Levels of Organochlorine Pesticide Residues in Some Organs of the Ganges Perch, Lates calcarifer, from the Ganges–Brahmaputra–Meghna Estuary, Bangladesh

Levels of organochlorine pesticide residues (p,p′ DDT, DDD, DDE, Aldrin, Dieldrin, Lindane, Heptachlor and BHC) were analysed in the dry and wet seasons in four organs (muscle, liver, gut and egg samples) of Ganges Perch, Lates calcarifer, collected during October–November–December, 1996 and May–June–July, 1997 from the Ganges–Brahmaputtra–Meghna estuary. The residues were analysed by using gas-chromatography (GC) in electron capture detector (ECD) mode and were verified by thin layer chromatography (TLC). Among the four organs analysed, the residues were found in the order egg > gut > muscle > liver. The pesticide residues were found in the order ∑DDT > Heptachlor >Dieldrin > Aldrin. Higher levels of residues were found during the dry season due to high lipid content in fishes. A positive correlation was observed between the pesticide residues (∑DDT and ∑OCs) and lipid contents of fish, and the correlation was found to be linear. The concentrations of pesticide residues in muscle, liver and gut were below the FAO/WHO (1993) recommended permissible limit except in eggs.     

Rural development planning in Pakistan

Summary and Perspectives Most of the rural development plans and green revolution technology attempted in Pakistan between the years 1950 and 1970 were a part of induced transformations and institutional innovations. These attempts did bring some advances in productivity in Pakistan. In recent years, Panjab broke the international records in wheat production. But, a review of rural development efforts and wide application of induced innovations provide mixed results. Since 1972, the Integrated Rural Development has been adopted as a model for country's agrarian reforms, because of the gains at Shadab Project. The success of Shadab was impressive indeed, but Pakistan's economy, history, and society call for caution and raise scepticism, as were rightly pointed out byRuttan (12) for Integrated Rural Development Program.Success of Shadab Project was in large part due to well guided input of human resources devoted to organizational, management and technical assistance. Extensive extension services, model demonstration farms, publicity, and the training of farmers in various new techniques of agriculture were provided. The history of other development efforts prove that similar intensity of resource input cannot be maintained, when the program is generalized.Furthermore, the administrative freedom usually available in pilot projects of limited geographic extent to tailor programs precisely to local, national, and human endowments is usually not available in widespread use due to administrative inconveniences. Likewise, resources of physical, and institutional infrastructure are likely to diminish when the program is spread widely. Another perspective which worries the historical-cultural geographers is the dominant cultural attitudes and preferences of the village people in Pakistan.Pakistani way of life does not set man so much against the nature, as he often has been in the western world. Man is viewed as a part of nature, who can be happy and successful if he adjusts himself to his habitat. Rural Pakistan values leisure as an end in itself, and believes in its predestiny as set by one's luck. This luck-leisure attitude is one of the graces of rural Pakistan, and often serves as an impediment to quick induced changes, which did not evolve from within their own society.Deh Nareja, which this author is studying for the past 23 years as his laboratory to study rural changes, is a good example. Deh Nareja is an assemblage for six villages, with about 1000 people, located 15 km southwest of Tatta. The Deh is linked with Tatta, a tourist town and headquarter of the district administration, by a canal path and a surfaced road. Proximity and spatial linkage with Tatta have made the people of Deh Nareja more mobile, than their counterparts in other villages. In spite of this interchange, and exposure of farmers to other ways of life in the town, Deh Nareja remains a repository of traditional values, and traditional agriculture.Comparison of two maps of Deh Nareja, substantiates this point (Fig. 2). In order to improve the field ditches and save the water lost to seepage and spills, a survey was done in early 1960, to lay the fields in a rectangular pattern. Equal amount of land which belonged to a farmer as an irregular field was given to the farmer in a rectangular pattern (Fig 3). It took considerable amount of time and resources to accomplish the task, but the rural people resisted this change to the extent that the entire plan had to be abandoned. The traditional sentimental love of one's own land, its hereditary linkage were far more important than an efficient irrigation and agriculture.However, consequent to March 1972 land reforms, certain changes were visible in the attitude of the farmers. During a visit again to Deh Nareja and to a number of other villages in Pakistan in the summer of 1976, a certain optimism and hope was noticeable amongst the villagers. The farmers seemed to be more conscious of their rights; they were more aggressive, and were looking forward to a better future. Comparing with their former subdued and downtrodden condition, their changed situation and perceptions can better be expressed by the term agro-nauts. The term agro-naut is introduced here for the present conscious, partly reliant, and aggressive farmers, as against subdued, downtrodden and exploited peasants. Like astronauts, these agro-nauts still do not know their destiny or ramifications of induced changes, but seem to be prepared to accomplish something new. The first ever national conference of agro-nauts convened at Mandi Bahauddin, Panjab, and adoption of a national farmers charter were the steps in the right direction to enhance the confidence of the agro-nauts.Under this changed situation, the Integrated Rural Development Program, seems to have some potential, if environmental, cultural and historical roots of Pakistan are not ignored, and package transformations are induced without destroying the present producing ability of the farmers.     

