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1.
The forests of southeastern Africa are vulnerable to damage imposed by tropical cyclones operating in the South Indian Ocean. We undertook a geographical analysis to determine the relative vulnerability of forests given tropical cyclones recorded during the 1959–2008 storm seasons. From this analysis, eastern coastal forests of Madagascar seem to be the most vulnerable, although return intervals for severe storms vary along the eastern coast, and are shorter (about 10 years) through the central portion of the country. Therefore, the central lowland to upper montane rainforests on the eastern coast seem to be more vulnerable to damage from tropical cyclones than others in the area. While not as extensive, western coastal forests of Madagascar are also as vulnerable in part due to the recurvature of storms in the Mozambique Channel. Though the coastal forests of Mozambique are all nearly equal in terms of vulnerability, the return interval for severe storms to this area is highly variable. The inland Miombo forests of southeast Africa are less vulnerable to damage from tropical cyclones; however, portions of western Mozambique and Zimbabwe have experienced strong tropical storms in the last 50 years. A number of caveats and limitations associated with the data and analyses are noted. Given the broad scale of the study, the relative vulnerability and the return intervals for severe storms should be considered general representations of these phenomena for the southeastern African coast and the island of Madagascar. 相似文献
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We study hurricane risk on the U.S. Gulf Coast during 1950‐2005, estimating the wind damage and storm surge from every hurricane in this extended period. Wind damage is estimated from the known path and wind speeds of individual storms and calibrated to fit actual damage reports for a sample of Gulf Coast storms. Storm surge is estimated using the SLOSH model developed by NOAA. These models provide the first comprehensive overview of the hurricane storm hazard as it has been experienced over a fifty‐six‐year period. We link the estimated damage with information on the population and specific socio‐demographic components of the population (by age, race, and poverty status). Results show that white, young adult, and nonpoor populations have shifted over time away from zones with higher risk of wind damage, while more vulnerable population groups–the elderly, African Americans, and poor—have moved in the opposite direction. All groups have moved away from areas with high risk of storm surge since 1970. But in this case, perhaps because living near the water is still perceived as an amenity, those at highest risk are whites, elderly, and nonpoor households. Here exposure represents a trade‐off between the risk and the amenity. 相似文献
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Soren M. Newman Matthew S. Carroll Pamela J. Jakes Daniel R. Williams Lorie L. Higgins 《社会与自然资源》2014,27(11):1161-1176
Wildfire is one of several potential disturbances that could have extraordinary impacts on individuals and communities in fire-prone areas. In this article we describe disturbance risk perceptions from interviews with residents in three Florida communities that face significant wildfire and hurricane risk. Although they live in areas characterized by emergency managers as having high wildfire risk and many participants have direct experience with wildfire, residents tended to share high hurricane and low wildfire risk perceptions. The different perceptions of risk seem linked to several factors: direct hurricane experience, different scales of impact, the local “hurricane culture,” effectiveness of local ordinances and development patterns, perceived predictability of the event, and perceived ability to control the event. This study shows that residents may perceive and act to reduce risk for one disturbance in relation to their perceptions, concern, and actions for another. 相似文献
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Allison R. LeBlanc Lisa M. Kennedy Kam-biu Liu Chad S. Lane 《Journal of Paleolimnology》2017,58(2):135-150
We reconstructed the late-Holocene environmental history of a coastal lagoon in semi-arid southwestern Hispaniola through multiproxy analysis of a sediment core, including pollen, macroscopic and microscopic charcoal, loss-on-ignition analysis (LOI), stable isotope analysis, bulk density, and magnetic susceptibility. Four chronological accelerator mass spectrometry radiocarbon dates indicated that our core represents the past ~1000 years. We interpreted ten hurricanes events over the past millennium from high-resolution geological proxies, LOI data, and ostracod valve stable oxygen isotope data, thus producing the first long record of hurricanes from the Dominican Republic. Geological proxies indicated a high-energy event abruptly changed the ecosystem state of our core site from a shallow mangrove wetland to a lacustrine environment ~330 cal yr BP. We interpret the driver of that event to be the landfall of a strong hurricane that initiated lowland flooding, mangrove mortality, and subsequent peat collapse at the core site. Pollen data indicated that during the relatively moist Medieval Warm Period (MWP), hurricanes led to temporary declines in tropical dry forest taxa that recovered within several decades following disturbance. By comparison, during the relatively arid Little Ice Age (LIA), when precipitation was highly variable in the circum-Caribbean, closely spaced hurricanes seemed to delay forest recovery. Sedimentary charcoal concentrations revealed increased fire activity after inferred hurricane landfalls in the MWP, providing evidence of a link between enhanced biomass and fuel availability during moister periods and burning in recently disturbed dry forests and scrub of our semi-arid study region. Our interpretations of increased aridity and precipitation variability, indicated by alternating thin layers of microbial mats with evaporite layers, along with more frequent hurricanes from ~330 cal yr BP to present, generally agree with other sedimentary records from the circum-Caribbean, and may be linked to a more southerly position of the Intertropical Convergence Zone during the LIA. 相似文献
