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排序方式: 共有166条查询结果,搜索用时 15 毫秒
111.
Jeong Joo Bong Jung Hoi-Soo Lee Jun-Ho Park Kyung Kyu Kim Seok Yun Woo Han Jun 《Ocean Science Journal》2022,57(3):451-466
Ocean Science Journal - Dadae Beach located in the Nakdong River estuary has been continuously evolving as the result of natural and anthropogenetic activities. Due to the geographic... 相似文献
112.
113.
The static modeling and dynamic simulation are essential and critical processes in petroleum exploration and development. In this study, lithofacies models for Wabiskaw Member in Athabasca, Canada are generated by multipoint statistics(MPS) and then compared with the models built by sequential indicator simulation(SIS). Three training images(Tls) are selected from modern depositional environments;the Orinoco River Delta estuary, Cobequid bay-Salmon River estuary, and Danube River delta environment. In order to validate lithofacies models, average and variance of similarity in lithofacies are calculated through random and zonal blind-well tests.In random six-blind-well test, similarity average of MPS models is higher than that of SIS model. The Salmon MPS model closely resembles facies pattern of Wabiskaw Member in subsurface. Zonal blind-well tests show that successful lithofacies modeling for transitional depositional setting requires additional or proper zonation information on horizontal variation, vertical proportion, and secondary data.As Wabiskaw Member is frontier oilsands lease, it is impossible to evaluate the economics from production data or dynamic simulation. In this study, a dynamic steam assisted gravity drainage(SAGD)performance indicator(SPIDER) on the basis of reservoir characteristics is calculated to build 3 D reservoir model for the evaluation of the SAGD feasibility in Wabiskaw Member. SPIDER depends on reservoir properties, economic limit of steam-oil ratio, and bitumen price. Reservoir properties like porosity,permeability, and water saturation are measured from 13 cores and calculated from 201 well-logs. Three dimensional volumes of reservoir properties are constructed mostly based on relationships among properties. Finally, net present value(NPV) volume can be built by equation relating NPV and SPIDER. The economic area exceeding criterion of US$ 10,000 is identified, and the ranges of reservoir properties are estimated. NPV-volume-generation workflow from reservoir parameter to static model provides costand time-effective method to evaluate the oilsands SAGD project. 相似文献
114.
Xiaosi Su Shuai Lu Wenzhen Yuan Nam Chil Woo Zhenxue Dai Weihong Dong Shanghai Du Xinyue Zhang 《Hydrogeology Journal》2018,26(5):1573-1589
The spatial and temporal distribution of redox zones in an aquifer is important when designing groundwater supply systems. Redox zonation can have direct or indirect control of the biological and chemical reactions and mobility of pollutants. In this study, redox conditions are characterized by interpreting the hydrogeological conditions and water chemistry in groundwater during bank infiltration at a site in Shenyang, northeast China. The relevant redox processes and zonal differences in a shallow flow path and deeper flow path at the field scale were revealed by monitoring the redox parameters and chemistry of groundwater near the Liao River. The results show obvious horizontal and vertical components of redox zones during bank filtration. Variations in the horizontal extent of the redox zone were controlled by the different permeabilities of the riverbed sediments and aquifer with depth. Horizontally, the redox zone was situated within 17 m of the riverbank for the shallow flow path and within 200 m for the deep flow path. The vertical extent of the redox zone was affected by precipitation and seasonal river floods and extended to 10 m below the surface. During bank filtration, iron and manganese oxides or hydroxides were reductively dissolved, and arsenic that was adsorbed onto the medium surface or coprecipitated is released into the groundwater. This leads to increased arsenic content in groundwater, which poses a serious threat to water supply security. 相似文献
115.
A two‐dimensional semi‐analytical solution to analyse stream–aquifer interactions in a coastal aquifer where groundwater level responds to tidal effects is presented. The conceptual model considered is a two‐dimensional subsurface system with stream and coastline boundaries at right angles. The dimensional and non‐dimensional boundary value problems were solved for water level in the aquifer by successive application of Laplace and Fourier transform techniques, and the results were obtained by numerical inversion of the transformed solution. The solution was then verified by reducing the solutions to one‐dimensional known problems and comparing the results with those from previous studies. Hypothetical examples were used to examine the characteristics of water‐level variations due to the variations in stream stage and the fluctuations in tide level. Sensitivity analysis indicated that streambed leakance has no influence over the amplitude of groundwater fluctuations, but that the effect of stream stage increases with increasing leakance. Little difference was observed in the water level for different aquifer penetration ratios with narrow stream width. Increases in streambed leakance caused increases in the effect of aquifer penetration by the stream on the water level. An increased specific yield value resulted in decreased amplitude of water fluctuations and mean water level, and showed that water‐level variations due to stream and tidal boundaries are sensitive to specific yield. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
116.
