Save the rivers of Bangladesh
River is one of the most important blessings in nature for all mankind, which the 160 million people of the country depend on for food, water and habitation. At the same the nature is also adverse when the river does not flow without the natural volume of flow of the hydrological principles of water resources. Today's rivers of Bangladesh are the worse victim of pollution, especially in the capital Dhaka and its surrounding rivers pollution levels are high. That is why the present situation of the river pollution is very critical to retrieve natural volume of the rivers flow throughout the country.
Due to rapid growth of population, unplanned city expansion, industrialization and urbanization the rivers surrounding the capital cities surface and ground water of the country is unprotected from production of household waste, medical waste, industrial waste, toxic chemicals waste from factories are posing a serious threat to human health in the capital city and to aquatic flora and fauna found in water bodies throughout the river and its canal system. The careless disposal of untreated wastewater and solid waste in to the rivers and its water system significantly contributes to the poor quality of the water. The water quality not only depends on the water itself but also depends on the toxic substances into the other ecosystem.
Government declared Dhaka city is surrounding river Buriganga, Turag, Balu and the river Shitalakhya as Ecologically Critical Area (ECA) in 2009. Buriganga is still considered one of the most highly polluted rivers in the world. Reckless pollution and river-bank grabbing continue to afflict other rivers including Dhaleshwari, Bangshi, Karnaphuli, Mayur, Rupsha, Bhairab, Surma and the river Brahmaputra are also being polluted.
Buriganga River: Buriganga River a tide-influenced river passing through west and south of Dhaka City. There is a traditional story behind naming it. In ancient times one course of the Ganges used to reach the Bay of Bengal through Dhaleshwari. This course gradually shifted and ultimately lost its link with the main channel of the Ganges and was renamed as the Buriganga. The water levels during high and low tides in this river astonished the Mughals.
The Buriganga originated from the Dhaleshwari near Kalatia. Its average width and depth are 400 Meter (m) and 10m respectively. This river is only 27 Kilometer (km) long. The Turag has joined the Buriganga at Kamrangirchar of Dhaka City. In fact, the main flow of the Buriganga comes from the Turag. It meets with the Dhaleshwari at Munshiganj.
The present head of the Buriganga near Chhaglakandi has silted up and opens only during flood, but the lower part is still open throughout the year. The downstream junction with the Dhaleshwari fluctuates from time to time according to changes in the position of the latter river; at present it lies about 3.22 km southwest of Fatullah. Its course by Dhaka is stable, fixed by the resistant clays marking the southern edge of the Madhupur tract. (Banglapedia, 2015).
Due to Industrial effluent, untreated sewage, domestic wastewater (human, food and factory waste), rivers water body becomes toxic pollution. In the dry season, the dissolved oxygen (DO) level becomes very low. The pollutants have dissolved all Biochemical Oxygen Demand (BOD) in the bank of the river Buriganga and its call biologically dead river like a septic tank. There is no fish or aquatic life in this river apart from zero oxygen survival kind of organisms.
According to the UNB, water experts Prof Ainun Nishat and Buet Prof Md Mujibur Rahman and green activists Poribesh Bachao Andolon (POBA) Chairman Abu Naser Khan and Bangladesh Paribesh Andolan (BAPA) General Secretary MA Matin also said it is not possible to fully improve the water quality of the Buriganga without preventing pollution by other industries, Dhaka Wasa and city corporation.
Prof Rahman, who has long been monitoring the Buriganga water pollution, said: "Over 60,000 kgs of BOD is dumped into the Buriganga every day from industrial and domestic sources through the drainage system and there's no effective effort in sight to reduce it."
Abu Naser Khan said the water flow of the Buriganga River has increased as this rainy season has witnessed huge amount of rain, contributing to a slight improvement of its water quality. The POBA chairman said there are two major challenges stopping both point and nonpoint sources of pollution and encroachment of the rivers to bring life back to the Buriganga and other rivers surrounding the capital.
In the first four months of 2012, the Dissolved Oxygen (DO) level was almost zero at all points of the Buriganga. In 2011, the DO level varied from 0.1 to 5.1 milligrams per litre (mg/l), according to a report of the Department of Environment (DoE).The latest DoE test found the level of average DO in the Buriganga water was 0.1 in the first two months of 2017 compared to 0.00 in January and February 2016. It also found the level of BOD came down to 10.4mg per litre in January and 24.4 milligrams (mg) per litre in 2017. It was 11.5mg and 29.1mg in January and February 2016.
Turag River: Turag River is the upper tributary of the Buriganga, a major river in Bangladesh. The Turag originates from the Bangshi River, the latter an important tributary of the Dhaleshwari River, flows through Gazipur and joins the Buriganga at Mirpur in Dhaka District.
Turag is one of the most important rivers in the capital city of Dhaka in Bangladesh which is used for various purposes and has a great influence on the economic, environmental, agricultural and industrial growth of the city as well as the country. Turag River originates from the Bangshi River, latter an important tributary of the Dhaleshwari River, flows through Gazipur and joins the Buriganga at Mirpur in Dhaka. Most of the industries are growing enormously on the bank of the river.
The Turag River is the upper tributary of the Buriganga, a major river in Bangladesh. The most pollution sources of Turag river water are various consumer goods industries (soap and detergent), garments industries, pharmaceuticals industries, lots of tanneries, dyeing industries, aluminum industries, battery manufacturing, match industries, ink manufacturing industries, textile, paint, iron industries, pulp and paper factories, chemical factories, frozen food factories and Steel workshop etc. Most of the industries discharge their effluents directly or indirectly into the Turag River without any treatment causing pollution of the surface water. Moreover, many sewerage and municipal sewage drainage system have become a dumping ground of all kinds of solid, liquid and chemical waste that polluted the river bank.
From six locations of the Turag River during wet (Monsoon) season in 2015, water samples were collected from Birulia Bridge to Tongi Bridge. Average condition of the water quality was found: DO mg/1 5.40, COD mg/1 3.56 and BOD mg/1 0.17, according to published researchers of Department of Civil and Environmental Engineering, Uttara University, Dhaka and International Journal of Innovative Science Engineering and Technology (IJISET) vol.3 Issue 1, January 2016.
(To be continued…)
The writer is a freelance contributor