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Factors controlling the survival of coastal dunes during multiple hurricane impacts in 2004 and 2005: Santa Rosa barrier island, Florida 总被引：3，自引：1，他引：2
Santa Rosa Island is an 85 km-long, wave-dominated low-lying barrier island situated along the northwestern Florida coast, facing the Gulf of Mexico. The entire island was severely impacted by Ivan, a strong category 3 hurricane that made landfall about 45 km to the west in September of 2004. Ten months later in July of 2005, Dennis, another category 3 hurricane, made landfall about 30 km east of the western tip of the island. Santa Rosa Island is characterized by well-developed but relatively low dunefields, described in this paper as incipient and established dunes, based on the presence of grassy and woody types of vegetation, respectively. The dunes were severely eroded by the two hurricanes. This paper investigates the factors controlling the regional-scale destruction and survival of the dunefields.Dune survival is controlled by: 1) hurricane characteristics, including intensity, duration, and frequency, and 2) morphological parameters including width of the barrier island, height and width of the dunefields, vegetation type, distance of the dunes to the ocean, and continuity of the dunefields. Three processes of dune destruction are described including, from most to least severe, inundation, overwash, and scarping. The interaction of all the above factors determines the different dune responses to the storm impacts. In general, the extensive and densely woody vegetated dunefields near the bay-side shoreline survived the storms, while the discontinuous dunes with grassy vegetation near the Gulf shoreline were almost completely destroyed. 相似文献
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Following the 1938 hurricane that damaged much of the New England coast, New London, Connecticut, responded like most communities by leveraging federal and state funds to rebuild and augment engineered mitigation structures. Eighty years of subsequent storm experience, however, illustrates that a small number of nonstructural mitigation projects, especially private property acquisitions, have had significant long-term effects on New London's coastal resiliency, especially in the Ocean Beach neighborhood. Archival research identifies that these nonstructural mitigation projects were not initially intended to reduce hurricane or flooding risk but were aimed at removing structures determined to be public nuisances and reducing fire hazard. Therefore, New London's post-1938 mitigation experience underscores how community-scale mitigation planning following one disaster can greatly affect the outcome of future disasters. Analytically, New London's experience offers a compelling case study to critically compare two competing environmental mitigation approaches following the same disaster and to offer insight into the environmental legacies of both. 相似文献
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Unseasonable floods are floods that occur in the season of lowest flood frequency, or dry season. Such floods pose a unique problem to flood planners and forecasters, yet little research has investigated the physical processes associated with unseasonable floods. The purpose of this study is to construct a synoptic climatology of extreme unseasonable floods for the southeastern United States. Results indicate that the types of storms creating unseasonable floods are location specific, with four unique regions across the study area: Carolina (tropical storms/hurricanes), Georgia Coastal Plain (Gulf depressions), Gulf-Atlantic (frontal), and Tennessee (frontal with upper-air enhancement). The precipitation created by these storms is low to moderate, rarely exceeding the 10-year 24-hour storm total. The precipitation levels suggest that a combination of meteorological conditions and land-surface conditions create the extreme events. A statistical analysis indicates that high soil-moisture levels combine with the moderate rains to produce extreme unseasonable floods. [Key words: unseasonable floods, synoptic climatology, land-surface conditions, southeastern United States.] 相似文献
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Oil Spills and Community Resilience: Uneven Impacts and Protection in Historical Perspective 
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下载免费PDF全文 Louisiana's coastal residents have endured centuries of hurricanes and decades of oil spills. Locally based, inherent resilient practices have enabled them to persist in place. This paper documents the evolution of actions taken by Louisiana's coastal residents that constitute effective resilient activities in the aftermath of disruptive events. It compares the efforts that arose from coastal communities that were rooted in local environmental knowledge with generic external programs designed to enable hazard mitigation, emergency response, and recovery form damaging hurricanes and oil spills. Additionally, it will identify points of opportunity to fortify resilience by integrating inherent and formal resilience. 相似文献
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Natural Environmental Hazards and Their Management: A Case Study of Sagar Island, India 总被引：1，自引：0，他引：1
