Vegetation response to climate and climatic extremes in northwest Bangladesh: a quantile regression approach     

Uddin  Mohammad Ahsan  Kamal  A. S. M. Maksud  Shahid  Shamsuddin 《Theoretical and Applied Climatology》2022,148(3-4):985-1003

Theoretical and Applied Climatology - The present study assessed the vegetation response to climate in the water-stressed northwest Bangladesh (NWB). The quantile regression analysis was employed...  相似文献   

Damage and management of cyclone Sidr-affected homestead tree plantations: a case study from Patuakhali, Bangladesh   总被引：1，自引：0，他引：1  

Md. Zamiul Haq  Mahbub Robbani  Mohammad Ali  Md. Mainul Hasan  Md. Mahmudul Hasan  Md. Jashim Uddin  Monjila Begum  Jaime A. Teixeira da Silva  Xiao-Ying Pan  Md. Rezaul Karim 《Natural Hazards》2012,64(2):1305-1322

Geographically, Bangladesh is considered to be one of the most cyclone-prone areas in the world. The super cyclone Sidr in 2007 was one of the most devastating disasters to have ever occurred in Bangladesh, having wind speeds of 223?km/h with a tidal surge of 6.1?C7.6?m high. In order to draw a pre- and post-Sidr damage and management scenario, a survey was conducted at Dumki upazila, Patuakhali district in Bangladesh with a pretested questionnaire. Primary data were collected through a questionnaire, while secondary data were collected from pertinent offices as well as academic journals. The major focus of this study was to assess the state of pre-Sidr tree plantations (woody and fruit trees), the devastation caused by Sidr on these tree plantations, and post-Sidr recovery and further sustainable management initiatives to counteract a possible future neo-Sidr. The post-Sidr study showed that about 16.84 million woody and fruit trees were uprooted by Sidr. A total of 3,120 rain tree (Samanea saman L.), 7,548 mahogany (Swietenia mahagoni L.), 1,444 royal siris (Albizzia richardiana L.), 702 white siris (Albizzia procera L.), 1,214 mango (Mangifera indica L.), 1,092 coconut (Cocos nucifera L.), 1,380 jackfruit (Artocarpus heterophyllus L.), and 7,640 betel nut (Areca catechu L.) trees were sampled among which 922, 1,662, 382, 210, 106, 38, 362, and 1,652 trees, respectively, were markedly damaged by Sidr. Sexually propagated woody trees with a damaged taproot were vulnerable to heavy wind during the cyclone. Fruit trees were more resistant to the cyclone than other types of trees, and the lack of proper tree training and pruning was one of the principal causes of the severe damage to woody trees. Hence, plantations of woody tree saplings with damaged taproots are strongly discouraged. However, proper training and pruning of homestead trees together with plantation of fruit trees rather than woody trees is suggested as a possible effective management strategy to protect the homestead ecosystem from devastation by future cyclones in Bangladesh.  相似文献   

Multiwavelength Observations of a Failed Flux Rope in the Eruption and Associated M-Class Flare from NOAA AR 11045     

Pankaj Kumar  Ablishek K. Srivastava  B. Filippov  R. Erdélyi  Wahab Uddin 《Solar physics》2011,272(2):301-317

We present the multiwavelength observations of a flux rope that was trying to erupt from NOAA AR 11045 and the associated M-class solar flare on 12 February 2010 using space-based and ground-based observations from TRACE, STEREO, SOHO/MDI, Hinode/XRT, and BBSO. While the flux rope was rising from the active region, an M1.1/2F class flare was triggered near one of its footpoints. We suggest that the flare triggering was due to the reconnection of a rising flux rope with the surrounding low-lying magnetic loops. The flux rope reached a projected height of ≈0.15R _⊙ with a speed of ≈90 km s⁻¹ while the soft X-ray flux enhanced gradually during its rise. The flux rope was suppressed by an overlying field, and the filled plasma moved towards the negative polarity field to the west of its activation site. We found the first observational evidence of the initial suppression of a flux rope due to a remnant filament visible both at chromospheric and coronal temperatures that evolved a couple of days earlier at the same location in the active region. SOHO/MDI magnetograms show the emergence of a bipole ≈12 h prior to the flare initiation. The emerged negative polarity moved towards the flux rope activation site, and flare triggering near the photospheric polarity inversion line (PIL) took place. The motion of the negative polarity region towards the PIL helped in the build-up of magnetic energy at the flare and flux rope activation site. This study provides unique observational evidence of a rising flux rope that failed to erupt due to a remnant filament and overlying magnetic field, as well as associated triggering of an M-class flare.  相似文献   

