Relative sea-level rise hazards: The case of Bangladesh Delta

Abstract:

In Bangladesh, the Ganges, Brahmaputra, and Meghna Rivers come together to form the largest river delta in the world. This low-lying region of the Bay of Bengal is one of the most densely populated in the world and is prone to monsoonal flooding, potentially aggravated by intensified cyclones due to climate change. In this context, sea-level rise, along with tectonic, sediment load and groundwater extraction induced land uplift/subsidence, significantly exacerbate the Bangladesh’s coastal vulnerability. Here we present the goals and results of a Belmont Forum/IGFA-funded project, BanD-AID (http://Belmont-SeaLevel.org). For the last 5 decades, we analyze the decadal / multi-decadal sea level in this region. To do this, we use a reconstruction of sea level past variations over the past 50 years based on the joint statistical analysis of tide gauge records and grids of sea level from a ocean circulation model. We also determine the relative sea level trend, which reflects the sea level change felt by the population locally, by combining space geodetic observations, including satellite altimetry and GPS, together with tide gauges, and different reconstructed sea-level approaches. This unique combination of different techniques offers the possibility to better quantify the major contributions to the relative sea-level rise at the Bangladesh delta, towards addressing its coastal vulnerability and future sustainability.