WATER QUALITY LIMITATION FOR TURBIDITY BASED SEDIMENT MEASUREMENT IN RIVERS

Abstract

The concentration and size of sediment particles are mainly affected flow and climate conditions, soil properties, topography, and plant cover properties. The direct water sampling method has many difficulties to represent continuous monitoring of sediment transport, especially during extreme flow conditions Turbidity based estimating of suspended sediment is widely used for river studies due to its simply and cheap using. The strong relationship between turbidity and suspended sediment concentrations has led to the use of turbidimetry to estimate sediment concentration. The use of turbidity values for SSC is an indirect method and based on to determine the statistical relationship between these values; the relationship could be linear, non-linear or polynomial. But this relation is affected by water pollution, colloids and plankton units, air bubbles and other suspended materials in the water sample rather than mineral suspended particles. In this study, Seapoint Turbidity Meter sensor was used to provide accurate, reliable, automated and continuous time series of suspended-sediment concentrations under different water quality conditions in river. The study was conducted at river conditions, and two different water qualities were considered depend on electrical conductivity and turbidity values. The first sampling point was chosen close the source of river for obtaining clear water and second one was chosen at polluted point by waste water of city. The regression analyses were applied between the sediment concentrations with the turbidity values to observe of different water quality effects and were evaluated using determination coefficient (R²) and regression equation. Sediment concentration values were varied between 0.02 and 1.12 g/l during sampling season depend on rainfall and river discharge but these values and water quality parameters were found extremely high and unstable due to pollution of waste water pollution of city.  Fairly high R² value (0.971) was obtained for first station water which has relatively clear, but week relationship (0.273) was obtained of between the sediment concentrations and the turbidity values for second station due to water pollution. This problem is important limitation for turbidity based sediment measurement, and it should be considered to more accurately estimate sediment concentration with turbidity values

Keywords

• Suspended sediment,turbidity,water pollution,environmental

References

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