The effect of sediment type on the relationship between reflectance and suspended sediment concentration


The use of remotely-sensed optical data to estimate the suspended sediments concentration (SSC)of water is dependent upon the correlation between SSC and reflectance. The strength of this relationship was hypothesized to vary with sediment type, as it is known that sediments, when dry, differ in their particle size distributions, colour and therfore reflectance properties. To test this were reflectance of pure water with four concentrations of white clay and red silt were measured in the laboratory using a spectroradiometer. The correlation between SSC and reflectance varied with wavelenght and sediment type. For white clay the correlations were very high ( 0.98)in visible and near-infrared wavelenghts but for the red silt was lower ( 0.8)in blue wavelenghts increasing to much higher levels ( 0.98)in blue/green and longer wavelenghts. It was concluded that sediment types can affect the strenght of the correlation between SSC and reflectance and that this will be noticeable at shorter wavelengths.

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