Geochemical assessment of arsenic contamination in well water and sediments from several communities in the Nawalparasi District of Nepal     

Akiko Nakano  Kiyoshi Kurosawa  Uddin Md. Shamim  Masakazu Tani 《Environmental Earth Sciences》2014,72(9):3269-3280

Arsenic contamination of well water is a serious issue in the Nawalparasi District of the Terai region in Nepal. A local investigation was carried out on 137 tube wells in 24 communities of the district in December 2011. The investigation revealed that the average arsenic concentration in the tube wells was 350 μg/L, and that nearly 98 % of the wells exceeded the WHO guideline arsenic level limit of 10 μg/L. Highly contaminated well water, with more than 400 μg/L of arsenic, was found within the limited depth ranges of 18–22 and 50–80 m. High arsenic levels exceeding 500 μg/L were detected in shallower wells at Patkhauli, Mahuawa, Thulokunwar, and Goini located between 27.517° and 27.543°N and between 83.648° and 83.748°E. Boring sampling at five communities of Kashiya, Goini, Sanokunwar, Thulokunwar, and Mahuawa revealed two aquifers located at the two depths around 14–22 and 41–50 m in each community. Dark gray or black-colored peaty clay layers rich in organic matter were distributed at depths of 18–21 m beside the upper aquifers with high arsenic concentration in each community. Positive correlations were shown between iron and arsenic in the sediments from the five communities. It can be inferred that these results were caused by dissolution of iron-oxyhydroxide molecules with arsenic from solid phases. Microbial metabolisms have a great potential to induce the dissolution and release arsenic attached on the solid phases into aqueous phases depending on the level of redox potential and pH.  相似文献   

Helical Eruptive Prominence Associated with a Pair of Overlapping CMEs on 21 April 2001     

Syed Salman Ali  Wahab Uddin  Ramesh Chandra  D. L. Mary  Bojan Vršnak 《Solar physics》2007,240(1):89-105

The eruption of limb prominence on 21 April 2001 associated with two coronal mass ejections (CMEs) is investigated. Hα images reveal two large-scale eruptions (a prominence body and a southern foot-point arch), both showing helical internal structure. These two eruptions are found to be spatially and temporally associated with the corresponding CMEs. The kinematics and the study of geometrical parameters of the prominence show that the eruption was quite impulsive (with peak acceleration ≈470 m s⁻²) and has taken place for relatively low pitch angle of helical threads, not exceeding tan θ≈1.2. The stability criteria of the prominence are revisited in the light of the model of Vršnak (1990, Solar Phys. 129, 295) and the analysis shows that the eruption violates the instability criteria of that model. Finally, the energy stored in the prominence circuit and the energies (kinetic, potential, and magnetic) of the associated CMEs are estimated and it is found that there was enough energy stored in the prominence to drive the two CMEs. S.S. Ali is on leave from Aligarh Muslim University, Aligarh, 202 002, India.  相似文献   

Companion Event and Precursor of the X17 Flare on 28 October 2003     

C. H. Mandrini  P. Demoulin  B. Schmieder  E. E. Deluca  E. Pariat  W. Uddin 《Solar physics》2006,238(2):293-312

A major two-ribbon X17 flare occurred on 28 October 2003, starting at 11:01 UT in active region NOAA 10486. This flare was accompanied by the eruption of a filament and by one of the fastest halo coronal mass ejections registered during the October–November 2003 strong activity period. We focus on the analysis of magnetic field (SOHO/MDI), chromospheric (NainiTal observatory and TRACE), and coronal (TRACE) data obtained before and during the 28 October event. By combining our data analysis with a model of the coronal magnetic field, we concentrate on the study of two events starting before the main flare. One of these events, evident in TRACE images around one hour prior to the main flare, involves a localized magnetic reconnection process associated with the presence of a coronal magnetic null point. This event extends as long as the major flare and we conclude that it is independent from it. A second event, visible in Hα and TRACE images, simultaneous with the previous one, involves a large-scale quadrupolar reconnection process that contributes to decrease the magnetic field tension in the overlaying field configuration; this allows the filament to erupt in a way similar to that proposed by the breakout model, but with magnetic reconnection occurring at Quasi-Separatrix Layers (QSLs) rather than at a magnetic null point. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.  相似文献   

Study of a large helical eruptive prominence associated with double CME on 21 April 2001     

Syed Salman Ali  Wahab Uddin  Ramesh Chandra 《Journal of Astrophysics and Astronomy》2006,27(2-3):347-352

