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121.
C. B. Millham C. F. Culver 《Journal of the American Water Resources Association》1979,15(6):1776-1780
ABSTRACT: A competitive relationship exists between power production and navigation in the allocation of water resources along the Snake-Columbia River Complex. This report identifies the energy losses within the power system and the replacement costs of water diversion which resulted from commercial and recreational navigation of the Complex over the period 1975–1977. 相似文献
122.
本文根据城市污水处理工程的特点,提出从设计、施工、调试三个方面对项目的费用、进度和质量进行控制的方法和建议。 相似文献
123.
Lloyd G. Antle 《Journal of the American Water Resources Association》1979,15(5):1408-1417
ABSTRACT: Recreation has produced substantial employment, incomes, economic development, and migration impacts since completion of the McCle-lan-Kerr Arkansas River Navigation System. These impacts support the influence of navigation, hydropower, flood control, and channel stabilization outputs on regional development. The marked success is not without substantial costs in public resources, including manpower which are devoted to recreational management. Increasing the share of financial resources obtained from recreational users and transfer of management responsibilities to nonfederal agencies, including private concessionaires is recommended. 相似文献
124.
Cost‐Effective Placement of Best Management Practices in a Watershed: Lessons Learned from Conservation Effects Assessment Project
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Lyubov A. Kurkalova 《Journal of the American Water Resources Association》2015,51(2):359-372
This article reviews the key, cross‐cutting findings concerning watershed‐scale cost‐effective placement of best management practices (BMPs) emerging from the National Institute of Food and Agriculture Conservation Effects Assessment Project (CEAP) competitive grants watershed studies. The synthesis focuses on two fundamental aspects of the cost‐effectiveness problem: (1) how to assess the location‐ and farmer‐specific costs of BMP implementation, and (2) how to decide on which BMPs need to be implemented and where within a given watershed. Major lessons learned are that (1) data availability remains a significant limiting factor in capturing within‐watershed BMP cost variability; (2) strong watershed community connections help overcome the cost estimation challenges; (3) detailing cost components facilitates the transferability of estimates to alternative locations and/or economic conditions; and (4) implicit costs vary significantly across space and farmers. Furthermore, CEAP studies showed that (5) evolutionary algorithms provide workable ways to identify cost‐effective BMP placements; (6) tradeoffs between total conservation costs and watershed‐scale cost‐effective water quality improvements are commonly large; (7) quality baseline information is essential to solving cost‐effectiveness problem; and (8) systemic and modeling uncertainties alter cost‐effective BMP placements considerably. 相似文献
125.
Carl D. Soulsbury Philip J. Baker Graziella Iossa Stephen Harris 《Behavioral ecology and sociobiology》2008,62(8):1289-1298
The costs of dispersal are an important factor promoting natal philopatry, thereby encouraging the formation of social groups.
The red fox, Vulpes vulpes, exhibits a highly flexible social system and one that is thought to represent a possible stage in the evolution of more
complex patterns of group-living. Although the potential benefits accruing to philopatric offspring have previously been studied
in this species, the potential costs of dispersal have received less attention. We contrasted survival rates, nutritional
status, injuries and reproductive output of dispersing and non-dispersing male and female foxes in an urban population to
assess the relative costs of dispersal versus natal philopatry. Mortality rates were not significantly higher for dispersing
foxes, either in the short- or long-term. There was no evidence of increased nutritional stress in dispersing individuals.
Dispersing individuals did, however, exhibit greater levels of wounding, although this did not appear to affect survival.
Dispersing females were more likely to miss a breeding opportunity early in their reproductive lifespan. In contrast, both
dispersing and non-dispersing males were unlikely to breed in their first year. We conclude that the major fitness component
in females affected by dispersing is age at first reproduction. 相似文献
126.
Striking a Balance between Biodiversity Conservation and Socioeconomic Viability in the Design of Marine Protected Areas 总被引:4,自引:0,他引:4
C. J. KLEIN†‡‡ A. CHAN† L. KIRCHER† A. J. CUNDIFF‡† N. GARDNER† Y. HROVAT† A. SCHOLZ§ B. E. KENDALL† S. AIRAMɧ§ 《Conservation biology》2008,22(3):691-700
Abstract: The establishment of marine protected areas is often viewed as a conflict between conservation and fishing. We considered consumptive and nonconsumptive interests of multiple stakeholders (i.e., fishers, scuba divers, conservationists, managers, scientists) in the systematic design of a network of marine protected areas along California's central coast in the context of the Marine Life Protection Act Initiative. With advice from managers, administrators, and scientists, a representative group of stakeholders defined biodiversity conservation and socioeconomic goals that accommodated social needs and conserved marine ecosystems, consistent with legal requirements. To satisfy biodiversity goals, we targeted 11 marine habitats across 5 depth zones, areas of high species diversity, and areas containing species of special status. We minimized adverse socioeconomic impacts by minimizing negative effects on fishers. We included fine‐scale fishing data from the recreational and commercial fishing sectors across 24 fisheries. Protected areas designed with consideration of commercial and recreational fisheries reduced potential impact to the fisheries approximately 21% more than protected areas designed without consideration of fishing effort and resulted in a small increase in the total area protected (approximately 3.4%). We incorporated confidential fishing data without revealing the identity of specific fisheries or individual fishing grounds. We sited a portion of the protected areas near land parks, marine laboratories, and scientific monitoring sites to address nonconsumptive socioeconomic goals. Our results show that a stakeholder‐driven design process can use systematic conservation‐planning methods to successfully produce options for network design that satisfy multiple conservation and socioeconomic objectives. Marine protected areas that incorporate multiple stakeholder interests without compromising biodiversity conservation goals are more likely to protect marine ecosystems. 相似文献
127.
