Retrieval of water quality parameters by hyperspectral remote sensing in lake TaiHu, China

Monitoring and restoration the water quality of lake need proper water quality parameters. Traditional measurement of water quality, requiring laborious laboratory work, is expensive and time consuming. Hyperspectral measurement can offer fast and easy way for estimating trophic status. Hyperspectral data on 7-8, March, 2004 and water chemical data from 1997 to 2003 was used for retrieval of water quality parameters. The quantification of spectra with water quality parameters: chlorophyll a, suspended solids, total nitrogen(TN), total phosphorus(TP), chemical oxygen demand(COD), secchi depth(SD) were regressed. Results showed that the reflectance ratio of R702/R685, R620/R531 and R554/R675 had high correlations with the concentration of chlorophyll a, suspended solids and total phosphorus respectively; TN, COD can be calculated from TP or Chl a for good relations between them; SD is negatively correlated with suspended solids concentration, total phosphorus (TP) (less than 0.25 mg/L) linearly correlated with logarithm chlorophyll a concentration; trophic status index (TSI) exponentially correlated with COD concentration.