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Relative role and extent of marine and groundwater inundation on a dune‐dominated barrier island under sea‐level rise scenarios 
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下载免费PDF全文 Climate change and sea‐level rise will have severe impacts on coastal water resources around the world. However, whereas the influence of marine inundation is well documented in the literature, the impact of groundwater inundation on coastal communities is not well known. Here, core analysis, groundwater monitoring, and ground penetrating radar are utilized to assess the groundwater regime of the surficial aquifer on Bogue Banks Barrier Island (USA). Then, geospatial techniques are used to assess the relative roles and extents of groundwater and marine inundation on the dune‐dominated barrier island under sea‐level rise scenarios of 0.2, 0.5, and 1.0 m above current conditions by 2100. Additionally, the effects of rising water tables on onsite wastewater treatment systems (OWTS) are modelled using the projected sea‐level rise scenarios. The results indicate that the surficial aquifer comprising fine to medium sands responds quickly to precipitation. Water‐level measurements reveal varying thicknesses of the vadose zone (>3 to 0 m) and several groundwater mounds with radial flow patterns. Results from projected sea‐level rise scenarios suggest that owing to aquifer properties and morphology of the island, groundwater inundation may occur at the same rate as marine inundation. Furthermore, the area inundated by groundwater may be as significant as that affected by marine inundation. The results also show that the proportion of land in the study area where OWTS may be perpetually compromised by rising water tables under worst case scenarios may range from ~43 to ~54% over an 86‐year‐period. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Numerical simulations of a single‐degree‐of‐freedom (SDOF) structure, rigidly supporting a tuned liquid damper (TLD) and subjected to both real and artificially generated earthquake ground motions, show that a properly designed TLD can significantly reduce the structure's response to these motions. The TLD is a rigid, rectangular tank with shallow water in it. Its fundamental linear sloshing frequency is tuned to the structure's natural frequency. The TLD is more effective in reducing structural response as the ground excitation level increases. This is because it then dissipates more energy due to sloshing and wave breaking. A larger water‐depth to tank‐length ratio than previous studies suggested, which still falls within the constraint of shallow water theory, is shown to be more suitable for excitation levels expected in strong earthquake motions. A larger water‐mass to structure‐mass ratio is shown to be required for a TLD to remain equally effective as structural damping increases. Furthermore, the reduction in response is seen to be fairly insensitive to the bandwidth of the ground motion but is dependent on the structure's natural frequency relative to the significant ground frequencies. Finally, a practical approach is suggested for the design of a TLD to control earthquake response. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Neil Trentham Leda Sampson Manda Banerji 《Monthly notices of the Royal Astronomical Society》2005,357(2):783-792
Redshift surveys such as the Sloan Digital Sky Survey (SDSS) have given a very precise measurement of the galaxy luminosity function down to about MR =−17 (≈ MB =−16) . Fainter absolute magnitudes cannot be probed because of the flux limit required for spectroscopy. Wide-field surveys of nearby groups using mosaic CCDs on large telescopes are able to reach much fainter absolute magnitudes, about MR =−10 . These diffuse, spiral-rich groups are thought to be typical environments for galaxies, so their luminosity functions should be the same as the field luminosity function. The luminosity function of the groups at the bright end ( MR < −17) is limited by Poisson statistics and is far less precise than that derived from redshift surveys. Here we combine the results of the SDSS and the surveys of nearby groups, and we supplement the results with studies of Local Group galaxies in order to determine the galaxy luminosity function over the entire range −25 < MR < −9 . The average logarithmic slope of the field luminosity function between MR =−19 and MR =−9 is α=−1.26 , although a single power law is a poor fit to the data over the entire magnitude range. We also determine the luminosity function of galaxy clusters and demonstrate that it is different from the field luminosity function at a high level of significance; there are many more dwarf galaxies in clusters than in the field, due to a rise in the cluster luminosity function of α∼−1.6 between MR =−17 and MR =−14 . 相似文献
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Alex K. Manda J. Randall Etheridge Cynthia Grace-McCaskey Thomas R. Allen Robert Howard 《Ground water》2021,59(1):123-130
