Reading: Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka


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Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka


T. N. Wickramaarachchi ,

University of Ruhuna, LK
About T. N.
Senior Lecturer, Department of Civil & Env. Engineering
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H. Ishidaira,

University of Yamanashi, JP
About H.
Associate Professor, Interdis. Graduate Schoolof Medicine and Engineering
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T. M. N. Wijayaratna

University of Ruhuna
About T. M. N.
Senior Lecturer, Department of Civil & Env. Eng
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Human induced impacts on the river systems result in decrease in water quality, which is generally reflected by an increase of particulate matter in rivers. Turbidity and suspended solids are part of physical and aesthetic parameters and good indicators of other pollutants that are carried as sediment in suspension.

Study objectives were to define the relation between turbidity and total suspended solid (TSS) concentration in Gin river at Baddegama (6°11'23" N, 80°11'53" E) in developing an estimation technique for TSS load, and to reveal how turbidity and TSS load vary with the streamflow. Linear regression model developed between turbidity and TSS concentration showed strong positive correlation (R2 = 0.98). Results strongly suggest turbidity is a suitable monitoring parameter for TSS, where TSS evaluation is crucial when logistical and financial constraints make TSS sampling impractical. Mean daily TSS loads in the Gin river at Baddegama during 2000-2009 were modeled in the study using load-discharge rating curve for estimating constituent loads in rivers. Relatively strong relationship (R2 = 0.85) was observed between the rating curve estimated and observed TSS loads. Estimated TSS loads were having substantial temporal variation and generally peaked in May and October, coinciding with the high flows. Turbidity which ranged between 2.3 NTU (Nephelometric Turbidity Units) and 195 NTU significantly exceeded the maximum permissible limits of the water quality standards set for the potable water as well the inland waters of Sri Lanka. Since there was no specific water quality standards developed for TSS in Sri Lanka to compare with the present values, TSS concentrations were compared with the permissible total solid levels. TSS concentrations which ranged between 2.4 mg/l and 204 mg/l were well below the maximum permissible total solid level cited in the Sri Lanka standards for potable water. Understanding on this turbidity and TSS characteristics in Gin river flow might be useful for water managers and planners to adjust operations accordingly at water treatment plants.


ENGINEER, Vol. 46, No.04, pp. 43-51, 2013

How to Cite: Wickramaarachchi, T.N., Ishidaira, H. and Wijayaratna, T.M.N., 2013. Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka. Engineer: Journal of the Institution of Engineers, Sri Lanka, 46(4), pp.43–51. DOI:
Published on 21 Oct 2013.
Peer Reviewed


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