Crustal reflection structure in the uplifting zone of Songliao Basin and disconnecting Moho interface   总被引：6，自引：0，他引：6  

S.A.Faisal 《中国科学D辑(英文版)》2004,47(6):514-521

Songliao Basin is one of the most important bases for oil-gas resources of China. Therefore, the mecha-nism of petroleum occurrence and basin dynamics have been paid much attention to by geo-scientists all the time. With multi-phase tectonic movements en-dured by the basin, its tectonic pattern is very complex. Thereinto, three faults, that is, western Neijiang fault(NNE25), eastern Yilan-Yitong fault (NNE30) and Sunwu-Shuangliao fault, extend along south-north direction and cut Songliao…  相似文献   

Wetter or colder during the Last Glacial Maximum? Revisiting the pluvial lake question in southwestern North America     

Kirsten M. Menking  Roger Y. Anderson  Nabil G. Shafike  Kamran H. Syed  Bruce D. Allen 《Quaternary Research》2004,62(3):174-288

Well-preserved shorelines in Estancia basin and a relatively simple hydrologic setting have prompted several inquiries into the basin's hydrologic balance for the purpose of estimating regional precipitation during the late Pleistocene. Estimates have ranged from 86% to 150% of modern, the disparity largely the result of assumptions about past temperatures. In this study, we use an array of models for surface-water runoff, groundwater flow, and lake energy balance to examine previously proposed scenarios for late Pleistocene climate. Constraints imposed by geologic evidence of past lake levels indicate that precipitation for the Last Glacial Maximum (LGM) may have doubled relative to modern values during brief episodes of colder and wetter climate and that annual runoff was as much as 15% of annual precipitation during these episodes.  相似文献   

Effect of loading rate on the volume change behavior of unsaturated residual soil     

Bujang B. K. Huat  Faisal Hj. Ali  F. H. Choong 《Geotechnical and Geological Engineering》2006,24(6):1527-1544

Residual soils occur in most countries of the world but those that occur in greater area and depth are usually found in the tropical humid areas. This research examines the effects of loading rate of applied or net mean stress on the volume change behavior of an unsaturated granitic residual soil. Three loading rates were adopted: fast, slow and extra slow loading rate. It was observed that the loading rate of applied or net mean stress has a pronounced effect on the void ratio and degree of saturation but has an insignificant effect on the water content of residual soils subjected to constant matric suction.  相似文献   

Water infiltration characteristics of unsaturated soil slope and its effect on suction and stability   总被引：3，自引：1，他引：3  

Bujang B. K. Huat  Faisal HJ. Ali  T. H. Low 《Geotechnical and Geological Engineering》2006,24(5):1293-1306

Rainfall has been considered the cause of the majority of slope failures and landslides that happened in regions experiencing high seasonal rainfalls. The mechanism of the failures was mainly due to the lost of matric suction of soils by rainwater. This paper presents the results of a laboratory model study on the effect of slope angle and surface cover on water infiltration into soil and soil matric suction. A field infiltration test is carried out for comparison. A parametric study is also done to examine the effect of permeability ratio, development of perched water table and rainfall intensity on the factor of safety against instability of a soil slope. Results of the model study show that different surface covers on slopes have an effect on the water infiltration. Generally the covered surface (grass or geosynthetic net) has a lower infiltration rate compared with the bare (no cover) surface. On the effect of slope angle, it was observed that water infiltration decrease with increase in the slope steepness. With regards to the movement of the wetting front, it appears that water infiltration is more at the toe compared with the top of the model slope. Based on the parametric study, it is found factor of safety of the slope against instability drops for slope with higher ratio of permeability for the permeable and impermeable stratum. As the perched water table is formed, the factor of safety decreased. The rainfall intensity also has a marked effect on the slope factor of safety. The higher the intensity of the rainfall, the higher is the infiltration rate into the soil, hence the lower is the factor of safety against slope instability.  相似文献   

Spatial pattern of arsenic contamination in shallow wells of Bangladesh: regional geology and nonlinear dynamics     

Faisal Hossain  Bellie Sivakumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(1-2):66-76

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The Use Of Environmental Isotopes And Chloride As Natural Tracers To Investigate The Effects Of Depressurisation Of A Coastal Aquifer For Lignite Mining,India     

B.S. Sukhija  D.V. Reddy  P. Nagabhushanam  Syed Hussain  V.Y. Giri 《Hydrogeology Journal》1996,4(2):70-88

