Present‐day subsidence in the Ganges‐Brahmaputra‐Meghna Delta: eastern amplification of the Holocene sediment loading contribution

Y. Krien (1) , M. Karpytchev (2) , V. Ballu (2) , Melanie Becker (2) , C. Grall (3) , S. Goodbred (4) , S. Calmant (5) , C.K. Shum (6) , Z. Khan (7)

1 LARGE - Laboratoire de Recherche en Géosciences et Energies [UR2_1]
2 LIENSs - LIttoral ENvironnement et Sociétés
3 LDEO - Lamont-Doherty Earth Observatory
4 Vanderbilt University [Nashville]
5 LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales
6 OSU - Ohio State University [Columbus]
7 Institute of Water Modelling

The subsidence of the Ganges-Brahmaputra-Meghna Delta (GBMD) drastically increases the adverse impacts of coastal flooding and exacerbates the vulnerability of populations from ongoing rapid sea level rise. We focus here on estimating the present-day subsidence rates induced by the loading of sediments continuously deposited within the GBMD over the past 11,000 years. By constructing a realistic GBMD 3-D numerical model with laterally variable mantle and lithospheric structure, we demonstrate for the first time that the presence of the strong Indian Craton and the weakened Indo-Burma margin results in significant amplification of subsidence driven by sediment loading in the eastern part of the delta, where the population density is the highest (>1,000 habitants per km 2). Although uncertainties remain regarding the amplitude of subsidence, the rate estimates (2-3 mm/year) are found to be comparable to the present-day global mean sea level rise.

Domaines: Géophysique [physics.geo-ph]

Y. Krien, M. Karpytchev, V. Ballu, Melanie Becker, C. Grall, et al.. Present‐day subsidence in the Ganges‐Brahmaputra‐Meghna Delta: eastern amplification of the Holocene sediment loading contribution. Geophysical Research Letters, 2019, 46 (19), pp.10764-10772. ⟨10.1029/2019GL083601⟩. ⟨hal-02293106⟩