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11.
Sanghcul Lee Gregory W. McCarty Glenn E. Moglen Megan W. Lang Ali M. Sadeghi Timothy R. Green In‐Young Yeo Martin C. Rabenhorst 《水文研究》2019,33(2):305-315
Ecosystem services provided by depressional wetlands on the coastal plain of the Chesapeake Bay watershed (CBW) have been widely recognized and studied. However, wetland–groundwater interactions remain largely unknown in the CBW. The objective of this study was to examine the vertical interactions of depressional wetlands and groundwater with respect to different subsurface soil characteristics. This study examined two depressional wetlands with a low‐permeability and high‐permeability soil layer on the coastal plain of the CBW. The surface water level (SWL) and groundwater level (GWL) were monitored over 1 year from a well and piezometer at each site, respectively, and those data were used to examine the impacts of subsurface soil characteristics on wetland–groundwater interactions. A large difference between the SWL and GWL was observed at the wetland with a low‐permeability soil layer, although there was strong similarity between the SWL and GWL at the wetland with a high‐permeability soil layer. Our observations also identified a strong vertical hydraulic gradient between the SWL and GWL at the wetland with a high‐permeability soil layer relative to one with a low‐permeability soil layer. The hydroperiod (i.e., the total time of surface water inundation or saturation) of the wetland with a low‐permeability soil layer appeared to rely on groundwater less than the wetland with a high‐permeability soil layer. The findings showed that vertical wetland–groundwater interactions varied with subsurface soil characteristics on the coastal plain of the CBW. Therefore, subsurface soil characteristics should be carefully considered to anticipate the hydrologic behavior of wetlands in this region. 相似文献
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B. Yeo S. C. Yen V. K. Puri B. M. Das M. A. Wright 《Geotechnical and Geological Engineering》1993,11(1):1-14
Summary Laboratory model test results for permanent settlement of a shallow square foundation supported by geogrid-reinforced sand and subjected to cyclic loading are presented. During the application of the cyclic load, the foundation was subjected to a sustained static load. Tests were conducted with only one type of geogrid and at one relative density of compaction of sand. Based on the model test results, the nature of variation of the permanent settlement of the foundation with the intensity of the static loading and the amplitude of the cyclic load intensity are presented in a non-dimensional form. 相似文献
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The DNA-damage defense mechanism was studied in black seabreams after oxidative stress caused by exposure to sodium hypochlorite (NaOCl). Liver, muscle, and brain tissues were obtained after different NaOCl-exposure times (0, 24, 48, 72, and 96 h) and concentrations (0.5, 1, 1.5, 2, and 3 mg/L), after which oxoguanine glycosylase (OGG1) and superoxide dismutase (SOD) mRNA-expression levels were analyzed. At all NaOCl concentrations tested, liver OGG1 expression increased to a maximum in a time-dependent manner after NaOCl exposure and then decreased. In muscles, OGG1 expression increased over time following exposure to a low concentration of NaOCl (0.5, 1, and 1.5 mg/L), whereas it showed a mixed pattern (both increases and decreases observed) in the high-concentration groups (2 and 3 mg/L). SOD mRNA expression increased over time, both in the liver and muscles. In the brain, both OGG1 and SOD mRNA expression levels were highest after exposure to the lowest NaOCl concentration (0.5 mg/L), whereas basal levels were maintained over time at higher concentrations. These results indicate that OGG1 and SOD provide resistance to oxidative stress in black seabreams. In addition, continuous exposure to oxidative stress can suppress enzyme expression, suggesting a risk for long-term exposure to NaOCl. 相似文献
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Courtney G. Flint Xin Dai Douglas Jackson-Smith Joanna Endter-Wada Sara K. Yeo Rebecca Hale 《社会与自然资源》2017,30(8):885-902
