Statistic analysis of suspended sediment concentration in offshore waters based on field measurement of reflectance hyper-spectral

Remote sensing measurement with field spectrometer was carried to acquire the reflectance hyper-spectral data of the case II waters in the Yangtze River estuary. At the meantime, the surface water samples at depth of 0.5 m were bottled for suspended sediment concentration measurement and analyzed in laboratory. The current velocity was also measured synchronically with the spectral measurement. It was found that the reflectance amplitudes vary with the suspended sediment concentration. Two peaks exist in yellow-green (560-720 nm) band and near-infrared band (810 nm) respectively. At wave length above 650 nm a strong correlation exists between spectral reflectance and suspended sediment concentration. In the interval of wave length from 690 nm to 900 nm the reflectance is sensitive to variation of sediment concentration with correlation coefficient higher than 0.75. Based on the least-square method, the exponential relationship between spectral reflectance and sediment concentration as well as the power function relationship between spectral reflectance ratio and sediment are established. It is found that the exponential relationship for wave length at 670 nm and 715 nm has higher correlation coefficient. But the quadratic polynomial relationship for spectral reflectance ratio at wave length at 810 nm and 690 nm has better accuracy for estimation of sediment concentration.