Geomorphological Mapping of Old Brahmaputra Flood plain Using Remote Sensing and GIS in and around Mymensingh Sadar, Bangladesh

Abstract

 A geomorphological map of Mymensingh Sadar (Paurashava) and its surroundings has been constructed through visual image interpretation based on toposheets, aerial photographs and satellite images. The study area comprises mainly two geomorphic units: Mymensingh terrace (Older flood plain) and Younger flood plain. The geomorphic units are further classified into point bars, lateral bars, natural levees, flood plains, flood basins, backswamps, abandoned channels, active channels depending on their image/photo characteristics. Ground checking and randomly distributed boreholes and auger holes have been done to find out the extent and the near surface lithology of the geomorphic units. Mymensingh Terrace/Older Flood Plain areas are composed mainly of silty and clayey sediments. Whereas Younger Flood Plain is composed mainly of very fine to medium sandy sediments. Older flood plain is comparatively elevated than Younger flood plain. The rivers flowing through the Mymensingh Terrace (older flood plain) are incised indicating that the terrace has been uplifted. The Mymensingh Terrace sediments are more compacted compared to Younger flood plain area and are suitable for constructing any structure while the Younger flood plain area are suitable for shallow structures only.