Geomorphic response to an active transpressive regime: a case study along the Chaman strike‐slip fault,western Pakistan     

Shams Ul‐Hadi  Shuhab D. Khan  Lewis A. Owen  Abdul S. Khan 《地球表面变化过程与地形》2013,38(3):250-264

The Chaman left‐lateral strike‐slip fault bounds the rigid Indian plate boundary at the western end of the Himalayan‐Tibetan orogen and is marked by contrasting topographic relief. Deformed landforms along the fault provide an excellent record for understanding this actively evolving intra‐continental strike‐slip fault. The geomorphic response of an active transpessional stretch of the Chaman fault was studied using digital elevation model (DEM) data integrated with Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Visible and Near Infrared/Short Wave Infrared (VNIR/SWIR) and images from GeoEye‐1. Geologic and geomorphic mapping helped in reconstructing the Late Quaternary landscape history of this transpessional strand of the Chaman strike‐slip fault and the associated Spinatizha thrust fault in western Pakistan. Topographic analysis of a part of the transpression (the thrust bounded Roghani ridge) revealed northward growth of the Spinatizha fault with the presence of three water gaps and two corresponding wind gaps. Geomorphic indices including stream length‐gradient index, mountain front sinuosity, valley floor width to valley height ratios, and entrenchment of recent alluvial fan deposits were used to define the lateral growth and direction of propagation of the Spinatizha fault. Left‐lateral displacement along Chaman fault and uplift along the Spinatizha fault was defined using topographic analysis of the Roghani ridge and geomorphic mapping of an impressive alluvial fan, the Bostankaul fan. The landforms and structures record slip partitioning along the Indian plate boundary, and account for the convergence resulting from the difference in the Chaman fault azimuth and orientation of the velocity vector of the Indian plate. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The Impact of Geology of Recharge Areas on Groundwater Quality: A Case Study of Zhob River Basin,Pakistan   总被引：1，自引：0，他引：1  

Muhammad Umar  Amir Waseem  Muhammad Amjad Sabir  Akhtar Muhammad Kassi  Abdul Salam Khan 《洁净——土壤、空气、水》2013,41(2):119-127

Groundwater is a major source of water supply for domestic and irrigation uses in semiarid, remote but rapidly developing Kilasaifullah district part of Zhob River Basin, located at Pakistan–Afghanistan Border. Zhob River is among few major rivers of perennial nature in Balochistan, which flows from WSW to ENE and falls in Gomal River, a tributary of Indus River. Keeping in view the important geopolitical position and rapid development of the region, this study is primarily focused on groundwater chemistry for contamination sources as well as agriculture development. Water samples from open and tube wells are analyzed and calculated for electrical conductivity (EC), total dissolved solids (TDS), turbidity, pH, K⁺, Na⁺, Ca²⁺, Mg²⁺, HCO, Cl^?, NO, SO, PO, sodium percent (Na%), sodium adsorption ratio (SAR), Kelly's index (KI), and heavy metals (Fe, Cu, Cr, Zn, Pb, and Mn). On the basis of the chemical constituents two zones within the study area are identified and possible causes of the contaminants are pointed out. Two recharge areas were responsible for the different chemical results in groundwater, e.g., zone A was recharged from NNW saline geological formations (Nisai, Khojak, Multana, Bostan formations, and Muslim Bagh ophiolites), which are concentrated with high sodium and chloride. On the other hand Zone B was sourced from SSW from carbonate rich rocks (Alozai, Loralai, Parh formations, and Muslim Bagh ophiolites). The groundwater is classified as C2–S1, C3–S1, C3–S2, C4–S2 on the basis of EC and SAR values which indicate that most of the water of both zones can be used for irrigation safely except the samples plotted in C3–S2 and C4–S2 categories which could be dangerous for soil and crops. Groundwater samples are plotted in good to permissible limits with some samples excellent to good and few samples belong to doubtful category based on sodium percent. Groundwater of zone A is unsuitable for irrigation use due to higher values of KI (more than one) but water of zone B are good for irrigation based on KI. In general, water of both zones is suitable for irrigation but care should be taken during the selection of crops which are sensitive to alkalinity or sodium hazards particularly in zone A.  相似文献   

Evaluation of Bioavailability and Partitioning of Aluminum in Sediment Samples of Different Ecosystems by Modified Sequential Extraction Methods     

Sumaira Khan  Tasneem G. Kazi  Muhammad B. Arain  Nida F. Kolachi  Jameel A. Baig  Hassan I. Afridi  Abdul Q. Shah 《洁净——土壤、空气、水》2013,41(8):808-815

