sheltered areas was dominated by macroalgae, while the low midlittoral was dominated by bare rock and barnacles. In contrast, filter-feeding animals prevailed at exposed shores, probably explaining the higher abundance of the predator Stramonita haemastoma at these locations. Limpets were more abundant at the midlittoral zone of all shores while sea urchins were exclusively found at the sublittoral fringe of moderately exposed shores, therefore, adding grazing pressure on these areas. The results showed patterns of coexistence, distribution and abundance of those organisms in this subtropical area, presumably as a result of wave action, competition and prey availability. It also brought insights on the influence of top-down and bottom-up processes in this area.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Multi-level concrete buildings requrre substantial temporary formwork structures to support the slabs during construction. The primary function of this formwork is to safely disperse the applied loads so that the slab being constructed, or the portion of the permanent structure already constructed, is not overloaded. Multi-level formwork is a procedure in which a limited number of formwork and shoring sets are cycled up the building as construction progresses. In this process, each new slab is supported by a number of lower level slabs. The new slab load is, essentially, distributed to these supporting slabs in direct proportion to their relative stiffness. When a slab is post-tensioned using draped tendons, slab lift occurs as a portion of the slab self-weight is balanced. The formwork and shores supporting that slab are unloaded by an amount equivalent to the load balanced by the post-tensioning. This produces a load distribution inherently different from that of a conventionally reinforced slab. Through , theoretical modelling and extensive on-site shore load measurement, this research examines the effects of post-tensioning on multilevel formwork load distribution. The research demonstrates that the load distribution process for post-tensioned slabs allows for improvements to current construction practice. These enhancements include a shortening of the construction period; an improvement in the safety of multi-level form work operations; and a reduction in the quantity of form work materials required for a project. These enhancements are achieved through the general improvement in safety offered by post-tensioning during the various formwork operations. The research demonstrates that there is generally a significant improvement in the factors of safety over those for conventionally reinforced slabs. This improvement in the factor of safety occurs at all stages of the multi-level formwork operation. The general improvement in the factors of safety with post-tensioned slabs allows for a shortening of the slab construction cycle time. Further, the low level of load redistribution that occurs during the stripping operations makes post-tensioned slabs ideally suited to reshoring procedures. Provided the overall number of interconnected levels remains unaltered, it is possible to increase the number of reshored levels while reducing the number of undisturbed shoring levels without altering the factors of safety, thereby, reducing the overall quantity of formwork and shoring materials.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The middle classes form the bulk of Indian migrants who head for Australian shores today. Yet, within Australia, general knowledge of the conditions that drive Indians’ determined search for opportunities overseas is limited to the few who have contact with international students and migrants from the sub-continent, and the skewed, melodramatic antics of Bollywood. It is my suggestion that a broader understanding of the underlying reasons that push Indians to migrate to societies like Australia can be had through readings of Chetan’s Bhagat’s four hugely popular novels: Five Point Someone, One night @the Call Center, The 3 mistakes of My life and Two States. Bhagat is a graduate of India’s famed Indian Institute of Technology and a former Non-Resident Indian investment banker who has since returned to live in Delhi. His experiences make him the perfect mouthpiece for middle India and his paperbacks depict that stratum of Indian society’s obsessions with social mobility, marriage, regional and religious divides with great sympathy and conviction. Drawing on observations made during a recent visit to India, I illustrate what an exploration of Bhagat’s paperbacks reveals about everyday, contemporary India and what it adds to Australian understandings of Indians and India today.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This book examines public worrying over 'ethnic crime' and what it tells us about Australia today. How, for instance, can the blame for a series of brutal group sexual assaults in Sydney be so widely attributed to whole ethnic communities? How is it that the arrival of a foundering boatload of asylum-seekers mostly seeking refuge from despotic regimes in 'the Middle East' can be manipulated to characterise complete cohorts of applicants for refuge 'and their immigrant compatriots' as dangerous, dishonest, criminally inclined and inhuman? How did the airborne terror attacks on the USA on 11 September 2001 exacerbate existing tendencies in Australia to stereotype Arabs and Muslims as backward, inassimilable, without respect for Western laws and values, and complicit with barbarism and terrorism? Bin Laden in the Suburbs argues that we are witnessing the emergence of the 'Arab Other' as the pre-eminent 'folk devil' of our time. This Arab Other functions in the national imaginary to prop up the project of national belonging. It has little to do with the lived experiences of Arab, Middle Eastern or Muslim Australians, and everything to do with a host of social anxieties which overlap in a series of moral panics. Bin Laden in the Suburbs analyses a decisive moment in the history of multiculturalism in Australia. 