Perception of the rip current hazard on Galveston Island and North Padre Island,Texas, USA

The hazard posed by a rip current depends in part on the ability of beach users to identify a rip current and to associate surf conditions with the potential for rip currents. Understanding which visual features beach users associated with rip currents is an important step in the development of appropriate programs and educational materials aimed at improving the ability of beach users to identify a rip current. A face-to-face survey (n = 392) was conducted to assess the ability of beach users to identify a rip current using five near eye-level photographs that simulate the view of the beach and surf zone as the respondent approached the beach. The survey was conducted on three heavily used public beaches in Texas (Galveston, Port Aransas, and Corpus Christi) at the height of the summer beach season in 2012. Only 13 % of respondents correctly selected the photograph showing the most hazardous conditions and correctly identified the precise location of the rip current on the photograph. The majority of beach users (87 %) incorrectly indicated that the photograph with the heaviest surf represented the most hazardous surf conditions and greatest potential for the development of rip currents, or failed to identify rip currents in photographs. Respondents who were able to correctly identify the rip current tended to recognize the breaking wave pattern, areas of darker water, or the proximity to structures as key visual characteristics of rip currents and also had higher self-reported abilities to swim in rough water and escape a rip current.     

The Ayres raised beach,Isle of Man

The area fringing the north coast of the Isle of Man, known as the Ayres, consists of beach deposits lying three or four metres above high-tide level (about 6 m above O.D. at Douglas). This raised beach extends from Phurt on the east coast to Sartfield on the west where it is cut out by modern coastal erosion. The fossil fauna is recent in character; Lamplugh (1903) used this as a basis for correlation with other raised beaches and platforms around the island.     

Public perceptions on coastal erosion in the Maltese Islands: a case study of St George’s Bay (St Julians) and Pretty Bay (Birżebbuġa)

With 60% of the world’s population living within the coastal zone, coastal erosion is considered as a global problem. The coasts of the Maltese Islands hold a variety of formations resulting from coastal erosion. Beach nourishment is one of the protective measures taken against coastal erosion. This paper focuses on two of the nourished beaches within the Maltese Islands, St George’s Bay (St Julians) and Pretty Bay (Birżebbuġa), that have undergone extensive sand augmentation during the past decades and looks at the extent of how coastal erosion and beach replenishment may have influenced public perception. Through a triangulation of interviews, it seeks to understand the views of beach users, researchers, representatives, and beach managers. It presents divergences in interviewee opinions and ideas on St George’s Bay and Pretty Bay and illustrates that public perception tends to reflect the type of urban area surrounding each replenished beach. Recommendations and suggestions are also presented to promote awareness towards coastal processes and their impacts.

     

Morphodynamics of a mesotidal rocky beach: Palmeras beach,Gorgona Island National Natural Park,Colombia

The response of a rocky beach to different possible combinations of hydrodynamic conditions (tides, waves, oceanic currents) has been little studied. In this work, the morphodynamic response to different hydrodynamic forcing is evaluated from sedimentological and geomorphological analysis in seasonal and medium term (19 years) scale in Palmeras beach, located in the southwest of Gorgona Island National Natural Park (NNP), a mesotidal rocky island on the Colombian Pacific continental shelf. Palmeras is an important nesting area of two types of marine turtles, with no anthropogenic stress. In the last years, coastal erosion has reduced the beach width, restricting the safe areas for nesting and conservation of these species. Until now, the sinks, sources, reservoirs, rates, and paths of sediments were unknown, as well as their hydrodynamic forcing. The beach seasonal variability, from October 2010 to August 2012, was analyzed based on biweekly or monthly measurements of five beach profiles distributed every 200 m along the 1.2 km of beach length. The main paths for sediment transport were defined from the modeling of wave currents with the SMC model (Coastal Modeling System), as well as the oceanic currents, simulated for the dry and wet seasons of 2011 using the ELCOM model (Estuary and Lake COmputer Model). Extreme morphologic variations over a time span of 19 years were analyzed with the Hsu and Evans beach static equilibrium parabolic model, from one wave diffraction point which dominates the general beach plan shape. The beach lost 672 m³/m during the measuring period, and erosional processes were intensified during the wet season. The beach trends responded directly to a wave mean energy flux change, resulting in an increase of up to 14 m in the width northward and loss of sediments in the beach southward. This study showed that to obtain the integral morphodynamic behavior of a rocky beach it is necessary to combine information of hydrodynamic, sedimentology and geomorphology in different time scales.     