Here we present a preliminary analysis of a helical eruptive prominence at the east limb of the Sun on 21 April 2001. Unusually this eruption is associated with a double CME. We have tried to study the morphology of the event, energy budget of the prominence and associated CMEs. Our analysis shows that the prominence and first CME started simultaneously from the limb and prominence carries sufficient energy to feed both the CMEs. Moreover, it is also concluded that CMEs are magnetically driven and internally powered.  相似文献   

Mineralogical profiling of alluvial sediments from arsenic-affected Ganges-Brahmaputra floodplain in central Bangladesh     

A. Uddin  M. Shamsudduha  J.A. SaundersM.-K. Lee  K.M. AhmedM.T. Chowdhury 《Applied Geochemistry》2011,26(4):470-483

Mineral assemblages (heavy and light fractions) and sedimentological characteristics of the Quaternary alluvial aquifers were examined in the central Bengal Basin where As concentrations in groundwater are highly variable in space but generally decrease downward. Chemical compositions of sediment samples from two vertical core profiles (2-150 m below ground level, bgl) were analyzed along with groundwater in moderately As-enriched aquifers in central Bangladesh (Manikganj district), and the As mobilization process in the alluvial aquifer is described. Heavy minerals such as biotite, magnetite, amphibole, apatite and authigenic goethite are abundant at shallow (<100 m below ground level (mbgl)) depths but less abundant at greater depths. It is interpreted that principal As-bearing minerals were derived from multiple sources, primarily from ophiolitic belts in the Indus-Tsangpo suture in the northeastern Himalayan and Indo-Burman Mountain ranges. Authigenic and amorphous Fe-(oxy)hydroxide minerals that are generally formed in river channels in the aerobic environment are the major secondary As-carriers in alluvial sediments. Reductive dissolution (mediated by Fe-reducing bacteria) of Fe-(oxy)hydroxide minerals under anoxic chemical conditions is the primary mechanism responsible for releasing As into groundwater. Authigenic siderite that precipitates under reducing environment at greater depths decreases Fe and possibly As concentrations in groundwater. Presence of Fe(III) minerals in aquifers shows that reduction of these minerals is incomplete and this can release more As if further Fe-reduction takes place with increased supplies of organic matter (reactive C). Absence of authigenic pyrite suggests that SO₄ reduction (mediated by SO₄-reducing bacteria) in Manikganj groundwater is limited in contrast to the southeastern Bengal Basin where precipitation of arsenian pyrite is thought to sequester As from groundwater.  相似文献   

Eruptive prominence associated with limb flare of 25 January 1991     

Wahab Uddin  V. K. Verma 《Astrophysics and Space Science》1996,243(1):173-177

We have observed an eruptive prominence at the east solar limb on 25 January 1991 which started earlier than 0623 UT and was associated with a limb flare (S16 E90) of class 1B/ X10.0. We have recorded a huge mass ejection in the corona by the limb flare associated eruptive prominence. The eruptive prominence ejected a part of the loop in the corona with maximum speed of about 1280 km/sec. The ejected material attain height upto 150,000 km in the corona and finally faded/disappeared in the corona. During the ascending phase of the prominence material in the corona there was a unscrewing of the loop system associated with the eruptive prominence. The type II, III, and IV radio bursts were also reported by a number of Radio Observatories during observation of the eruptive prominence. The high flux of sudden ionospheric disturbances and the solar radio emissions on fixed frequencies (245–80000 MHz) were also recorded. The eruptive prominence associated with limb flare also shows increased proton flux (>10 MeV) during its occurence. The flare was classified as X10.0 flare. In this paper we have analysed the observed data and compared it with the theoretical model of the solar flare.On leave from his original Institute  相似文献   

Preliminary design of an underground reservoir for pumped storage     

Nasim Uddin Ph.D.  P.E.  M. Asce 《Geotechnical and Geological Engineering》2003,21(4):331-355

The current interest in the potential utilization of subsurface space for the storage of a wide variety of materials is responsive to the increasing pressures of environmental concerns, particularly as it applies to the development of urban or suburban space. These pressures, in conjunction with the continuing development of underground excavation technology, combine to provide a situation within which the concept of subsurface space utilization is becoming increasingly attractive relative to more conventional surface developments. Underground pumped storage is currently an economically viable alternative to the conventional above ground type of facility, and is made increasingly attractive by consideration of the reduced environmental impact, which the underground concept make possible. This paper is intended to provide an introduction to the engineering challenges of underground pumped storage, with particular reference to a limestone mine located some 671m below the ground surface and having a volume of 9.6 million m³. To this end, the paper presents the numerical modeling and analyses to establish a powerhouse setting that would provide both a structurally stable excavation under the loading conditions imposed by the high-pressure brine, and eliminate the possibility of significant brine inflow to the excavated caverns.  相似文献