May 6, 2014
Seven of South Asia’s river deltas, including the Ganga-Brahmaputra, the Krishna and the Indus, are sinking faster than sea-level rise because of dam construction upstream
One or two people leave their homes in the Sundarbans forests of the Ganga-Brahmaputra delta each day, perhaps never to return. It’s but a small vignette of a larger tragedy being played out across South Asia’s delta regions where land is fast sinking as the sea waters rise, leaving millions of people vulnerable to disasters like cyclones and floods.
The mouth of the Ganga-Brahmaputra mega-delta in Bangladesh, the largest in the world, is dotted with 139 small islands called polders. An embankment protects each polder from daily tides. Every year, as embankments are breached and repaired several times over, the embankments rise higher and higher.
Local communities know they have little hope of seeing their families thrive in this land, said Anurag Danda, head of the climate change and Sundarbans landscape programmes of WWF-India. Every family in the Sundarbans, for instance, that can afford it sends its able-bodied members away. “They understand that they can’t be here for all time to come… Migration on a daily basis is already happening.”
The heartbreak and hopelessness finds echo across large swathes of South Asia. According to studies, the deltas of the Ganga-Brahmaputra in Bangladesh, the Indus river in Pakistan, the Krishna, the Godavari, Brahmani and Mahanadi in south India and the Irrawaddy in Myanmar are sinking faster than the rate of sea-level rise. The main reason for the deltas disappearing is the presence of hundreds of dams along the lengths of these rivers.
Of the seven, the Krishna delta is sinking the fastest and the Ganga and Indus have the largest affected areas.
Communities living in these South Asian deltas are already feeling the effects of the sinking land. As saline ocean waters creep further, inland farmlands are being damaged and ground water contaminated. A sinking delta is also more vulnerable to extreme climate events like Cyclone Aila that tore through the low-lying Ganga-Brahmaputra delta in 2009 leaving hundreds dead and many thousands homeless.