An absolute chronology for the raised beach and associated deposits at Sewerby,East Yorkshire,England

The raised beach sediments revealed in the cliffs at Sewerby, East Yorkshire are widely regarded as Ipswichian in age. Previously reported evidence for this dating is reviewed and new results from a range of luminescence dating techniques applied to the blown sand deposit overlying the raised beach are reported. These provide the first absolute date for the Sewerby site of 120.84 ± 11.82 ka, which places the blown sand at the boundary between oxygen isotope stages (OIS) 5e and 5d. As the underlying raised beach is little older than the blown sand, it probably formed during OIS Stage 5e as suggested by the faunal evidence.     

Factors influencing human beach choice on three South African beaches: A multivariate analysis

Knowledge of recreational use patterns, preferences and opinions of beach users can be useful in developing beaches in such a way as to ensure quality recreational experiences. This paper investigated, by means of questionnaire survey, a) the factors influencing human beach choice on three beaches with different levels of development and b) whether respondents on the different beaches considered different characteristics important on an ideal beach. By means of multiple discriminant analysis, visitors could be classified according to the beaches they were interviewed on, based solely on the different reasons given for visiting the beach as well as on the characteristics they considered important on a beach.Although factors relating to level of beach development were the most important in influencing beach choice on highly developed King's Beach and undeveloped Sardinia Bay, traditional/historical, socio-economic factors and accessibility (all unrelated to beach development) were more important on semi-developed Joorst Park, visited by people of a lower-socio-economic level. These people considered Joorst Park underdeveloped but were prevented by socio-economic restraints from visiting a beach of their choice, eg King's Beach. The highly and semi-developed beaches were visited for their facilities, social activities and accessibility. The undeveloped beach was visited for experiencing nature, peace and quiet, its few people and because dogs were allowed there. In addition, respondents' opinions were obtained on litter, additional facilities, preferred distances between groups on the beach and in the surf and whether dogs and off-road vehicles should be allowed on beaches. More basic facilities (toilets and refuse bins) were considered necessary on all beaches, especially on the semi-developed beach. Beyond a minimal level of amenities, additional comforts were undesired by users on the undeveloped beach and limited funds should rather be used to upgrade and improve beaches such as Joorst Park, that are already developed to attract people with greater demands for a wider range of facilities. However, beaches with different levels of development are necessary to cater for people who desire different recreational experiences. Limiting beach access beyond a certain number of visitors seems to be unpopular with the public.     

Wind action and sand movement near Holkham Bay,North Norfolk Coast,England

In Holkham Bay, North Norfolk Coast, England, a wide beach and coastal dunes have formed as a result of wave action and wind activity. This article describes the experiments and field observations that were carried out to explore the nature of wind activity that is presently affecting the morphology of the beach and dunes.The experiments and field observations indicate: (1) Sand is blown off the beach surface very soon after it is exposed during the low tide if the wind velocity is above 3.0 m/sec. (2) Winds from the south, east, and west in Holkham Bay are offshore winds and do not exert much influence on dune formation in the area. (3) The dominant winds (those that exert most marked effect on the beach and dunes) are the northerly, northeasterly and the northwesterly winds. (4) The average annual accretion rate of sand by the wind on the beach is about 3,600 m³. (5) Knowing the annual accretion rate and the volume of aeolian dunes, it is possible to determine their relative ages.     