Sunando Bandyopadhyay 《Singapore journal of tropical geography》1997,18(1):20-45
The reclamation of Sagar island from the Sundarban mangrove wetlands of the western Ganga Brahmaputra delta was initiated in 1811. At present the island is almost wholly settled. The major natural environmental hazards (NEH) that affect the island are tropical cyclones, coastal erosion, tidal ingression and dunal encroachment. Human adjustments to these problems include acceptance, technological control, relocation, regulation and emergency measures. Seven different agencies manage the existing NEH-prevention projects of the island, often with little coordination. Important schemes managed by these agencies include coastal and interior embankments, mangrove plantations, storm refuges, resettlement projects and vegetation wind-breaks. Their efficiency ranges from excellent to very poor. Since a large outlay is inconceivable, the island's hazard prevention projects should mobilise existing resources in a more rational and coordinated manner. The long-term solution to the problems, however, lies in an accelerated socio-economic development of the region. 相似文献
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Hurricane 07B in the Godavari Delta, Andhra Pradesh, India: vulnerability, mitigation and the spatial impact 总被引：1，自引：0，他引：1
Greg O'Hare 《The Geographical journal》2001,167(1):23-38
Few hurricane impact studies provide robust spatial parameters of damage or relate geographical patterns of destruction accurately to storm trajectories or agencies. A detailed spatial analysis is, therefore, presented of the destruction caused by tropical hurricane 07B which made landfall on 6/7 November 1996 over the Godavari Delta region, Andhra Pradesh, eastern India. Patterns of destruction by storm surge, wind and flood water are quantitatively mapped for death tolls, house destruction and agricultural damage using local administrative ( mandal ) data bases. Results show that most impact occurred near the coast, but a well-defined path of destruction across the central part of the delta can be identified. Such mapping studies fail to indicate the types of individuals and social groups most affected by the storm hazard and their response to it. An investigation of landowning farmers, female migrant rural labourers and fishing communities in the delta shows that poverty and social ordering in Indian society puts differential limits on the risk reduction abilities of individuals and social groups in the face of the cyclone hazard. The paper also demonstrates that 'top down' institutional measures to reduce the effects of storm damage such as those introduced in the aftermath of hurricane 07B, including early storm warning and evacuation procedures and rehabilitation programmes, remain largely ineffective. It is suggested that the introduction of more 'bottom up' community-based programmes which seek to improve the risk awareness and risk avoiding abilities of affected individuals and groups would be much more beneficial. The case material on hurricane 07B and its effects are placed in context by reviewing and updating long and medium-term time series records of storm frequencies and impacts in the Bay of Bengal and particularly along the eastern coastline of India. 相似文献
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In this paper, we assess interstorm cyclone variations in intensity and motion for heavy-snow events at three north-central U.S. stations: Minneapolis, Madison, and Indianapolis. Daily data for the period from 1966 to 1996 were used to select the 157 storm events. Heavy-snow cyclone track location (latitude and longitude) and intensity (central pressure) means and standard deviations are calculated for each station and related to snowfall magnitude. The most northwesterly of the three stations, Minneapolis, had the largest median heavy-snowfall total and also the largest standard deviation in heavy-snowfall amount. Statistical analysis of surface cyclone parameters reveals significant interstation differences in storm trajectory and intensity measures for all cyclones and cyclogenesis group subsets. Chi-square tests suggest that the distribution of storms by month and cyclogenesis type is significantly nonrandom for all stations. Summary findings indicate that Midwestern heavy-snow events are dominated by southern Great Plains cyclones and that storms from secondary cyclogenic regions contribute to significant differences at the three selected locations. [Key words: cyclones, snowfall, Midwest.] 相似文献
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Catastrophic hurricane history revealed by organic geochemical proxies in coastal lake sediments: a case study of Lake Shelby,Alabama (USA) 总被引：2，自引：0，他引：2
We developed a new method for reconstructing millennia-long hurricane records from coastal environments that uses Organic
Geochemical Proxies (OGPs) of organic carbon and nitrogen concentrations and their δ13C and δ15N compositions. The new method is independent of presence/absence of sand layers and improves significantly the severe-storm
history resolution. The subject of this investigation is a 1.5 m long sediment core raised at 2.8 m water depth from the center
of Lake Shelby, Alabama, a freshwater lake located approximately 250 m from the Gulf of Mexico, from which an overwash sand-layer
based record was previously derived. The core contains two distinct sediment units; an upper 62 cm thick, fine-grained, organic-rich
lacustrine sapropel (gyttja) that shows no visible structures except one sand lamina at 23.7 cm depth, and an underlying 90 cm
thick, organic-poor lagoon/estuary clay unit. The sapropel unit was deposited over a 682 ± 30 cal year time interval (1320–2002 A.D.)
