Bangladesh is believed to be extremely vulnerable to climate change, which may result in abnormal spatio-temporal pattern in rainfall and increased variability of temperature across the region. Consequently, the frequency and intensity of various natural hazards are expected to increase, which may affect the availability of fresh water on the surface as well as underground. That’s why mapping of water body and its continuous monitoring is important (Regional Water Report 37, FAO 2011).This study aims at identifying water body in the coastal belt of Bangladesh using Landsat 5 TM time-series satellite images for the year 2000, 2005 and 2010. Satellite derived indices e.g. WRI, NDVI, NDWI, MNDWI, AWEI, NDMI are computed from Landsat data of 2000, which were compared with the base map for selecting the best index for water body identification. The result shows that NDWI is more robust in extracting water bodies compared to other indices. Furthermore, unsupervised and supervised image classification techniques have been applied on all three years data. Both the index images as well as the classified images are reclassified to produce binary images showing water and non-water area. Average accuracy of the classification is 88%. Result shows that there is remarkable increase in water area after 2005. The reason might be attributed to the fact that the study area has suffered from several natural calamities during the study period.Keywords: Water Security, Landsat Satellite Image, Remote Sensing Indices, Mapping and Monitorin