Sequential extraction procedures are widely used to characterize the different operational fractions with different potential toxicity of metals in environmental solid samples. The present work describes the application of different analytical approaches for sequential extraction of aluminum to evaluate its mobility, availability, and persistent chemical forms in sediment samples of different fresh water ecosystems (lake, canal, and river). The conventional BCR three‐stage sequential extraction procedure (C‐BCR) was modified at each stage, by applying ultrasonic device (U‐BCR), in order to shorten the required shaking time of 16 h for each three steps (excluding the hydrogen peroxide digestion in step 3, which was not performed with ultrasonic bath), could be completed in 40, 50, and 45 min, respectively. The aluminum in all extracts were determination by atomic absorption spectrometry using nitrous oxide – acetylene flame. The accuracy of results obtained from C‐BCR and proposed U‐BCR was verified with literature reported values of certified sediment sample (BCR 701). The overall recoveries of aluminum obtained by proposed U‐BCR were found in the range of 96.7–113% of those values obtained with C‐BCR for all fractions. Use of ultrasonic device, provided a large saving in extraction time relative to conventional shaking. It was observed that major part of Al in real sediment samples (80–83% of total Al) were bound to residual fraction. The acid soluble fraction of aluminum extracted by 0.11 mol/L CH₃COOH has good correlation with aluminum content in corresponding water samples of each ecosystem.  相似文献   

Vulnerability assessments and their planning implications: a case study of the Hutt Valley, New Zealand     

Shabana Khan 《Natural Hazards》2012,64(2):1587-1607

An understanding of vulnerability is not only crucial for the survival of the exposed communities to extreme events, but also for their adaptation to climate change. Vulnerability affects community participation in hazard mitigation, influences emergency response and governs adaptive capacity for the changing environmental and hazards characteristics. However, despite increased awareness, assessments and understanding of the processes that produce vulnerability, disaster risks prevail. This raises questions on the effectiveness of vulnerability assessments and their applications for hazard mitigation and adaptation. The literature includes a range of vulnerability assessment methods, wherein frequently the selection of any particular method is governed by the research objectives. On the other hand, hazard mitigation plans and policies even though mention vulnerability, their implementation pays less attention to the variations in its nature and underlying causes. This paper explores possible reasons for such gaps by exploring a case study of the Hutt Valley, New Zealand. It brings out the limitations of different vulnerability assessment methods in representing the local vulnerability and challenges they bring in planning for the vulnerability reduction. It argues that vulnerability assessment based on any particular method, such as deprivation index, principle component analysis, composite vulnerability index with or without weight, may not reveal the actual vulnerability of a place, and therefore, a comprehensive vulnerability assessment is needed.  相似文献   

Occurrence of scheelite-powellite in the rocks of Mahakoshal Group, Wyndhamganj area, Sonbhadra district, Uttar Pradesh     

M. A. Khan  Asfar Hakim  S. Syed Ameer Rasool  V. P. Sinha 《Journal of the Geological Society of India》2012,80(4):579-583

Scheelite and Powellite occur as dissemination and fractures filling in the hornfels and tourmaline-garnet granite in the Palaeoproterozoic rocks of Mahakoshal Group, at about 2.5 km north of Wyndhamganj, Sonbhadra district, Uttar Pradesh. This new find opens new vistas for the search of tungsten mineralization along the contact zones of Mahakoshal Group and the younger granite.  相似文献   

Annual and seasonal trends of cooling, heating, and industrial degree-days in coastal regions of Saudi Arabia   总被引：1，自引：0，他引：1  

Shafiqur Rehman  Luai M. Al-Hadhrami  Shamsuddin Khan 《Theoretical and Applied Climatology》2011,103(3-4):479-488

In this study, we systematically analyze the changing properties of reference evapotranspiration (ETref) across China using Penman?CMonteith (P-M) method, exploring the major sensitive meteorological variables for ETref, and investigating influences of human activities, mainly urbanization in this study, on ETref changes in both space and time. We obtain some important conclusions: (1) decreasing annual and seasonal ETref is observed in the east, south and northwest China. However, a long strip lying between these regions is identified to be characterized by increasing ETref; (2) in the regions east to 100°E, the net total solar radiation is the main cause behind the decreasing ETref. In northwest China, however, relative humidity is recognized as the most sensitive variable for the ETref; (3) in the east and south China, urbanization greatly influences the ETref by directly decreasing net solar radiation. The increased air pollution and aerosols in the highly urbanized regions are the main driving factors causing decreasing net radiation; and (4) this study reveals accelerating hydrological cycle from south to north China. Besides, increasing ETref in the source regions of large rivers in China may pose new challenges for the basin-scale water resource management. The results of this study highlight the integrated effects of climate changes and human activities on ETref changes in different regions of China, which will be of great scientific and practical merits in in-depth understanding of hydrological cycle alterations under the changing environment in China.  相似文献   

Assessment of health safety from ingestion of natural radionuclides in seafoods from a tropical coast, India     

