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1.
Vizianagaram–Srikakulam coastal shoreline consisting of beaches, mangrove swamps, tidal channel and mudflats is one of the vulnerable coasts in Andhra Pradesh, India. Five site-specific parameters, namely rate of geomorphology, coastal elevation, coastal slope, shoreline change and mean significant wave height, were chosen for constructing coastal vulnerability index and assessing coastal landscape vulnerability. The findings revealed a shift of 2.5 km in shoreline towards the land surface because of constant erosion and that of 1.82 km towards the sea due to accretion during 1997–2017. The rate of high erosion was found in zones IV and V, and high accretion was found in zones II and III. Coastal vulnerability index analysis revealed constant erosion along shoreline and sea level rise in the study area. Most of the coast in zone V has recorded very high vulnerability due to erosion, high slope, significant wave height and sea level rise. Erosion and accretion, significant wave height, sea level rise and slope are attributed to high vulnerability in zones III and IV. Zone II recorded moderate vulnerability. Relatively lower slope, mean sea wave height and sea level rise have made this zone moderately vulnerable. Very low vulnerability was found in zone I, and low vulnerability was recorded in zone II. Accretion, low slope and low sea level rise were found to be causative factors of lower vulnerability. Thus, zones III, IV and V should be accorded higher priorities for coastal management. The findings can be helpful in coastal land planning and management and preparing emergency plans of the coastal ecosystems.  相似文献   

2.
Oil spills is one of the most important hazards in the estuarine and coastal water. In recent decades, engineers try to predict the status of oil slick to manage the pollution spreading. The prediction of oil slick transport is carried out mainly by means of numerical models. In the current study, the development and application of a two-phase fluid flow model to simulate oil transport in the marine environment are presented. Different transport and fate processes are included in the developed model. The model consists of the Lagrangian method for the advection process, the Random Walk technique for horizontal diffusion process and the empirical equations for the fate processes. The major forces for driving oil particles are fluid current, wind speed and turbulent flow. Therefore, the multi-component hydrocarbon method has been included to the developed model in order to predict fate processes. As prediction of particle velocity components is of major importance for oil slick advection, therefore the binomial interpolation procedure has been chosen for the particle velocity components computations. In addition, shoreline boundary condition is included in the developed model to simulate shore response to oil slick transport near the beaches. The results of the model applications are compared with the analytical solutions, experimental measurements and other numerical models cited in literature. Comparisons of different sets of results represent the capability of developed model to predict the oil slick transport. In addition, the developed model is tested for two oil spill cases in the Persian Gulf.  相似文献   

3.
The extensive oil drilling and transportation activities in the Arabian Gulf increased the possibility of oil spills and the consequent threat of oil pollution to the regional ecology. The available literature concerning the main aspects of the physical oceanographic characteristics affecting the movement and spreading of oil spill in the Gulf are reviewed. It is concluded that evaporation, wind-driven currents, and sandfall are important as weathering processes, while tidal currents cause lateral spreading of the slick. Oil spill modelling has shown some usefulness in estimating the trajectories of few major spills illustrated by reference to three models developed for the Gulf. The performance of these models, their capabilities and limitations are reviewed. Recommendations are made to gather more data on the behavior of oil spills in this particular environment.  相似文献   

4.
An algorithm for mapping the vulnerability of sea-coastal zones is described. Normalization of the distribution densities of the biotic groups to the annual average abundance for presenting these data in identical measurement units is offered. Sensitivity of biota to oil should be normalized to the maximum permissible concentrations for the species inhabiting the water column and to the maximum permissible thickness of the film that has contacted with the water surface. All parameters should be estimated by the metric scale. The proposed algorithm makes it possible to calculate the vulnerability of a sea-coastal zone to oil pollution caused by oil spills.  相似文献   

5.
Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria （genus Pseudomonas） and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis （0.422, 0.377, and 0.250 nm d-spacing） in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.  相似文献   

