Dynamics of land use/cover changes and the analysis of landscape fragmentation in Dhaka Metropolitan, Bangladesh
Dynamics of land use/cover changes and the analysis of landscape fragmentation in Dhaka Metropolitan, Bangladesh
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DOI：
10.1007/s10708-010-9399-x
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发表时间：
2012-06-01
期刊：
影响因子：
2.7
通讯作者：
Rahman, Md.
中科院分区：
文献类型：
--
作者：
Dewan, Ashraf;Yamaguchi, Yasushi;Rahman, Md.
由于大规模土地利用/覆盖变化而导致的快速城市扩张，特别是在发展中国家，成为一个令人担忧的问题，因为城市化在多个层面上推动了环境变化。孟加拉国首都达卡在过去几十年中经历了飞速的城市发展，对环境造成了许多不利影响。本文试图记录孟加拉国达卡市土地利用/覆盖变化的时空模式，并量化景观结构。使用地理信息系统的多时相遥感数据，评估土地利用/覆盖变化的动态，并计算转换矩阵以了解土地利用/覆盖变化的速率和模式。随后将得出的土地利用统计数据与景观指标相结合，以确定土地利用变化对景观破碎化的影响。在 1975 年至 2005 年研究期间，达卡的土地利用/覆盖发生了显着变化。快速城市化的表现是农业用地大幅减少，城市建成区面积从1975年的5,500公顷增加到2005年的20,549公顷。与此同时，耕地面积从12,040公顷减少到6,236公顷。同样，湿地和植被覆盖面积分别减少至约 6,027 公顷和 2,812 公顷。因此，观察到景观格局和构成的急剧变化。由于建成区的快速增加，景观变得高度碎片化。分析表明，平均斑块大小减小，而斑块数量增加。景观多样性下降，城市主导地位增强，整体景观马赛克变得更加连续、同质和聚集。为了制定可持续的土地利用规划并确定未来景观变化以实现健全的资源管理策略，本研究预计将对世界快速城市化的城市产生重大影响，提供有关长期土地利用变化及其对景观结构影响的基线信息。
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 spatiotemporal 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.