Geophysical interpretation of the Rashidpur structure Surma Basin,Bangladesh

The Rashidpur structure is located in the southern part of the Surma Basin, Bangladesh. This paper presents an integrated interpretation of seismic and other geophysical data considering the available geologic information in terms of hydrocarbon potential of this structure. The study area lies within a gravity high and a high magnetic intensity. Fifteen seismic sections of the study area have been analyzed to interpret the subsurface geology, structure and stratigraphy. Based on the analysis of seismic sections and correlation with well data, four prominent reflecting horizons have been identified. The litho-stratigraphy of the Rashidpur structure is prepared on the basis of well information. The lithological sequences encountered in the Rashidpur structure range in age from Miocene to Plio-Pliestocene. The gas producing sands of the structure are within Bokabil to Bhuban Formations of the Miocene age. The seismic study indicates that the Rashidpur structure is a narrow, NS elongated anticline affected by a major reverse fault on the eastern flank. It is an asymmetrical anticline with the axis swinging slightly to the east on the northern plunge and thus attaining a slight concavity to the east. There are various geophysical indications of hydrocarbons in this structure.     

Post-disaster recovery in the cyclone Aila affected coastline of Bangladesh: women’s role,challenges and opportunities

Natural Hazards - The present study deals with the gender aspects of water, sanitation and hygiene (WaSH) situation in post-cyclone Aila period in Bangladesh. Data were collected using...     

Observed Trends in Extreme Temperature over the Klang Valley,Malaysia

This study investigates the recent extreme temperature trends across 19 stations in the Klang Valley, Malaysia, over the period 2006-16. Fourteen extreme index trends were analyzed using the Mann-Kendall non-parametric test, with Sen’s slope as a magnitude estimator. Generally, the annual daily mean temperature, daily mean maximum temperature, and daily mean minimum temperature in the Klang Valley increased significantly, by 0.07°C yr~(-1), 0.07°C yr~(-1)and 0.08°C yr~(-1),respectively. For the warm temperature indices, the results indicated a significant upward trend for the annual maximum of maximum temperature, by 0.09°C yr~(-1), and the annual maximum of minimum temperature, by 0.11°C yr~(-1). The results for the total number of warm days and warm nights showed significant increasing trends of 5.02 d yr~(-1)and 6.92 d yr~(-1),respectively. For the cold temperature indices, there were upward trends for the annual minimum of maximum temperature,by 0.09°C yr~(-1), and the annual minimum of minimum temperature, by 0.03°C yr~(-1), concurrent with the decreases in the total number cold days (TX10P), with-3.80 d yr~(-1), and cold nights (TN10P), with-4.33 d yr~(-1). The 34°C and 37°C summer days results showed significant upward trends of 4.10 d yr~(-1) and 0.25 d yr~(-1), respectively. Overall, these findings showed upward warming trends in the Klang Valley, with the minimum temperature rate increasing more than that of the maximum temperature, especially in urban areas.     

Socio-structural forces predicting global water footprint: socio-hydrology and ecologically unequal exchange

ABSTRACT

Growth in water use and threatened shortages of water have become increasingly important in the modern world system. Natural resources are exploited extensively by capitalist interests in industrially advanced nations, while the lower strata of the world system, the underdeveloped societies, are left with limited access to natural resources for their productive processes, particularly water resources. We contribute to socio-hydrological research by examining underlying socio-structural factors that play a part in the process of deteriorating conditions of global water resources. Drawing on a world-systems perspective, this study examines how socio-structural forces – world-system position, per capita beef consumption, per capita energy consumption, and urbanization – affect per capita water footprint, which includes an accounting of “virtual water” consumption. We find that per capita beef consumption and per capita energy consumption have significant positive direct effects, and the world-system position has a significant indirect and total effect on per capita water footprint.     

Parameter uncertainty of the AWBM model when applied to an ungauged catchment

In this study, a quantitative assessment of uncertainty was made in connection with the calibration of Australian Water Balance Model (AWBM) for both gauged and ungauged catchment cases. For the gauged catchment, five different rainfall data sets, 23 different calibration data lengths and eight different optimization techniques were adopted. For the ungauged catchment case, the optimum parameter sets obtained from the nearest gauged catchment were transposed to the ungauged catchments, and two regional prediction equations were used to estimate runoff. Uncertainties were ascertained by comparing the observed and modelled runoffs by the AWBM on the basis of different combinations of methods, model parameters and input data. The main finding from this study was that the uncertainties in the AWBM modelling outputs could vary from ?1.3% to 70% owing to different input rainfall data, ?5.7% to 11% owing to different calibration data lengths and ?6% to 0.2% owing to different optimization techniques adopted in the calibration of the AWBM. The performance of the AWBM model was found to be dominated mainly by the selection of appropriate rainfall data followed by the selection of an appropriate calibration data length and optimization algorithm. Use of relatively short data length (e.g. 3 to 6 years) in the calibration was found to generate relatively poor results. Effects of different optimization techniques on the calibration were found to be minimal. The uncertainties reported here in relation to the calibration and runoff estimation by the AWBM model are relevant to the selected study catchments, which are likely to differ for other catchments. The methodology presented in this paper can be applied to other catchments in Australia and other countries using AWBM and similar rainfall–runoff models. Copyright © 2014 John Wiley & Sons, Ltd.     

