Retrieval of chlorophyll a and suspended solid concen-trations by hyperspectral remote sensing in Taihu Lake,China

Chlorophyll a (chl-a) and suspended solid concentrations are two frequently used water quality parameters for monitoring a lake. Traditional measurement of chl-a and suspended solids, requir-ing laborious laboratory work, which is often expensive and time consuming. Hyperspectral re-mote-sensing measurement provides a fast and easy tool for estimating water trophic status. In situ hy-perspectral data on March 7–8, July 6–7, September 20 and December 7–8, 2004 and the corresponding water chemical data were used to regress the algorithm of water quality parameters. Results showed that the peak of water leaving radiance around 700 nm (R700) varied proportionally with chl-a concentration, and moved to infrared when algal bloom occurred. The reflectance ratio of R702/R685 was well correlated with chl-a when water surface in no algal bloom case and the correlation coefficient was better if absorp-tion of phycocyanin was considered. The reflectance ratio R620/R531 was highly correlated to the concen-tration of suspended solids. The relationship between suspended solids and other band groups were also compared. Secchi disk depth could be calculated by non-linear correlation with suspended solids concen-tration.