Abstract We have obtained the residual depth and residual geoid anomalies of the South Atlantic Ocean and interpreted them in terms of upper mantle processes. Starting from the 5’ X 5’ SYNBAPS data, we computed the 1° X 1° mean water depth. We digitized a recent sediment thickness map of the South Atlantic and corrected for the isostatic sediment loading effects. A plot of the corrected basement depth against crustal ages shows a good match to the depth‐age curve of the plate model. We then subtracted the predicted plate model depths from the corrected basement depths and obtained the 1° X 1° residual depth. The residual depth anomalies have positive values over the topographic highs and relative negative values over the ocean basins. A prominent asymmetry is observed between the residual depth over the Argentine Basin and that over the Cape Basin. We have obtained the 1° X 1° residual geoid of the South Atlantic by subtracting both the long wavelength features and the geoid variations due to the plate cooling from the 1° X 1° Seasat altimeter derived geoid. The long wavelength features are represented by the degree and order 10 geoid of GEM1OC, and the geoid variations due to the plate cooling effects are predicted by the plate model geoid‐age relationship. The residual geoid anomalies also show an asymmetry although weaker than the case of the residual depth, between the Argentine and Cape basins. By taking the 5° X 5° averages, we removed possible plate bending effects on the depth and geoid anomalies. We then compared those two data sets with respect to the reported hot spot tracks in the South Atlantic. The residual depth generally shows positive values over the hot spot tracks, whereas the residual geoid does not show any sign of them. A prominent asymmetric feature of depth and geoid anomalies is observed over the Argentine and Cape basins. This asymmetry is probably caused by hotter and less dense materials beneath the Cape Basin. Hot spots or other mantle upwellings may be the heat sources. 相似文献
117.
Groundwater nitrate contamination and risk assessment in an agricultural area,South Korea 总被引:2,自引:1,他引:1
Jae-Yeol Cheong Se-Yeong Hamm Jeong-Hwan Lee Kwang-Sik Lee Nam-Chil Woo 《Environmental Earth Sciences》2012,66(4):1127-1136
The nitrate of groundwater in the Gimpo agricultural area, South Korea, was characterized by means of nitrate concentration,
nitrogen-isotope analysis, and the risk assessment of nitrogen. The groundwaters belonging to Ca–(Cl + NO3) and Na–(Cl + NO3) types displayed a higher average NO3
− concentration (79.4 mg/L), exceeding the Korean drinking water standard (<44.3 mg/L NO3
−). The relationship between δ18O–NO3
− values and δ15N–NO3
− values revealed that nearly all groundwater samples with δ15N–NO3
− of +7.57 to +13.5‰ were affected by nitrate from manure/sewage as well as microbial nitrification and negligible denitrification.
The risk assessment of nitrate for groundwater in the study area was carried out using the risk-based corrective action model
since it was recognized that there is a necessity of a quantitative assessment of health hazard, as well as a simple estimation
of nitrate concentration. All the groundwaters of higher nitrate concentration than the Korean drinking water standard (<44.3 mg/L NO3
−) belonged to the domain of the hazard index <1, indicating no health hazard by nitrate in groundwater in the study area.
Further, the human exposure to the nitrate-contaminated soil was below the critical limit of non-carcinogenic risk. 相似文献
118.
This study examines the stability of an embankment used in stone quarry reclamation built of local natural soil mixed with stone dust. Stone dust is a fine-grained and low-strength material, whereas soil is coarser with higher strength. Test results show that the shear strength and maximum dry unit weight of the mixed material increase with a decrease in the stone dust. After reviewing various domestic and international standards for slope stability, this study suggests a three-grade slope stability rating system (“unstable,” “requires attention” and “stable”) for embankments built of soil mixed with stone dust. A series of slope stability analysis aims to define stable heights, slope angles and mix ratios for such embankments. Safe slope gradients should be 1:1.8 or higher for 10 m high embankments. Embankments 15 m in height should use a mix ratio less than 50% and a slope gradient of 1:1.8 or higher. The safe dimensioning and design guideline values determined by this study should be useful for the construction of new, as well as the stability evaluation of existing embankments that have been made from mixed soils containing stone dust. 相似文献
119.
In this study, the propagation of monochromatic water waves over an arbitrarily varying topography is numerically investigated. A finite element model is developed by formulating the diffraction of waves caused by depth changes. Not only the propagating mode but also the evanescent modes are included in the model. The model developed is applied to the study of strong reflection of monochromatic waves over a sinusoidally varying topography. Predicted reflection coefficients are compared with those of available laboratory experiments and the eigenfunction expansion method. A very good agreement is observed. 相似文献
120.
Byung?Ho?Choi Efim?PelinovskyEmail author Ho?Jun?Lee Seung?Buhm?Woo 《Natural Hazards》2005,36(3):355-381
Prognostic characteristics of tsunamis in the East (Japan) Sea based on numerical simulations are investigated by using linear
long wave theory. Due to the lack of observed data, the concept of the synthetic catalogue is applied to generate possible
tsunami scenarios. It includes four real events that occurred in the East (Japan) Sea during the 20th century, 24 hypothetical
tsunamigenic earthquakes located in the gap zones of the seismic map, and 76 idealized model ‘hydrodynamic’ sources covering
the eastern part of the East (Japan) Sea uniformly. The tsunami wave height distributions along the East (Japan) Sea coastline
due to these hypothetical events are computed. From the geographical distributions of tsunami wave height for all possible
events, it is found that there exist several coastal locations where the tsunami risk is relatively lower than in other zones.
The relation between the maximal value of the tsunami height and its average value is analyzed. It is found that the maximal
tsunami height does not exceed the mean wave height times a constant. The uniform bounded curve for all areas can be obtained
if the mean wave height is replaced by the modified mean wave height (1/3 of largest waves). The problem of quantitative definition
of the prognostic tsunami wave height for each location based on the data from the synthetic catalogue is discussed. The results
of tsunami wave height analysis based on the synthetic catalogue can be used as a tool for coastal disaster mitigation planning. 相似文献