Researchers report estimates of land subsidence rates in the Ganges-Brahmaputra-Meghna delta. The Ganges-Brahmaputra-Meghna delta, covering most of Bangladesh and part of eastern India, is highly vulnerable to climate-driven sea-level rise. Land subsidence can exacerbate the effects of sea-level rise, but disentangling the contributions of sea-level rise, land subsidence, and river dynamics to relative water level presents a challenge. Mélanie Becker and colleagues analyzed 101 monthly stream and tide gauge records across the delta from the Bangladesh Water Development Board and the Permanent Service for Mean Sea Level database. By regionally aggregating the records to filter local effects, the authors obtained robust estimates of variations in relative water level (RWL) from 1968 to 2012. During this period, RWL in the delta increased by approximately 3 mm/year on average, similar to or slightly faster than the rate of global mean sea-level increase during the same period. By combining the RWL estimates with satellite altimetry measurements of absolute sea level during 1993-2012, the authors estimated maximum expected land subsidence rates in the range of 1 to 7 mm/year. If these subsidence rates continue through the end of the current century, then the relative sea-level rise in the delta by 2100 could reach 140 cm in some regions, doubling the rise previously projected under a greenhouse gas emission mitigation scenario, according to the authors.
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Article #19-12921: "Water level changes, subsidence, and sea level rise in the Ganges-Brahmaputra-Meghna delta," by Mélanie Becker et al.
MEDIA CONTACTS: Mélanie Becker, Littoral, Environment and Societies/Centre national de la recherche scientifique, La Rochelle, FRANCE; tel: +33-5-16-49-65-42; e-mail: < melanie.becker@univ-lr.fr >; Fabrice Papa, Laboratoire d'Etudes en Géophysique et Océanographie Spatiales/Institut de Recherche pour le Développement, Toulouse, FRANCE; tel: +55-61-99-159-7224; e-mail: < fabrice.papa@ird.fr >; Mikhail Karpytchev, Littoral, Environment and Societies/University of La Rochelle, FRANCE; tel: +33-5-46-45-72-06; e-mail: < mikhail.karpytchev@univ-lr.fr >
Proceedings of the National Academy of Sciences