Public participation in groundwater projects is increasing, however, the efficacy of the data collected in such studies, is not well-documented in the literature. In this study, the authors describe a citizen science project focused on measuring and recording groundwater levels in an aquifer and evaluate whether the groundwater data collected by the participants are trustworthy. A total of 31 participants were initially recruited to measure and record groundwater levels from 29 monitoring wells on a barrier island. Following recruitment, the authors provided training to the citizen scientists by introducing groundwater concepts, and showing the participants how to measure, record and report groundwater level data (over an 81-day period) with an electronic water level meter. The water level data recorded by the citizen scientists (i.e., 35 time series datasets with over 450 unique measurements) were then compared to high frequency data recorded by automated water level loggers that were already deployed in the groundwater monitoring wells to assess the trustworthiness of the data. Trustworthiness was evaluated using measures of reliability (i.e., consistency in measuring the same thing), validity (i.e., degree to which results are truthful), and other standard graphical and statistical techniques. The results suggest that with proper training, guidance, and motivation, citizen scientists can collect trustworthy groundwater level data that could be useful for monitoring the sustainability of aquifers and managing of groundwater levels. It is noted however, that such positive outcomes require significant investments of time and effort on the part of the project managers. 相似文献
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A method of estimating bulk potential permeability in fractured-rock aquifers using field-derived fracture data and type curves 总被引：1，自引：0，他引：1
Alex K. Manda Stephen B. Mabee David F. Boutt Michele L. Cooke 《Hydrogeology Journal》2013,21(2):357-369
A method is devised for estimating the potential permeability of fracture networks from attributes of fractures observed in outcrop. The technique, which is intended as a complement to traditional approaches, is based on type curves that represent various combinations of fracture lengths, fracture orientations and proportions (i.e., intensities) of fractures that participate in flow. Numerical models are used to derive the type curves. To account for variations in fracture aperture, a permeability ratio (R) defined as the permeability of a fracture network in a domain divided by the permeability of a single fracture with identical fracture apertures, is used as a dependent variable to derive the type curves. The technique works by determining the point on the type curve that represents the fracture characteristics collected in the field. To test the performance of the technique, permeabilities that were derived from fractured-rock aquifers of eastern Massachusetts (USA) are compared to permeabilities predicted by the technique. Results indicate that permeabilities estimated from type curves are within an order of magnitude of permeabilities derived from field tests. First-order estimates of fracture-network permeability can, therefore, be easily and quickly acquired with this technique before more robust and expensive methods are utilized in the field. 相似文献
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The investigations on the Plasma Laser Star Model of QSOs reported in our previous paper are continued. Here we assume that QSOs are early type stars with temperatures in the range 104–105 K. It is pointed out that the spectral lines of such stars may have asymmetric shapes and large broadening leading to errors in measurement up to 20 Å. The conventional red-shift theory, however, allows fitting errors much more than this amount for many QSO emission lines. By taking the abundances of elements in QSO atmsopheres identical with the average cosmic abundance we analyze and compare the interpretations of the emission lines of 330 QSOs (263 QSOs are from Burbidgeet al.'s list and the rest are more recently discovered (QSOs) according to the new and the conventional theories. 相似文献
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Atsuyoshi Manda Atsuhiko Isobe Kouichi Omura Yusaku Kyozuka 《Journal of Oceanography》2000,56(2):141-152
Sea surface temperature (SST) and sea surface salinity variations at Fukue Island (located southwest of the Tsushima Straits) were investigated. In spring, low-frequency SST fluctuations with periods of 10–20 days predominate. Synthetic analysis of in situ observation and satellite infrared image reveals that these SST fluctuations are caused by movement of mixed warm water masses which have a temperature intermediate between those of the Kuroshio and the East China Sea (ECS) shelf waters. Since these fluctuations do not correspond with those in the Tsushima Straits, it is indicated that these water masses can hardly pass the Tsushima Straits while retaining their original water properties. In July, SST fluctuations with a period of several days are also found at Fukue Island. Since these SST fluctuations show an opposite correspondence with its salinity fluctuations and a good correspondence with the SST fluctuations at Okinoshima in the Tsushima Straits, it is inferred that warm and low-salinity water originated from the ECS shelf water causes these fluctuations and intrudes into the Tsushima Straits. 相似文献