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51.
Harry F Lins Eugene Z. Stakhiv 《Journal of the American Water Resources Association》1998,34(6):1255-1264
ABSTRACT: Among the many concerns associated with global climate change, the potential effects on water resources are frequently cited as the most worrisome. In contrast, those who manage water resources do not rate climatic change among their top planning and operational concerns. The difference in these views can be associated with how water managers operate their systems and the types of stresses, and the operative time horizons, that affect the Nation's water resources infrastructure. Climate, or more precisely weather, is an important variable in the management of water resources at daily to monthly time scales because water resources systems generally are operated on a daily basis. At decadal to centennial time scales, though, climate is much less important because (1) forecasts, particularly of regional precipitation, are extremely uncertain over such time periods, and (2) the magnitude of effects due to changes in climate on water resources is small relative to changes in other variables such as population, technology, economics, and environmental regulation. Thus, water management agencies find it difficult to justify changing design features or operating rules on the basis of simulated climatic change at the present time, especially given that reservoir-design criteria incorporate considerable buffering capacity for extreme meteorological and hydro-logical events. 相似文献
52.
Cumulative environmental change: Conceptual frameworks,evaluation approaches,and institutional perspectives 总被引:5,自引:0,他引:5
Cumulative environmental change or cumulative effects may result from the additive effect of individual actions of the same
nature or the interactive effect of multiple actions of a different nature. This article reviews conceptual frameworks of
cumulative environmental change and describes analytical and institutional approaches to cumulative effects assessment (CEA).
A causal model is a common theoretical construct, although the frameworks vary in their emphasis on different components of
the model. Two broad approaches to CEA are distinguished: one scientific and the other planning oriented. These approaches
should not be interpreted as competing paradigms but rather different interpretations of the scope of CEA. Each approach can
provide a distinct but complementary contribution to the analysis, assessment, and management of cumulative effects. A comparison
of the institutional and legislative response to CEA in Canada and the United States shows that Canada is following the American
example of incorporating the analysis and assessment of cumulative effects into regulatory actions and administrative procedures
that also govern environmental impact assessment. 相似文献
53.
ABSTRACT The effect of hydrologic and chemical processes on salinization of stored waters was determined for two small floodwater-retarding structures located in western Oklahoma. One structure, already designed to accommodate a large influx of sediment, was further overdesigned hydrologically by upstream diversion of approximately one-half the inflow. Over a 2-year period, the total salinity of stored waters increased approximately 22 times and the stored water volume decreased to 1/33 its initial volume in the overdesigned structure, while both volume and salinity of stored waters remained comparatively stable in the other structure. The lack of sufficient dilution by better quality surface runoff and the increased residence time of water in the impoundment apparently caused most of the salinity increase. The bulk of the salt load entering the over-designed structure, to be concentrated later by evaporation, was associated with base rather than storm inflow. After base inflow ceased, substantial losses of salt load and stored water occurred concurrently. The loss was not adequately explained by chemical precipitation in association with evaporation. Seepage and evaporation-associated variables appeared to account for much of the hydrologically unexplained loss of stored waters. 相似文献
54.
Roger L. Hothem David G. Lonzarich Jean E. Takewaka Harry M. Ohlendorf 《Environmental monitoring and assessment》1998,50(1):67-84
Organochlorines, metals, and trace elements were measured in liver, kidney, or whole-body tissues of canvasbacks (Aythya valisineria), lesser scaups (A. affinis), and greater scaups (A. marila) collected from San Francisco Bay and three coastal areas of California during the winter of 1986–1987. Potentially toxic concentrations of mercury (mean 10.4 µg/g, dry weight) and selenium (mean 32.7 µg/g, dry weight) were found in livers of scaups and canvasbacks from several San Francisco Bay sites. These elements varied spatially, temporally, and between species, with the highest concentrations found in late winter. Mean concentrations of mercury, selenium, and cadmium were generally higher in scaups than in canvasbacks. Of all the organochlorines included in the analyses, only p,p'-DDE and total PCBs were detected in all samples in this study. Mean whole-body concentrations of DDE and PCBs from San Francisco Bay ducks collected in late winter varied spatially and between species, but the concentrations were not considered toxic. Causes for inter-specific differences are unclear, but may be attributable to differences in diet, movement, or physiology. 相似文献
55.
The quality assessment of coastal waters of a tourist resort, on the basis of water quality criteria was attempted by using different quantitative approaches. Five variables related to eutrophication, that is nitrate, nitrite, ammonia, phosphate and chl were analyzed. Graphical methods were applied to all variables as well as unvariate statistical methods on the total inorganic nitrogen. Cluster analysis based on the five variables was also applied as an approach for numerical classification of the coastal waters. Comparison between the unvariate and multivariate methods used, was attempted to assess the validity of the procedures. The suitability of the methods used in coastal water management is also discussed. 相似文献
56.
Investigation into local peoples’ perceptions can produce useful information that could be incorporated into the decision-making
process to help resolve environmental problems. Within the arena of land degradation, a number of studies have also been conducted
to explore local peoples’ views of the problem. However, the perceptions of land-degrading practices of the general public
have so far not been actively solicited. This study aimed to contribute to this area of research by adopting the psychometric
scaling technique to empirically explore the lay public’s ecological risk perceptions of land-degrading activities in Minqin
County in Gansu Province, northern China. The primary data were collected via a questionnaire survey (n = 1,138) administered between 14 and 31 December 2002. The major findings of the survey were: (1) Respondents perceived the
ecological risks posed by different land-degrading activities to be different. (2) There was a considerable incongruence in
the way in which mining of groundwater was conceived by experts and laymen, respectively. (3) Respondents were pretty unsure
of expert knowledge. (4) Respondents’ ecological risk perceptions were significantly affected by their personal attributes.
