Dynamics of land use/cover changes and the analysis of landscape fragmentation in Dhaka Metropolitan, Bangladesh   总被引：3，自引：0，他引：3  

Ashraf M. Dewan  Yasushi Yamaguchi  Md. Ziaur Rahman 《GeoJournal》2012,77(3):315-330

Rapid urban expansion due to large scale land use/cover change, particularly in developing countries becomes a matter of concern since urbanization drives environmental change at multiple scales. Dhaka, the capital of Bangladesh, has been experienced break-neck urban growth in the last few decades that resulted many adverse impacts on the environment. This paper was an attempt to document spatio-temporal pattern of land use/cover changes, and to quantify the landscape structures in Dhaka Metropolitan of Bangladesh. Using multi-temporal remotely sensed data with GIS, dynamics of land use/cover changes was evaluated and a transition matrix was computed to understand the rate and pattern of land use/cover change. Derived land use statistics subsequently integrated with landscape metrics to determine the impact of land use change on landscape fragmentation. Significant changes in land use/cover were noticed in Dhaka over the study period, 1975–2005. Rapid urbanization was manifested by a large reduction of agricultural land since urban built-up area increased from 5,500?ha in 1975 to 20,549?ha in 2005. At the same time, cultivated land decreased from 12,040 to 6,236?ha in the same period. Likewise, wetland and vegetation cover reduced to about 6,027 and 2,812?ha, respectively. Consequently, sharp changes in landscape pattern and composition were observed. The landscape became highly fragmented as a result of rapid increase in the built-up areas. The analysis revealed that mean patch size decreased while the number of patches increased. Landscape diversity declined, urban dominance amplified, and the overall landscape mosaics became more continuous, homogenous and clumped. In order to devise sustainable land use planning and to determine future landscape changes for sound resource management strategies, the present study is expected to have significant implications in rapidly urbanizing cities of the world in delivering baseline information about long term land use change and its impact on landscape structure.  相似文献   

Obliquely propagating nonextensive dust-ion-acoustic solitary waves in a dusty magnetoplasma     

S. Ashraf  S. Yasmin  M. Asaduzzaman  A. A. Mamun 《Astrophysics and Space Science》2013,343(1):145-151

An impact model of gravity designed to emulate Newton’s law of gravitation is applied to particles with relative motions at slow and relativistic speeds. Based on this model, a gravitational interaction mode is then conceived between photons and massive particles. This implies a deflection perpendicular to the propagation direction of a photon twice as large as expected from the mass-energy relation of photons—in accordance with observations and the General Theory of Relativity. The longitudinal interaction is compatible with the energy and momentum conservation principles applied to massless entities, and the results are consistent with the observed Shapiro delay.  相似文献   

Effect of exo-polysaccharides producing bacterial inoculation on growth of roots of wheat (Triticum aestivum L.) plants grown in a salt-affected soil     

M. Ashraf M. Sc.  M. S.  S. Hasnain Ph.D.  O. Berge Ph.D. 《International Journal of Environmental Science and Technology》2006,3(1):43-51

Effect of soil salinity on physico-chemical and biological properties renders the salt-affected soils unsuitable for soil microbial processes and growth of the crop plants. Soil aggregation around roots of the plants is a function of the bacterial exo-polysaccharides (EPS), however, such a role of the EPS-producing bacteria in the saline environments has rarely been investigated. Pot experiments were conducted to observe the effects of inoculating six strains of EPS-producing bacteria on growth of primary (seminal) roots and its relationship with saccharides, cations (Ca²⁺, Na⁺, K⁺) contents and mass of rhizosheath soils of roots of the wheat plants grown in a salt-affected soil. A strong positive relationship of RS with different root growth parameters indicated that an integrated influence of various biotic and abiotic RS factors would have controlled and promoted growth of roots of the inoculated wheat plants. The increase in root growth in turn could help inoculated wheat plants to withstand the negative effects of soil salinity through an enhanced soil water uptake, a restricted Na⁺ influx in the plants and the accelerated soil microbial process involved in cycling and availability of the soil nutrients to the plants. It was concluded that inoculation of the EPS-producing would be a valuable tool for amelioration and increasing crop productivity of the salt-affected soils.  相似文献   

Natural environmental radioactivity and estimation of radiation exposure from saline soils     

