Seismo-stratigraphic and structural interpretation of seismic data of Titas gas field,Bengal basin,Bangladesh     

Md. Sultan-Ul-Islam  Md. Aminul Islam  Md. Hasan Latif  Md. Aftabuzzaman  Syed Mustafizur Rahman  Md. Ismail Molla  Mohamed Ragab Shalaby 《Journal of the Geological Society of India》2017,89(4):471-481

In the present study, seismic interpretation has been carried out over Titas structure of Bengal basin, Bangladesh to figure out its seismo-stratigraphic and structural behavior. Seven well marked reflecting horizons (R-01 to R-07) have been identified within the Neogene sedimentary sequences using 18 seismic sections and well log data. A new seismic stratigraphy of Neogene sequences has been proposed for the Titas structure ruling out the traditional lithostratigraphy. The studied structure has been divided into 3 megasequences (MS1, MS2 and MS3). Reflector R-01 and R-03 represent the tops of the megasequence 2 (MS2) and megasequence 1 (MS1) respectively. These well marked reflectors are correlated with the top of the traditional litho-groups called Tipam and Surma. Reflectors R-02 and R-04 represent acoustic impedance boundaries within MS2 and MS1 due to lithological gradation. However, R-02 and R-04 are not considered as sequence/ formation boundaries because geologically these are not well defined. Reflectors R-05, R-06 and R-07 represent top of the gasbearing zones A, B and C that belongs to MS1. All these interfaces or reflectors are anti-form with a central long crestal zone. It forms a north-south trending semi-domal sub-surface anticlinal structure having a semi-dome shaped closure. The structure is asymmetric with steeper eastern flank and gentler western flank. The crestal region is essentially plain with discontinuous reflection. The semidomal nature of the anticline is in contrast to the neighboring narrow anticlines. Structural pattern suggests its development in relation to the NE-SW trending stress field due to convergence of Indian plate with Burmese plate. Structures of the shallower and deeper reflectors are formed at different phases of structural development.  相似文献   

Evaluation of the effect of water management interventions on water level of Gaza coastal aquifer     

Mazen Abualtayef  Ghada Abdel Rahman  Ismael Snounu  Khalid Qahman  Hasan Sirhan  Ahmed Khaled Seif 《Arabian Journal of Geosciences》2017,10(24):555

Gaza coastal aquifer (GCA) is the most precious natural source where it is the only source of water for different uses. Groundwater crisis in Gaza includes two major folds: shortage of water supply and contamination. The extraction of groundwater currently exceeds the aquifer recharge rate. As a result, the groundwater level is falling continuously leading severely deterioration of GCA. The main objective of this study is to analyze and evaluate the current and proposed water resources management plans and their effect on the water level of GCA. In this respect, the available quantities of rainfall that could be harvested and infiltrated from different types of land-use based on existing and planned situations are studied using GIS tool and numerical models for GCA using V-MODFLOW environment for simulating four scenarios: (i) existing management practice (no action scenario), (ii) proposed Palestinian Water Authority (PWA) stormwater infiltration plan, (iii) proposed Gaza Emergency Technical Assistance Program (GETAP) interventions, and (iv) combination between second and third scenarios. The management scenarios were tested with the calibrated flow model for the target period between 2016 and 2040. The simulation results of existing management practice scenario show that there are several depression zones in Gaza Strip; in southern part from ??18 to ??24 m MSL in 2020 and 2040, in the northern part from ??7 to ??12 m MSL in 2020 and 2040, and in the middle regions experienced a small decline in groundwater level. The simulation results of proposed PWA scenario indicate similar depression zones as per first scenario but with good enhancement of water level, ??17 to ??18 m MSL in the southern part and ??3 to ??6 m MSL in the northern part in 2020 and 2040, respectively. The simulation results of GETAP intervention scenario show a positive impact on groundwater level. The results of fourth scenario show good enhancement of water level, in which the water level in the northern part ranges from +?3 to +?6 m MSL in 2020 and 2040, while in the south part ranges from ??15 to +?4 MSL in 2020 and 2040.  相似文献   