As far as the policy implications of these findings are concerned, this study accentuates that we must be aware of, and involved
in, the environmental perceptions of the lay public in order to succeed in guiding any human-environment tensions along more
sustainable trajectories and navigating the transition to sustainability. 相似文献
57.
Roger Cropp Albert Gabric Dien van Tran Graham Jones Hilton Swan Harry Butler 《Ambio》2018,47(6):671-681
We investigate the correlation between stress-related compounds produced by corals of the Great Barrier Reef (GBR) and local atmospheric properties—an issue that goes to the core of the coral ecosystem’s ability to survive climate change. We relate the variability in a satellite decadal time series of fine-mode aerosol optical depth (AOD) to a coral stress metric, formulated as a function of irradiance, water clarity, and tide, at Heron Island in the southern GBR. We found that AOD was correlated with the coral stress metric, and the correlation increased at low wind speeds, when horizontal advection of air masses was low and the production of non-biogenic aerosols was minimal. We posit that coral reefs may be able to protect themselves from irradiance stress during calm weather by affecting the optical properties of the atmosphere and local incident solar radiation. 相似文献
58.
Four populations of the native annual grassTriplasis purpurea were surveyed on coastal beaches along the south shore of Staten Island, NY, to determine the potential of this species to
colonize shoreline habitats mostly devoid of other vegetation. If the species can establish and maintain dense populations,
it may have conservation value for urban beaches disturbed by human activities. For two populations, survivorship, growth,
and reproduction were monitored at different distances from shore to determine the ability of this species to maintain viable
populations. At three sites,T. purpurea occurred in >75% of all quadrats and the highest density was 1195 plants/m2 at 74 m from shore in one recently disturbed site. Density generally increased with increasing distances from shore at low
tide (from ca. 40 – 90 m). Plants showed the greatest growth and reproduction at close distances to shore (30 – 40 m); part
of this effect was due to density in one population, but when density effects were removed statistically, there still remained
a decline in growth and reproduction with increasing distance from shore. Improved vigor nearest to shore may be due to continual
sand deposition. Survivorship showed a Type I pattern, with low mortality throughout the growing season. By colonizing newly-deposited
and continually shifting sands,T. purpurea can contribute to the earliest stages of ecological succession along disturbed beaches in eastern North America and may be
valuable to the development and management of urban coastal plant communities. 相似文献
59.
Four populations of the native annual grassTriplasis purpurea were surveyed on coastal beaches along the south shore of Staten Island, NY, to determine the potential of this species to
colonize shoreline habitats mostly devoid of other vegetation. If the species can establish and maintain dense populations,
it may have conservation value for urban beaches disturbed by human activities. For two populations, survivorship, growth,
and reproduction were monitored at different distances from shore to determine the ability of this species to maintain viable
populations. At three sites,T. purpurea occurred in >75% of all quadrats and the highest density was 1195 plants/m2 at 74 m from shore in one recently disturbed site. Density generally increased with increasing distances from shore at low
tide (from ca. 40–90 m). Plants showed the greatest growth and reproduction at close distances to shore (30–40 m); part of
this effect was due to density in one population, but when density effects were removed statistically, there still remained
a decline in growth and reproduction with increasing distance from shore. Improved vigor nearest to shore may be due to continual
sand deposition. Survivorship showed a Type I pattern, with low mortality throughout the growing season. By colonizing newly-deposited
and continually shifting sands,T. purpurea can contribute to the earliest stages of ecological succession along disturbed beaches in eastern North America and may be
valuable to the development and management of urban coastal plant communities. 相似文献
60.
Efroymson RA Peterson MJ Giffen NR Ryon MG Smith JG Hargrove WW Roy WK Welsh CJ Druckenbrod DL Quarles HD 《Journal of environmental management》2008,88(4):1452-1470
Habitat valuation methods were implemented to support remedial decisions for aquatic and terrestrial contaminated sites at the East Tennessee Technology Park (ETTP) on the US Department of Energy (DOE) Oak Ridge Reservation in Oak Ridge, TN, USA. The habitat valuation was undertaken for six contaminated sites: Contractor's Spoil Area, K-901-N Disposal Area, K-770 Scrapyard, K-1007-P1 pond, K-901 pond, and the Mitchell Branch stream. Four of these sites are within the industrial use area of ETTP and two are in the Black Oak Ridge Conservation Easement. These sites represent terrestrial and aquatic habitat for vertebrates, terrestrial habitat for plants, and aquatic habitat for benthic invertebrates. Current and potential future, no-action (no remediation) scenarios were evaluated primarily using existing information. Valuation metrics and scoring criteria were developed in a companion paper, this volume. The habitat valuation consists of extensive narratives, as well as scores for aspects of site use value, site rarity, and use value added from spatial context. Metrics for habitat value were expressed with respect to different spatial scales, depending on data availability. There was significant variation in habitat value among the six sites, among measures for different taxa at a single site, between measures of use and rarity at a single site, and among measures for particular taxa at a single site with respect to different spatial scales. Most sites had aspects of low, medium, and high habitat value. Few high scores for current use value were given. These include: wetland plant communities at all aquatic sites, Lepomid sunfish and waterbirds at 1007-P1 pond, and Lepomid sunfish and amphibians at K-901 pond. Aquatic sites create a high-value ecological corridor for waterbirds, and the Contractor's Spoil Area and possibly the K-901-N Disposal Site have areas that are part of a strong terrestrial ecological corridor. The only example of recent observations of rare species at these sites is the gray bat observed at the K-1007-P1 pond. Some aspects of habitat value are expected to improve under no-action scenarios at a few of the sites. Methods are applicable to other contaminated sites where sufficient ecological data are available for the site and region. 相似文献