Distribution of tritium and stable isotopes in precipitation in Syria     

Abdul Rahman Al Charideh  Boulos Abou Zakhem 《水文科学杂志》2013,58(5):832-843

Abstract

The paper discusses aspects of the isotopic composition (tritium and stable isotopes) of precipitation, which was monitored from 2000 to 2003 at 12 stations in Syria. The seasonal variations in δ¹⁸O are smaller at the western stations than at the eastern ones due to low seasonal temperature variations. A good correlation between δ²H and δ¹⁸O was obtained for each station, and the slopes of the local meteoric water lines are significantly lower than the Global Meteoric Water Line. Values of d-excess decrease from 19‰ at the western stations to 13‰ at the eastern ones, indicating the influence of precipitation generated by air masses coming from the Mediterranean Sea. A reliable altitude effect represented by depletion of heavy stable isotopes (δ¹⁸O and δ²H), of about??0.21‰ and??1.47‰ per 100 m elevation, respectively, was observed. Monthly tritium contents in precipitation, and seasonal variations, are less at the western stations than at the eastern ones. The weighted mean tritium values are between 3 and 9 TU, and increase with distance from the Syrian coast by 1 TU/100 km.

Citation Al Charideh, A. R. & Abou Zakhem, B. (2010) Distribution of tritium and stable isotopes in precipitation in Syria. Hydrol. Sci. J. 55(5), 832–843.  相似文献   

Viewing Angle Effect on the Remote Sensing Monitoring of Wheat and Rice Crops     

Hafizur Rahman  D. A. Quadir  A. Z.M. Zahedul Islam  Sukumar Dutta 《国际地球制图》2013,28(1):74-79

Abstract

Bidirectional reflectance characteristics of a wheat and a rice canopy were studied using radiometric measurements over the two canopies with an Exotech Radiometer Model 100AX. For both rice and wheat, the measurements exhibited significant variations in reflectance amplitude for varying viewing zenith angles and their values decreased from backward to forward scattering direction. Reflectance obtained its maximum value in the backscatter direction for the viewing angle that corresponds approximately to the solar zenith angle at the time of measurements. Canopy background condition (irrigated or non‐irrigated) was an important determining factor of canopy reflectance particularly in the near‐infrared region of the solar spectrum. Furthermore, bidirectional response characteristics of a vegetation canopy were influenced by the amount of vegetation cover.  相似文献   

Linking Coastal Disasters and Migration: A Case Study of Kutubdia Island,Bangladesh     

Munshi Khaledur Rahman  Bimal Kanti Paul  Andrew Curtis  Thomas W. Schmidlin 《The Professional geographer》2013,65(2):218-228

On 4 August 2012, the southeastern part of Kutubdia Island, Bangladesh, experienced coastal erosion and flooding associated with tidal waves, storms, and continuous heavy rainfall for two days. This provided a unique opportunity to study the relationship between rapid-onset disasters and migration decisions of individual households perpetually living under environmental risk. Using Kutubdia Island as a case study, this article examines the migration decisions of respondents in the immediate aftermath of two extreme natural events. Relevant data were primarily collected from a questionnaire survey conducted nearly two months after the occurrence of the event. The study's findings support the view that both environmental and nonenvironmental factors lead to migration. The article outlines several areas for further research on the links between migration and environmental stress.  相似文献   

Socio‐economic and ecological challenges of small‐scale fishing and strategies for its sustainable management: A case study of the Old Brahmaputra River,Bangladesh     

Nesar Ahmed  Sanzidur Rahman  Stuart W. Bunting  Cecile Brugere 《Singapore journal of tropical geography》2013,34(1):86-102

Socio‐economic and ecological challenges faced by the small‐scale fishers dependent on the Old Brahmaputra River, Bangladesh are assessed using a combination of questionnaire survey, co‐monitoring of fish catch, focus group discussions and key informant interviews. Results reveal that the fishers are involved in professional, seasonal or subsistence fishing. Fish catches from the river have declined significantly because of overfishing, destructive use of fishing gear, water pollution, siltation, rapid urbanization and human encroachment, thereby threatening the health of the river ecosystem as well as the future of small‐scale fishing. We evaluate various social, economic and ecological challenges faced by the fisher communities. We propose a conceptual framework that recognizes linkages among social, economic and ecological aspects in devising a sustainable river fisheries management system. We recommend effective legal enforcement of policies and regulations, strong institutional collaboration and active fisher community participation in management to ensure sustainable use of the resource base.  相似文献   

