Salinity increasing in south-west region

Increasing salinity is affecting crop production and shrinking fresh water availability in the country’s south-western region, posing threat to lives and livelihoods in around one-thirds of the whole country.
The salinity is increasing due to withdrawal of river water upstream in India in one hand and sea-level rise, caused by climate change, on the other hand, said experts.
The salinity intrusion rose abruptly in the south-western part of the country immediately after the commissioning of the Farakkah Barrage over the trans-boundary river Ganges by India in 1975 and later in 2007 and 2009 due to cyclones Sidr and Aila, water resources specialist Ainun Nishat said.
‘The low flow in the river Padma is changing biodiversity of the world’s largest mangrove forest Sundarbans and affecting crop production and livelihoods in the south-west with salinity concentration increasing,’ he said.
Nishat, also professor emeritus at BRAC University, said increased salinity had also caused displacement and internal migration of marginalised people, particularly from Aila-affected areas of Khulna and Sathkhira, in 2009.
The people in the region will face a serious crisis of drinking water if salinity level continues to go up, he added.
Estimated salinity concentration has threatened crop production and a significant yield loss has already been noticed in the dry season in the coastal areas that include around 133 upazilas of 19 districts, mostly under Barisal and Khulna divisions, a recent study revealed.
The study identified salinity intrusion as the most pressing problem for yield reduction as 830,000 million hectares of land at coastal Bangladesh is affected by soil salinity at different degrees.
It estimated that 0.3 m sea level rise in coastal areas would cause a net reduction of 0.5 million tonnes of rice production.
The most common response of plant towards salinity is reduction in growth, say the findings.
‘Due to salinity intrusion, crop pattern in many areas of the coastal districts of Khulna and Satkhira have changed remarkably in the last 10-15 years. Many peasants have migrated from the area and changed their livelihoods following the cyclone Aila,’ said Dacope upazila agriculture officer Mosaddeque Hossain.
He said farmers are now returning to paddy cultivation as they were incurring losses from shrimp culture, responsible for increasing salinity concentration in soil.
‘They are now cultivating salinity-tolerant high-yielding varities including paddy and vegetables and getting good produces,’ said the agriculture officer who worked at several salinity affected upazilas in Khulna and Sathkhira in the last 15 years.
He said farmers were now being motivated to dig small ponds to preserve fresh water for irrigation so they could cultivate diversified crops for their survival.
Published in June 2015 by Gobeshona, a non-government organisation researching the affects of climate change in Bangladesh, the study estimated salinity concentration of surface water was 1.3 dS/m, which was 0.8 dS/m higher than the earlier estimation by Integrated Coastal Zone Management Plan in 2003.
The study tested irrigation water collected between October and December 2011 from lower Meghna river at Gosairghat upazila in Shariatpur district and interviewed experts and local farmers.
‘In the changing scenario of sea level rise, it has been predicted that the increasing concentration of salinity would create more pressure on the farmer[s] by reducing yield on one hand and threatening livelihood, income generation and food security on the other hand.’
The study recommends leaching and selecting salinity tolerant crop varieties as adaption techniques.
Agriculture production is likely to decrease as saline-containing water reduces plant growth.
The report opined salinity has negative impacts on domestic cattle in terms of deterioration of the milk production and reproductive health.
‘In low to moderate concentration, salinity affects crop production by lowering the soil-water potential and increases concentration of salt at the root zone,’ it said.
Experts said the highest contributor of fresh water to the lower Meghna is the river Padma, the combined flow of Ganges and Brahmaputra that provides 90 per cent of total fresh water in Bangladesh.
The implementation of the proposed barrage over the trans-boundary river Padma at Pangsha in Rajbari would help reduce salinity and therefore protect Sundarbans and its biodiversity, state minister for water resources, Muhammad Nazrul Islam said.
He told New Age that the implementation of the $ four billion Ganges Barrage project would take seven years, but the cost might return in five years from additional fish and agricultural production in the country’s south-western districts.
The construction of the barrage, which would mainly check salinity intrusion and provide irrigation facility in the country’s south-western region, is now pending ‘clearance’ from New Delhi, according to officials.