Ability of beach users to identify rip currents at Pensacola Beach, Florida

Quasi-permanent rip current hot spots at Pensacola Beach, Florida, pose a significant hazard to beach users, largely because the hot spots are located at or close to the primary access points. While an increase in the number of lifeguards has led to a decrease in the number of drownings since 2004, the number of rescues and contacts has increased to over a 30,000 year. Despite warning signs at access points along the beach, it is not clear whether beach users are able to identify a rip channel or an active rip current. To assess beach users’ knowledge of rip currents and their ability to identify rip channels and currents, 97 surveys were conducted between June and September of 2010 at Pensacola Beach. Beach users were asked to identify rip channels in oblique photographs taken on green, yellow and red flag days when the potential for rip currents is low, medium and high, respectively. A majority of participants suggested that they could identify a rip channel or current (if present), but less than 20 % of beach users were able to identify the rip channels and currents. The majority of participants identified heavy surf areas as the location of the rips versus the relatively flat water of the current or the darker color water of the channel. Results further suggest that most beach users, and particularly local participants, are overconfident in their ability to identify rip channels and currents. The focus of beach users on heavy surf as an indication of the rip current potential and the overconfidence in identifying a rip channel or current affects the spatial distribution of beach users and to some degree the location of rescues and drownings. While it can be quite difficult for the average beach user to identify rip channels and active rip currents, the results of the study suggest a need for further education efforts to reduce the rip hazard, particularly in areas where lifeguards are not permanently stationed.     

Quantifying rates of coastal progradation from sediment volume using GPR and OSL: the Holocene fill of Guichen Bay, south-east South Australia

Guichen Bay on the south‐east coast of South Australia faces west towards the prevailing westerly winds of the Southern Ocean. The bay is backed by a 4 km wide Holocene beach‐ridge plain with more than 100 beach ridges. The morphology of the Guichen Bay strandplain complex shows changes in the width, length, height and orientation of beach ridges. A combination of geomorphological interpretation, shallow geophysics and existing geochronology is used to interpret the Holocene fill of Guichen Bay. Six sets of beach ridges are identified from the interpretation of orthorectified aerial photographs. The ridge sets are distinguished on the basis of beach‐ridge orientation and continuity. A 2·25 km ground‐penetrating radar (GPR) profile across the beach ridges reveals the sedimentary structures and stratigraphic units. The beach ridges visible in the surface topography are a succession of stabilized foredunes that overlie progradational foreshore and upper shoreface sediments. The beach progrades show multiple truncation surfaces interpreted as storm events. The GPR profile shows that there are many more erosion surfaces in the subsurface than beach ridges on the surface. The width and dip of preserved beach progrades imaged by GPR shows that the shoreface has steepened from around 2·9° to around 7·5°. The changes in beach slope are attributed to increasing wave energy associated with beach progradation into deeper water as Guichen Bay was infilled. At the same time, the thickness of the preserved beach progrades increases slightly as the beach prograded into deeper water. Using the surface area of the ridge sets measured from the orthophotography, and the average thickness of upper shoreface, foreshore and coastal dune sands interpreted from the GPR profile, the volume of Holocene sediments within three of the six sets of beach‐ridge accretion has been calculated. Combining optically stimulated luminescence (OSL) ages and volume calculations, rates of sediment accumulation for Ridge Sets 3, 4 and 5 have been estimated. Linear rates of beach‐ridge progradation appear to decrease in the mid‐Holocene. However, the rates of sediment accumulation calculated from beach volumes have remained remarkably consistent through the mid‐ to late Holocene. This suggests that sediment supply to the beach has been constant and that the decrease in the rate of progradation is due to increasing accommodation space as the beach progrades into deeper water. Changes in beach‐ridge morphology and orientation reflect environmental factors such as changes in wave climate and wind regime.     

烟台第一海水浴场沙源匮乏型海滩地貌和表层沉积物粒度特征

在烟台第一海水浴场,利用经纬仪进行2条海滩横剖面形态测量,并在不同地貌单元采集沉积物样品进行粒度分析。测量显示,该海滩仅有小规模沙坝和沟槽体系。后滨上有风成沉积,但滩肩和海岸沙丘发育均不明显。粒度分析结果表明,海滩沉积物以中砂、粗砂为主,杂以砾或细砂,比山东半岛其他海滩沉积物明显要粗。由陆向海沉积物呈带状分布,平均高潮线附近和沙坝迎水坡侵蚀作用均显著。因此认为缺乏沙源供应的基岩岬湾式海岸是导致沙滩地貌发育不典型、海滩侵蚀作用显著的主要原因。     

