Pollution in the Buriganga River, Bangladesh
A dated StudyForA example of river pollution, monitoring and management in Dhaka. Confirm that your centre selected the Buriganga before using it as your required river example.
Exam scope and assessment notes
Cambridge IGCSE (9–1) Geography 0976, 2027–2029 syllabus, Topic 1.3.9. The syllabus does not prescribe one universal set of named detailed specific examples: centres select places suited to their learners. Sixteen optional StudyForA evidence packs now cover all sixteen example objectives, but the centre's choices are unconfirmed. Match each pack to your centre's chosen place and replace any mismatch before treating the course as complete. Original StudyForA explanations and self-check practice are not Cambridge papers, official grades or teacher-marked coursework. Map, graph and written answers are not automatically assessed. Paper 4 practice uses supplied or invented data and cannot certify safe fieldwork, equipment use or real data collection. Centre-set coursework and specialist teacher review remain pending. This is the separate 9–1 qualification. Cambridge limits this 9–1 syllabus to certain zones: in June it is available in Administrative Zone 3 and for centres in Oman and the UAE; in November it is available in Zone 3 only. Confirm the exam series and entry with your centre. Cambridge also says an entry cannot be switched from 9–1 to A*–G after the entries deadline.
Before you begin
- No previous Geography course is assumed. Use the supplied map, data or scenario; distinguish observation from explanation and support conclusions with evidence.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What can a DO reading of 0.0 mg/L suggest for aquatic organisms at the sampled location?
What you will learn
- Locate the Buriganga in the Dhaka river system
- Explain how sewage, industrial effluent and solid waste affect river water
- Interpret dated dissolved-oxygen and BOD monitoring evidence
- Evaluate source control, enforcement, treatment and river restoration
Several urban sources affect one river
The Buriganga flows along Dhaka's southern edge and connects with the wider river system. The Bangladesh Department of Environment's monitoring of ten sites in 2021 identified direct discharges of untreated industrial effluent, municipal waste and tannery waste, as well as lower dry-season river flow, as causes associated with depleted dissolved oxygen (DO). Sewage and solid waste are additional pressures in Dhaka's connected waterways. Pollution can therefore come from many points and sectors; moving one industry does not remove every source.
In the Department of Environment's 2021 measurements, DO reached 0.0 mg/L at Bosila Bridge in March. Biochemical oxygen demand (BOD), a measure of oxygen used as organic matter decomposes, reached 40 mg/L at Mirpur Bridge in December; the report compares this with its stated fisheries standard of 6 mg/L. These are single-site, dated readings, not a current river-wide average. The report says samples were not collected in October and November, so seasonal coverage is incomplete.
Pollution affects ecosystems and people
When untreated organic waste decomposes, it can consume oxygen in the water. Low DO makes it harder for aquatic organisms to survive; water-quality problems can damage freshwater ecosystems, fisheries and river uses. A World Bank environmental review of Dhaka rivers reported that moving tanneries away from the Buriganga improved some indicators, including BOD, COD and electrical conductivity, but DO did not improve significantly because municipal sewage, other industrial pollution and other sources remained. The example shows why source control must include both factories and city wastewater.
Contaminated water and poor sanitation can expose nearby communities to health risks and reduce quality of life. Pollution also affects livelihoods and navigation when waste accumulates in waterways. Impacts differ by location, exposure and water use; students should support claims with evidence rather than assume every resident has the same risk.
Management must stop waste at its source
The Department of Environment monitors water and inspects discharge sources. In an August 2026 parliamentary statement, the environment minister reported that 101 of 155 industries along the Buriganga that were required to have effluent treatment plants (ETPs) had installed them; nine establishments had been shut after enforcement operations from January 2025 to July 2026. Installation is not proof that a plant operates effectively, so inspection, operating records and water-quality monitoring matter.
The same 2026 statement described a coordinated plan to identify industrial sources, require working ETPs, close unauthorised drains, remove waste from canals and drains, improve sewage treatment and restore water flow. A World Bank programme approved in February 2026 plans support for sanitation and solid-waste services, real-time pollution monitoring and restoration plans for four Dhaka rivers. These are announced or funded plans, not completed water-quality outcomes.
Tannery relocation illustrates a mixed result: some indicators improved, while dissolved oxygen remained poor because other discharges persisted. Dredging or removing visible waste can improve navigation and clear accumulated material, but it will not keep a river clean if sewage and industrial effluent continue to enter it. Sustainable management combines treatment at the source, enforcement, sewerage and solid-waste services, monitoring, community cooperation and protection of river flow.
Evaluate change with comparable evidence
Compare measurements from the same locations, seasons and methods over time. DO and BOD show different aspects of water quality, and a single reading cannot represent every part of a river. Separate actions already reported from future plans; then judge whether discharge has fallen and river conditions have improved for ecosystems and communities.
