Khulna is among the areas in Bangladesh worst affected by climate change and rising salinity. The problem is worsening every year, as natural disasters and other factors contribute to the degradation of rivers, allowing seawater to spread further inland and reach settlements in the northern parts of the division.
Data from the Soil Resource Development Institute (SRDI) show that salinity is widespread across the country’s southern coastal areas, with the highest levels recorded in Khulna division. By contrast, salinity is less severe in the coastal regions of Barishal and Chattogram.
Amarendranath Biswas, principal scientific officer at the SRDI’s Batiaghata Salinity Centre in Khulna, told TIMES that several factors are responsible for the problem. The main ones are geographical conditions and global climate change, which is raising sea levels. Various human activities are also contributing to it.
The SRDI has conducted several studies on rising salinity in Khulna division. Their findings show that climate change is raising sea levels, allowing seawater to penetrate further into coastal areas than before.
Salinity rises during the dry season and continues to increase until the rains begin. When rainfall is low, salinity remains high.
Surveys show that river salinity reaches its highest levels each year during the dry season, particularly in March, April and May. It generally peaks in April. Salinity is lowest during the monsoon and post-monsoon period, from July to October. From November, after the monsoon, salinity gradually rises as river water levels fall.
The limited network of rivers in Khulna division is another factor. Many areas have few rivers or none at all. With less freshwater flowing through the region, salt from the sea has been moving northwards through the soil year after year.
Researchers have also identified the Farakka Barrage, which India began operating in the 1970s, as a contributing factor. They say that after India commissioned the barrage in 1975 and began diverting water from the Ganges, freshwater flows into rivers in Bangladesh’s south-western region declined during the dry season, particularly in the Gorai-Madhumati and Kobadak rivers. This weakened the rivers’ natural ability to flush out salt.
The problem is less severe in Barishal and Chattogram, where the natural flow of rivers has not been disrupted to the same extent. As a result, these areas have experienced less salinity.
Extensive shrimp farming in southern Khulna is another contributing factor, as the industry requires saline water. Canals are dug to bring water into farmland for shrimp cultivation, increasing salinity in the areas where the farms operate.
Embankments built along rivers are also sometimes breached to bring in water for cultivation. This further contributes to rising soil salinity.
Farmland shrinking at an alarming rate
Agriculture and people’s health are among the areas suffering the greatest damage from rising salinity.
SRDI research shows that Khulna district had 165,789 hectares of agricultural land and 48,031 hectares of land unsuitable for agriculture in 2010.
By 2024, agricultural land had fallen to 155,497 hectares, while land unsuitable for agriculture had increased to 56,370 hectares. Over 14 years, agricultural land declined by 10,292 hectares, while non-agricultural land increased by 8,339 hectares.
Within Khulna district, the highest proportions of saline land are found in Dacope and Koyra, where 100% of land is affected, followed by Paikgachha at 99%.
The proportion of saline land in the remaining upazilas ranges from 70% to 96%.
In 21% of the district’s area, salinity exceeds 16 decisiemens per metre. Decisiemens is a scientific unit used to measure soil salinity, indicating the amount of dissolved salt present in the moisture surrounding plant roots.
Salinity ranges from 12.1 to 16 decisiemens per metre in 30% of the area, 8.1 to 12 in 23%, 4.1 to 8 in 20%, and 2 to 4 in 5%.
The Department of Agricultural Extension says no crops grow in soil with salinity levels of 12 to 16 decisiemens per metre. Some crops can grow when salinity is between 8 and 12, while soil with levels below 8 is considered suitable for cultivation.
Across Khulna division, 91% of the land in Bagerhat and 85% in Satkhira are affected by salinity. The problem has also spread beyond the coast, affecting 21% of the land in Jashore and 35% in Narail.
Overall, 69% of the division’s area is affected by salinity, while nearly 45% has salinity levels of 12 to 16 decisiemens per metre, making it unsuitable for cultivation.
Rising salinity is also having a negative impact on freshwater fish production.
Health risks and school absenteeism
The effects of salinity extend beyond farmland and livelihoods to people’s health.
According to a 2014 World Bank report, workers who spend hours working in saline water face higher rates of high blood pressure and heart disease. Even apparently healthy and physically fit workers are suffering strokes at relatively young ages and losing their ability to earn a living. Their medical expenses are pushing entire families towards debt and poverty.
Data from the Directorate General of Health Services’ Management Information System (DGHS-MIS) show that Khulna has the highest stroke mortality rate among Bangladesh’s eight divisions, at 0.17 deaths per 1,000 people. Chattogram has the lowest rate, at 0.06.
The recorded rate of stroke cases in Khulna division stands at 1.77 per 1,000 people, the highest in the country. By contrast, Rangpur has the lowest rate, at 0.62 per 1,000 people.
Hossain Ali, resident physician at Khulna Medical College Hospital, told TIMES, “We are seeing many patients with kidney complications, which are potentially linked to water salinity. Increased salinity in drinking water can aggravate hypertension.”
SM Naim Ahsan, an official of the Jaago Foundation’s Strengthening Hope, Integrated Emergency Leadership, and Disaster Preparedness (SHEILD) project, has been working for years on the effects of climate change and salinity in coastal areas.
He said people in coastal communities lack access to safe drinking water because of salinity. They treat water with alum or boil it before drinking. Water treatment facilities in areas affected by salinity are inadequate compared with demand.
A survey of 1,200 people in Dacope and Mongla found that 65% to 70% were directly affected in various ways by salinity.
Several surveys have also found that people from Dacope and Koyra have moved to Khulna and other cities across the country after losing their homes to climate change and major cyclones.
Salinity is also contributing to school absenteeism and dropouts. Naim Ahsan said that during a visit to a school in Dacope, his team found only 41 of its 117 students present. The parents of those who were absent had sent their children to work in watermelon fields or fish farms instead of attending school. The same situation was also observed in Mongla.
“Cultivable land is shrinking. As a result, families send their children to work at an early age to meet household expenses,” he said.
What can be done?
The Department of Agricultural Extension in Khulna says it is developing crop varieties suited to the region’s soil and water conditions. It is also exploring the potential for sunflower cultivation in saline areas. Off-season watermelons and vegetables grown along the embankments of fish farms can also tolerate salinity.
However, no clear solutions are known for the health problems people are experiencing as salinity continues to rise.
Professor Md Abdullah Yousuf Al Harun of the Environmental Science Discipline at Khulna University suggests that the best way to tackle salinity is to adapt to the environment. “We need to harvest rainwater and build large reservoirs. We are lagging behind in many areas, and the government needs to become more efficient in addressing this issue,” said Abdullah, who is working with a Dutch organisation on salinity issues.
