![Sample our Geography journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5937/TOC-Subject-Sample-2021-Geography.jpg"})
ABSTRACT
Topographical changes in riverine floodplains need to be measured for assessing geomorphological dynamics and protecting floodplain areas, although topographic evaluation in disaster-prone floodplain in South Asia has been limited due to the lack of multitemporal, high-definition digital elevation models (DEMs) derived from modern techniques including airborne laser scanning, structure-from-motion (SfM) photogrammetry accompanied with Unmanned Aerial Vehicle (UAV, often referred as drone), and field-based mapping approaches. Here we conducted a preliminary study at two locations of Teesta River (Brahmaputra’s tributary) in Bangladesh using the UAV-SfM techniques and generated high-resolution DEMs. The selected locations represent dynamic changes of sediment and water on the floodplain over the years, and the UAV-SfM approach can be an effective method for monitoring those changes, but an archive of the past data has been unavailable. Here we evaluated the topographic changes by comparing the UAV-SfM-derived DEMs of 2022 with global DEM products (NASADEM of 1999), which are often the only available choice of DEMs in this river floodplain. The elevation differences of these two sets of DEMs were in the range of −5.23 to −84.66 m, and volumetric changes of −4.11 ± 0.15 to −86.25 ± 0.20 million m3, likely dominated by erosional processes towards the left side bank where the elevation errors are supposed to be several meters for UAV-DEM and ca. 5–12 m for NASADEM. Although it is not easy to accurately evaluate the absolute values of the changes, these changes may be associated with the upper basin’s morphodynamics.
Acknowledgements
We are grateful to Professor Mohammed Jamal Uddin (Jahangirnagar University, Bangladesh), Md. Abul Kashem Majumder (Hydrogeologist), and Bangladesh Water Development Board for their kind assistance in the field investigation. We are grateful to the editorial team, particularly Karin Ebert and anonymous reviewers for their constructive comments and insightful suggestions, which significantly improved our manuscript.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
Notes on contributors
B. M. Refat Faisal
B. M. Refat Faisal, is a Senior scientific officer (SSO) at Bangladesh Space Research and Remote Sensing Organization (SPARRSO), Dhaka, Bangladesh. My research interests include multiscale fluvial-geomorphology, sediment connectivity, LULC planning, and fluvial risk management towards sustainable river basin management. In particular, the land surface processes from the Himalayan mountains to the coast using Unmanned Aerial Systems (UAS) (i.e., UAV-SfM, Lidar) are focused on nowadays. Also, I am interested in satellite remote sensing-based crop information science, particularly crop production forecasting and estimation.
Yuichi S. Hayakawa
Yuichi S. Hayakawa, is at the Faculty of Environmental Earth Science, Hokkaido University, Japan. My research interests include Geomorphology, Geoarchaeology and Geospatial Information Analysis at various fields of studies in physical geography, environmental geosciences, and geospatial information science (GIS) are of my research interest. In particular, measurements and spatial analyses of land surface processes in areas from mountain watersheds to coasts are tackled to clarify the relationships between natural processes and human activities therein.