6.
This paper deals with the prediction, in real time, of the motion of experimental oil slicks. The experiments were conducted during September 1983 offshore near Halifax on the east coast of Canada. The objectives of the experiments were (i) to determine the suitability of oil spill dispersants as countermeasures and (ii) the testing and verification of oil spill trajectory models and systems.The Atmospheric Environment Service (AES) participated in the experiments to test the capability of its oil spill motion prediction system in providing real-time trajectory forecasts. The experiment consisted of three sets of spills. Each set had a control slick and a test slick. Sixteen barrels of crude oil were used in each spill. The test slicks were used to test the effectiveness of various dispersants, the control slicks were used to verify trajectory forecasts.The spill trajectories and oil weathering information obtained from the system during the experiments demonstrated the relative ease with which the system could handle the required input and provide timely forecasts. The accuracy of these forecast trajectories was confirmed by observations, and their utility was demonstrated by their application in the operational decision-making process.  相似文献   

7.
In many coastal regions throughout the world, there is increasing pressure to harden shorelines to protect human infrastructures against sea level rise, storm surge, and erosion. This study examines waterbird community integrity in relation to shoreline hardening and land use characteristics at three geospatial scales: (1) the shoreline scale characterized by seven shoreline types: bulkhead, riprap, developed, natural marsh, Phragmites-dominated marsh, sandy beach, and forest; (2) the local subestuary landscape scale including land up to 500 m inland of the shoreline; and (3) the watershed scale >500 m from the shoreline. From 2010 to 2014, we conducted waterbird surveys along the shoreline and open water within 21 subestuaries throughout the Chesapeake Bay during two seasons to encompass post-breeding shorebirds and colonial waterbirds in late summer and migrating and wintering waterfowl in late fall. We employed an Index of Waterbird Community Integrity (IWCI) derived from mean abundance of individual waterbird species and scores of six key species attributes describing each species’ sensitivity to human disturbance, and then used this index to characterize communities in each subestuary and season. IWCI scores ranged from 14.3 to 19.7. Multivariate regression model selection showed that the local shoreline scale had the strongest influence on IWCI scores. At this scale, percent coverage of bulkhead and Phragmites along shorelines were the strongest predictors of IWCI, both with negative relationships. Recursive partitioning revealed that when subestuary shoreline coverage exceeded thresholds of approximately 5% Phragmites or 8% bulkhead, IWCI scores decreased. Our results indicate that development at the shoreline scale has an important effect on waterbird community integrity, and that shoreline hardening and invasive Phragmites each have a negative effect on waterbirds using subestuarine systems.  相似文献   

8.
Increased freshwater and nutrient runoff associated with coastal development is implicated in dramatically altering estuarine communities along eastern US shorelines. We examined effects of three categories of shoreline development on high-marsh environments within Murrells Inlet, South Carolina, USA by measuring sediment nutrients, porewater salinity, plant species diversity, and above- and belowground plant biomass. Effects on new plant growth also were examined in plot clearing and transplantation experiments. Greater nutrient availability in sediments along developed shorelines was reflected in greater aboveground biomass and nitrogen storage in Juncus roemerianus plant tissue. Plant species composition was not significantly different among levels of shoreline development. Zinc concentrations were greater in sediments from developed shorelines and may represent an easily measured indicator of shoreline development. Recently accelerating shoreline development in the southeastern USA may alter plant production, nitrogen storage, and sediment metal content in salt marshes.  相似文献   

9.
Biological impacts of oil on sandy shore ecosystems remain incompletely understood, especially following smaller spills on subtropical beaches. Here we quantified changes to benthic assemblages on a sandy beach following the 270-t spill of heavy fuel oil from the Pacific Adventurer that occurred in March 2009 off Moreton Island in Eastern Australia. Assessments of ecological impacts are based on spatial contrasts between multiple reference and impact sites sampled 1 week and 3 months after the spill. Benthic invertebrate assemblages exposed to oil had significantly fewer individuals of fewer species 1 week after the spill, markedly changing their ecological structure. Biological differences consistent with oil-related mortality were significant on the lower shore and in the swash and remained so 3 months after the spill. This signals a lack of recovery of these communities in the short term, despite the fairly rapid removal of oil. Results show that, despite the relatively small size of the spill, heavy fuel oil contamination can cause substantial impacts on sandy beach ecosystems, and that recovery may be prolonged.  相似文献   

