Abstract: Secchi disk transparency is a measure of the transparency of a water body, and it is influenced by the abundance of organic and inorganic particulate and dissolved matter. Secchi disk transparency may be determined from hyperspectral remote sensing data. The advantage of high spectral resolution reflectance data (hyperspectral data) is the possibility of quantitative analysis due to diagnostic absorption bands. This study was conducted to establish correlations between hyperspectral reflectance spectra and secchi disk transparency in Nanhu Lake, Changchun．Reflectance spectra were measured from June to September in 2004, with ASD FieldSpec spectrometer. Based on in situ water sampling and reflectance measurements, algorithms have been developed. The single band R520nm, the spectra ratio of (R530-R860)/(R740-R860), and the reflectance first-derivative of 610nm, which showed a linear relationship, were all found to be significantly correlated with secchi disk transparency. The algorithms have been applied to evaluate secchi disk transparency, and the determination coefficient R2 gained using the first-derivative of 610nm was higher than that gained with other two models. The validation using independent in situ reference data showed RMSE of 4.97–9.68 m. There is satisfactory correspondence between hyperspectral models and secchi disk transparency, and it is possible to monitor the water quality of Nanhu Lake using hyperspetral remote sensing data.

Key words: Transparency, Secchi Disk, Hyperspectral, Model, Nanhu Lake