Evaluation of the river Padma morphological transition in the central Bangladesh using GIS and remote sensing techniques

Abstract

ABSTRACT Since decades, the characteristics of the major tributaries and distributary channels and their dynamics over time have got significant scientific interests. Recently, thanks to Remote Sensing (RS) and Geographical Information System(GIS), new studies focused on evaluating the river dynamics at the reach scale appeared, covering also remote regions worldwide. This study provides an overview of the morphological changes of the River Padma, Bangladesh, during the last four decades. The River Padma was very dynamic and constantly changed its position, planform, and other morphological properties because of variation in flow, sedimentation, and boundary condition. Five sets of geo referenced Landsat images from 1979 to 2019 were scrutinized using ERDAS Imagine and ArcGIS to visualize the erosion, accretion, bank line migration, bar growth, as well as changes in planform, and channel bed elevation. The results indicated that bank and channel positions, as well as central bars along with geometry, changed dramatically over time, and the River Padma turned into sinuous-braided from straight-wandering planform. From 1989 to 1999, heavy discharge during the monsoon season eroded around 283 km2 land along 100 km reach. This study also revealed that the average width of the River Padma increased about 3.5 km and the overall bar area increased by 40%. This study demonstrated that the right bank of the River Padma was more unstable than the left bank during the last four decades. The findings of this study might help to prepare better management strategies for agricultural land, homestead as well as inland navigation projects across the floodplain.