Factor and cluster analysis of water quality data of the groundwater wells of Kushtia, Bangladesh: Implication for arsenic enrichment and mobilization     

Md. Golzar Hossain  A. H. M. Selim Reza  Mst. Lutfun-Nessa  Syed Samsuddin Ahmed 《Journal of the Geological Society of India》2013,81(3):377-384

The study area is located in the southwestern part of Bangladesh. Twenty-six groundwater samples were collected from both shallow and deep tube wells ranging in depth from 20 to 60 m. Multivariate statistical analyses including factor analysis, cluster analysis and multidimensional scaling were applied to the hydrogeochemical data. The results show that a few factors adequately represent the traits that define water chemistry. The first factor of Fe and HCO₃ is strongly influenced by bacterial Fe (III) reduction which would raise both Fe and HCO₃ concentrations in water. Na, Cl, Ca, Mg and PO₄ are grouped under the second factor representing the salinity sources of waters. The third factor, represented by As, Mn, SO₄ and K is related to As mobilization processes. Cluster analysis has been applied for the interpretation of the groundwater quality data. Initially Piper methods have been employed to obtain a first idea on the water types in the study area. Hierarchical cluster analysis was carried out for further classification of water types in the study area. Twelve components, namely, pH, Fe, Mn, As, Ca, Mg, Na, K, HCO₃, Cl, SO₄ and NO₃ have been used for this purpose. With hierarchical clustering analysis the water samples have been classified into 3 clusters. They are very high, high and moderately As-enriched groundwater as well as groundwater with elevated SO₄.  相似文献   

Understanding indigenous people’s perception on climate change and climatic hazards: a case study of Chakma indigenous communities in Rangamati Sadar Upazila of Rangamati District, Bangladesh     

Md. Nazmul Huda 《Natural Hazards》2013,65(3):2147-2159

This study explores the relationship between perception on climate change as well as climatic hazards and socio-demographic characteristics such as age, gender, occupation, exposure to mass media, amount of land, education, and income. Following simple random sampling technique, a total of 384 households were sampled from Rangamati Sadar Upazila of Bangladesh and were interviewed through a predesigned semistructured questionnaire. The findings of the study reveal that a substantial number of respondents (61 %) perceive that climate is changing moderately over the years. The bivariate results indicate that age, gender, education, occupation, income, amount of land, and access to mass media are significantly associated with perception on climate change as well as climatic hazards. In addition, age, education, and exposure to mass media are also found as significant predictors of climate change perception. Education has been found as the single best predictor.  相似文献   

Community-based disaster risk and vulnerability models of a coastal municipality in Bangladesh     

Md. Nazrul Islam  Md. Abdul Malak  M. Nazrul Islam 《Natural Hazards》2013,69(3):2083-2103

Bangladesh is one of the most natural hazard-prone countries in the world with the greatest negative consequences being associated with cyclones, devastating floods, riverbank erosion, drought, earthquake, and arsenic contamination, etc. One way or other, these natural hazards engulfed every corner of Bangladesh. The main aim of this research paper is to carry out a multi-hazards risk and vulnerability assessment for the coastal Matlab municipality in Bangladesh and to recommend possible mitigation measures. To this aim, hazards are prioritized by integrating SMUG and FEMA models, and a participation process is implemented so as to involve community both in the risk assessment and in the identification of adaptation strategies. The Matlab municipality is highly vulnerable to several natural hazards such as cyclones, floods, and riverbank erosion. The SMUG is a qualitative assessment, while FEMA is a quantitative assessment of hazards. The FEMA model suggests a threshold of highest 100 points. All hazards that total more than 100 points may receive higher priority in emergency preparedness and mitigation measures. The FEMA model, because it judges each hazard individually in a numerical manner, may provide more satisfying results than the SMUG system. The spatial distributions of hazard, risk, social institutions, land use, and other resources indicate that the flood disaster is the top environmental problem of Matlab municipality. Hazard-specific probable mitigation measures are recommended with the discussion of local community. Finally, this study tries to provide insights into the way field research combining scientific assessments tools such as SMUG and FEMA could feed evidence-based decision-making processes for mitigation in vulnerable communities.  相似文献   

Site amplification investigation in Dhaka, Bangladesh, using H/V ratio of microtremor   总被引：2，自引：1，他引：1  

Mehedi Ahmed Ansary  Md. Saidur Rahman 《Environmental Earth Sciences》2013,70(2):559-574