10.
Marsh shoreline, an important habitat for juvenile penaeid shrimps, was extensively oiled in coastal Louisiana by the Deepwater Horizon oil spill of 2010. The effect of this spill on growth was examined for brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus held for 7 days in field mesocosms in Barataria Bay during May and August 2011, respectively. The experiments each had 10 treatment combinations, five apparent oil levels, each one with and without added food. Mesocosms were placed in northern Barataria Bay along shorelines that varied in oiling (designated as heavy, moderate, light, very light, or none based on NOAA surveys), and shrimp in half the mesocosms received additional food. Polycyclic aromatic hydrocarbon (PAH) concentrations determined from sediment cores collected at each mesocosm were significantly higher at heavy and moderate than very light shorelines and also higher at moderate than light and none shorelines. Brown shrimp grew more slowly at heavy than very light or none shorelines, and a statistically significant negative relationship was detected between brown shrimp growth rates and sediment PAH concentrations. In August, PAH sediment concentrations had decreased significantly from the values measured in May, no significant difference in white shrimp growth rates was detected among oiling levels, and no relationship was detected between white shrimp growth and sediment PAH concentrations. Both brown shrimp and white shrimp grew more rapidly in mesocosms where food was added. Our study shows that exposure to nonlethal concentrations of petroleum hydrocarbons can reduce growth rates of juvenile penaeid shrimps.  相似文献   

11.
This paper presents a new method for coastal vulnerability assessment (CVA), which relies upon three indicators: run-up distance (as a measurement of coastal inundation), beach retreat (as a measurement of potential erosion), and beach erosion rate (obtained through the shoreline positions in different periods). The coastal vulnerability analysis of Sele Coastal Plain to storm impacts is examined along a number of beach profiles realized between 2008 and 2009. This particular study area has been selected due to its low-lying topography and high erosion propensity. Results are given in terms of an impact index, performed by combining the response due to coastal inundation, storm erosion, and beach erosion rate. This analysis is implemented on the basis of morphosedimentary characteristics of the beach, wave climate evaluation, and examination of multitemporal aerial photographs and topographic maps. The analysis of the final results evidences different coastal responses as a function of the beach width and slope, which in turn depend on the local anthropization level. The comparison of this method with a Coastal Vulnerability Index method evidences the better attitude of CVA index to take into account the different beach features to explain the experienced damages in specific stretches of the coastline considered.  相似文献   

12.
Submerged aquatic vegetation (SAV) is an ecologically and economically valuable component of coastal estuaries that acts as an early indicator of both degrading and improving water quality. This study aimed to determine if shoreline hardening, which is associated with increased population pressure and climate change, acts to degrade SAV habitat quality at the local scale. In situ comparisons of SAV beds adjacent to both natural and hardened shorelines in 24 subestuaries throughout the Chesapeake and Mid-Atlantic Coastal Bays indicated that shoreline hardening does impact adjacent SAV beds. Species diversity, evenness, and percent cover were significantly reduced in the presence of riprap revetment. A post hoc analysis also confirmed that SAV is locally affected by watershed land use associated with increased population pressure, though to a lesser degree than impacts observed from shoreline armoring. When observed over time, SAV recovery at the local level took approximately 3 to 4 years following storm impacts, and SAV adjacent to natural shorelines showed more resilience to storms than SAV adjacent to armored shorelines. The negative impacts of shoreline hardening and watershed development on SAV shown here will inform coastal zone management decisions as increasing coastal populations and sea level rise drive these practices.  相似文献   

13.
Overwash vulnerability assessment based on long-term washover evolution   总被引：1，自引：1，他引：0  
An integrated methodology for evaluation of overwash vulnerability is developed with respect to the historical washover evolution of a barrier island system. Three different aspects of overwash are addressed in the vulnerability indices developed: overwashed shoreline ratio, maximum overwash intrusion recurrence, and complete barrier overwash. The indices were applied to the barriers in the Ria Formosa system in Southern Portugal using an aerial photography catalogue covering the period 1947–2001. Historical trends of washover evolution were observed to be different between the barriers analysed, but generally, there was a decrease in washover number and dimensions throughout the analysed period. The final overwash diagnostic obtained allowed an integrated overwash vulnerability rating to be defined for each barrier, with vulnerabilities ranging from low to extreme. The methodology has produced results that may assist coastal managers with information concerning barrier island system overwash hazard, define the temporal and geographical distributions of overwash, and provide indications as to where overwash is most likely to occur in the future.  相似文献   

