Climate change 'responsible' for rising salinity in rivers

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Mashiur Rahaman
The levels of salinity in the water of six major rivers in the country's south-western region have increased rapidly in recent years, threatening catastrophic ecological imbalance and disruption in crop production.
Salinity in fresh-water rivers namely Pashur, Kazibachha, Rupsha, Sailmari, Daratana and Madhumati has gone several folds up over years. Experts have directly held the rapid change of climate responsible for this ruinous consequence.
"This growing level of salinity in fresh-water rivers would be a disaster for crop production and ecological balance in the region," Anwar Hossain, principal scientific officer of Salinity Management and Research Centre of Soil Resource Development Institute (SRDI) told the FE.
The record of river-water salinity collected from these six rivers at different times explains the pace of disaster approaching towards us, he said adding that initiative to collect data of current situation has been undertaken.
"What we have observed in our study on the basis of randomly collected symptoms makes us afraid of a very disastrous discovery regarding the level of salinity," he added.
Sea-level rise, uncertain rainfall and decreasing water-flow from upstream rivers are directly responsible for this, he explained.
Year-wise river water salinity record compiled by the SRDI shows that the level of salinity in Pashur river water has increased by 3.38 DeciSiemen/metre (ds/m) within only five years.
The SRDI data shows that the level of salinity in the Pashur river was 3.8 ds/m in 1990. Within only five years, the salinity level increased dramatically to 7.14 ds/m in 1995. The highest level of salinity in its water was 22.0 ds/m, recorded in May 1995.
Rapidly increasing water salinity level was also recorded in Kazibachha river. Its level of salinity was recorded at 1.84 ds/m in 1990 that went up many folds in the next five years, reaching the level of 6.0 ds/m in 1995. The highest level of water salinity in this river was recorded in May 1995 at 21.2 ds/m, the SRDI data revealed.
The mighty river Rupsha, the source of life to the people of Khulna and Bagerhat has also been polluted with salt water entering from the sea. According to salinity level record of the river water, level of salinity increased from 1.6 ds/m (in 1990) to 6.2 ds/m (in 2007). Within 17 years, salinity level in its water jumped up by 4.6 ds/m with highest 27.7 ds/m recorded in May 2007.
Saline-water intrusion was also recorded in the Sailmari river of Dumuria-Khulna area. Level of salinity was recorded at 1.23 ds/m in 1990 that jumped up to 5.96 ds/m in 1995. Within only five years, the level increased by 4.73 ds/m with a maximum 21.7 ds/m recorded in May 1995, the SRDI data shows.
In the water of Daratana river, located in Bagerhat district, water salinity increased by 3.96 ds/m between 1990-1995. According to the yearly record, presence of salt component in its water was at 2.24 ds/m in 1990 which was recorded at 6.2 ds/m in 1995. The highest salinity pollution in this river was recorded in May 1992 at 17.1 ds/m.
Madhumati river, another key fresh-water source for agriculture and industrial uses in Bagerhat district was also badly polluted with increasing saline water.