B.M. Saidur Rahman: Bangladesh is one of the most densely populated and food-insecure countries in the world. Agriculture is the main source of livelihood for about 70% of the population, and contributes to about 15% of the gross domestic product (GDP). To meet the growing demand for food, Bangladesh has achieved remarkable success in increasing its crop production, especially rice, over the last few decades. This success is largely attributed to the expansion of groundwater irrigation, which covers about 75% of the irrigated area in the country. Groundwater irrigation has enabled farmers to grow high-yielding varieties of rice and other crops during the dry season (boro), which accounts for more than half of the annual rice production. Groundwater irrigation has also reduced the dependence on unreliable and inadequate surface water sources, and increased the resilience and adaptation capacity of farmers to climate change and variability.

However, groundwater irrigation also poses serious challenges for the environment and sustainability of water resources in Bangladesh. Groundwater irrigation can have negative effects such as:

• Declining groundwater levels:Groundwater is being extracted at a faster rate than it can be recharged, leading to declining water levels. This is particularly a problem the Barind Tract in northwest region of Bangladesh, where the groundwater table has fallen by up to 10 meters in some areas over the past few decades.

• Increased salinity:As groundwater levels decline, saltwater from the Bay of Bengal can intrude into freshwater aquifers, increasing the salinity of the water. This can make the water unsuitable for irrigation and drinking.

• Land subsidence:Declining groundwater levels can also lead to land subsidence, which is the sinking of the land surface. This can damage infrastructure, such as roads and buildings, and make it more difficult to grow crops.

• Reduced crop yields:High salinity levels and declining water levels can both lead to reduced crop yields. This can have a significant impact on food security in Bangladesh, where agriculture is a major source of income and employment.

• Increased energy costs:Groundwater extraction requires energy, either to pump water from deep wells or to power irrigation pumps. As groundwater levels decline, the cost of pumping water increases.
• Increase greenhouse gas emission:Groundwater irrigation can also increase greenhouse gas emissions from rice fields, which contribute to global warming.
• Deteriorating water quality:Groundwater pollution is a growing problem in Bangladesh, due to agricultural runoff, industrial waste, and sewage. This can make the water unsafe to drink or use for irrigation and affect our ecosystems.

The Solution: An integrated Approach

To reduce the negative effects of groundwater irrigation on the environment in Bangladesh, we need an integrated approach that addresses the interlinked biophysical, socio-economic and institutional dimensions of groundwater management. We need to balance the needs of farmers and ecosystems, and ensure the sustainability of groundwater resources in a changing climate. Some possible measures are:

• Improve water use efficiency:This can be done by using more efficient irrigation methods, such as drip irrigation, sprinkler irrigation, alternative furrow irrigation and by adopting water-saving agricultural practices, such as alternate wetting and drying (AWD) and System of Rice Intensification (SRI) for rice cultivation.
• Promote surface water irrigation:Surface water irrigation, such as canal irrigation and river lift irrigation, is a more sustainable alternative to groundwater irrigation. The government of Bangladesh is investing in expanding surface water irrigation coverage, and farmers should be encouraged to adopt these technologies.
• Diversify agricultural production:Farmers should be encouraged to grow crops that require less water, such as wheat, maize, pulses and oilseeds, instead of water-intensive crops such as rice.
• Climate Smart Agriculture:Selecting drought, salt, flood, pest and diseases tolerant crop varieties and adopting practices that increase crop productivity, reduce greenhouse gas emissions, enhance adaptation to climate change and save water.
• Collect hydrological information:Improving the availability and quality of hydrogeological data and information, to reduce the uncertainty and risk of groundwater development. Better data and information can help to identify suitable locations for groundwater extraction, monitor groundwater levels and quality, assess groundwater recharge and discharge rates, evaluate groundwater potential and availability, and plan groundwater allocation and regulation.
• Irrigation infrastructure management:Investing in irrigation infrastructure and management, to improve water delivery and application efficiency and reduce water losses and wastage. Improved irrigation infrastructure can include lining or piping of canals or channels, installation or maintenance of pumps or valves, construction or rehabilitation of storage tanks or ponds, etc.
• Raise awareness about the importance of sustainable groundwater management:Farmers, extension workers and other stakeholders need to be trained up about the negative effects of groundwater overexploitation and the benefits of sustainable groundwater management practices.

These measures can help to overcome the irrigation-based poverty traps in agriculture, by increasing farmers’ crop productivity, income and resilience. They can also help to protect the environment, by conserving or restoring groundwater resources, maintaining or enhancing ecosystem services, mitigating or adapting to climate change, and reducing greenhouse gas emissions.

 The Conclusion: A Call for Action

Groundwater irrigation is a double-edged sword for Bangladesh. On one hand, it has enabled the country to achieve remarkable success in increasing its food production and food security. On the other hand, it has posed serious challenges for the environment and sustainability of water resources. To reduce the negative effects of groundwater irrigation on the environment in Bangladesh, we need an integrated approach that addresses the interlinked biophysical, socio-economic and institutional dimensions of groundwater management. We need to balance the needs of farmers and ecosystems, and ensure the sustainability of groundwater resources in a changing climate.

We need to call for action from all stakeholders, including governments, donors, researchers, practitioners, farmers and civil society, to support and implement the measures suggested. We believe that by working together, we can reduce the negative effects of groundwater irrigation on the environment in Bangladesh, and ensure the sustainability of groundwater irrigation in a changing climate.

Figure 1: Surface irrigation by a re-excavated micro canal, monirampur, jessore.