Agricultural Land Cover Change in Gazipur, Bangladesh, in Relation to Local Economy Studied Using Landsat Images

Abstract

Land classification is conducted in Gazipur district, located in the northern neighborhood of Dhaka, the capital of Bangladesh. Images of bands 1 - 5 and 7 of Landsat 4 - 5 TM and Landsat 7 ETM+ imagery recorded in years 2001, 2005 and 2009 are classified using unsupervised classification with the technique of image segmentation. It is found that during the eight year period, paddy area increased from 30% to 37%, followed by the increase in the homestead (55% to 57%) and urban area (1% to 3%). These changes occurred at the expense of the decrease in forest land cover (14% to 3%). In the category of homestead, the presence of different kinds of vegetation often makes it difficult to separate the category from paddy field, though paddy exhibits accuracy of 93.70% - 99.95%, which is better than the values for other categories. In addition, the analysis based on digital elevation model reveals that paddy cultivation is implemented in lowland rather than highland. Homestead areas have spread from south (low elevation) to north (high elevation), in association with the decrease in forest-covered areas.