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41.
Flash floods are characterized by their suddenness, fast and violent movement, rarity, small scale but high level of damage. They are particularly difficult to forecast accurately and there is little lead time for warning. This makes motorists especially vulnerable. Assuming that these flash flood hazard specificities may be the significant factors leading to difficulties for drivers to perceive danger, we used cognitive mapping combined with GIS data processing to assess motorists' flash flood risk perception on their daily itineraries. The analysis of 200 mental maps collected allows planners to have maps highlighting dangerous areas where risk perception is weak and to identify reasons for this. 相似文献
42.
Jean-Christophe Gaillard Catherine C. Liamzon Jessica D. Villanueva 《Environmental Hazards》2013,12(4):257-270
Between 14 November and 4 December 2004, four successive tropical depressions and typhoons lashed the Eastern coast of Luzon in the Philippines. Heavy rainfall triggered massive landslides and devastating flash floods, which brought tremendous damage and killed more than 1600 people. Immediately after the disaster, there was a media and political consensus to incrimate ‘extraordinary’ natural phenomena and widespread deforestation as responsible for the catastrophe. We argue that the tragedy that befell the municipalities of General Nakar, Infanta and Real, among other devastated areas, is enmeshed in a deeper tangle of causal factors that are political, socio-economic and demographic in nature. These factors include unmanaged population growth, difficult access to land and resources, corruption within the government, and power of the elite. 相似文献
43.
Populations of bivalve filter feeders are distributed throughout the oligohaline waters of the Chesapeake Bay system and, to a lesser extent, in tidal fresh waters as well. Previous studies indicate these bivalves significantly diminish phytoplankton concentrations in one major tributary, the Potomac River, and observed chlorophyll concentrations suggest bivalve influence on phytoplankton in other oligohaline reaches. We incorporated a model of these bivalves into an existing eutrophication model of the system. The model indicated that bivalves may reduce phytoplankton concentrations in oligohaline and tidal fresh waters throughout the system but the most significant effects were noted in the Potomac and Patuxent tributaries. Bivalve impacts were related to hydraulic residence time. The greatest phytoplankton reductions occurred in the regions with the longest residence time. Model carbon and nutrient budgets indicated bivalves removed 14% to 40% of the carbon load, 11% to 23% of the nitrogen load, and 37% to 84% of the phosphorus load to the regions where their impact on computed chlorophyll was greatest. 相似文献
44.
Vicky J. Meretsky Noel F. R. Snyder Steven R. Beissinger David A. Clendenen and James W. Wiley 《Conservation biology》2000,14(4):957-967
Abstract: The remnant wild population of California Condors ( Gymnogyps californianus ) of the 1980s exhibited a rapid population decline caused by high mortality rates among adult and immature birds. The most prominent mortality factor was lead poisoning resulting from ingestion of bullet fragments in carcasses. Successful captive breeding has allowed many birds to be released to the wild since 1992, based originally on an assumption that exposure to lead could be prevented by food subsidy. The mortality of released birds, however, has generally exceeded levels needed for population stability calculated from simple population models. Collision with overhead wires was the most frequent cause of death in releases before 1994. Lead poisoning again surfaced as a problem starting in 1997 as older birds began feeding on carcasses outside the subsidy program. Although poisonings have been treated successfully by chelation therapy in recaptured birds, food subsidy is proving an ineffective solution to lead exposure. The best long-term solution appears to be either the creation of large reserves where hunting is prohibited or the restriction of hunting to nontoxic ammunition in release areas. Until sources of lead contamination are effectively countered, releases cannot be expected to result in viable populations. In addition, problems involving human-oriented behavior have resulted in the permanent removal of many released birds from the wild. The most promising reduction in human-oriented behavior has been achieved in one release of aversively conditioned, parent-reared birds. Rigorous evaluation of the factors reducing attraction to humans and human structures has been hampered by confounding of techniques in releases. Behavioral problems could be more quickly overcome by adoption of a comprehensive experimental approach. 相似文献
45.