MICHAEL R. BOSWELL ROBERT E. DEYLE RICHARD A. SMITH E. JAY BAKER 《Environmental management》1999,23(3):359-372
/ A method is presented for estimating probable public costs resulting from damage caused by hurricanes, measured as local government expenditures approved for reimbursement under the Stafford Act Section 406 Public Assistance Program. The method employs a multivariate model developed through multiple regression analysis of an array of independent variables that measure meteorological, socioeconomic, and physical conditions related to the landfall of hurricanes within a local government jurisdiction. From the regression analysis we chose a log-log (base 10) model that explains 74% of the variance in the expenditure data using population and wind speed as predictors. We illustrate application of the method for a local jurisdiction-Lee County, Florida, USA. The results show that potential public costs range from $4.7 million for a category 1 hurricane with winds of 137 kilometers per hour (85 miles per hour) to $130 million for a category 5 hurricane with winds of 265 kilometers per hour (165 miles per hour). Based on these figures, we estimate expected annual public costs of $2.3 million. These cost estimates: (1) provide useful guidance for anticipating the magnitude of the federal, state, and local expenditures that would be required for the array of possible hurricanes that could affect that jurisdiction; (2) allow policy makers to assess the implications of alternative federal and state policies for providing public assistance to jurisdictions that experience hurricane damage; and (3) provide information needed to develop a contingency fund or other financial mechanism for assuring that the community has sufficient funds available to meet its obligations. KEY WORDS: Hurricane; Public costs; Local government; Disaster recovery; Disaster response; Florida; Stafford Act 相似文献
128.
129.
Summary. Induction of secondary metabolites to herbivore damage is a widespread phenomenon among plants and serves to enhance resistance
by reducing suitability or increasing toxicity of foliage. Post-damage responses of primary metabolites are less well known;
reductions in primary metabolites may increase resistance by decreasing palatability or nutritional suitability for herbivores
or by potentiating toxicity of secondary metabolites. In this study, we examined response to simulated herbivory in Pastinaca sativa, the wild parsnip, in both primary and secondary metabolites. We found that induction of secondary metabolites in response
to damage is largely restricted to a single class of compounds, the furanocoumarins. These prooxidant compounds are known
to be toxic to a wide variety of insect herbivores. The only primary metabolite that responded to damage was total soluble
protein, which increased significantly 24 h after damage. After 24 h, the correlation between total furanocoumarins and total
sugars was significant and negative (r = − 0.697). This correlation likely reflects an independent response of sugar to damage,
rather than a diversion of resources into furanocoumarin production, inasmuch as this correlation at 3 h, after furanocoumarin
induction had taken place, was not significant. In other secondary metabolite pathways, damage produced a significant decline
in farnesene and a C-16 unsaturated fatty acid, 7,10,13-hexadecatrienoic acid, each of which may potentiate the furanocoumarin
defense response. Farnesene may enhance photooxidative activation of the furanocoumarins and 7,10,13-hexadecatrienoic acid
may serve as a precursor to jasmonic acid, a key hormone in regulating induction responses. With few key exceptions, quantities
of both primary and secondary metabolites in wild parsnip foliage are unaffected by damage. Those that are affected may well
play a role in resistance of parsnips to herbivores.
Received 1 July 1998; accepted 28 September 1998. 相似文献
130.
汤吉军 《中国人口.资源与环境》2009,19(6)
本文区分了确定性和不确定性条件下生态环境资源的定价与补偿机制的关系.在不确定性条件下,生态环境资源有不可逆性,往往会产生沉淀成本,由此产生期权价值,难以依靠传统的边际成本定价实现生态环境资源补偿,往往造成资源投资补偿不足.如果生态环境资源具有完全可逆性,那么就不会存在资源破坏和环境恶化问题.正是由于生态资源环境具有显著的不可逆性,沉淀成本普遍存在,特别是在未来不确定性的条件下,需要考虑期权价值对生态环境资源定价的影响,从而发现资源定价的根本原则在于生态环境资源价格中需要包括期权价值,特别是资源消耗导致未来资源消耗的减少.否则,由于期权价值没有进入生态环境资源价格里,很容易造成过度或掠夺开采生态资源.因此,合理的生态环境资源定价是建立生态环境资源补偿机制最根本的制度保障,也是市场完善的重要体现. 相似文献