Arsenic incorporation into authigenic pyrite, Bengal Basin sediment, Bangladesh

Sediment from two deep boreholes (∼400 m) approximately 90 km apart in southern Bangladesh was analyzed by X-ray absorption spectroscopy (XAS), total chemical analyses, chemical extractions, and electron probe microanalysis to establish the importance of authigenic pyrite as a sink for arsenic in the Bengal Basin. Authigenic framboidal and massive pyrite (median values 1500 and 3200 ppm As, respectively), is the principal arsenic residence in sediment from both boreholes. Although pyrite is dominant, ferric oxyhydroxides and secondary iron phases contain a large fraction of the sediment-bound arsenic between approximately 20 and 100 m, which is the depth range of wells containing the greatest amount of dissolved arsenic. The lack of pyrite in this interval is attributed to rapid sediment deposition and a low sulfur flux from riverine and atmospheric sources. The ability of deeper aquifers (>150 m) to produce ground water with low dissolved arsenic in southern Bangladesh reflects adequate sulfur supplies and sufficient time to redistribute the arsenic into pyrite during diagenesis.     

Heavy metal biosorption potential of a Malaysian Rhodophyte (<Emphasis Type="Italic">Eucheuma denticulatum</Emphasis>) from aqueous solutions

Biosorption is a promising technology for the removal of heavy metals from industrial wastes and effluents. In the present study, biosorption of Pb²⁺, Cu²⁺, Fe²⁺ and Zn²⁺ onto the dried biomass of Eucheuma denticulatum (Rhodophyte) was investigated as a function of solution pH, contact time, temperature and initial metal ion concentration. The experimental data were evaluated by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The sorption isotherm data followed Langmuir and Freundlich models, and the maximum Langmuir monolayer biosorption capacity was found as 81.97, 66.23, 51.02 and 43.48 mg g^?1 for Pb²⁺, Cu²⁺, Fe²⁺ and Zn²⁺, respectively. The sorption kinetic data followed pseudo-second-order and intraparticle diffusion models. Thermodynamic study revealed feasible, spontaneous and endothermic nature of the sorption process. Fourier transform infrared analysis showed the presence of amine, aliphatic, carboxylate, carboxyl, sulfonate and ether groups in the cell wall matrix involved in metal biosorption process. A total of nine error functions were applied in order to evaluate the best-fitting models. We strongly suggest the analysis of error functions for evaluating the fitness of the isotherm and kinetic models. The present work shows that E. denticulatum can be a promising low-cost biosorbent for removal of the experimental heavy metals from aqueous solutions. Further study is warranted to evaluate its potential for the removal of heavy metals from the real environment.     

Effect of soil cohesion and friction angles on reverse faults

Severe faults have caused many earthquakes around the world throughout history.More recently,earthquakes have occurred in Taiwan,China(Chi-Chi fault),and elsewhere,causing loss of lives and destroying many buildings and structures.These tectonic movements have gained attention from engineers,and in the past 15 years,the focus has been on faulting mechanisms.In this study,a physical model(1 g)was fabricated and used to evaluate the impact of a reverse fault in a field with a tunnel.In the 1 g model,researchers installed additional gauges on the tunnel,so that all the displacements could be adjusted,and all the responses could be monitored during faulting.An experimental study of various soil properties(cohesion and friction angles)in reverse faults on the tunnel lining were carried out and are described herein.A comparison of results for different levels of soil cohesion revealed that it can dramatically reduce the displacement by as much as 40%,and that friction angles of 27ocan record approximately 60%more displacements than at 37o.Furthermore,a comparison of fault angles of 30oand 60oindicates that the displacements can be different by more than 43%in cohesionless soil and about 64%for a friction angle of 27o.     

Sources and transports of organochlorine pesticides in the Nanshan underground river,China

Karst areas have much higher ecological vulnerability and are prone to be contaminated. Organochlorine pesticides (OCPs) were detected in waters and sediment from the two sites of the karst Nanshan underground river system, China, to understand the sources and transport of OCPs in the underground river systems. Obviously, seasonal variations were found both in the waters and the sediments. Detected OCPs ranged from 61 to 936 ng L^?1 in the groundwaters and 51–3,842.0 ng g^?1 in the underground sediments, respectively. OCPs in groundwaters were mixture of younger and older residues from commercial sources. The maximum OCPs in the sediments of the underground river were historically older residues from commercial sources. The sources of OCPs in the waters and sediments of the underground river indicated that the surface systems play an important role in OCPs transport and pollution in the underground river. Karst features were liable for the transport behavior.     

LOCAL SCOUR ESTIMATION AT BRIDGE SITE: MODIFICATION AND APPLICATION OF LACEY FORMULA

In the recent years, it has been established that b/h or h/b (b = length of the structure in the lateral direction and h = approach flow depth) is the dominant factor for the estimation of local scour depth around abutments and piers. One of the major limitations of the Lacey formula is that it predicts only one value of the scour depth for a specific river because of the absence of important parameters b and h. Therefore, its application is quite uncertain for variable b and h. Considering its limitations and experimental facts of flow concentration and shear stress amplification close to above structures, the original Lacey formula is modified introducing the parameters b and h. The applicability of the original as well as modified Lacey formula is tested to the data collected from major rivers in Bangladesh.