Water quality study using Oceansat imagery over Penang Island

Environmental monitoring through the method of traditional ship sampling is time consuming and requires a high survey cost. This study uses an empirical model, based on actual water quality of total suspended solids (TSS) measurements from the Penang Island, Malaysia to predict the TSS values based on optical properties of Oceansat satellite digital imagery. The proposed algorithm is based on the reflectance model that is a function of the inherent optical properties of water, which can be related to its constituent´s concentrations. Water samples were collected simultaneously with the airborne image acquisition and later analyzed in the laboratory. Water sample´s locations were determined by using a handheld GPS. The digital numbers for each band corresponding to the sea-truth locations were extracted and then converted into radiance values and reflectance values. The reflectance values were used for calibration of the water quality algorithm. The efficiency of the proposed algorithm was investigated based on the observations of correlation coefficient (R) of 0.98 and root-mean-square deviations (RMS) of 8.5121 mg/l with the sea-truth data. This algorithm was then used to map the TSS concentration over Penang Island, Malaysia. The TSS map was color-coded and geometrically corrected for visual interpretation. This study indicates that TSS mapping can be carried out using remote sensing technique of the satellite digital photography system over Penang Island, Malaysia.