The degree of damage during earthquakes strongly depends on dynamic characteristics of buildings as well as amplification of seismic waves in soils. Among the other approaches, microtremor is, perhaps, the easiest and cheapest way to understand the dynamic characteristics of soil. Non-reference microtremor measurements have been carried out in 45 locations in and around the capital Dhaka city of Bangladesh. Subsoil investigations (Standard Penetration Test and Shear Wave Velocity) have also been executed in those locations. Soil model has been developed for those locations for site response analysis by means of the program SHAKE. Among those 45 locations, predominant frequency of microtremor observation varies from 0.48 to 3.65 Hz. Out of those 45, for 35 locations Transfer function obtained from the program SHAKE have higher frequency compared to microtremor H/V ratio and for one location it has lower predominant frequency. For six locations, frequencies obtained from two methods are identical. For three other locations, there are no similarities between predominant frequency obtained from microtremor and transfer function. The seismic Vulnerability Index (Kg) for 45 sites varies between 0.45 and 31.85. Ten sites have been identified as having moderate vulnerability of soil layers to deform.  相似文献   

Suspended sediment load prediction of river systems: GEP approach   总被引：1，自引：1，他引：0  

H. Md. Azamathulla  Yong Chong Cuan  Aminuddin Ab. Ghani  Chun Kiat Chang 《Arabian Journal of Geosciences》2013,6(9):3469-3480

This study presents gene expression programming (GEP), an extension of genetic programming, as an alternative approach to modeling the suspended sediment load relationship for the three Malaysian rivers. In this study, adaptive neuro-fuzzy inference system (ANFIS), regression model, and GEP approaches were developed to predict suspended load in three Malaysian rivers: Muda River, Langat River, and Kurau River [ANFIS (R ²?=?0.93, root mean square error (RMSE)?=?3.19, and average error (AE)?=?1.12) and regression model (R ²?=?0.63, RMSE?=?13.96, and AE?=?12.69)]. Additionally, the explicit formulations of the developed GEP models are presented (R ²?=?0.88, RMSE?=?5.19, and AE?=?6.5). The performance of the GEP model was found to be acceptable compare to ANFIS and better than the conventional models.  相似文献   

Environmental impact assessment on water quality deterioration caused by the decreased Ganges outflow and saline water intrusion in south-western Bangladesh   总被引：3，自引：0，他引：3  

Md. Mokhlesur Rahman  Muhammad Qumrul Hassan  Mohammad Saiful Islam  S. Z. K. M. Shamsad 《Environmental Geology》2000,40(1-2):31-40

 This paper deals with an environmental impact assessment of low water flow in the river Ganges during a dry period at the Khulna and Mongla port areas in south-western Bangladesh. Large-scale surface water withdrawal in India after commissioning the Farakka Barrage causes a drastic fall in the Ganges low-flow condition within the Bangladesh territory during every dry period. The average lowest discharge in the Ganges is 552 m³/s, which is about 73% less than that in the pre-Farakka time. This has caused the deterioration of both surface and groundwater quality of the study area. Salinity is the principal cause of water quality degradation in the area. Present observation shows that the surface water of the area is sulphate-chloride dominated, which signifies high salinity whereas the groundwater is categorized as of medium to high salinity. To maintain the Rupsa River's maximum salinity below 1000 μS/cm the discharge in the Ganges should be ∼1500 m³/s, whereas that at Garai basin is ∼10 m³/s. If this present situation continues it will be a crippling blow to the environment of the area in the long term. An integrated multidisciplinary approach to hydrogeological research is urgently required to salvage the area from further deterioration. Received: 9 August 1999 · Accepted: 8 March 2000  相似文献   

Lake and reservoir water quality affected by metals leaching from tropical soils, Bangladesh   总被引：2，自引：0，他引：2  

Md. R. Islam  W. P. Lahermo  R. Salminen  S. Rojstaczer  V. Peuraniemi 《Environmental Geology》2000,39(10):1083-1089

 The release of metals during weathering has been studied in order to assess its geochemical controls and possible effects on environmental health in Bangladesh. A total of 27 soil samples and 7 surface water samples were collected from four locations covering three major regions in the country. Results show that weathering effects are a strong function of climatic conditions. Surface waters are typically enriched in Al, Mg, Ca, Na, K, As, Ba, Cr, Cu, Ni, Pb and Zn. The solubility of metal ions, organometallic complexes, co-precipitation or co-existence with the colloidal clay fraction are the main processes that lead to metal enrichment in lake and reservoir water. Aluminium concentrations exceed World Health Organization (WHO) drinking-water standards in all samples, and in two regions, arsenic concentrations also significantly exceed WHO standards. The elevated levels of As indicate that arsenic contamination of water supplies in Bangladesh is not confined to groundwater. Received: 4 June 1999 · Accepted: 17 August 1999  相似文献   

