Document Type

Article

Publication Date

2017

DOI

10.1525/elementa.263

Publication Title

Elementa- Science of the Anthropocene

Volume

5

Issue

78

Pages

1-12

Abstract

Since the 1960s, ~5000 km2 of tidal deltaplain in southwest Bangladesh has been embanked and converted to densely inhabited, agricultural islands (i.e., polders). This landscape is juxtaposed to the adjacent Sundarbans, a pristine mangrove forest, both well connected by a dense network of tidal channels that effectively convey water and sediment throughout the region. The extensive embanking in poldered areas, however, has greatly reduced the tidal prism (i.e., volume of water) transported through local channels. We reveal that >600 km of these major waterways have infilled in recent decades, converting to land through enhanced sedimentation and the direct blocking of waterways by embankments and sluice gates. Nearly all of the observed closures (~98%) have occurred along the embanked polder systems, with no comparable changes occurring in channels of the Sundarbans (2 of new land in the last 40–50 years, the rate of which, ~2 km2/yr, offsets the 4 km2/yr that is eroded at the coast, and is equivalent to ~20% of the new land produced naturally at the Ganges-Brahmaputra tidal rivermouth. Most of this new land, called ‘khas’ in Bengali, has been reclaimed for agriculture or aquaculture, contributing to the local economy. However, benefits are tempered by the loss of navigable waterways for commerce, transportation, and fishing, as well as the forced rerouting of tidal waters and sediments necessary to sustain this low-lying landscape against rising sea level. A more sustainable delta will require detailed knowledge of the consequences of these hydrodynamic changes to support more scientifically-grounded management of water, sediment, and tidal energy distribution.

Rights

© 2017 The Author(s)

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/.

Data Availability

Article states: "Datasets associated with this submission are provided in Supplemental Material. Any associated data not included in Supplemental will be archived with corresponding author, CAW, and housed at Louisiana State University. As per NSF guidelines, this material will be made publically accessible, and access and permission to use this associated data can be provided after a formal written request is received and accepted."

Supplemental materials are linked in the PDF version of the article and also available online at https://doi.org/10.1525/elementa.263

Corresponding author: Carol Wilson

Original Publication Citation

Wilson, C., Goodbred, S., Small, C., Gilligan, J., Sams, S., Mallick, B., & Hale, R. (2017). Widespread infilling of tidal channels and navigable waterways in the human-modified tidal deltaplain of southwest Bangladesh. Elementa-Science of the Anthropocene, 5(78), 1-12. doi:10.1525/elementa.263

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