In the lush and fertile plains of Bangladesh, an innovative discovery has revolutionised the way people think about groundwater management and irrigated agriculture.
This groundbreaking concept, known as the Bengal Water Machine (BWM), has demonstrated a remarkable ability to enhance freshwater storage through a unique approach to groundwater pumping.
Researchers have unveiled how this method can rival even the world’s largest dams in terms of water capture and storage.
BWM operates on a simple yet profound principle. By incrementally increasing groundwater pumping during the dry season for irrigation, farmers effectively lower the groundwater levels.
This, in turn, enhances the infiltration of surface water into the aquifers during the monsoon season. The cumulative effect of this process, conducted by approximately 16 million smallholder farmers in the Bengal Basin from 1988 to 2018, resulted in the capture of 75 to 90 km3 of freshwater.
To put it in perspective, this volume is equivalent to 12-14 times the volume of water stored in the Kaptai Lake in southeast of Bangladesh.
The implications of this discovery are far-reaching. The Bengal Water Machine not only provides a reliable source of water for irrigation during dry seasons but also helps mitigate the risks of monsoonal floods.
By lowering groundwater levels before the monsoon, the aquifers have more capacity to store incoming floodwaters, reducing the risk of flooding. This dual benefit makes the Bengal Water Machine an attractive solution for regions struggling with both water scarcity and flood risks.
This system has also played a crucial role in sustaining agriculture, particularly dry-season rice cultivation, which is vital for food security in Bangladesh.
The collective action of millions of farmers using this method has ensured a stable water supply for their crops, despite the variability in annual rainfall. This stability is essential in a country where rice is not only a staple food but also a significant part of the economy.
BWM, therefore, supports both livelihoods and food security on a large scale.
However, the BWM is not without its challenges.
One significant issue is the risk of groundwater depletion in areas where induced recharge is insufficient to replenish the extracted water.
This can render groundwater inaccessible to households relying on shallow hand tubewells, posing a serious problem for local communities.
Additionally, the effectiveness of this system varies with the region's surface geology. Areas with low permeability soils such areas with as the Madhupur and Barind clays and hilly areas may not benefit from enhanced groundwater recharge, limiting the method's applicability. It does not work well in the coastal areas and should not be promoted to avoid saltwater intrusion into coastal aquifers.
These practical and geological constraints necessitate careful planning and localised implementation strategies to ensure the system’s success.
Moreover, the increased groundwater pumping during the dry season can lead to reduced surface water discharge to rivers and wetlands. This decline in surface water flows can adversely impact the ecosystems dependent on them, affecting biodiversity and reducing the water available for other uses.
Managing and optimising the Bengal Water Machine also requires careful planning and long-term hydrological monitoring. Policies need to be tailored to specific regions (for example, the Old Brahmaputra floodplains) to balance the benefits of groundwater pumping with the risk of depletion. This means implementing restrictive groundwater use permits in areas with low recharge rates while allowing more flexible use where groundwater is more abundant.
Such targeted policies can help maximize the benefits of the Bengal Water Machine while mitigating potential negative impacts such as depletion and reduction in river flows in dry season.
Despite these challenges, the BWM represents a scalable and sustainable solution for groundwater management that can be adapted globally. Its potential for enhancing climate resilience is particularly noteworthy.
By increasing the storage of seasonal freshwater surpluses, the system helps buffer agricultural systems against the impacts of droughts and variable rainfall, making it a vital tool for climate adaptation.
In a world increasingly affected by climate change, innovative solutions like the Bengal Water Machine are essential for building resilience and ensuring sustainable water management.
However, there are barriers to the widespread adoption of this strategy.
One significant hurdle is the lack of awareness among policymakers and stakeholders about the benefits and operational details of the BWM.
There is considerable misunderstanding of this concept among the general public and researchers from non-hydrogeology backgrounds.
Additionally, the financial and technical resources required for implementation and monitoring are often beyond the reach of local governments and communities.
Institutional challenges, such as bureaucratic hurdles and fragmentation among various government agencies, also impede progress.
Overcoming these barriers requires concerted efforts to raise awareness, mobiliz\se resources, and streamline institutional processes.
Furthermore, community engagement is crucial for the successful implementation of the BWM. Farmers and local communities need to be involved in the planning and management processes to ensure that the system meets their needs and is sustainable in the long term.
Training programs and awareness campaigns can help empower communities to take an active role in managing their water resources effectively.
The BWM’s success in the Bengal Basin highlights its potential to revolutionise groundwater management.
With the right support and awareness, this nature-based solution could play a crucial role in securing water resources and enhancing climate resilience for millions of people.
As the world faces increasing water scarcity and climate variability, innovative approaches like the Bengal Water Machine offer a beacon of hope for sustainable water management.
BWM represents a pioneering step in groundwater management, offering both opportunities and challenges. Its successful implementation hinges on tailored policies, robust monitoring, and community engagement.
By addressing these challenges and leveraging the system’s benefits, water security, agricultural productivity, and building resilience to climate change can be enhanced.
BWM stands as a testament to the power of innovative thinking and collective action in solving some of the most pressing water management challenges.
Dr Mohammad Shamsudduha is a teacher at the Department of Risk and Disaster Reduction, University College London, UK
He can be reached at m.shamsudduha@ucl.ac.uk
Declaimer: All opinions and views expressed in this article are those of the author and do not necessarily reflect the stance of Bangladesh First
