The groundwater table in parts of Bangladesh's Barind region has fallen by nearly 20 metres over the past four decades, raising fresh concerns over the sustainability of irrigation and agricultural production in the country's northwest.

In some parts of Rajshahi, Naogaon, Chapainawabganj, Joypurhat, and areas of Dinajpur, Natore and Bogura, groundwater levels now reach depths of 33 to 36 metres during the dry season, compared to around 16 metres in 1985, experts said at a consultation workshop in Dhaka on Tuesday.

They stressed the need to reduce dependence on groundwater by harvesting rainwater, restoring ponds and canals, and expanding water-efficient irrigation technologies.

The recommendations were presented at a consultation workshop titled "Groundwater Conservation: Barind Area Resilient and Innovative Development (BARIND)", attended by representatives from the Ministry of Agriculture, the Barind Multipurpose Development Authority (BMDA), the Institute of Water Modelling (IWM), the Asian Development Bank (ADB), and other research organisations.

At the event, Dr Rafiqul I Mohamed, secretary of the Ministry of Agriculture, said Bangladesh receives abundant rainfall during the monsoon, but little effort is made to conserve it for later use.

"If we can preserve every drop of rainwater and use it for irrigation, we can significantly reduce pressure on groundwater," he said.

"We are continuously extracting groundwater and pushing the water table further down. Conserving and using surface water should be our top priority," he added.

The agriculture secretary also said efficient water management could unlock greater agricultural and economic potential in northern Bangladesh. 

He urged improving transport and market connectivity so that vegetables, mangoes and rice produced in the region can reach domestic and export markets more efficiently.

Goutam Chandra Mridha, director for Irrigation, Groundwater and Wetland Management at the Institute of Water Modelling (IWM), said annual groundwater recharge across the Barind region ranges between 100 mm and 515 mm, with the lowest recharge recorded in Rajshahi, Naogaon, Chapainawabganj, Joypurhat and parts of Dinajpur, Natore and Bogura.

He said the region consumes around 18,907 million cubic metres (MCM) of water annually, of which 85.81 percent is used for agriculture.

Excessive groundwater extraction for dry-season irrigation has led to a steady decline in water tables across Rajshahi, Naogaon, Chapainawabganj, Natore, Bogura and parts of Pabna, he said.

According to the study, groundwater levels during the dry season have reached 33 to 36 metres in Nachole, Tanore, Niamatpur and Porsha upazilas.

Experts at the workshop noted that although the Barind region receives substantial surface water during the monsoon, much of it cannot be stored for use in the dry season.

They said the region has around 151,000 ponds and 907 major wetlands, which could be rehabilitated to retain large volumes of rainwater. Rivers including the Teesta, Mahananda, Dharla, Atrai, Dudhkumar, Bangali and Dhepa also have significant potential to support surface water irrigation.

The experts also called for changes in cropping patterns and irrigation practices, recommending reduced dependence on water-intensive Boro rice, greater cultivation of less water-demanding crops, and wider adoption of buried pipelines, sprinkler systems and drip irrigation to minimise water losses.

They warned that without immediate action to conserve groundwater through rainwater harvesting, restoration of ponds, canals and wetlands, and improved irrigation efficiency, the Barind region could face growing risks to agriculture, food security and the environment.

Among others, Dr Takeshi Ueda, director of Agriculture, Food, Nature and Rural Development (SD2) at ADB; Dr Shingo Kimura, principal natural resources and agriculture economist at ADB; BMDA Chairman Md Hasan Zafir Tuhin; and BMDA Executive Director Abu Sayed Md Kamruzzaman also addressed the workshop.