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351.
The objective of this paper is to investigate the variation of geomorphology and runoff characteristics in saturated areas under different partial contributing area (PCA) conditions. Geomorphologic information and hydrologic records from two mid‐size watersheds in northern Taiwan were selected for analysis. The PCA ratio in the watershed during a storm was assumed equal to the ratio of the surface‐flow volume to the direct runoff volume from measured hydrologic data. The extents of PCA regions were then determined by using a topographic‐index threshold. Consequently, the geomorphologic factors in saturated and unsaturated areas could be calculated using a digital elevation model, and these factors could then be linked to a geomorphology‐based IUH model for runoff simulation, which can consider both the surface‐ and subsurface‐flow processes in saturated and unsaturated areas, respectively. The results show that geomorphologic characteristics in the saturated areas vary significantly with different PCA ratios especially for higher order streams. A large PCA ratio results in a sharp hydrograph because the quick surface flow dominates the runoff process, whereas the hydrologic response in a low PCA case is dominated by the delayed subsurface flow. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
352.
353.
For the analysis of non‐linear problems, the displacement‐controlled method (DCM) has a more extensive application scope and more powerful abilities than the load‐controlled method (LCM). However, difficulties of the DCM's procedure not amenable to most finite element implementations of the conventional LCM have restricted its applications in geomechanics. By means of Sherman–Morrison's theorem, the solution of DCM is improved. The improved procedure is characterized by high efficiency, good numerical stability and a programme structure similar to LCM. Two aspects of applications of DCM are illustrated. The first application is to compute the response of a structure under a given load level like the conventional finite element analysis. The second application is to trace the equilibrium path of a structure under a given load distribution type. A simple but effective algorithm is presented for automatically adjusting the step length in tracing the equilibrium path. Examples illustrate that the proposed procedures are suited for modelling complicated non‐linear problems in geomechanics. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
354.
355.
Hyun KyuLee Chul H.Lee Maurice H. P. M.van Putten 《Monthly notices of the Royal Astronomical Society》2001,324(3):781-784
The electric charge on rotating black holes is calculated to be ∼ BJ in the force-free configuration of Ghosh, with a horizon flux of ∼ BM 2 . This charge is gravitationally weak for B ∼1015 G , so that the Kerr metric applies. Being similar to the electric charge of a magnetar, both electric charge and magnetic flux should be, in sign and order of magnitude, continuous during stellar collapse into a black hole. Extraction of the rotational energy from newly formed black holes may proceed by interaction with the magnetic field. 相似文献
356.
In this paper, we perform an inverse method to simultaneously estimate aquifer parameters, initial condition, and boundary conditions in groundwater modelling. The parameter estimation is extended to a complete inverse problem that makes the calibrated groundwater flow model more realistic. The adjoint state method, the gradient search method, and the least square error algorithm are combined to build the optimization procedure. Horizontal two‐dimensional groundwater flow in a confined aquifer is exemplified to demonstrate the correlation between unknowns, the contribution of observation, as well as the suitability of applying the inverse method. The correlation analysis shows the connection between storage coefficient and initial condition. Besides, transmissivity and boundary conditions are also highly correlated. More observations at different location and time are necessary to provide sufficient information. A time series of unsteady head is requested for estimation of storage coefficient and initial condition. Observation near boundary is very effective for boundary condition estimation. The observation at pumping well mostly contributes to the estimation of transmissivity. According to all observations, it is possible to identify parameters, initial condition, and boundary condition simultaneously. Furthermore, the results not only illustrate the traditional assumption of known boundary condition but also initial condition, which may cause an incorrect estimation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
357.
The Sanggok mine used to be one of the largest lead-zinc mines in the Hwanggangri mining district, Republic of Korea. The
present study characterizes the heavy metal contamination in the abandoned Sanggok mine creek on the basis of physico-chemical
properties of various kinds of water samples (mine, surface and groundwater). Hydrochemistry of the water samples is characterized
by the relatively significant enrichment of Ca2+, HCO3
–, NO3
– and Cl– in the surface and groundwaters, whereas the mine water is relatively enriched in Ca2+, Mg2+, heavy metals, and HCO3
– and SO4
2–. The more polluted mine water has a lower pH and higher Eh, conductivity and TDS values. The concentrations of some toxic
elements (Al, As, Cd, Cu, Fe, Mn, Pb, Se, Sr, Pb and Zn) are tens to hundreds of times higher in the mine water than in the
unpolluted surface and groundwaters. However, most immobile toxic pollutants from the mine drainage were quickly removed from
the surface water by the precipitation of Al and Fe oxyhydroxides. Geochemical modeling showed that potentially toxic heavy
metals might exist largely in the forms of MSO4
2– and M2+ in the mine water. These metals in the surface and groundwaters could form M2+, CO3
2– and OH– complex ions. Computer simulation indicates that the saturation indices of albite, alunite, anhydrite, chlorite, fluorite,
gypsum, halloysite and strontianite in the water samples are undersaturated and have progressively evolved toward the saturation
condition. However, barite, calcite, chalcedony, dolomite, gibbsite, illite and quartz were in equilibrium, and only clay
minerals were supersaturated. Ground and mine waters seemed to be in equilibrium with kaolinite field, but some surface water
were in equilibrium with gibbsite and seceded from the stability field of quartz. This indicates that surface water samples
in reaction with carbonate rocks would first equilibrate with carbonate minerals, then gibbsite to kaolinite. Investigations
on water quality and environmental improvement of the severely polluted Sanggok creek, as well as remediation methods on the
possible future pollution of the groundwater by the acid mine drainage from the abandoned metal mines, are urgently required.
Received: 4 February 2000 · Accepted: 9 May 2000 相似文献
358.
Kang Hee Jin Tamang Bibek Jin Jihuan Lee Seungjoo Kim Yongseong 《Acta Geotechnica》2023,18(2):1057-1072
Acta Geotechnica - Although Ordinary Portland Cement (OPC) has been widely used as one of the significant grouting materials, there are many drawbacks to its application in the field. In this... 相似文献
359.
Groundwater level (GWL) varies periodically or non-periodically with various factors including precipitation, river stage (RS) change, sea level, and dewatering activities. In this study, the effect of influence components on the prediction of GWL using an artificial neural network (ANN) was investigated. Six regions with different hydrologic and geologic conditions were collected and adopted in the investigation using various input combinations. In urban areas with a high surface paved ratio, GWL was mainly affected by RS. In rural areas, the permeability of ground showed a significant impact on GWL. For such cases, the moving average (MA) was a suitable component as it could reflect both time lag and the effect of preceding precipitation. It was shown that site-specific influence component should be firstly identified and introduced into input for more enhanced and reliable prediction of GWL using ANN. The effect of learning data length (LDL) was less significant. In urban and rural areas, the introduction of RS and MA into ANN input significantly improved the prediction performance, respectively, which was consistent with the correlation analysis of GWL influence components. 相似文献
360.
Okuhata Brytne K. El-Kadi Aly I. Dulai Henrietta Lee Jonghyun Wada Christopher A. Bremer Leah L. Burnett Kimberly M. Delevaux Jade M. S. Shuler Christopher K. 《Hydrogeology Journal》2022,30(1):231-250
Hydrogeology Journal - Fresh groundwater is a critical resource supporting coastal ecosystems that rely on low-salinity, nutrient-rich groundwater discharge. This resource, however, is subject to... 相似文献