14.
Detrimental effects of engineering works on the coast and a wish to conserve parts of the coastline have increased realization among coastal managers of the need to examine shoreline problems and proposals for protection in a wider spatial context than the site itself and over a longer time scale than the past few years. This paper outlines the approach taken in one region of the United Kingdom, the central south coast of England, to provide that wider perspective. Authorities responsible for coastal protection and sea defenses formed a coastal group, which, among other activities, commissioned research aimed at providing a greater understanding on which to base shoreline management decisions. A major project undertaken was a sediment transport study in which all existing information relating to coastal sediment processes in the region was collated and analyzed. All inputs, flows, and outputs of sediment were documented. Links between processes were examined for each part of the region. Finally, nine littoral cells of sediment circulation were identified and were suggested as forming a framework for shoreline management. The methods of compilation and analysis are outlined here and are exemplified for one area in the region. The approach is recommended as a cost-effective basis for strategic management of the coast in developed regions.  相似文献   

15.
Epikarst communities: biodiversity hotspots and potential water tracers   总被引：1，自引：0，他引：1  
There is an exceptionally rich aquatic fauna in the epikarst, the skin of karst. High species richness in the epikarst, coupled with its special vulnerability as the first point of entry of nearly all toxic spills, makes its protection especially important. The epikarst fauna may also be an useful tool in tracing the potential route of pollutants. Copepods in epikarst have extremely local distributions, and their body size is such that they are largely at the mercy of directional flows. In a series of caves in southwest Slovenia and West Virginia, a significant fraction of the copepod species occur in less than 100 m of linear extent. This suggests a pattern of highly restricted lateral flow under normal conditions and the distribution of copepods could potentially be used to trace water movement. Under high flow conditions as would often be the case with toxic spill, mounding of water may increase the lateral radius of flow. Nevertheless, copepods may be useful tracers.  相似文献   

16.
Integrated risk assessment of multi-hazards in China   总被引：1，自引：0，他引：1  
Maps of population exposure, vulnerability and risk to natural hazards are useful tools for designing and implementing disaster risk mitigation programs in China. The ranking of provinces by relative risk to natural hazards would provide a metric for prioritizing risk management strategies. Using provinces as our study unit, from the perspectives of hazard exposure, susceptibility, coping capacity and adaptive capacity, this study first constructed China’s disaster risk index for five types of major natural hazards: earthquakes, floods, droughts, low temperatures/snow and gale/hail. Then, the relative risk level at the provincial scale in China was assessed. Finally, the hotspots with the highest hazard exposure, vulnerability and risk were identified. The results showed that high exposure was a significant risk driver in China, whereas high vulnerability, especially social vulnerability, amplified the risk levels. Similar to the population exposure to disasters, the relative risk levels in the southwestern, central and northeastern regions of China were significantly higher than those in the eastern, northern and western regions. The high-risk regions or hotspots of multi-hazards were concentrated in southern China (less-developed regions), while the low-risk regions were mainly distributed in the eastern coastal areas (well-developed regions). Furthermore, a nonlinear relationship existed between the disaster risk level and poverty incidence as well as per capita GDP, demonstrating that disaster losses in middle-income areas are likely to increase if economic policies are not modified to account for the rising disaster risk. These findings further indicated that research on disaster risk should focus not only on hazards and exposure but also on the vulnerability to natural disasters. Thus, reducing vulnerability and population exposure to natural hazards would be an effective measure in mitigating the disaster risk at hotspots in China.  相似文献   

17.
While the ecological impacts of crude oil exposure have been widely studied, its sublethal effects on phytoplankton community structure in salt marsh estuaries have not been well documented. The purpose of this study was to simulate oil spill conditions using a microcosm design to examine short-term (2 day) changes in phytoplankton community composition and total biomass following exposure to crude oil obtained from the Deepwater Horizon oil spill and a mixture of Texas crude oils. Microcosm experiments were performed in situ in North Inlet Estuary near Georgetown, SC. A control and six replicated experimental treatments of crude oil additions at final concentrations of 10, 50, or 100 μl l−1 of either Deepwater Horizon spill oil or the Texas crude mixture were incubated under in situ conditions. Photopigments were analyzed using high-performance liquid chromatography and community composition was determined using ChemTax. Total phytoplankton biomass (as chl a) declined with increasing crude oil concentrations. Prasinophytes, the most abundant microalga in both experiments, showed no response to oil exposure in one experiment and a significant negative response in the other. Diatoms euglenophytes and chlorophytes appeared relatively resistant to oil contamination at the exposure levels used in this study, maintaining or increasing their relative abundance with increasing oil concentrations. Chlorophytes and cyanobacteria increased in relative abundance while cryptophyte abundance decreased with increasing oil concentrations. The results of these experiments suggest that low levels of crude oil exposure may reduce total biomass and alter phytoplankton community composition with possible cascade effects at higher trophic levels in salt marsh estuaries.  相似文献   

