Location: The GBM Delta is one of the world’s largest (~100,000 km2), draining land from Bangladesh, Bhutan, China, India and Nepal.

Lead PI: Steve Goodbred, Vanderbilt University

Challenges: The delta covers most of Bangladesh and part of West Bengal, India, with many of the 147 million people (in 2000) living in the delta under extreme poverty and facing multiple challenges. The population is expected to increase by 28% by 2015. Already 30% of  Bangladesh is within 5 m of sea level, experiencing tidal water movement 100 km inland during the dry season  and relative sea-level rise that exceeds global-mean sea-level rise, demonstrating subsidence. Together these factors make the GBM delta one of the most vulnerable coastal regions in the 21st century.

Ensemble CCSM experiments predict 11% higher rainfall during the Asian monsoon, which would result in a larger sediment supply to the GBM delta in the future. In contrast, the proposed construction of numerous mega dams and major diversions upstream in India and China threaten sediment starvation to the sinking delta plain, as well as reduced water availability in the dry season, which is already a serious problem. Reduced river flows and intensive shrimp farming cause severe saltwater intrusion in the coastal fringe degrading the ecosystem, and ultimately making the land uninhabitable. Furthermore, tropical storms associated with the Indian Monsoon system affect the GBM delta coastline every few years, and over the last decade, two major cyclones (Sidr in 2007 and Aila in 2009) caused flooding and hundreds of fatalities while displacing an estimated 1 million people. 

Approaching a Solution: The DELTAS project will work toward a science-based GBM-customized integrative modeling framework which will be implement, in collaboration with regional experts, to assess delta vulnerability to current and future conditions and guide sustainable management and policy.  At the heart of the GBM sustainability lies the question of how patterns of flooding and sediment aggradation offset delta sinking due to rising sea level and subsidence. This is a first order question to sustainability of the landscape, regardless of land use and management decisions. For the GBM delta specifically, the immense population and associated pressures on natural resources brings to the forefront the question of how environmental changes are affecting the socio-ecosystem services in coastal Bangladesh. The integrated assessment of these circumstances will aim to reveal whether there are management alternatives that will more effectively sustain ecosystem services, and populations and their livelihoods in coastal Bangladesh.

 

Map of widespread flooding and subsidence 1999-2009. Click image to zoom. 
Credit: Irina Overeem and Steckler

Rice farmer, Ganges Delta
Photo Credit: Irina Overeem