Landslides and stability of coastal cliffs of Cox's Bazar area,Bangladesh

Successive applications of two-dimensional circular slip limit equilibrium analysis of slices have been made to the three sections of the Cox's Bazar Coastal Cliff. These three sections have been found to be stable (S), quasistable (QS), and unstable (U) with factors of safety (Fs) of 1.269 ± 0.01, 1.13 ± 0.0504, and 1.01 ± 0.058, respectively. In the quasistable and unstable sections, the slopes suffered shallow slidings with slip circles parallel to the surface of slopes.The main causes of these slidings are steepness of slopes, lack of vegetation cover, erosion of toe accumulations by run-off water and waves during high tides. The influence of the slope geometry and the material's strength properties of slopes on safety factors are evaluated. The steeper cliffs reach an unstable condition faster than the more gentle cliffs as their heights change by an equal amount. Again, the high cliffs reach an unstable condition faster than the lower cliffs as slope inclinations change by an equal amount. The safety factor increases with a corresponding increase of friction angle (ø°) and vice versa.Abbreviations BK Bahar chara to Kalatali chara - KR Kalatali chara to Reju khal - RI Reju khal to Boro Inani khal - Fs Factor of Safety - S Stable - QS Quasistable (semistable) - US Unstable     

Tractorization of agriculture in Pakistan

Perhaps, nothing else symbolizes modernization of agriculture more than the use of tractors in the developing countries. Pakistan is no exception in this regard, where tractors, its accompanying machines, tube-wells, and biological technology is seen as the only mechanism to salvage the precarious economy. In recent years, the pace of mechanization has increased, in spite of the fact that practioners and planners have widely divergent views on the merits of tractorization.This paper attempts to present the characteristics of Pakistan's agriculture from an adaptive view-point, suggesting critical elements that sustain its long-term viability. The role of cultural and genetic information is analyzed to explain the man-environment relationship. In the final section, role of tractors and their impact on agriculture is discussed. Tube-wells, other machines, fertilizers, and biological technology are not discussed in this paper.     

A study of groundwater irrigation water quality in south-central Bangladesh: a geo-statistical model approach using GIS and multivariate statistics