GPR studies over the tsunami affected Karaikal beach,Tamil Nadu,south India

In this study, results of GPR profiling related to mapping of subsurface sedimentary layers at tsunami affected Karaikal beach are presented . A 400 MHz antenna was used for profiling along 262 m stretch of transect from beach to backshore areas with penetration of about 2.0 m depth (50 ns two-way travel time). The velocity analysis was carried out to estimate the depth information along the GPR profile. Based on the significant changes in the reflection amplitude, three different zones are marked and the upper zone is noticed with less moisture compared to other two (saturated) zones. The water table is noticed to vary from 0.5 to 0.75 m depth (12–15 ns) as moving away from the coastline. Buried erosional surface is observed at 1.5 m depth (40–42 ns), which represents the limit up to which the extreme event acted upon. In other words, it is the depth to which the tsunami sediments have been piled up to about 1.5 m thickness. Three field test pits were made along the transect and sedimentary sequences were recorded. The sand layers, especially, heavy mineral layers, recorded in the test pits indicate a positive correlation with the amplitude and velocity changes in the GPR profile. Such interpretation seems to be difficult in the middle zone due to its water saturation condition. But it is fairly clear in the lower zone located just below the erosional surface where the strata is comparatively more compact. The inferences from the GPR profile thus provide a lucid insight to the subsurface sediment sequences of the tsunami sediments in the Karaikal beach.     

Microtextures of detrital sand grains from the Tecolutla,Nautla, and Veracruz beaches,western Gulf of Mexico,Mexico: implications for depositional environment and paleoclimate

Detrital sand grains from three beaches (Tecolutla, Nautla, and Veracruz) along the western Gulf of Mexico were studied by a scanning electron microscope, to investigate the depositional environment and paleoclimate. Totally, 24 microtextures are identified; among them, 13 are grouped as mechanical origin, 5 as mechanical and/or chemical origin, and 6 as chemical origin. These microtextures are nonuniformly distributed among the three beach areas. Concoidal fractures, straight and arcuate steps at Tecolutla and Veracruz beaches indicate that the sand grains were derived from the crystalline rocks. The abundance of angular outline grains at the Nautla beach supports for short transportation probably close to the source area. The domination of rounded sand grains in the Veracruz beach reveals that the sediments were derived by the aeolian mechanism. Chattermark trials at the Veracruz beach sands are indicating a wet tropical climate. Chemical features like silica globules, silica pellicle, and trapped diatoms in the Tecolutla and Veracruz beach sands suggest a silica saturated environment. Similarly, chemical etching and solution pits are common in the Veracruz beach sands, which are probably linked to the contaminated sea water. Desiccation crack at Veracruz beach sands is an indicator of temperature changes in the beach environment. Broken benthonic foraminifera Elphidium discoidale sp. present in the Veracruz beach indicates a high-energy littoral environment.     

Rip current escape strategies: lessons for swimmers and coastal rescue authorities

Lagrangian flow of two rip currents was measured using human drifters to understand how variations in surf zone circulation affect exit positions of floating swimmers. Based on these results, two escape strategies were assessed, ‘do nothing’ and ‘swim parallel to the beach’. The drifter paths and exit positions were analysed to determine the best escape strategy for passive swimmers in each scenario. Of the two methods, doing nothing to allow the rip current to take a swimmer is the most effective strategy. More than 75% of rip current flow scenarios could hinder chances of escape of swimmers if the wrong direction was chosen to swim parallel to the beach to safety. This is because in many situations a swimmer encounters not only a rip current flowing offshore but also a longshore current flowing parallel to the beach. The best education campaign for the public, in addition to only swimming on a patrolled beach, would be to promote the ‘do nothing’ rip current escape strategy, as it covers all flow scenarios without reducing a swimmer’s chance of survival.     

Young people’s voiceless politics in the struggle over urban space

This article discusses the particularity of young people’s politics as it unfolds in the practice of everyday life. By exploring a conflict concerning the use of a public park in the City of Oulu, Finland, we discuss how young people may participate in struggles over urban space trough politics that is not based on voice but voicelessness. This political engagement can be understood as a form of nonparticipatory politics that is easily left unnoticed—politics that shirks civic involvement, customary participatory practices and articulated resistance. We deem it important to acknowledge such action as political for two reasons. First, voiceless politics is a weapon of the weak: It is used when other political agencies are not feasible e. Viewing non-participation as apolitical will only further marginalize those who practice politics in such ways. Second, it is important to find ways of acknowledging nonparticipatory action because, while not commonly understood as politics, it is not easily bypassed in political struggles either. By distinguishing political aspects from young people’s urban behaviors, instead of hearing their presence as mere noise, provides tools for bringing their politics to the public agenda and thus developing more democratic urban spaces.     

