Up to 200,000 coastal people may be forced to migrate annually to the country's inland areas to find alternative livelihoods due to climate change induced salinity and sea level rises, according to a new study.

Researchers from International Food Policy Research Institute (IFPRI) and the Ohio State University jointly conducted the study examining for the first time the complex relationship between flooding, soil salinity, rural livelihood and migration, along with providing some adaptation strategies.

The study, “Coastal Climate Change, Soil Salinity and Human Migration in Bangladesh” was conducted last year and was based on two different datasets collected in 2003-2011 and 2005-2010. Coauthored by IFPRI's Valerie Mueller from IFPRI and Joyce Chen from Ohio State University, the study was released yesterday.  

It shows how increased soil salinity from rising sea levels would compel nearly 140,000 coastal residents to migrate to another location within their district, while nearly 60,000 would move to alternative districts, says Valerie Mueller, senior research fellow, IFPRI.

However, the study does not specify the exact year when the relocation would begin but rather points out the worst case scenario, said Drew Sample, IFPRI's international press officer, when contacted.

Due to a rise in soil salinity, Chittagong and Khulna districts, home to Bangladesh's second and third largest cities, may witness the highest intra-district migration, estimated between 15,000 and 30,000 migrants per year.

Districts without large cities, like Bagerhat, Bhola and Feni, would expect smaller flows within their districts, with the migrants' numbers estimated between 5000 and 15,000, but more people may leave the areas and head for the capital Dhaka. 

However, it warned that with the country's five largest cities in the saline belt, migration would not reduce vulnerability to sea-level rise in the long run.

Additionally, soil salinity would also bring forth further problems.

The study found increasing soil salinity would likely reduce the financial capacity of the people, decreasing international migration. Internal migration, on the other hand, might rise nearly 25 percent. 

“Financial constraints limit poor households from moving over longer distances, signaling a trapped population dynamic, raising concerns that the most vulnerable households may be the least resilient in the face of climate change,” adds Chen.

According to the study, the total annual crop revenue of a family living in the coastal belt would fall by up to 21 percent each year if the salinity level increased from mild to a moderate level.

As the salinity level increases in the coastal area, households are moving towards aquaculture, to offset the loss of income from crop production.

 “As soil salinity increases from low to high salinity levels, we see a nearly 57 percent increase in share of revenue from aquaculture,” says Mueller.

The study suggests that the government take up a two-pronged approach: a compensation-based resettlement programme and development strategies aimed at taking advantage of the labour surplus and promoting modern economic activities such as manufacturing, in less populated areas. 

The study analysed socio-economic data from the country's Bureau of Statistics' Sample Vital Registration System and agricultural production data from Household Income and Expenditure Surveys, covering nearly half a million coastal households in a year.