ABSTRACT: Increasing specialization separates animal production from cropland, complicating manure management. To assist policy targeting efforts, we highlight areas where on-farm use of manure may be problematic. Matching confined animal production with land, on the farm- rather than at the county-level, gives our analysis an advantage over previous studies in avoiding aggregation problems. With manure-based water quality problems, data aggregated to the county level may fail to convey the heterogeneity of animal production across regions and animal types. Aggregation bias blurs the distinction between areas with specialized animal production and those that merely have numerous animals. We estimate bias from using county aggregates, show its distribution spatially and by animal sector, and link it to concentration. Ongoing vertical integration in agriculture likely alters in-county variability in facility scale and scope, and may influence decisions about which data we should gather and use. 相似文献
46.
Limitations of Captive Breeding in Endangered Species Recovery 总被引:17,自引:0,他引:17
Noel F.R. Snyder Scott R. Derrickson Steven R. Beissinger James W. Wiley Thomas B. Smith William D. Toone Brian Miller 《Conservation biology》1996,10(2):338-348
The use of captive breeding in species recovery has grown enormously in recent years, but without a concurrent growth in appreciation of its limitations. Problems with (1) establishing self-sufficient captive populations, (2) poor success in reintroductions, (3) high costs, (4) domestication, (5) preemption of other recovery techniques, (6) disease outbreaks, and (7) maintaining administrative continuity have all been significant. The technique has often been invoked prematurely and should not normally be employed before a careful field evaluation of costs and benefits of all conservation alternatives has been accomplished and a determination made that captive breeding is essential for species survival. Merely demonstrating that a species' population is declining or has fallen below what may be a minimum viable size does not constitute enough analysis to justify captive breeding as a recovery measure. Captive breeding should be viewed as a last resort in species recovery and not a prophylactic or long-term solution because of the inexorable genetic and phenotypic changes that occur in captive environments. Captive breeding can play a crucial role in recovery of some species for which effective alternatives are unavailable in the short term. However, it should not displace habitat and ecosystem protection nor should it be invoked in the absence of comprehensive efforts to maintain or restore populations in wild habitats. Zoological institutions with captive breeding programs should operate under carefully defined conditions of disease prevention and genetic/behavioral management. More important, these institutions should help preserve biodiversity through their capacities for public education, professional training, research, and support of in situ conservation efforts. 相似文献
47.
Leverett R. Smith Thomas M. Holsen Noel C. Ibay Ronald M. Block Anthony B. De Leon 《Chemosphere》1985,14(9):1383-1389
We have studied the acute toxicity of fluoride ion to , , and juvenile . LC50 values varied with species and (due to precipitation) initial water hardness. Exposure to elevated fluoride levels in water resulted in increased blood fluoride levels in . 相似文献
48.
Using Insurance to Enhance Nitrogen Fertilizer Application to Reduce Nitrogen Losses to the Environment 总被引:2,自引:0,他引:2
The advantage of using insurance to help a farmer adopt a best nitrogen management plan (BNMP) that reduces the impact of agricultural production on the environment is analytically and empirically demonstrated. Using an expected value analysis, it is shown that an insurance program can be structured soas to reduce a farmer's cost of bearing the adoption risk associated with changing production practices and, thus, to improve the farmer's certainty equivalent net return thereby promoting the adoption of a BNMP. Using the adoption of growing-season only N fertilizer application in Iowa as a case study, it is illustrated how insurance may be used to promote the adoption of this practice to reduce N fertilizeruse. It is shown that it is possible for a farmer and an insurance company both to have an incentive to develop an insurance adoption program that will benefit both the farmer and the insurance company, increasing net social welfare and improving environmental quality in Iowa. 相似文献
49.
50.
Claudel Noel 《Waste management (New York, N.Y.)》2010,30(6):1138-1148
The solid waste management industry in Haiti is comprised of a formal and an informal sector. Many basic activities in the solid waste management sector are being carried out within the context of profound poverty, which exposes the failure of the socioeconomic and political system to provide sufficient job opportunities for the urban population. This paper examines the involvement of workers in the solid waste management industry in Greater Port-au-Prince and the implications for livelihood strategies. The findings revealed that the Greater Port-au-Prince solid waste management system is very inclusive with respect to age, while highly segregated with regard to gender. In terms of earning capacity, the results showed that workers hired by the State agencies were the most economically vulnerable group as more than 50% of them fell below the official nominal minimum wage. This paper calls for better salary scales and work compensation for the solid waste workers. 相似文献