The indigenous ecotourism and social development in Taroko National Park area and San-Chan tribe, Taiwan

This paper explores the socio-cultural influence of the newly established ecotourism, which integrates cultural revitalization, ecological conservation and social development, in both Taroko National Park area and San-Chan aboriginal community. Many cases in different parts of the world indicate that the Indigenous peoples have developed patterns of resource use and management practices that reflect detailed knowledge of local geography and ecosystem, and contribute to the natural conservation through their living practices. The guidelines of Indigenous knowledge and culture lay the base for the development of ecotourism. A critical evaluation of the conceptualization of Indigenous knowledge is therefore, essential to the success of an alternative strategy to development for aboriginal communities. Participatory observation in the field of ecotourism activities and brief interviews are the major study methods, with several workshops conducted to supplement data collection for the two case studies. The Taroko area came into contact with tourists in a relative early era due to its famous natural features and national park. Its growing ecotourism is the result of cooperation among local residents, environmentalists, and academics, each with very different concepts of ecotourism operation. The national park and public sectors have also played significant role in shaping the content of ecotourism. In San-Chan community, due to the negative impacts generated by the unregulated mass tourism expansion, the local Indigenous people decide to close the public access to the attractive creek for 3?years, while at the same time promote ecotourism for poverty alleviation. These two cases embrace the ??Nature?? as an important element in their construction of new place identity and community development. However, their spatial location in- or outside the national park produces significant differences and sociopolitical implications on the operations of ecotourism.     

Genetic type,distribution patterns and controlling factors of beach and bars in the second member of the Shahejie formation in the Dawangbei Sag,Bohai Bay,China

As an important reservoir type in the Bohai Bay Basin, China, lacustrine beach and bar sands which refer to the shallow water complex deposited mainly by nearshore, delta‐rim and buried hill‐related beaches as well as longshore bars were developed in a particular stage in the evolution of those faulted Cenozoic continental depressions. In the Chezhen Depression, for example, the Second Member of the Oligocene Shehejie Formation (abbr. as Es2 hereafter) formed during the rifting‐to‐thermal subsidence transitional stage. Although well developed in Es2, beach and bar sands are difficult to recognize owing to their relative thinness. The paper summarizes sedimentary characteristics of lacustrine beach and bar sands on cores and logs. Low‐angle cross‐stratification, swash stratification, as well as occasional small‐scale hummocky cross‐stratification resulted from storms can be observed in beach and bar sands. The paper distinguishes bars and beaches from each other in Es2 mainly based on the grain‐size, bed thickness, facies succession and log responses. In order to predict the distribution of beach and bars, a chrono‐stratigraphic correlation framework of Es2 in the study strata is established using a high‐resolution sequence stratigraphic approach. Es2 strata are sub‐divided into six medium‐scale cycles and the mapping of the high‐frequency cycles allows the geographic and stratigraphic distribution of both beach and bar sands to be predicted. The study shows that beach and bars are better developed in times of base‐level fall than in base‐level rise. Factors such as lake‐level fluctuation, sediment supply, palaeogeomorphology and palaeowind direction have exerted control on the formation and distribution of beach and bar sands. Finally, the genetic pattern of beach and bar sands in the Es2 unit has been constructed, which provides a foundation for the prediction of beach and bars reservoir in continental basins in general. Copyright © 2011 John Wiley & Sons, Ltd.     