18.
Although the western-Mediterranean coast of Egypt between Sallum and Alexandria, ~550 km long, has maintained a considerable equilibrium throughout history, developers have built traditional protective structures in an effort to form sheltered recreational beaches without taking into consideration its geomorphologic characteristics, coastal processes and their harmful impact on the coastal environment and human safety. The improper practices in this environmentally valuable region have induced us to undertake an initiative to carry out a morphodynamic analysis to provide a framework for understanding the relationship between coastal morphology and the prevailing dynamic forces. Based on the degree of natural protection or wave sheltering, the study shoreline can be categorized into four distinct morphotypical stretches: (1) high-energy wave-exposed shores and the outer margins of the rocky headlands, (2) moderate to high wave-energy beaches along semi-exposed embayments and bays mostly downdrift of the rocky headlands, (3) low-wave energy at semi-exposed headland lee-sided and pocket beaches, and (4) calm wave-sheltered enclosing water basins for safe anchorages, moorings and recreation beaches. The results deducted will have practical applications for shoreline management initiatives regarding sustained sites suitable for future beachfront development such as safe swimming conditions, sport facilities, water intakes and sheltered areas for vessels. In addition, benefits realized by the understanding of the morphodynamic processes would enhance our awareness of the significance of the role of western coast morphodynamics in supporting sustainable development via shoreline management. As far as sustainability is concerned, the selection of appropriate sites would help avoiding or minimizing the formation of the hard structures needed for creating safe recreation beaches. On a national scale, results reached could provide reliable database for information that can be used in establishing a sustainable shoreline management plan, which is, in turn, an essential part when implementing an Integrated Coastal Zone Management Plan for this region of attraction.  相似文献   

19.
Tar residues are common on the coastline of the Monterey Bay National Marine Sanctuary. These coastal tar residues have been washed ashore and usually occur on headlands near the high-tide line. In this study, 18 coastal tar residues were collected and analyzed to determine their carbon isotopic compositions and the values of selected biomarker ratios. All of the residues have very heavy (13C-enriched) carbon isotopic compositions spanning a narrow range (δ13C = ?22.2 to ?23.4‰), and 28,30-bisnorhopane is present in all samples. These same geochemical characteristics are found in Monterey Formation oils from which the coastal tar residues were likely derived. These coastal residues could result from natural seeps or from accidental spills. Statistically the coastal tar residues can be organized into three groups, each of which may represent different spill or seep events. Seven samples of potential local representative sources for the tar residues were examined, but none could account for the coastal tars.  相似文献   

20.
Shoreline is one of the rapidly changing landform in coastal area. So, accurate detection and frequent monitoring of shorelines are very essential to understand the coastal processes and dynamics of various coastal features. The present study is to investigate the shoreline changes along the coast between Kanyakumari and Tuticorin of south India, where hydrodynamic and morphologic changes occur continuously after the December 2004 tsunami. Multi-date satellite data of Indian Remote Sensing (IRS) satellites (1999, 2000, 2003, 2005, and 2006) are used to extract the shorelines. The satellite data is processed by using the ERDAS IMAGINE 9.1 software and analyzed by ArcGIS 9.2 workstation. The different shoreline change maps are developed and the changes are analyzed with the shoreline obtained from the Survey of India Toposheets (1969). The present study indicates that accretion was predominant along the study area during the period 1969–1999. But recently (from 1999 onwards), most of the coastal areas have experienced erosion. The study also indicates the reversal of shoreline modifications in some coastal zones. The coastal areas along the headlands have experienced both erosion and accretion. Though the coastal erosion is due to both natural and anthropogenic activities, the coastal zones where sand is mined have more impacts and relatively more rate of erosion than that of other zones. Improper and in-sustainable sand mining leads to severe erosion problem along this area. So the concept of sustainable management should be interpreted in the management of the near-shore coastal sand mining industry.  相似文献   

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