Effect of Land Cover Changes on Flooding: Example from Greater Dhaka of Bangladesh

要旨

This study is an example of identifying the relationship between land cover changes and river flows making use of remote sensing data and simultaneously analyzing the relevant hydro-meteorological information in Greater Dhaka of Bangladesh. Using the supervised classification technique and post classification change detection method, pattern and trend of land cover changes were evaluated between 1960 and 2005. It is found that significant portions of lowlands, water bodies, and agricultural lands were converted to built-up areas and landfill sites. Built-up area has increased to about 344% compared to that of 1960. Landsat TM and RADARSAT SAR data were employed to estimate flooding for the three greatest floods of 1988, 1998, and 2004. 47.1% areas were flooded in 1988 while in 1998 and 2004 inundation areas were 53% and 43%, respectively. This information was subsequently integrated with the hydro-meteorological data and indicates that the flood risk potential is elevating in Greater Dhaka. Results revealed that rapid changes in land cover play a crucial role in intensifying the flood process.