江苏海岸带中段低潮滩现代演变趋势遥感分析

通过多期遥感资料,在潮水位基本相同的前提下,对江苏沿海中段低潮滩的时空演变从三个方面进行了分析,进一步指出其演变趋势已由淤转蚀,并已威胁到中潮滩,滩涂资源呈逐年减少的趋势;强调海涂资源并非是取之不尽用之不竭,唤醒人们要更加珍惜和使用好每一寸自然资源的意识。     

Orinoco地层油的开发特征及组分研究

Orinoco地层油具有较高的气油比和沥青质含量,在模拟油藏开发状况时,使用油罐油和天然气配制的模拟油。利用大直径长岩心模型进行压力衰竭实验,得到Orinoco地层油的流动特点及模拟开发效果。结果显示：(1)高于泡点压力阶段,模拟油显现弹性驱动特征,采收率很低;(2)在泡点和“拟泡点”之间的降压阶段,模拟油表现出缓慢的膨胀性能,采收率近似线性增加,斜率接近1,此时具有最大的开采效益;(3)低于拟泡点压力阶段,产气量增大,采收率增加缓慢。实验测定了Orinoco地层油的详细组分,并以此为依据配制模拟油。对模拟油PVT性质进行分析,结论是：气油比和少量的轻质组分对相对体积的影响很小,沥青等重质组分对气体保持稳定状态起主要作用;脱气状态的地层油在60 ℃时粘度仍高达6 194 mPa·s,而较高的气油比使地层油粘度陡降,特别在压力降低至泡点压力后,仍存在一个粘度缓慢变化的阶段,显示了Orinoco地层油的独特之处。     

The geological sources of Hg contamination in Kejimkujik National Park,Nova Scotia,Canada: a GIS approach

Recent studies have shown that mercury (Hg) levels in many fish from remote lakes exceed the recommended guidelines for human consumption. Most of these studies conclude that the source of contamination lies in the atmosphere. Kejimkujik National Park (KNP), Nova Scotia, Canada, is considered to be a pristine ecosystem in which fish and loon Hg levels are anomalously high. Studies in the park have shown that atmospheric Hg concentrations may not be high enough to account for the Hg levels in the biota, indicating that the park may be an unusual system in terms of Hg distribution and migration. In an attempt to summarise and synthesise the numerous Hg data sets which have been produced in the park over the last 5-10 years, a geographic information systems (GIS) approach was used to create a common database using the watersheds in the park as the common parameter. By using a GIS database, new relationships and correlations are established and the spatial distribution of Hg levels is more readily evaluated and quantified. The results indicate that geological sources of Hg, arising from biotite-rich granite rocks, may play a larger role in the contamination of the park than previously thought.     

The Berchtesgaden National Park (Bavaria, Germany): a platform for interdisciplinary catchment research

The Berchtesgaden National Park (Bavaria, Germany), a study site of the UNESCO Man and the Biosphere program in the catchment of Berchtesgadener Ache, is introduced as a platform for interdisciplinary research. As the investigation of how human activities affect the natural resources in the park area, which has been defined a main aim of the program, naturally requires expertise from different scientific fields, interdisciplinary research has been fostered in the national park plan since the very beginning of the Man and the Biosphere program in 1981. To analyze the complex interactions and mutual dependencies between socio-economic and natural systems, a variety of monitoring programs have been initialized in different disciplines (e.g. climate sciences, zoology, botany) that are addressed in this paper. As a result of these research efforts, the park offers a profound data basis to be used in future studies (e.g. land cover classifications, maps of geological and soil conditions). Detailed information is provided on a climate monitoring network that has been installed in the park starting in the year 1993. The network has been continuously extended over the years and now provides extraordinary comprehensive information on meteorological conditions in the park, setting the basis for current as well as for potential future climate-related studies. A special characteristic of the station network is the fact that it covers a large range of elevations from 600 m a.s.l in the valleys to 2,600 m a.s.l in the summit regions and is therefore able to capture altitudinal gradients in meteorological variables as typical for Alpine regions. Due to the large number of stations in high elevations (15 stations are in elevations higher than 1,500 m a.s.l) the network provides information on the complex hydrometeorological conditions in summit regions which are often insufficiently represented in observation networks due to the increased costs for maintenance of climate stations in these locations. Beside the various monitoring programs, a variety of numerical models have been (further) developed for application in the park area that make extensive use of the different data collected and therefore largely benefit from the comprehensive data pool. The potential and necessity of the climate monitoring network for modelling studies is demonstrated by utilizing the meteorological recordings in the framework of a hydrometeorological simulation experiment. Further examples of environmental modelling efforts are shortly described together with preliminary model results.