An assessment of environmental impacts of quarry-blasting operation: a case study in Istanbul, Turkey     

Cengiz Kuzu  Hasan Ergin 《Environmental Geology》2005,48(2):211-217

This study evaluates the impacts resulting from quarry-blasting operation on nearby buildings and structures as it generates ground vibration, air blast, and fly rocks. In this paper, first blasting operation and its possible environmental effects are defined. Then the methods of blast-vibration prediction and commonly accepted criteria to prevent damage were introduced. A field experimental work was conducted to minimize the vibration effects at Saribayir quarry as it is an identical case for the many quarries situated in and around Istanbul, Turkey. Although the local surrounding geology and rock mechanics have great influence on vibrations as uncontrollable parameter, the charge weight per delay, delay period, geometric parameters of the blasts were changed to solve the existing vibration problem in the studied quarry. To obtain a realistic result, 10 blasts were carried out and 30 seismic records were made in different places mainly very close the buildings and the other vulnerable structures around the quarry. The evaluation is performed whether the vibration level are within safe limits or not. The prediction equation based on scaled distance concept is also determined, however, it is a site-specific model and need to be updated when the quarry advances. The safe blast parameters which minimize the environmental effect were determined for the Saribayir quarry.  相似文献   

Hydrodynamic Coefficients and Wave Excitation Forces for A Ship near A Quay     

M.HasanAdil  段文洋 《中国海洋工程》2004,18(1):119-128

In this paper,the effects of a quay or a solid jetty on hydrodynamic coefficients and vertical wave excitation forces on a ship woth or without forward speed are discussed.A modified simple Green function technique is used to calculate the 2D coefficients while the strip theory is used to calculate the 3D coefficients. Wave excitation forces are also calculated with the strip theory. Numerical results are provided for hydrodynamic coefficients and vertical wave excitation forces on a 200000 DWT tanker ship. It is found that the quay has a considerable effect on the hydrodynamic coefficients and wave excitation forces for a ship.  相似文献   

Destruction of a Holothuria scabra population by overfishing at Abu Rhamada Island in the Red Sea     

Hasan MH 《Marine environmental research》2005,60(4):489-511

Populations of Holothuria scabra at Abu Rhamada Island were investigated during 52 months, from July 1999 to October 2003. During the first 23 months (July, 1999-May, 2001) the Island had a robust population with a tri-modal size frequency distribution curve, very high densities (85.7-95.1 ind./100 m2 at the sandy habitat), high abundance (3362-3110 individuals) and biomass (46.7-34.3 kg/100 m2). Also, during this period most individuals were at depths between 4 and 6m and no individuals were recorded deeper than 15m. The population declined after harvesting began (June, 2001) and by March, 2002 the size frequency distribution showed a bimodal pattern with an obvious decrease in abundance of large individuals. There was also a slight reduction in densities (73.2-60.1 ind./100 m2 at the sandy habitat), abundance (2292-1682 individuals) and biomass (21.6-11.3 kg/100 m2), and a marked shift towards deeper waters. Overfishing reached its maximum during the final 19 months of the study, and by October, 2003, density (30.7-0.4 ind./100 m2 at the sandy habitat), abundance (802-10 individuals) and biomass (6.9-0.1 kg/100 m2) were all greatly reduced. The size frequency distribution of the population became unimodal, large animals disappeared and no recruits were seen. During this period, individuals were found at very deep depths (30 to >40 m). The study also showed that sandy substrate was the preferred habitat for H. scabra, accommodating the largest number of individuals. The population of H. scabra at Abu Rhamada Island was found to spawn biannually from 1999 to 2001, then only once during 2002 when high fishing pressure occurred, and ceased completely in 2003. The sex ratio was not significantly different from 1:1 before fishing begun, but shifted to an increasing male bias reaching 93% males by January 2003. None of the small animals remaining after January, 2003 could be sexed. Size at sexual maturity decreased from prefishing (185 mm for females and 160 mm for males) to 155 mm for females and 125 mm for males in January 2003. There was a positive relationship between fecundity and size. And oocyte/female was highest in 1999 (0.73-1.7 million) and 2000 (0.75-1.72 million), decreased during 2001 (0.2-0.85 million) to reach its minimum at 2002 (0.28-0.29 million).  相似文献   