Khan MF  Godwin Wesley S 《Marine pollution bulletin》2011,62(2):399-355

The activities of ²¹⁰Po and ²¹⁰Pb were determined in commonly consumed seafoods to evaluate the internal exposure and risk to humans residing Kudankulam coast where a mega nuclear power plant is under construction. The concentration of ²¹⁰Po in seafoods ranged from 1.2 ± 0.7 to 248 ± 8.1 Bq kg⁻¹. Meanwhile, ²¹⁰Pb ranged between 1.1 ± 0.05 and 14.8 ± 1.6 Bq kg⁻¹. The committed effective dose (CED) due to ²¹⁰Po and ²¹⁰Pb varied from 11.04 to 515.6 and 3.93 to 23.5 μSv yr⁻¹, respectively. The lifetime cancer risk for the public due to ²¹⁰Po was in the range of 3.47 × 10⁻⁵-1.62 × 10⁻³ and it was 4.03 × 10⁻⁵-1.96 × 10⁻⁴ due to ²¹⁰Pb. The activity intake, effective dose and cancer risk was found lesser than international guidelines and the seafood intake was considered to be safe for human consumption.  相似文献   

Assessment of probability multimodel seasonal forecast based on the APCC model data     

A. Yu. Bundel  V. N. Kryzhov  Young-Mi Min  V. M. Khan  R. M. Vilfand  V. A. Tishchenko 《Russian Meteorology and Hydrology》2011,36(3):145-154

The probability multimodel forecast system based on the Asia-Pacific Economic Cooperation Climate Center (APCC) model data is verified. The winter and summer seasonal mean fields T ₈₅₀ and precipitation seasonal totals are estimated. To combine the models into a multimodel ensemble, the probability forecast is calculated for each of single models first, and then these forecasts are combined using the total probability formula. It is shown that the multimodel forecast is considerably more skilful than the single-model forecasts. The forecast quality is higher in the tropics compared to the mid- and high latitudes. The multimodel ensemble temperature forecasts outperform the random and climate forecasts for Northern Eurasia in the above- and below-normal categories. Precipitation forecast is less successful. For winter, the combination of single-model ensembles provides the precipitation forecast skill exceeding that of the random forecast for both Northern Eurasia and European Russia.  相似文献   

Role of unbalanced slab resistive force in the 2004 off Sumatra mega-earthquake (<Emphasis Type="Italic">M</Emphasis><Subscript>w</Subscript> > 9.0) event     

Prosanta Kumar Khan 《International Journal of Earth Sciences》2011,100(7):1749-1758

Present study addresses the role of major plate-driving forces, particularly the slab pull and slab resistive forces, for the generation of 26 December 2004 M _w > 9.0 off Sumatra megathrust earthquake. Major controls on the plate-driving forces are normally visualized through age, speed, and average dip of the slab during subduction. Wide variation in age, plate obliquity, stress obliquity, subduction rate, dip angle, and flexing depth of the subducting oceanic lithosphere between Andaman and Sumatra thus allowed us for quantitative evaluation of the slab pull (F _SP) and slab resistive (F _SR) forces in three well-defined sectors (I, II and III). Computed values of these forces in the three sectors: (1) F _SP = 1.29 × 10¹³ N/m, F _SR = 1.41 × 10¹³ N/m; sector I, (2) F _SP = 2.10 × 10¹³ N/m, F _SR = 1.13 × 10¹³ N/m; sector II, and (3) F _SP = 2.08 × 10¹³ N/m, F _SR = 2.72 × 10¹³ N/m; sector III clearly suggest a spatial variation of stress regime in the subducting oceanic lithosphere. Excess F _SR in sectors I and III are interpreted as the causative forces behind the triggering of major seismic energy bursts near Sumatra and Andaman on 26 December 2004. A gap of minimum seismic energy burst near Great Nicobar possibly was controlled by the excess of F _SP in sector II. This study further advocates that the cyclic stress, resulted from unbalanced component of slab resistive force, had a definite control on the occurrence of 2004 off Sumatra megathrust earthquake around the flexing zone of the subducting lithosphere.  相似文献   

Modelling Short‐Scale Variability and Uncertainty During Mineral Resource Estimation Using a Novel Fuzzy Estimation Technique     

Khan Muhammad  Hylke J. Glass 《Geostandards and Geoanalytical Research》2011,35(3):369-385

For mineral resource assessment, techniques based on fuzzy logic are attractive because they are capable of incorporating uncertainty associated with measured variables and can also quantify the uncertainty of the estimated grade, tonnage etc. The fuzzy grade estimation model is independent of the distribution of data, avoiding assumptions and constraints made during advanced geostatistical simulation, e.g., the turning bands method. Initially, fuzzy modelling classifies the data using all the component variables in the data set. We adopt a novel approach by taking into account the spatial irregularity of mineralisation patterns using the Gustafson–Kessel classification algorithm. The uncertainty at the point of estimation was derived through antecedent memberships in the input space (i.e., spatial coordinates) and transformed onto the output space (i.e., grades) through consequent membership at the point of estimation. Rather than probabilistic confidence intervals, this uncertainty was expressed in terms of fuzzy memberships, which indicated the occurrence of mixtures of different mineralogical phases at the point of estimation. Data from different sources (other than grades) could also be utilised during estimation. Application of the proposed technique on a real data set gave results that were comparable to those obtained from a turning bands simulation.  相似文献