Water Quality Mapping around Dhaka City - ASSESS-HKH · 2015. 12. 12. · Water quality may be a useful tool for water resources managers and decision makers involved in sustainable

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Development of an Assessment System to Evaluate the Ecological Status of Selected Rivers in the Hindu Kush-Himalayan Region” (ASSESS-HKH)

Water Quality Mapping around Dhaka City

Lower Gangetic Plains: Moist Deciduous Forest (IMO 120)

Professor M. Fazlul Bari andProfessor A.B.M. Badruzzaman

Bangladesh University of Engineering and Technology (BUET), Dhaka

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Introduction:

Rivers around Dhaka city are affected by industrial activities, municipal sewage disposal, faecal contamination, agro-chemicals and sediment loading and population pressure

Maintaining a sufficient supply of clean water for the growing population is one of the major challenges, especially in the densely populated Dhaka city.

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Sampling design

• Sampling period: April 1- April 8, 2007 (Dry season)

Rivers selected: - Turag,- Balu,- Buriganga,- Shitalakkhya and - part of Dhaleshwari.

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Sampling design

Sampling Locations: Based on reconnaissance visits and discussion with local people 20 sites on 5 rivers around Dhaka city were selected for sampling and analysis. On the western side of Dhaka city:Part of Bongshi river and Turag river from Tongi bridge upto its confluence with Buriganga.

Southern side of Dhaka city:part of Dhaleshwari river and Buriganga

Northern side of Dhaka city:Tongi khal and part of Balu river

Eastern side of Dhaka city:Balu river and part of Shitalakkhya river

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Sampling for water quality mapping

Steps followed:

• Sampling at selected sites(10 samples/site)

• Analysis of physical and chemical parameters

• Field sorting and Identification of macroinvertebrates

• Further identification of macroinvertebrates in the Laboratory

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Level of pollution based on common macroinvertebrates

No pollution to slight pollution

Moderate pollution

Severe pollution

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Site Selection Criteria

Based on Sources:

1. Point sources; e.g. industrial effluent, municipal waste etc. and

2. Non-point sources; e.g. agricultural runoff

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1) Selection of Reference SitesWater quality (WQ) Class I

2) Selection of impaired sitesWQ Class II, III, IV, V

Stressor types – Organic pollution (eg.Balu, Turag, Buriganga etc.)

Based on species abundance and richness numerical scoreswere assigned to potential water quality classes, viz.

• Class I (none to very slight organic pollution), • Class II (moderate pollution), • Class III (critical pollution), • Class IV (heavy pollution), and • Class V (very heavy to extreme pollution).

Site Selection Criteria

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Pollution source

Point source Non-point source

Industrial effluent Municipal waste

Textile

Tannery

Dyeing

Agricultural runoff

Others

Others

Pollution Sources

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Source of Pollution

Industrial wastewater discharge in Turag river

Sewage discharge in Balu river

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Source of Pollution

Waste materials dumping in Turag river Sewage discharge in Bongshi river

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Sampling for water quality mapping

Sampling in Dhaleshwari river Sampling in Balu river

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Sampling in Turag river Sample sorting at Shitalakkhya river

Sampling for water quality mapping

14Sample sorting at Balu river Identification of macroinvertebrates

at Turag river

Sampling for water quality mapping

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Electrical conductivity measured at field

Field measurement of dissolved oxygen

Chemical parameters measured for water quality mapping

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Water Quality Class Per Site

River Site Water Quality ClassBalu1 Demra IV

Shitalakkhya 2 Demra III

Balu 3 Lanchata V

Balu 4 Ichhapura IV

Turag 5 Bindan VTurag 6 Thermog IV

Balu7 Dhopapara III

Balu 8 Pipulia III

Turag 9 Istema field IVTurag10 Tiebpur III

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Water Quality Class Per Site

River Site Water Quality ClassTurag11 Chapai IITurag12 Ashulia IV

Buriganga13 Postogola VDhaleshwari14 Ferighat IIIDhaleshwari15 Charkundolia IIIDhaleshwari16 Dharmaganj IVShitalakkhya17 Katchpur IVTurag18 Baimile VTurag19 Boroibari IIIBongshi Sutrapur III

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Water Quality Mapping aroundDhaka city

Five colors have been used to denote the WQ Classes

blue for water quality Class Igreen for water quality Class II yellow for water quality Class III orange for water quality Class IV and red indicates water quality Class V

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River Water Quality Map around Dhaka City

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Conclusion

Water quality may be a useful tool for water resources managers and decision makers involved in sustainable management and utilization of river resources.

Remarks:Screening protocol works better as visual examination corroborates the findings.NEPBIOS based scoring may not be similar to the screening protocol as species

diversity is different in each country.US approach based on order of macroinvertebrates may be compared with the

ASSESS-HKH approachPhysico-chemical parameters pH, BOD5 , etc. are not reflected in the water quality

map.Seasonal variation of the WQ should be addressed.

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