About 10.2 lakh hectare of land is now salinity-contaminated in 19 districts against 8.33 lakh hectares in 1973, according to a study by the Bangladesh Soil Resources Development Institute. It has caused crisis of potable water also in many areas.

The problem has been caused mainly due to decreasing flow of rivers in the dry season, when saline water from the sea intrudes deep into the mainland. Unplanned shrimp cultivation in recent years has aggravated the problem.

The salinity-contaminated area in spread up to 130 kilometres in Chittagong region and 180 kilometre in southwestern region from the sea-line.

Satkhira is the worst affected area where about 1.47 lakh hectares of cultivable land are salinity-contaminated out of total 2.28 lakh hectares. In Khulna, it is 1.45 lakh hectares out of total 2.11 lakh hectares.

In Shyamnagar in Satkhira, salinity has affected 88 percent of the cultivable lands.

Other affected districts are Khulna, Bagerhat, Patuakhali, Barguna and Bhola followed by Cox's Bazar, Chittagong, Noakhali and Pirojpur.

The districts with less than 25,000 hectares of affected land are Laxmipur, Gopalganj, Feni, Barisal, Jhalokathi and Madaripur.

New areas are being affected. The intensity is also increasing alarmingly, the survey said.

The problem is increasing as saline water of rivers and canals are being mixed with groundwater.

The survey showed that waters of 56 per cent of rivers and canals in the region are 'highly saline-affected' and can not be used for agriculture. Only 34 percent have salinity to a 'bearable limit'.

The shrimp cultivators, by holding saline water in enclosures almost round the year, send saline to the groundwater and nearby cultivable lands.

The survey shows lands under shrimp cultivation has increased to 1,15 lakh hectares now from only 1300 hectares in 1975 in Bagerhat and Khulna region.

"These people (shrimp cultivators) are not only harming neighbouring lands and sending salinity to the groundwater, they are also destroying the lands for a long period," Kushal Roy, who conducted several research projects on climate change in the region, told The Daily Star.

"After a land is uses for shrimp cultivation for 10 to 15 years, the soil can not grow any crop for a long time."

"Many farmers migrated to the town and started rickshaw-van pulling while some others have started working in shrimp enclosures," said Kushal.

The acute salinity has eliminated many sweet water crops, trees and fishes and forced people to shift to new professions. Many farmers in Satkhira now oppose unplanned shrimp cultivation as they can not grow paddy or other crops during dry season.

Salinity is also affecting growth of plants and vegetables. Green leaves turn yellowish and the trees wither away gradually.

According to forest department officials, about 75 lakh trees of Khulna and Satkhira have been affected with 'top dying' disease.

Indigenous species of fishes are declining in the region as saline water from the sea has reached rivers and canals.

Hit by salinity, Sundarbans, the largest mangrove forest is the world, is losing its bio-diversity.

Care Bangladesh has started some experimental measures at community level in Khulna-Satkhira region to improve people's ability to cope with the change. It is working with local NGOs and civil society to create awareness.