Southern Bangladesh’s irrigation and drinking water is threatened by saline intrusion. This study aimed to establish an irrigation water quality index (IWQI) using a geostatistical model and multivariate indices in Gopalganj district, south-central Bangladesh. Groundwater samples were taken randomly (different depths) in two seasons (wet-monsoon and dry-monsoon). Hydrochemical analysis revealed groundwater in this area was neutral to slightly alkaline and dominating cations were Na⁺, Mg²⁺, and Ca²⁺ along with major anions Cl^? and HCO₃ ^?. Principal component analysis and Gibbs plot helped explain possible geochemical processes in the aquifer. The irrigation water evaluation indices showed: electrical conductivity (EC) >750 µS/cm, moderate to extreme saline; sodium adsorption ratio (SAR), excellent to doubtful; total hardness (TH), moderate to very hard; residual sodium bicarbonate, safe to marginal; Kelly’s ratio >1; soluble sodium percentage (SSP), fair to poor; magnesium adsorption ratio, harmful for soil; and IWQI, moderate to suitable. In addition, the best fitted semivariogram for IWQI, EC, SAR, SSP, and TH confirmed that most parameters had strong spatial dependence and others had moderate to weak spatial dependence. This variation might be due to the different origin/sources of major contributing ions along with the influence of variable river flow and small anthropogenic contributions. Furthermore, the spatial distribution maps for IWQI, EC, SSP, and TH during both seasons confirmed the influence of salinity from the sea; low-flow in the major river system was the driving factor of overall groundwater quality in the study area. These findings may contribute to management of irrigation and/or drinking water in regions with similar groundwater problems.     

Critical state behaviour of weakly bonded soil in drained state

A series of consolidated drained triaxial test was performed on weakly bonded soils that were artificially prepared by mixing sand (87%) and kaolin (13%). To create weakly bond strength, samples were fired at 500°C for 5 h. A critical state (CS) concept was used to interpret the results in order to describe the behaviour of the studied soil. Defining the CS is not always straightforward. Several tests showed changing in deviator stress q and volumetric strain ε_v up to the end of tests. Hence, defining the CS requires careful assessments on q–ε_a, Δu–ε_a, q–p′ and v–ln p′ spaces which were performed. A ‘discontinuity’ approach was applied to position the CS on dilatant path in v–ln p′ spaces after considering stress-strain and volumetric strain curves. The critical state line in a v–ln p? space from bonded samples exhibited differences to the destructured samples. This suggests that the influence of cementation bond is substantially clear at lower stresses but as stresses increase beyond the stress yield, cementation degradation becomes more significant. The effect of bonding can be clearly visualised from the normalisation of the stress paths of destructured and bonded samples.     

Location-allocation modeling for emergency evacuation planning with GIS and remote sensing: A case study of Northeast Bangladesh

This work developed models to identify optimal spatial distribution of emergency evacuation centers(EECs) such as schools, colleges, hospitals, and fire stations to improve flood emergency planning in the Sylhet region of northeastern Bangladesh.The use of location-allocation models(LAMs) for evacuation in regard to flood victims is essential to minimize disaster risk.In the first step, flood susceptibility maps were developed using machine learning models(MLMs), including: Levenberg–Marquardt back propagation(LM-BP) neural network and decision trees(DT) and multi-criteria decision making(MCDM) method.Performance of the MLMs and MCDM techniques were assessed considering the area under the receiver operating characteristic(AUROC) curve.Mathematical approaches in a geographic information system(GIS) for four well-known LAM problems affecting emergency rescue time are proposed: maximal covering location problem(MCLP), the maximize attendance(MA), p-median problem(PMP), and the location set covering problem(LSCP).The results showed that existing EECs were not optimally distributed, and that some areas were not adequately served by EECs(i.e., not all demand points could be reached within a 60-min travel time).We concluded that the proposed models can be used to improve planning of the distribution of EECs, and that application of the models could contribute to reducing human casualties, property losses, and improve emergency operation.     

Influence of linear coupling between volumetric and shear strains on instability and post-peak softening of sand in direct simple shear tests

Acta Geotechnica - This paper focuses on the influence of volume change boundary condition on the instability and post-peak softening of sand. The laboratory program comprises an extensive series...     

Flood exposure and social vulnerability in the United States

Natural Hazards - Human exposure to floods continues to increase, driven by changes in hydrology and land use. Adverse impacts amplify for socially vulnerable populations, who disproportionately...