The salinity of the water is another name for suffering in the southern coastal community of Bangladesh. This community frequently faces severe natural calamities due to the geographical location of the region. The recent cyclones Sitrang (2022), Jawad (2021), Amphan (2020), and Fani (2019) are evidence of that. When the cyclones strike, the salinity intrusion increases in the surface and groundwater sources of the nearby areas. The intrusion of saline water causes salinity which impacts drinking water, agriculture, and many social and economic aspects of life in the coastal communities.
For understanding the salinity level with clarity, the entire coastal region of Bangladesh may be divided into 4 distinct geo-morphological zones:
- The southwest zone contains the Sundarbans and it is surrounded by the Baleswar River in the east and the Raimongal River in the west. The Gorai River is the main source of fresh water for this zone.
- The boundary of the southeast zone starts from the Feni River to Badarmokam having the Lower Meghna River as the western boundary of this region.
- The south-central zone is situated between the southeast zone and southwest zone which receives considerable freshwater from the Padma River and the Lower Meghna rivers.
- The Eastern Hill zone is in the Chittagong and Cox’s Bazar Districts with several flat beaches comprised of clay and sand. In this region, the Karnaphuli, Matamuhuri, Sangu, and Naf Rivers discharge freshwater through the plain.
At present, the rivers of the southwest zone suffer mostly from salinity intrusion among the four coastal zones. A groundwater salinity map of the coastal part of Bangladesh was prepared by Bangladesh Agricultural Development Corporation (BADC) using salinity observation wells data where it is evident that the southwestern zone is the highest saline water zone.
Salinity is the term that refers to the salt content dissolved in water. The general predominant ions in the water are sodium and chloride, and the substantial concentrations of ions are magnesium, calcium, sulfate ions, etc. In 2003, a technical report prepared by WHO and the FAO recommends not taking more than 5 grams of sodium chloride (or 2 grams of sodium) per day, while ensuring that the salt is iodized. But recent research shows sodium concentrations above 1000 milligrams per liter surrounding the high-moderate southwestern salinity zone of Bangladesh.
Acute salinity and impurity in drinking water have already affected 43 million people in Bangladesh. The financial condition has worsened the situation for people living under the poverty line. They are compelled to consume saline water regularly which pasts the danger level. Consumption of saline water over the years can cause serious long-term health issues. There is evidence for the relationship between excessive salt intake and cardiovascular diseases, such as heart disease, strokes, and high blood pressure. In the case of pregnant women, excessive salt intake can cause gestational hypertension and preeclampsia which can end up in maternal death.
According to Soil Resources Development Institute (SRDI), Ministry of Agriculture, Bangladesh, over the last 35 years, salinity has increased to 26% within the country. As per the 2020 edition of Germanwatch’s Climate Risk Index, Bangladesh is ranked 7th in the list of countries that are most affected by climate calamities during 1999-2018. This salinity is expected to rise shortly as a result of climate change which can be catastrophic for coastal communities. Some researches show that the aquifer saline zone may increase by 2.27 percent by the year 2050 and the freshwater zone will decrease by 3.44 percent. As a result, by 2050, the severe salinity zone is expected to increase by 14 percent.
Different solutions are present to desalinate water such as Reverse Osmosis (RO), nanofiltration (NF), and so on. But the main drawbacks of these solutions are all of them are highly expensive as they require large space and manpower to operate the desalination process and then transport the water to different coastal areas. The transportation cost of water is also high as the coastal community in southwestern districts are quite dispersed.
Under the current status quo, it is important to propose some cost-effective and portable desalination solutions that will be able to provide safe drinking water to the poor coastal community of Bangladesh. Hence, investing in new innovative technology has no alternative in that case. Finally, we need to acknowledge that salinity and its impact on the southwest coastal community is a serious issue that is going to be amplified in near future. Thus, the government and non-government institutions need to come forward to find solutions and adaptation strategies for it.
Sabrina Rashid Sheonty is a water resource engineer, working at Matrix Solutions Inc, Canada
