Rising salinity levels in the Sundarbans are partly responsible for growing rural-urban migration which is putting greater pressure on urban infrastructure.
Rising sea levels and more frequent storm surges are increasing both water and soil salinity in the Sundarbans, a dense mangrove forest that straddles the India-Bangladesh border. Rising salinity is attributed to multiple factors including climate change, rising sea levels, reduced water flow in rivers due to diversions upriver in India and poor water management in the brackish shrimp aquaculture industry.
With more than a quarter of its population living near the Bay of Bengal coast, powerful monsoons and rising sea levels, Bangladesh is particularly vulnerable to salt water intrusion. The increased popularity of financially lucrative shrimp production has also significantly contributed to agricultural degradation.
The agricultural sector is most affected by rising salinity. In the districts of Khulna and Bagerhat, for example, over 100,000 hectares of land has been affected, with large tracts completely barren and unable to support crop production. The proportion of arable land throughout Bangladesh has decreased by 7.3 per cent since 2000, a rate faster than the two per cent decline experienced in South Asia as a whole. Many farmers switched from cultivating paddy to shrimp as a result of environmental change, however, in some areas even this has become challenging.
Rising salinity levels also have an impact upon the availability of potable water. Most Bangladeshis rely upon groundwater sources for drinking water. Coastal regions, however, have limited access to safe groundwater due to the presence of high salt content in the region. In some coastal areas, deep tubewells have been used to reach fresh water aquifers, but these are not always located in convenient locations and are becoming increasingly saline.
Faced with deteriorating employment prospects and worsening living conditions, many rural dwellers opt to migrate to urban areas. Population growth rates in many coastal districts have become negative while the rate of growth in urban slums has risen considerably in recent years. The districts of Jhalakathi, Barisal, Khulna and Bagerhat, in the south-west of the country, have experienced the sharpest decline in population while the populations of urban areas have consistently increased.
Rural-urban migration has resulted in an increase in urban slums as, according to the Bangladesh Census of Slum Areas and Floating Population 2014, the number of slum households has increased by 77 per cent since 1997. The number of slums has also risen by 366 per cent over the same period.
The increasing number of people living in urban slums has resulted in a looming public health crisis, as many of these areas do not have adequate access to water or sanitation facilities. Addressing the lack of basic services in urban areas will be vital if this health crisis is to be avoided. As Bangladeshi cities face multiple infrastructural deficits, however, addressing a lack of water infrastructure might not be a high priority.
The Bangladeshi Government is beginning to take steps towards adapting to the salinity challenge, ostensibly to stem the push factors driving rural-urban migration. In the popular tourist destination of Cox’s Bazar, for instance, a solar-powered desalination project has begun. The development of salt-tolerant rice has also started. These efforts are in the early stages and much work remains to be done in adapting Bangladeshi agriculture to the changing environmental circumstances.
Global Food and Water Crises Research Programme