Stream Sediment Rate Estimation using Optical Sensing

Sediments carried by the rivers cause capacity reduction in reservoirs which impacts the hydro-power generation, effective irrigation management for communities and agricultural sectors. Cost effective measurement tools for accurate prediction of the sedimentation rate is vital in our country. This paper describes the development of an optical sensing based sedimentation rate estimation mechanism. Correlation between Total Suspended Solid (TSS) and turbidity (NTU) is developed during sensor calibration stage. Empirical data samples (from the Uma oya limb to Rantambe reservoir in Sri Lanka) were collected over a period of 25 days and used for calibration. Under laboratory conditions, the results from the linear regression analysis revealed that the relationship of the Turbidity and the TSS is 1NTU is equal to 1.5 mg/l. The ISO 7027 Turbidity Technique method was used to determine the concentration of suspended particles in water samples and tested using the optical sensing mechanism. Correlation between turbidity and sensor value was developed and the quantity of sediment in mg/s was determined. Using the optical sensing mechanism, the results evidenced reasonably accurate for short term sediment rate estimation.