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71.
Abstract This paper considers the complexity in resolving the conflicts between mine drainage, water supply, and environmental protection for the coal basin of North China, and presents a management optimization framework that addresses these multiple conflicting issues simultaneously in the most cost effective manner. Due to the various unpredictable accidents which may occur in the coal mining process, such as water bursts, gas leaks, fire and collapse of coal beds, the beneficial use of drainage water from the coal mines is generally low. This case study attempts to address the problem of low beneficial usage for drainage water using the Jiaozuo coal mining district in Henan Province, China. By combining a finite-element groundwater simulation model with an optimization code, the economic benefits of using the drainage water as a stable water supply is maximized, while the adverse impact of mine drainage on the environment is controlled. The results indicate that the management model developed in this study achieves an excellent economic outcome and can serve as a potentially powerful tool for solving mining-related water management problems in the coal basin of North China. Citation Wu, Q., Hu, B. X., Wan, L. & Zheng, C. (2010) Coal mine water management: optimization models and field application in North China. Hydrol. Sci. J. 55(4), 609–623. 相似文献
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74.
Australian farmers navigate their contemporary circumstances through the use of different business and legal arrangements that are shaped by the commercial realities of farming and the aspirations of farm-owning households. In posing the question ‘Family or Enterprise?’, this paper examines the extent to which various household and farm business indicators are associated with different forms of farm ownership, namely sole proprietorships, partnerships, trusts and companies. Results from a postal survey of farm enterprises in Victoria, Australia suggest that both household and enterprise factors contribute to the business structure used, although the strongest determinants appear to be those factors that are less well understood in the rural geographical and sociological literature: household composition, farmer age and farm size. Greater scrutiny of the business instruments deployed by farmers to manage family and enterprise pressures should inform expectations of the fate of family farming in advanced financialised economies. 相似文献
75.
An array of samples from the eastern Upper Basin Member of the Plateau Rhyolite (EUBM) in the Yellowstone Plateau, Wyoming, were collected and analyzed to evaluate styles of deposition, geochemical variation, and plausible sources for low δ18O rhyolites. Similar depositional styles and geochemistry suggest that the Tuff of Sulphur Creek and Tuff of Uncle Tom’s Trail were both deposited from pyroclastic density currents and are most likely part of the same unit. The middle unit of the EUBM, the Canyon flow, may be composed of multiple flows based on a wide range of Pb isotopic ratios (e.g., 206Pb/204Pb ranges from 17.54 to 17.86). The youngest EUBM, the Dunraven Road flow, appears to be a ring fracture dome and contains isotopic ratios and sparse phenocrysts that are similar to extra-caldera rhyolites of the younger Roaring Mountain Member. Petrologic textures, more radiogenic 87Sr/86Sr in plagioclase phenocrysts (0.7134–0.7185) than groundmass and whole-rock ratios (0.7099–0.7161), and δ18O depletions on the order of 5‰ found in the Tuff of Sulphur Creek and Canyon flow indicate at least a two-stage petrogenesis involving an initial source rock formed by assimilation and fractional crystallization processes, which cooled and was hydrothermally altered. The source rock was then lowered to melting depth by caldera collapse and remelted and erupted. The presence of a low δ18O extra-caldera rhyolite indicates that country rock may have been hydrothermally altered at depth and then assimilated to form the Dunraven Road flow. 相似文献
76.
Jennifer A. Jay Matthew E. Pritchard Michael E. West Douglas Christensen Matthew Haney Estela Minaya Mayel Sunagua Stephen R. McNutt Mario Zabala 《Bulletin of Volcanology》2012,74(4):817-837
Using a network of 15 seismometers around the inflating Uturuncu Volcano from April 2009 to 2010, we find an average rate
of about three local volcano-tectonic earthquakes per day, and swarms of 5–60 events a few times per month with local magnitudes
ranging from −1.2 to 3.7. The earthquake depths are near sea level, more than 10 km above the geodetically inferred inflation
source and the Altiplano Puna Magma Body. The Mw 8.8 Maule earthquake on 27 February 2010 triggered hundreds of earthquakes
at Uturuncu with the onset of the Love and Rayleigh waves and again with the passage of the X2/X3 overtone phases of Rayleigh
waves. This is one of the first incidences in which triggering has been observed from multiple surface wave trains. The earthquakes
are oriented NW–SE similar to the regional faults and lineaments. The b value of the catalog is 0.49, consistent with a tectonic origin of the earthquakes. We perform ambient noise tomography using
Love wave cross-correlations to image a low-velocity zone at 1.9 to 3.9 km depth below the surface centered slightly north
of the summit. The low velocities are perhaps related to the hydrothermal system and the low-velocity zone is spatially correlated
with earthquake locations. The earthquake rate appears to vary with time—a seismic deployment from 1996 to 1997 reveals 1–5
earthquakes per day, whereas 60 events/day were seen during 5 days using one seismometer in 2003. However, differences in
analysis methods and magnitudes of completeness do not allow direct comparison of these seismicity rates. The rate of seismic
activity at Uturuncu is higher than at other well-monitored inflating volcanoes during periods of repose. The frequent swarms
and triggered earthquakes suggest the hydrothermal system is metastable. 相似文献
77.