N. Akhtar  M. Tufail  M. Ashraf 《International Journal of Environmental Science and Technology》2005,1(4):279-285

The study was conducted for the investigation of amount of radioactivity in the barren and cultivated soil of Bio saline Research Station in Pakka Anna, established by Nuclear Institute for Agriculture and Biology (NIAB) in 1990, 34 km. away from the city of Faisalabad, in the Punjab province of Pakistan. The studies were done on an area of about 100 hectares of two types of virgin and fertilized saline soils. The technique of gamma ray spectrometry was applied using HPGe (high purity germanium) gamma ray detector and a PC based MCA. Activity concentration levels due to ⁴⁰K, ¹³⁷Cs, ²²⁶Ra and ²³²Th were measured in 250 saline soil samples collected at a spacing of about 4 hectares at the depth level of 0–25 cm. with a step of 5 cm. depth. Activity concentrations ranges of the concerned radionuclides for both of the soils were as follows: ⁴⁰K, for virgin and cultivated saline soil was 500–610.2 and Bq/kg 560.2–635.6 respectively; ¹³⁷Cs, 3.57–3.63 and 1.98–5.15 Bq/kg ²³⁸U, 26.3–31.6 and 30.3–38.7 Bq/kg, and ²³²Th, 50.6–55.3 and 50.6–64.0 Bq/kg respectively. The absorbed dose rate in air lies in the region 63–73 nGyh^-1 and 68–83 nGyh^-1 for virgin and fertilized soils respectively. This indicates that this region lies in the area of higher radiation background, while comparing with the worlds’ average. The slightly higher value of dose in the fertilized farm may be due to the use of fertilizers for cultivation. Before the radiometric measurements, chemical analysis for concentration of Na, Ca and Mg was also carried out along with the measurement of electrical conductivity and pH of the soil samples.  相似文献   

Effect of earthquake energy input characteristics on hysteretic damper efficiency     

Hiroki Yamaguchi  Ashraf El‐Abd 《地震工程与结构动力学》2003,32(6):827-843

Robust performance of hysteretic dampers, used in controlling mid‐rise buildings, against change of earthquake characteristics is investigated in this paper. A shear type ten‐storey building incorporating hysteretic dampers is studied as a model under the assumption of elastic perfectly plastic behavior for inelastic frame and damper deformations. An energy‐based damper performance index is used to evaluate damper overall efficiency. Thirty‐five earthquake records are applied and the damper strength is optimized for each earthquake record to obtain the maximum performance index or the damper efficiency. Based on the obtained numerical results it is found that, besides the effect of maximum energy input on damper efficiency, other time‐dependant properties such as energy‐based effective duration and earthquake dominant period have great influence on the damper efficiency. A factor (α), which represents the combined effect of maximum energy input, effective duration and dominant earthquake period, is also derived for the prediction of damper efficiency. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Dynamic instability of frames having thin-walled columns     

Srinivasan Sridharan  M. Ashraf Ali 《地震工程与结构动力学》1988,16(5):705-717

Dynamic instability of single storey frames having thin-walled columns has been investigated. The lateral loads sustained by the frame are dynamic in character, while the axial loads are deemed to be quasi-statically applied. The analytical model employed by the authors has the capability of modelling the combined action of the two ‘companion’ local modes whose amplitudes are variable along the length of the column and any type of end conditions of the members. For given levels of axial loads sustained by the columns, the magnitudes of lateral loads causing instability can be significantly smaller than those corresponding to static buckling, provided the dynamic load is of sufficient duration. There exists, however, a threshold value of axial force carried by the columns, below which there is no elastic instability—static or dynamic. For columns with overall critical loads several times greater than the local critical load, there is no danger of elastic instability, but the deflections under dynamic lateral loads of less than 1 per cent of the axial load may reach such huge values that there is a serious danger of localized plastic collapse. It is also shown that moment frames having thin-walled columns such as those fabricated out of cold formed steel are extremely vulnerable to moderate seismic excitations.  相似文献   

Mapping soil electric conductivity using Bayesian kriging: A case study from Qasur,Pakistan     

Muhammad Imran  Ather Ashraf  Ateeq Ur Rehman 《Journal of the Geological Society of India》2016,88(6):711-717

Quality of soil data is vital to formulate agricultural policies at different scales. Current agricultural applications in Pakistan depend however, on average values of soil estimates over larger areas. In this work, model-based ordinary kriging (OK) and Bayesian kriging (BK) to interpolate soil data is used. The aim is to compare the two different methods for the accuracy of soil data prediction. For this soils were sampled for Electrical Conductivity (EC, dS m ^–1) at 759 different locations in the rural agricultural areas of Qasur Tehsil, Pakistan. Cross validation was used to compare the performance of OK and BK. Our results show strong skewness and spatial dependency of soil EC values in heterogeneous regions. Box-Cox transformation successfully reduced the level of skewness in the soil EC data (from 14.1 to 0.11). Contrary to OK, under-estimation of soil EC values was not evident in the BK interpolation. Mean square prediction error for BK (1.45) was significantly reduced as compared to that for OK (6.1). Considering these findings, BK is a better model to explain the sub-regional soil EC variability and estimating strategies for sustainable agricultural planning in Pakistan.  相似文献   