In order to mine lignite from the Neyveli opencast mines, about 200 km south of Madras, India, the Neyveli aquifer has been undergoing depressurisation continuously for almost three decades. To gain insight into the aquifer hydrodynamics, environmental-isotope and chloride measurements on selected groundwater samples were initiated two decades ago, and detailed studies were undertaken during 1985–91. This article demonstrates the effect of large-scale groundwater withdrawals on the hydrologic regime and the effects on environmental chloride and isotopic distributions. A feature common to both the radiocarbon and chloride data of 1991 is their marked variation in a small area between the recharge zone and the mine area where pumping is concentrated. Furthermore, an excellent correlation exists between the temporal increase in the apparent radiocarbon ages of groundwater sampled in 1991 and 1985 and the corresponding lowering of potentiometric levels. Isochlors based on 1991 and 1985 data also indicate a changed hydrologic regime. In certain areas, heavy withdrawals have resulted in increased groundwater salinity.  相似文献   

Recharge processes: piston flow vs preferential flow in semi-arid aquifers of India   总被引：3，自引：4，他引：3  

B. S. Sukhija  D. V. Reddy  P. Nagabhushanam  Syed Hussain 《Hydrogeology Journal》2003,11(3):387-395

Study of groundwater recharge processes is vital for quantification of total natural recharge to the aquifers. One of the recharge processes demonstrated earlier by tracer experiments in the unsaturated zone is that of piston flow movement of soil moisture. Based on this recharge process, environmental tritium, chloride and injected tritium studies have been carried out extensively in various geological environs of India. The purpose of this paper is to evaluate the validity of the piston flow concept in different geological environs viz. consolidated fractured and weathered granites, semi-consolidated sandstones and unconsolidated alluvial tracts, and quantify the contribution from this process as well as that from the preferential flow mechanism using different tracers. Analysis of tracer data demonstrates that the preferential flow recharge process contributes very significantly (an average of 75% of total recharge) in the case of fractured granites and is important (an average of 33% of total recharge) for semi-consolidated sandstones, whereas the preferential flow recharge component is minimal in unconsolidated alluvial tracts (piston flow model is applicable). These findings necessitate re-evaluation of the total natural recharge potential of the above mentioned geological environs in view of the significant preferential flow recharge that is evidenced and estimated. Electronic Publication  相似文献   

The design of visco‐acoustic weighted L1‐error frequency–space wavefield extrapolators          下载免费PDF全文

Syed Abdul Salam  Wail A. Mousa 《Geophysical Prospecting》2018,66(2):300-310

Seismic imaging is an important step for imaging the subsurface structures of the Earth. One of the attractive domains for seismic imaging is explicit frequency–space (f – x) prestack depth migration. So far, this domain focused on migrating seismic data in acoustic media, but very little work assumed visco‐acoustic media. In reality, seismic exploration data amplitudes suffer from attenuation. To tackle the problem of attenuation, new operators are required, which compensates for it. We propose the weighted L ₁ ‐error minimisation technique to design visco‐acoustic f – x wavefield extrapolators. The L ₁ ‐error wavenumber responses provide superior extrapolator designs as compared with the previously designed equiripple L ₄ ‐norm and L_∞‐norm extrapolation wavenumber responses. To verify the new compensating designs, prestack depth migration is performed on the challenging Marmousi model dataset. A reference migrated section is obtained using non‐compensating f – x extrapolators on an acoustic dataset. Then, both compensating and non‐compensating extrapolators are applied to a visco‐acoustic dataset, and both migrated sections are then compared. The final images show that the proposed weighted L ₁ ‐error method enhances the resolution and results in practically stable images.  相似文献   

Geo-Spatial Dynamics of Snow Cover and Hydro-Meteorological Parameters of Hunza Basin,HKH Region,Pakistan     

Ijaz Ahmad  Ahmad  Zulfiqar  Lisa  Mona  Mahmood  Syed Amer  Ali  Asad  Rehman  Obaid Ur 《Water Resources》2019,46(6):894-909

Water Resources - Snow cover dynamics play an important role in the hydrological characteristics of Upper Indus Basin (UIB) of Pakistan in terms of seasonal accumulation and depletions. The current...  相似文献   

Lithologic mapping of a forested montane terrain from Landsat 5 TM image     

Taufique H. Mahmood  Khaled Hasan  Syed Humayun Akhter 《国际地球制图》2019,34(7):750-768

Thick forest cover and poor infrastructures are the major hindrances for detailed lithologic mapping in an inaccessible montane landscape. To overcome these limitations, we utilize a Landsat 5 TM image to map lithology using vegetation and drainage pattern as an indicator of underlying rock types in a heavily forested region of the Chittagong Hill Tracts area located in southeastern Bangladesh. We use supervised and unsupervised classifiers for a vegetation-based approach while on-screen digitization is used for drainage patterns-based mapping. Field observations were used for mapping lithology and evaluating accuracy. Overall, our results agree well with the current geologic map and improve it by providing a more spatially detailed distribution of the sandstone and shale. The performances of all approaches are good at the inner and outer flanks of anticlines located in the study area while the drainage pattern mapping performs best at the mid-flank area.  相似文献