Sources for this lesson
- Cambridge IGCSE (9–1) Geography 0976 syllabus, 2027–2029 · objective 1.3.9
- Bangladesh Department of Environment · Draft final river-water-quality report with 2021 Buriganga monitoring
- World Bank · Dhaka Rivers Ecological Restoration environmental and social review
- Bangladesh Sangbad Sangstha · Parliamentary statement on the Buriganga action plan, 30 August 2026
- World Bank · Metro Dhaka Water Security and Resilience Program, 10 February 2026
Pause and explain
Why did some water-quality measures improve after tannery relocation while DO did not improve significantly?
Worked example
At one Buriganga site, DO was recorded at 0.0 mg/L and BOD at another site reached 40 mg/L in 2021. Explain what each measure indicates and why those values cannot be treated as a current river-wide average.
Show the worked solution
- DO is oxygen dissolved in the water; organisms need it to survive.
- BOD estimates oxygen demand as organic material decomposes; higher BOD can contribute to lower DO.
- Keep the measurement sites, months, year and incomplete sampling coverage in the conclusion.
Answer The zero DO reading at Bosila Bridge in March 2021 indicates no measurable dissolved oxygen in that sample, while the 40 mg/L BOD at Mirpur Bridge in December indicates high oxygen demand there. They came from different sites and months in a 2021 monitoring report, which also lacked October and November samples, so neither is a current river-wide average.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Use the 2021 monitoring readings to describe the Buriganga's water-quality problem. Explain DO and BOD and include one limitation of the evidence.
Give me a hint
Compare the measurements carefully: they came from different sites and months.
Compare my reasoning
- DO was 0.0 mg/L at Bosila Bridge in March 2021, so the sample had no measurable dissolved oxygen.
- BOD reached 40 mg/L at Mirpur Bridge in December 2021, indicating high oxygen demand as organic material decomposes.
- These readings are not from the same site or month, and the report has no October or November samples.
The Department of Environment recorded 0.0 mg/L DO at Bosila Bridge in March 2021 and a BOD of 40 mg/L at Mirpur Bridge in December. Together they indicate serious water-quality concerns at those samples, but the different sites and months and missing October and November data prevent them from representing a current river-wide average.
Look for these in your work
- DO and BOD interpreted accurately
- Sites and dates retained
- Sampling limitation explained
Explain how pollution sources affect the Buriganga and its users. Use evidence from monitoring or the tannery-relocation example.
Give me a hint
Connect a source to a water-quality change, then explain an ecological or human consequence.
Compare my reasoning
- Untreated sewage, municipal waste and industrial effluent add pollutants; reduced flow can concentrate some impacts in the dry season.
- Decomposing organic waste uses oxygen, raising BOD and potentially lowering DO.
- The World Bank review found some indicators improved after tannery relocation but DO did not improve significantly because other pollution remained.
- Low oxygen can harm aquatic life; polluted water also creates risks for people who depend on the river or connected waterways.
Untreated industrial and municipal discharges add pollutants to the Buriganga, and lower dry-season flow can worsen their concentration. Decomposition raises oxygen demand and can reduce DO, stressing aquatic life. After tannery relocation some measures improved but DO did not improve significantly, showing that other sources such as sewage still need control. Human impacts depend on exposure and water use.
Look for these in your work
- At least two sources identified
- A water-quality process explained
- Ecological or human impact linked to evidence
Evaluate whether a plan focused on dredging and closing illegal drains is enough to restore the Buriganga. Recommend what else must be measured.
Give me a hint
Separate removal of accumulated waste from prevention of new discharges and from evidence of recovery.
Compare my reasoning
- Dredging or waste removal can clear material and support navigability but does not stop sewage or factory effluent entering the river.
- Closing unauthorised drains helps, but effective ETP and sewage-treatment operation, solid-waste collection and enforcement also matter.
- Measure discharge sources, ETP operation, DO and BOD at fixed sites and comparable seasons, alongside ecosystem and community outcomes.
- Treat announced plans as intended action until results show cleaner water.
Dredging and closing illegal drains can remove accumulated material and one route of discharge, but the river will remain under pressure if sewage, industrial effluent and solid waste continue to enter it. A stronger plan requires working ETPs and sewage treatment, reliable waste collection, enforcement and repeated water-quality checks at comparable places and seasons. Announced actions should not be described as restored water quality until monitoring confirms improvement.
Look for these in your work
- Benefits and limits distinguished
- Source control measures added
- A suitable monitoring plan recommended
Common mistakes
- Treating the Buriganga as a single uniform sampling point
- Mixing up BOD and dissolved oxygen
- Presenting 2021 measurements as current conditions
- Claiming tannery relocation solved all pollution
- Treating ETP installation or a funded plan as proof of water-quality improvement
- Suggesting dredging alone will stop new pollution
- Using this optional case without checking your centre's selected river
What can you explain now?
What does BOD estimate: oxygen dissolved in a sample, or oxygen demand as organic matter decomposes?
Compare with the explanation
Oxygen demand as organic matter decomposes
DO measures oxygen in the water; BOD estimates the oxygen used during decomposition.
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Make it stick
Name two pollution sources, one dated DO or BOD measurement, and two complementary ways to manage pollution in the Buriganga.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.