Kinematic analysis and palaeoseismology of the Edremit Fault Zone: evidence for past earthquakes in the southern branch of the North Anatolian Fault Zone,Biga Peninsula,NW Turkey     

Hasan Sözbilir  Ökmen Sümer  Çağlar Özkaymak  Bora Uzel  Tayfun Güler  Semih Eski 《Geodinamica Acta》2016,28(4):273-294

The Edremit Fault Zone (EFZ) forms one of the southern segments of the North Anatolian Fault Zone (NAFZ) at the northern margin of the Edremit Gulf (Biga Peninsula, South Marmara Region, Turkey). Stratigraphic, structural and kinematic results indicate that basinward younging of the fault zone, in terms of a rolling-hinge mechanism, has resulted in at least three discrete Miocene to Holocene deformational phases: the oldest one (Phase 1) directly related to the inactive Kazda? Detachment Fault, which was formed under N–S trending pure extension; Phase 2 is characterised by a strike-slip stress condition, probably related to the progression of the NAFZ towards the Edremit area in the Plio–Quaternary; and Phase 3 is represented by the high-angle normal faulting, which is directly interrelated with the last movement of the EFZ. Our palaeoseismic studies on the EFZ revealed the occurrence of three past surface rupture events; the first one occurred before 13178 BC, a penultimate event that may correspond to either the 160 AD or 253 AD historical earthquakes, and the youngest one can be associated with the 6 October 1944 earthquake (M_w = 6.8). These palaeoseismic data indicate that there is no systematic earthquake recurrence period on the EFZ.  相似文献   

Influence of saturation on rainfall generated landslides in shale along Murree-Kohala road,Pakistan     

Farhan Ali  Khalid Farooq  Hasan Mujtaba  Ahmad Riaz  Ehsan Ulhaq 《Journal of the Geological Society of India》2016,88(6):718-724

On August 10, 2010 a series of landslides of more than 90,000 m³ occurred along the Muree-Kohala road in the northern area of Pakistan. A study was undertaken to evaluate the likely impacts of percent saturation and bulk density on mobilized shear strength along the basal rupture surface of the landslide. A series of unconfined compression test and unconsolidated undrained triaxial tests were performed on remolded samples of different densities with varied percentages of saturation. The results of these tests suggest that soil cohesion and friction decreases with increasing saturation. The tests also showed that the shear strength parameters tend to increase with increasing dry density; however, all the samples exhibited a noticeable loss of shear strength with increasing degree of saturation, independent of soil density.Limit equilibrium slope stability analyses were performed along the most probable failure planes, based on shear strength parameters corresponding to degrees of saturation, which varied between 30% to about 100%. This resulted in drop of factor of safety from FS = 1.64 down to 0.51 as the degree of saturation approaches unity.These results suggest that the causative factor in triggering the landslide along Murree-Kohala was the partial saturation of the zone that developed the basal rupture plane. As rain infiltrated the slope, the bulk unit weight of the soil increased, while the shear strength along the developing plane of rupture decreased sufficiently to concentrate shear strain when the material became more than 60% saturation (FS < 1.0).  相似文献   

Modeling river discharge time series using support vector machine and artificial neural networks     

Mohammad Ali Ghorbani  Rahman Khatibi  Arun Goel  Mohammad Hasan FazeliFard  Atefeh Azani 《Environmental Earth Sciences》2016,75(8):685

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Hydrogeology and hydrochemistry of the Upper Thal Doab (Pakistan)     

Zia Ul Hasan Shah  Zulfiqar Ahmad 《Environmental Earth Sciences》2016,75(6):527

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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