Quantifying climate-induced drought risk to livelihood and mitigation actions in Balochistan     

Ashraf  Muhammad  Arshad  Adnan  Patel  Praharsh M.  Khan  Adeel  Qamar  Huma  Siti-Sundari  Ristina  Ghani  Muhammad Usman  Amin  Ali  Babar  Jamilur Rehman 《Natural Hazards》2021,109(3):2127-2151

Natural Hazards - Climate change-induced disasters show the highest risk for agriculture and livelihoods in rural areas of developing countries. Due to changing rainfall pattern, the arid and...  相似文献   

The roles of network embeddedness,market incentives,and slack resources in the adoption of clean technologies by firms in developing countries     

Naeem Ashraf  Breeda Comyns  Ghulam Ali Arain  Zeeshan Ahmed Bhatti 《Climate Policy》2019,19(5):556-570

Worldwide carbon dioxide emissions continue to increase driven by fossil fuel consumption and industrial discharges. Progress on carbon emission reduction requires firms to adopt clean technologies which minimize material and energy consumption. Technological change is particularly required in developing countries, where industrial emissions often lead to chronic urban pollution problems. In this study, we explore the antecedents of clean technology strategy by firms in developing countries. We combine the contingent natural resource-based view with the relational view to examine how network embeddedness, market incentives and slack resources influence adoption of clean technology. The empirical support for our hypotheses comes from data obtained from 342 firms that operated in the carbon-offset market during the years 2007 to 2009. We find that a firm’s relational network structure influences adoption of clean technologies, particularly when market incentives are low. Contrary to one of the hypotheses, the results of our paper suggest a negative relationship between a firm’s slack resources and its clean technology strategy. Our study highlights the benefits of networks in fostering adoption of clean technology in developing countries. Furthermore, we find that high market incentives (carbon price) decrease the probability of clean technology adoption, so adding to the view that firms respond to carbon-offset rules to realize high carbon revenues at the lowest cost.

Key policy insights

• High market incentives (carbon price) decrease the probability that firms in developing countries will adopt clean technology.

• This adds to concerns about the capability of the Clean Development Mechanism to deliver sustainable development.

• Even where market incentives are low, firms in developing countries are more likely to adopt clean technologies when they are embedded in a closed network of connected partners.

• To stimulate adoption of clean technology in developing countries, policy makers should focus on initiatives to facilitate partnerships between organizations operating in the carbon market and create opportunities for knowledge sharing and learning.

• By changing the policy focus to networks of organizations, the carbon market can bring about positive change in terms of shifting the firm behaviour.

  相似文献   

Uptake of hazardous elements by spring onion (<Emphasis Type="Italic">Allium fistulosum</Emphasis> L.) from soil irrigated with different types of water and possible health risk     

Kafeel Ahmad  Zafar Iqbal Khan  Asma Ashfaq  Muhammad Ashraf  Nudrat Aisha Akram  Muhammad Sher  Hazoor Ahmad Shad  Vincenzo Tufarelli  Antonio Lonigro  Mariano Fracchiolla  Eugenio Cazzato 《Environmental Earth Sciences》2017,76(8):322

Bio-concentration of elements such as Mo, As, Se, Fe, Cu, Zn, Ni and Pb was analyzed in spring onion (Allium fistulosum L.) in three different locations of central Punjab, Pakistan. At location GW, relatively low level of hazardous elements was found in spring onion, suggesting that groundwater is a safe source of water for irrigating food crops. The pH of soil at wastewater irrigation was found less acidic (pH 7.4) than the other sites. The range of concentration in the different samples of spring onion was as follows: 6.15–8.16 mg kg^?1 for Mo, 2.77–4.28 mg kg^?1 for As, 0.395–0.705 mg kg^?1 for Se, 36.73–48.17 mg kg^?1 for Fe, 10.58–16.26 mg kg^?1 for Cu, 28.87–39.79 mg kg^?1 for Zn, 6.66–8.75 mg kg^?1 for Ni and 4.33–6.09 mg kg^?1 for Pb, respectively. High bio-concentration of Zn (15.37) from soil to spring onion was found at canal water irrigated location. The estimated daily intake of metal for spring onion was less, but the health risk index was higher than 1 for Mo, As, Cu, Pb and Ni, respectively. This was due to higher proportion of spring onion in diet, which consequently increased the health risk index for metals. Therefore, it is recommended to avoid growing vegetables in untreated urban and rural wastewater containing elevated amounts of metals.  相似文献