Public concerns about water issues are key considerations in responding to changing hydrologic conditions. Literature is mixed on the social profiles associated with resource-related risks. Using data from a household survey, we compare concerns about water shortage, climate change impacts on water supply, poor water quality, and flooding. We assess the combined influence of social and locational factors on each concern and variations across three valleys in northern Utah. Generalized linear mixed modeling is used, given the ordinal nature of most variables. Water shortage was the greatest concern, and female, older, nonwhite, and recreationally active respondents were generally more concerned about water issues than their counterparts. Education, income, and religious identity presented more complicated relationships with water concerns, with significant interaction effects with valley geography. This study has implications for improving public involvement in risk management and engendering support for future water policy and planning strategies to address these risks. 相似文献
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This paper presents a proposed method of aftershock probabilistic seismic hazard analysis (APSHA) similar to conventional ‘mainshock’ PSHA in that it estimates the likelihoods of ground motion intensity (in terms of peak ground accelerations, spectral accelerations or other ground motion intensity measures) due to aftershocks following a mainshock occurrence. This proposed methodology differs from the conventional mainshock PSHA in that mainshock occurrence rates remain constant for a conventional (homogeneous Poisson) earthquake occurrence model, whereas aftershock occurrence rates decrease with increased elapsed time from the initial occurrence of the mainshock. In addition, the aftershock ground motion hazard at a site depends on the magnitude and location of the causative mainshock, and the location of aftershocks is limited to an aftershock zone, which is also dependent on the location and magnitude of the initial mainshock. APSHA is useful for post‐earthquake safety evaluation where there is a need to quantify the rates of occurrence of ground motions caused by aftershocks following the initial rupture. This knowledge will permit, for example, more informed decisions to be made for building tagging and entry of damaged buildings for rescue, repair or normal occupancy. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Sae-Rim Yeo Jong-Ghap Jhun WonMoo Kim 《Asia-Pacific Journal of Atmospheric Sciences》2012,48(1):43-53
The boreal summer season could be divided into two periods in terms of the variability of western North Pacific subtropical high (WNPSH) based on the El Ni?o influence. The correlation analysis indicates that the WNPSH in the period of pentad 32?C37 (June 5 to July 4, first period) is not affected by El Ni?o, while that in the period of pentad 40?C45 (July 15 to August 13, second period) is strongly affected by sea surface temperature in the equatorial eastern Pacific in the previous winter. The different response of low-level circulation over the western North Pacific (WNP) to the El Ni?o forcing between two periods seems to be due to the difference of mean climatological fields over the WNP and the East Asian regions. The WNPSH in the first period is closely connected to the variability of North Pacific subtropical High. In the second period, on the other hand, the WNPSH variability is dominantly controlled by the convective activity over the WNPSH region and it is related with the El Ni?o forcing. The composite analysis on the relationship between the WNPSH and the East Asian summer monsoon exhibits distinct contrasts between two periods. In the first period, the East Asian stationary front exists all the time regardless of the strength of the WNPSH. On the other hand, in the second period the East Asian stationary front appears only when the WNPSH is strong, while there is no obvious East Asian frontal zone when it is weak. 相似文献
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The diverse causes and styles, the frequency and the losses arising from five Australian floods in 1998 are reviewed in this paper. Though mostly rare, the floods were not as unprecedented as commonly supposed. Damages to agriculture and infrastructure were significant, and probably over 10,000 houses experienced over-floor inundation. Key lessons include: the need for detailed damage assessments as a basis for damage reduction, the need to maximise safety and minimise property exposure at caravan parks, and the need for floodplain management strategies that better address both existing and future risk. A greater recognition of the distinctive nature of each flood event is required for the improvement of official and unofficial flood warning systems. Educators need to address the dynamic nature of flood awareness, as it declines over time, and as it varies from one individual to the next. Insurers need to adopt incentives for risk-reducing behaviour, so that efforts to mitigate damages are encouraged, not undermined. 相似文献
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Changzheng Ma Tat Soon Yeo Hwee Siang Tan Jun Wang Baixiao Chen 《Geoscience and Remote Sensing Letters, IEEE》2008,5(3):378-382