Assimilating transient groundwater flow data via a localized ensemble Kalman filter to calibrate a heterogeneous conductivity field 总被引:2,自引:2,他引:0
Juxiu Tong Bill X. Hu Jinzhong Yang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(3):467-478
A localized ensemble Kalman filter (EnKF) method is developed to assimilate transient flow data to calibrate a heterogeneous
conductivity field. To update conductivity value at a point in a study domain, instead of assimilating all the measurements
in the study domain, only limited measurement data in an area around the point are used for the conductivity updating in the
localized EnKF method. The localized EnKF is proposed to solve the problems of the filter divergence usually existing in a
data assimilation method without localization. The developed method is applied, in a synthetical two dimensional case, to
calibrate a heterogeneous conductivity field by assimilating transient hydraulic head data. The simulations by the data assimilation
with and without localized EnKF are compared. The study results indicate that the hydraulic conductivity field can be updated
efficiently by the localized EnKF, while it cannot be by the EnKF. The covariance inflation and localization are found to
solve the problem of the filter divergence efficiently. In comparison with the EnKF method without localization, the localized
EnKF method needs smaller ensemble size to achieve stabilized results. The simulation results by the localized EnKF method
are much more sensitive to conductivity correlation length than to the localization radius. The developed localized EnKF method
provides an approach to improve EnKF method in conductivity calibration. 相似文献
78.
Lunar meteoroid impact flashes provide a method to estimate the flux of the large meteoroid flux and thus their hazard to
spacecraft. Although meteoroid impacts on the Moon have been detected using video methods for over a decade, the difficulty
of manually searching hours of video for the rare, extremely brief impact flashes has discouraged the technique’s systematic
implementation. A prototype has been developed for the purpose of automatically searching lunar video records for impact flashes,
eliminating false detections, editing the returned possible flashes, and archiving and documenting the results. Several utilities
for measurement, analysis, and location of the flashes on the moon included in the program are demonstrated. Application of
the program to a year’s worth of lunar observations is discussed along with examples of impact flashes. 相似文献
79.
by Xinya Li Bill X. Hu William C. Burnett Isaac R. Santos Jeffery P. Chanton 《Ground water》2009,47(4):558-568
Submarine ground water discharge (SGD) is now recognized as an important water pathway between land and sea. It is difficult to quantitatively predict SGD owing to its significant spatial and temporal variability. This study focuses on quantitative estimation of SGD caused by tidally induced sea water recirculation and a terrestrial hydraulic gradient. A two-dimensional hydrogeological model was developed to simulate SGD from a coastal unconfined aquifer in the northeastern Gulf of Mexico, where previous SGD studies were performed. A density-variable numerical code, SEAWAT2000, was applied to simulate SGD. To accurately predict discharge, various influencing factors such as heterogeneity in conductivity, uncertain boundary conditions, and tidal pumping were systematically assessed. The tidally influenced sea water recirculation zone and the fresh water–salt water mixing zone under various tidal patterns, tidal ranges, and water table heights were also investigated. The model was calibrated and validated from long-term, intensive measurements at the study site. The percentage of fresh SGD relative to total SGD ranged from 4% to 50% under normal conditions. Based on simulations of two field measurements in summer and spring, respectively, the fresh water ratios were 9% and 15%, respectively. These results support the hypothesis that the SGD induced by tidally driven sea water recirculation is much larger than terrestrial fresh ground water discharge at this site. The estimates of total and fresh SGD are at the low and high ends, respectively, of the estimation ranges obtained from geochemical tracers (e.g., 222 Rn). 相似文献
80.
Using data assimilation method to calibrate a heterogeneous conductivity field conditioning on transient flow test data 总被引:1,自引:1,他引:0
Juxiu Tong Bill X. Hu Jinzhong Yang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(8):1211-1223
A data assimilation method is developed to calibrate a heterogeneous hydraulic conductivity field conditioning on transient
pumping test data. The ensemble Kalman filter (EnKF) approach is used to update model parameters such as hydraulic conductivity
and model variables such as hydraulic head using available data. A synthetical two-dimensional flow case is used to assess
the capability of the EnKF method to calibrate a heterogeneous conductivity field by assimilating transient flow data from
observation wells under different hydraulic boundary conditions. The study results indicate that the EnKF method will significantly
improve the estimation of the hydraulic conductivity field by assimilating continuous hydraulic head measurements and the
hydraulic boundary condition will significantly affect the simulation results. For our cases, after a few data assimilation
steps, the assimilated conductivity field with four Neumann boundaries matches the real field well while the assimilated conductivity
field with mixed Dirichlet and Neumann boundaries does not. We found in our cases that the ensemble size should be 300 or
larger for the numerical simulation. The number and the locations of the observation wells will significantly affect the hydraulic
conductivity field calibration. 相似文献