Intraspecific morphometric diversity of barramundi (Lates calcariferBloch, 1790) in the waters of southern Bangladesh     

Md Reaz CHAKLADER  Ashfaqun NAHAR  Md Abu HANIF  Muhammad A.B.SIDDIK 《中国海洋湖沼学报》2019,(4)

A total of 160 barramundi's(Lates calcarifer Bloch,1790)sampled from four rivers(Tentulia,Balaswar,Bakkhali,and Andarmanik)along the southern coastal region of Bangladesh were investigated in terms of morphometric characters to reveal the intraspecific variation.Twenty-five morphometric measurements were extracted using the conventional method and subjected to multivariate analyses(i.e.,principal component analysis(PCA),discriminate function analysis(DFA),cluster analysis(CA))to distinguish individuals from different rivers.The result demonstrated that twenty-two out of 2 5 measurements was statistically significant(Univariate ANOVA)among all four populations.PCA analy sis of morphometric characters resulted in two principal components,PC I and PCII which accounted for 79.25%and 4.28%of the total data variance.PC I-PC Ⅱ plot explained 83.5 3%of total variance differentiated the population of L.calcarifer into two groups.Discriminate analysis correctly classified about 88.1%of the examined fish into the four areas.The UPGMA dendrogram showed that Bakkhali populations were the most morphologically different populations in comparison to other populations,while Andarmanik and Balaswar populations were very close to each other.The strong morphometric variation between Bakkhali and Tentulia,Andarmanik and Balaswar was observed in the present study,suggested the evidence of the separate stock population of barramundi in these locations,which might require distinct stock management strategies for resource sustainability in the waters of southern Bangladesh.However,if these findings are supported by further molecular markers and geometric morphometry,this would be a strong indication of different stocks of this population in the four rivers of southern Bangladesh.  相似文献   

High temporal and spatial resolution observations of meso-scale features of pre- and mature summer monsoon cloud systems over Bangladesh     

Toru Terao  Md. Nazrul Islam  Fumie Murata  Taiichi Hayashi 《Natural Hazards》2008,44(3):341-351

Meso-scale characteristics of disturbances that bring about atmospheric disasters in pre- and mature monsoon seasons in Bangladesh are analyzed. Several types of meteorological instruments capable of observations with high temporal and spatial resolutions were introduced for the first time in this area to capture the meso-scale structure of rainfall systems. We installed an automatic weather station (AWS) and several automatic raingauges (ARGs) and utilized the weather radar of Bangladesh Meteorological Department (BMD). From the radar image in the summer of 2001 (16–18 July), a striking feature of the systematic diurnal variation in this area was elucidated. In these 3 days, the diurnal evolutions of convective activity were remarkably similar to each other, implying that this pattern can be understood as a typical response of local cloud systems to the diurnal variation of insolation under some summer monsoon situations. The ARG data show the difference in characteristics of rainfall between pre- and mature monsoon seasons. The short intense downpour tends to occur more frequently in the pre-monsoon season than in the mature monsoon season. The pre-monsoon rainfall also has clear diurnal variation with a peak that is more strongly concentrated in time. In the northern part the rainfall peak is found in between midnight and early morning, while it is observed in the daytime in central to western parts of the country. Two disaster cases caused by meso-scale disturbances are analyzed. Although they occurred in the same season, the structures of the cloud systems were largely different from each other. The disturbance brought about tornadoes on 14 April 2004, consisting of many spherical cloud systems of approximately 20 km size. On the other hand, another one that caused the tragic river water transport accident on 23 May 2004 had meso-scale rain band structure. The latter case was captured by the AWS located at Dhaka. Sudden changes in temperature, wind and pressure were observed clearly, showing the typical structure of convective rain bands.  相似文献   

Multi-resolution segmentation for object-based classification and accuracy assessment of land use/land cover classification using remotely sensed data     

Md. Rejaur Rahman  S. K. Saha 《Journal of the Indian Society of Remote Sensing》2008,36(2):189-201

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