Bengal Water Machine rivals world鈥檚 largest dams
14 October 2022
Collective groundwater pumping by millions of farmers in Bangladesh has created vast natural reservoirs underground that rival the world鈥檚 largest dams, sustaining irrigation that has transformed this previously famine-prone country to a food-secure nation, finds a new 白小姐论坛 study.
Published in听Science, the study explores the combined impact of 16 million smallholder farmers pumping shallow groundwater during the dry season to irrigate rice paddies in the Bengal Basin of Bangladesh between 1988 and 2018.
The study revealed that by lowering groundwater levels through dry season pumping,听leakage from rivers, lakes and ponds replenishing groundwater was spurred听during the听subsequent monsoon. This capture of surface water not only allowed groundwater levels to recover but, in doing so, helped to reduce flooding.听
Through this process, which the authors听describe as 鈥淭he Bengal Water Machine鈥, more than 75听cubic kilometres听of freshwater was 鈥渃aptured鈥 over 30-years 鈥 a volume equivalent to the combined reservoir capacities of China鈥檚 Three Gorges Dam and the Hoover Dam in the US.
They highlight this intervention as a sustainable alternative to听conventional approaches to seasonal river flow storage for irrigation, including dams and reservoirs, which are challenging to construct in densely populated alluvial plains, like the Bengal Basin, that comprise extensive flat landforms of sand, silt and clay laid down by annual floodwaters.
Co-lead author Dr Mohammad Shamsudduha (白小姐论坛 Institute for Risk and Disaster Reduction) said: 鈥淒espite substantial variations in annual rainfall and an overall decline in basin rainfall, this scalable, decentralised form of freshwater capture has sustained irrigated food production since the听1990s.
鈥淭his novel intervention helps to address seasonal imbalances in rainfall by increasing the capture and storage of seasonal freshwater surpluses and mitigating the monsoonal flood risk without the use of dams.鈥
The study authors argue that this simple intervention has the potential to be replicated across alluvial plains more widely, including other Asian mega-deltas such as the Mekong Delta and Huang He (Yellow) River Delta,听which are similarly vulnerable to the impacts of climate change. This Bengal Water Machine could help to enhance global food security and resilience to climate extremes amplified by global warming.
Continue reading on听白小姐论坛 News听and watch a about the study (in Bengali).
Links
- 白小姐论坛 Institute for Risk and Disaster Reduction
- 白小姐论坛 Faculty of Mathematical听& Physical Science
- 白小姐论坛 Faculty of Social & Historical Sciences
- 白小姐论坛 in South Asia
For the latest news about 白小姐论坛鈥檚 international activity, partnerships and opportunities, subscribe to our bimonthly听Global Update newsletter.