Print Email Facebook Twitter Tidal amplification and river capture in response to land reclamation in the Ganges-Brahmaputra delta Title Tidal amplification and river capture in response to land reclamation in the Ganges-Brahmaputra delta Author van Maren, D.S. (TU Delft Environmental Fluid Mechanics; Shanghai Estuarine and Coastal Science Research Center; Deltares) Beemster, J. G.W. (Wageningen University & Research) Wang, Zhengbing (TU Delft Coastal Engineering; Deltares) Khan, Z. H. (Institute of Water Modelling) Schrijvershof, R. A. (Deltares; Wageningen University & Research) Hoitink, A. J.F. (Wageningen University & Research) Date 2023 Abstract At a global scale, intertidal areas are being reclaimed for agriculture as well as urban expansion, imposing high human pressure on the coastal zone. The Ganges-Brahmaputra Delta (GBD) is an exponent of this development. In this delta, land reclamation accelerated in the 1960's to 1980's, when polders were constructed in areas subject to regular marine flooding. A comprehensive analysis of tidal channel evolution in the southwest GBD reveals how land reclamation leads to tidal amplification, channel shoaling, bank erosion, and interaction between channels in which one tidal river captures the storage area of a neighbouring river. We identify-two positive feedback mechanisms that govern these morphological changes. First, reclaiming intertidal areas results in immediate loss of tidal storage, which leads to amplification and faster propagation of the tides. In systems with abundant sediment supply, the blind tidal channels progressively fill in with sediment, leading to a continued loss of tidal storage and therefore further distorting the tides. Secondly, when intertidal areas of parallel (and inter-connected) river delta distributaries are asynchronously or unevenly reclaimed, one channel distributary may expand its intertidal area at the expense of the other. This is initiated by an increasing propagation speed of the tidal wave in the partially reclaimed distributary, travelling into the non-reclaimed distributary through connecting channels. These connecting channels progressively expand while the pristine channel shoals, and potentially degenerates. Both positive feedback loops are very stable and are responsible for pluvial flooding of polders, large-scale bank erosion, and poorly navigable primary waterways, including the navigation channel accessing Bangladesh's second-largest port. Interventions aiming to solve these problems have to account for the complex positive feedback mechanisms identified in this paper and be nature-based and holistic. Subject EstuaryFine sedimentsGanges-Brahmaputra deltaHuman impactsLand reclamationsTidal amplification To reference this document use: http://resolver.tudelft.nl/uuid:1547c36b-d00e-49a7-97dc-f0c751794cb5 DOI https://doi.org/10.1016/j.catena.2022.106651 ISSN 0341-8162 Source Catena, 220 Part of collection Institutional Repository Document type journal article Rights © 2023 D.S. van Maren, J. G.W. Beemster, Zhengbing Wang, Z. H. Khan, R. A. Schrijvershof, A. J.F. Hoitink Files PDF 1_s2.0_S0341816222006373_main.pdf 8.99 MB Close viewer /islandora/object/uuid:1547c36b-d00e-49a7-97dc-f0c751794cb5/datastream/OBJ/view