'Unlike most migrants, the Arab migrant is a subversive will ... They invade our shores, take over our neighbourhood and rape our women. They are all little bin Ladens and they are everywhere: Explicit bin Ladens and closet bin Ladens; Conscious bin Ladens and unconscious bin Ladens; bin Ladens on the beach and bin Ladens in the suburbs, as this book is aptly titled. Within this register ... even a single Arab is a threat. Contain the Arab or exterminate the Arab? A 'tolerable' presence in the suburbs, or caged in a concentration camp? ... The politics of the Western post-colonial state is constantly and dangerously oscillating between these tendencies today. It is this dangerous oscillation that is so lucidly exposed in this book'.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In light of the high stakes of the deepwater horizon civil trial and the important precedent-setting role that the case will have on the assessment of future marine disasters, the methodologies underpinning the calculations of damage on both sides will be subjected to considerable scrutiny. Despite the importance of the case, however, there seems to be a pronounced lack of convergence about it in the academic literature. Contributions from scientific journals frequently make comparisons to the Ixtoc I oil spill off the coast of Mexico in 1979; the legal literature, by stark contrast, seems to be much more focused on the Exxon Valdez spill that occurred off the shores of Alaska in 1989. This paper accordingly calls for a more thorough consideration of other analogs beyond the Exxon Valdez spill—most notably, the Ixtoc I incident—in arriving at an assessment of the damage caused by the Deepwater Horizon disaster.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Approximately 125 prehistoric rock paintings have been found in the modern territory of Finland. The paintings were done with red ochre and are almost without exception located on steep lakeshore cliffs associated with ancient water routes. Most of the sites are found in the central and eastern parts of the country, especially on the shores of Lakes Päijänne and Saimaa. Using shore displacement chronology, the art has been dated to ca. 5000 – 1500 BC. It was thus created mainly during the Stone Age and can be associated with the so-called ‘Comb Ware’ cultures of the Subneolithic period. The range of motifs is rather limited, consisting mainly of schematic depictions of stick-figure humans, elks, boats, handprints and geometric signs. Few paintings include any evidence of narrative scenes, making their interpretation a rather difficult task. In Finnish archaeological literature, the paintings have traditionally been associated with ’sympathetic’ hunting magic, or the belief that the ritual shooting of the painted animals would increase hunting luck. Some writers have also suggested totemistic and shamanistic readings of the art. This dissertation is a critical review of the interpretations offered of Finnish rock art and an exploration of the potentials of archaeological and ethnographic research in increasing our knowledge of its meaning. Methods used include ’formal’ approaches such as archaeological excavation, landscape analysis and the application of neuropsychological research to the study of rock art, as well as ethnographically ’informed’ approaches that make use of Saami and Baltic Finnish ethnohistorical sources in interpretation. In conclusion, it is argued that although North European hunter-gatherer rock art is often thought to lie beyond the reach of ‘informed’ knowledge, the exceptional continuity of prehistoric settlement in Finland validates the informed approach in the interpretation of Finnish rock paintings. The art can be confidently associated with shamanism of the kind still practiced by the Saami of Northern Fennoscandia in the historical period. Evidence of similar shamanistic practices, concepts and cosmology are also found in traditional Finnish-Karelian epic poetry. Previous readings of the art based on ‘hunting magic’ and totemism are rejected. Most of the paintings appear to depict experiences of falling into a trance, of shamanic metamorphosis and trance journeys, and of ‘spirit helper’ beings comparable to those employed by the Saami shaman (noaidi). As demonstrated by the results of an excavation at the rock painting of Valkeisaari, the painted cliffs themselves find a close parallel in the Saami cult of the 'sieidi', or sacred cliffs and boulders worshipped as expressing a supernatural power. Like the Saami, the prehistoric inhabitants of the Finnish Lake Region seem to have believed that certain cliffs were ’alive’ and inhabited by the spirit helpers of the shaman. The rock paintings can thus be associated with shamanic vision quests, and the making of ‘art’ with an effort to socialize the other members of the community, especially the ritual specialists, with trance visions. However, the paintings were not merely to be looked at. The red ochre handprints pressed on images of elks, as well as the fact that many paintings appear ’smeared’, indicate that they were also to be touched – perhaps in order to tap into the supernatural potency inherent in the cliff and in the paintings of spirit animals.