with a mean sedimentation rate of 0.79 ± 0.04 mm/year. Lake Shelby’s water column exhibits two contrasting states based on
water chemistry surveys (i) an “isolated”, stratified, mode under calm weather conditions with a relatively low trophic state,
and (ii) a “flooded” mode occurring during storm surges when nutrient-rich seawater floods the lake. Statistically significant
δ13C and δ15N positive excursions in organic matter, up to maximum values of −25 (‰ PDB) and 4 (‰ Air N2), respectively, are interpreted as geochemical responses to the marine intrusions that fertilize the lake, increase light
availability, and cause eutrophication spikes. Detailed OGPs analyses crossing a sand layer that offers visual evidence of
a catastrophic hurricane overwash event at 1717 A.D. exhibit large δ13C and δ15N positive shifts bounded by rapid returns to base values, thus confirming the validity of the hurricane identification by
the OGPs model. Our data indicate that 11 catastrophic hurricanes hit the Alabama coast over the past 682 years with a rough
recurrence interval of one in 62 years. 相似文献
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The climatology of winter cyclones crossing the western Great Lakes was investigated. Data concerning storm strength, place of origin, and surface and 500 mb level synoptic characteristics were obtained from the months of October through February, 1955–1976, for 469 cyclones. November cyclones had the lowest mean pressure and strongest pressure gradient of the 5 months examined, but cyclonic frequencies were greatest in December and January. In all months, cyclones originating in the southwestern United States were significantly deeper than storms of northern origins, and these cyclones crossed the western Lakes most frequently in November. In November, cyclogenesis in the southwest was related to departures of the observed flow from the mean monthly mid-tropospheric circulation with trough development over the west. Yearly variations in the number of severe November cyclones were related to differences of mean monthly 500 mb flow. 相似文献
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《自然地理学》2013,34(5):385-406
Researchers have utilized radar reflectivity returns and lightning flashes separately and together to locate convection with tropical cyclones (TCs). Most studies utilizing both datasets have examined TCs over the ocean, while landfall observations have been limited to a few TCs. This study employs a GIS to delineate regions of high radar reflectivity values within 45 landfalling TCs. The percentage of convective regions contained within each quadrant placed relative to storm motion and deep-layer vertical wind shear is calculated. These percentages are then compared to those from previous studies of quadrant-based lightning flash locations. Results indicate that the GIS-based radar analysis may be identifying TC regions that are electrically active. Both the radar- and lightning-based analyses show that convection shifts from the right to the front of the storm as forward velocity increases. Convection is located left of the shear vector when storm motion is 45-135° counterclockwise from the shear vector, and downshear when shear-minus-motion angles are 315-45°. Additionally, storms that became extratropical within 72 hours of landfall had more convection forward of the circulation center and left of the shear vector, and may produce less lightning than the remaining TCs. 相似文献
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ABSTRACT. Historically, storm tides wreaked havoc in the Bay of Fundy. With the tidal system resonating at close to the 12-hour, 25-minute dominant lunar tide of the Atlantic Ocean, variations in normal Fundy tides are in the main caused by astronomical factors. The strongest Fundy tides occur when the three elements—anomalistic, synodical, and tropical monthly cycles—peak simultaneously. The closest match occurs at intervals of 18.03 years, a time known as the Saros. Problems arise when storms coincide with these intervals. A strong Saros has coincided with several major historical storm tides in the Bay of Fundy, including the 1976 Groundhog Day storm, the 1869 Saxby Tide, and the 1759 storm tide. With continuing global sea-level rise and regional crustal subsidence, the possible recurrence of destructive storm tides has grave implications for property owners and settlements in the Fundy coastal zone. 相似文献
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The Queensland Gold Coast has been Australia's premier holiday resort for more than 20 years, and has had increasing attraction as a retirement area for people from elsewhere in Australia. A mixture of canal estates, beach-front residences, retail trade outlets and high-rise apartment and hotel buildings extends onto the fore-dune. Tropical cyclones approaching the area have caused widespread damage to public and private property, and a recent analysis has pointed to the Gold Coast as one of the areas potentially vulnerable to the effects of super tropical cyclones. The nature and extent of hazard awareness and of public and private loss mitigation measures and their overall effectiveness are critical, if property damage and threats to life and the local economy are to be kept to a minimum. Surveys of hazard awareness of Gold Coast residents and of their approaches to loss mitigation and adjustment indicate a low level of preparedness despite past tropical cyclones, and point to the need for better public education. 相似文献