SEMINAR AT CARE CENTER

We would like to invite scientists, lecturers, students attend the seminar on March 08, 2018 presenting by Dr. Celine Grall, Lamont - Doherty Earth Observatory Columbia University, New York.

SUBSIDENCE RATE AND DRIVING FORCES IN THE BENGAL DELTA AND OTHER LARGE DELTA PLAINS

C. Grall LDEO of Columbia University, Palisades, NY, USA

Recent studies show critical variability in subsidence rates among large delta plains that directly impact on the coastal management of those highly vulnerable environments. This variability poses the question of the discrepancy of subsidence driving forces in large delta plains that this study aims to address.

Holocene subsidence rate and pattern are determined in the Bengal Delta based on a novel and simple stratigraphic approach. Results provide evidence of moderate Holocene subsidence over the delta, gently increasing seaward from 2 ± 0.7 mm/yr in the middle fluvial delta to 4 ± 1.4 mm/yr in the lower tidal delta.

This pattern of subsidence is reconstructed by modelling that account for sediment compaction and glacio-isostatic adjustments. Results suggest that about 2/3 of observed Holocene subsidence may be associated with the compaction of the underlying sedimentary column that react to the load of sediment deposited by mechanical and chemical compaction.

In delta plains where higher organic, clay content and sediment supplies are observed, such as the Mekong Delta, compaction rates can be significantly higher than in the Bengal Delta.