Finite element analyses of layered visco‐elastic system under vertical circular loading     

Q. Xu  M. S. Rahman 《国际地质力学数值与分析法杂志》2008,32(8):897-913

Analyses for the response of a linear visco‐elastic system subjected to axi‐symmetric vertical circular loading are presented. Hankel transforms with respect to the radial spatial coordinate are used to reduce the three‐dimensional problem to that involving only a single spatial dimension, which is then discretized using the finite element method. Three techniques are employed to handle the time factor in the visco‐elastic material: (i) direct time integration; (ii) Fourier transforms; and (iii) Laplace transforms. These methods are compared and evaluated through their numerical results. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

First Record of <Emphasis Type="Italic">Porpita porpita</Emphasis> (Cnidaria: Hydrozoa) from the coral reef ecosystem,Bangladesh     

M. Shah Nawaz Chowdhury  S. M. Sharifuzzaman  Sayedur Rahman Chowdhury  Md. Rashed-Un-Nabi  M. Shahadat Hossain 《Ocean Science Journal》2016,51(2):293-297

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Seasonal prediction of Indian summer monsoon rainfall in NCEP CFSv2: forecast and predictability error     

Samir Pokhrel  Subodh Kumar Saha  Ashish Dhakate  Hasibur Rahman  Hemantkumar S. Chaudhari  Kiran Salunke  Anupam Hazra  K. Sujith  D. R. Sikka 《Climate Dynamics》2016,46(7-8):2305-2326

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Spatio-temporal analysis of road traffic accident fatality in Bangladesh integrating newspaper accounts and gridded population data     

Munshi Khaledur Rahman  Thomas Crawford  Thomas W. Schmidlin 《GeoJournal》2018,83(4):645-661

Road traffic accidents pose serious threats to human lives and often cause premature deaths, disabilities, and socioeconomic impacts. The objective of this study is to analyze the fatal road traffic accidents in Bangladesh by performing a space–time characterization of fatality rates involving an innovative newspaper-based method in concert with gridded population data to construct a road traffic fatality database. Kernel density estimation, temporal data plots and space–time pattern mining tools that combine the Getis-Ord Gi* statistic with the Mann–Kendall test are used to describe spatio-temporal hotspots/coldspots and trends. Results show different patterns between the urban and rural areas of Bangladesh and higher rates of road traffic accidents occur in the metropolitan regions (Dhaka) and in a northern region centered on Sirajganj area. Most of the road traffic accidents took place in between 9:00 and 12:00 pm while the accident rates remain low between 12:00 and 3:00 am. Spacetime analysis results reveal a core region of persistently high rates along with four smaller regions with high and intensifying rates. The output of this study could be useful to reduce road traffic fatalities, injuries, increase awareness, and adopt necessary interventions for public safety through integrating both the local, regional, and central level decision makers of public transportation policy and issues in Bangladesh. The approach has potential to be translated to other developing countries.  相似文献   

FEG-EPMA mapping and Fe-Ti oxide mineral chemistry of Brahmaputra River sediments in Bangladesh: provenance and petrogenetic implications     

A. S. M. Mehedi Hasan  Ismail Hossain  Md. Aminur Rahman  Md. Sazzadur Rahman  Mohammad Nazim Zaman  Pradip Kumar Biswas 《Arabian Journal of Geosciences》2018,11(18):567

