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331.
The influence of field-scale heterogeneity on the infiltration and entrapment of dense nonaqueous phase liquids in saturated formations 总被引:1,自引:0,他引:1
Numerical simulations are used for the systematic exploration of the migration and entrapment of dense nonaqueous phase liquids (DNAPLs) in heterogeneous formations. Ensembles of realizations of random, spatially correlated permeability fields are generated and employed in model simulations of a spill event. Statistical techniques are then used to quantify the sensitivity of model predictions to input parameters, thereby identifying the parameters or processes that may be of primary importance in the determination of organic liquid distributions in heterogeneous systems. Results of the study indicate that the most critical factors in modeling organic entrapment include the spill release rate, reliable estimates of the mean, variance, and vertical correlation scale of the formation permeability, and an accurate representation of the correlation between the capillary pressure–saturation function and the permeability. In contrast, the hydraulic gradient and cross-correlation of residual saturations with permeabilities are found to have only minor influence on organic liquid distributions in such heterogeneous formations. 相似文献
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When animals die in traps in a mark-recapture study, straightforward likelihood inferences are possible in a class of models.
The class includes M0, Mt, and Mb as reported by White et al. (Los Alamos National Laboratory, LA-8787-NERP, pp 235, 1982), those that do not involve heterogeneity.
We include three Markov chain “persistence” models and show that they provide good fits in a trapping study of deer mice in
the Cascade-Siskiyou National Monument of Southern Oregon where trapping mortality was high.
相似文献
Fred L. RamseyEmail: |
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Prioritizing Pacific Salmon Stocks for Conservation 总被引:3,自引:1,他引:2
Fred W. Allendorf David Bayles Daniel L. Bottom Kenneth P. Currens Christopher A. Frissell David Hankin James A. Lichatowich Willa Nehlsen Patrick C. Trotter & Thomas H. Williams 《Conservation biology》1997,11(1):140-152
Over 300 native stocks of Pacific salmon, steelhead, and coastal cutthroat trout (Oncorhynchus spp.) are at risk of extinction in the Pacific Northwest. With only limited resources available for conservation and recovery, prioritization of these stocks may become necessary if meaningful measures are to be implemented. We propose criteria by which prioritization may be guided. First, we rank stocks for risk of extinction, either by population viability analysis or by a set of surrogate measures. Then we rank stocks for biological consequences of extinction, using sets of questions designed to establish the genetic and evolutionary consequences and the ecological consequences if a stock were to become extinct. Together, these rankings allow stocks to be prioritized for a range of possible actions, with those stocks at highest risk and bearing the greatest biological consequences of extinction receiving attention first. Application of the prioritization process to 20 Pacific anadromous salmonid stocks worked as intended, although data limitations are considerable. The process is most likely to work successfully when applied to many stocks on which data exist, when several experts carry out the prioritization, and when the results are peer reviewed. 相似文献
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Fred Curtis 《The Environmentalist》1985,5(2):129-135
Summary This paper describes the demand and supply information requirements to determine whether a curriculum for a new program, Natural Resources Planning and Management (NRPM), should be developed by Athabasca University (AU). Demand considerations assist in determining forecasted job opportunities and student needs. Supply considerations, including the type and location of existing natural resource programs and their student enrollment levels, assist in determining the enrollment level, the type of degree program, and that the student profile of AU's NRPM graduates will be high, particularly in western Canada. AU has, therefore, been advised to offer an undergraduate bachelor's degree in NRPM. This paper also serves as a model, for organizing demand and supply information for any new university or college program.Fred Curtis, is Professor and Co-ordinator of Regional Systems Engineering, at the University of Regina, Regina, Saskatchewan, Canada. His teaching and research areas include environmental and behavioural systems engineering. His recent publications focus on environmental impact assessment procedures, environmental mediation, natural resources planning and management, energy conservation and land use planning and distance education. 相似文献