The present research deals with the FEG-EPMA mapping and Fe-Ti oxide mineral chemistry of Brahmaputra River sediments in Bangladesh. Major heavy minerals in the sediments consist of garnet (8.5–21.3%), kyanite (5.35–11.9%), monazite (2.3–5.3%), sillimanite (1.8–4.7%), zircon (3.6–9.1%), and a considerable amount of opaques mainly Fe-Ti oxide minerals (23.1–35.4%). The detrital Fe-Ti oxide minerals carry significant clues to the parent rocks or sources. In these contexts, detrital opaques (Fe-Ti oxides) have been analyzed with an electron probe microanalyzer (EPMA). These opaques (Fe-Ti oxide) display six types of textural patterns, dominantly seriate with granular, emulsion, and acicular sandwich structures and trellis type of textural patterns. These textural patterns belong to five intergrowths of Fe-Ti oxide minerals such as (1) ilmenite-hematite, (2) magnetite-ilmenite, (3) hematite-rutile, (4) ilmenite-hematite-rutile, and (5) ilmenite-rutile, where ilmenite-hematite intergrowth is common. Alteration is seen in both exsolved and unexsolved ilmenites. Textural patterns and mineral chemistry of the studied ilmenite minerals provide lines of evidence of low-temperature magmatic inheritance, later modified by diffusional processes. The estimated temperature and oxygen fugacity from the magnetite-ilmenite exsolution range from 547.6 to 558.2 °C and from 10^?21.4 to 10^?21.7, respectively. The data are also consistent with hematite-ilmenite temperature (between 537 and 540 °C) and oxygen fugacity (10^?21.7 to 10^?21.9) measurements in Cox’s Bazar beach placers. These temperatures and oxygen fugacities specify Fe-Ti oxide assemblages equilibrated in a T-fO₂ field very near to the FMQ buffer curve suggesting a crustal source (magmatic and/or metamorphic), which is modified significantly by metamorphic processes.  相似文献   

Spatio-temporal analysis of temperature variability,trend, and magnitude in the Hindu Kush region using Monte Carlo and Sen’s slope approaches     

Muhammad Dawood  Atta-ur Rahman  Sami Ullah  Ghani Rahman  Kamran Azam 《Arabian Journal of Geosciences》2018,11(16):471

The present study explores the spatial and temporal deviations in temperature using Monte Carlo (MC) and Sen’s slope (SS) approaches in the Hindu Kush (HK) region. Climate change holds sturdy association against the temperature trend that has generated adverse impacts in the form of floods. In this attempt, for trend analysis, temperature has been selected as a meteorological parameter. This study mainly focuses on exploring the tendency in average temperature with respect to time and the consequential flood recurrences in the region. For the current study, data regarding temperature were typically collected from Pakistan Meteorological Department. In the study region, there are a total of seven meteorological station falls namely Dir, Chitral, Drosh, Saidu, Malam Jabba, Kalam, and Timergara. The temperature time series data was calculated and analyzed using MC and SS approaches for trend detection in order to demonstrate the kind of fluctuation in the Hindu Kush region. The resultant analysis further revealed that in the meteorological station of Dir, a more significant positive trend (α?=?0.0001) was found in mean monthly maximum, minimum, and monthly normal temperature. Likewise, at Drosh, a positive trend is detected in mean monthly maximum (α?=?0.04), monthly minimum (α?=?0.003), and monthly average (α?=?0.0005). Moreover, at Saidu met station, there is also a trend detected in temperature sub-variables such as monthly maximum (α?=?0.0001) and monthly minimum (α?=?0.001). In addition to these, at Kalam, there is a temperature trend noted for monthly minimum (α?=?0.01) and monthly average (α?=?0.02). Furthermore, the analysis demonstrates that there is no trend detected in the remaining stations, i.e., Chitral, Malam Jabba, Drosh, and Timergara. The overall analysis discovered that there is a sturdy relationship between climate change phenomenon and temperature variability. After using SS test to the temperature data of mean monthly maximum (TMMMax), the results explored that Kalam station grips the highest magnitude, i.e., Q?=?0.76; however, Timergara shows the lowermost, i.e., Q?=???0.34. For the monthly minimum temperature (TMMMin), at Kalam again, the highest value (Q?=?0.005) was detected; however, other stations revealed a negative trend, except Drosh which express no change in terms of magnitude. Similarly, in terms of monthly normal temperature (TMNor), Timergara station (Q?=???0.4) verified a negative trend magnitude and Malam Jabba station again trendless. Among all, the met station of Malam Jabba which holds an altitude of 2591 m is a hilly station just followed by Kalam having 2103 m height; however, Dir holds 1375 m height and the rest of the met stations show low elevation. The main reason for the temperature difference is the altitude of the study region.  相似文献