17-Water quality assessment in Lakes using remote sensing

Abstract

Water quality of the fresh surface water sources like lakes and reservoirs are degraded by human activities. Industrial effluents and domestic sewage with high organic wastes are the main source for pollution in urban lakes. Monitoring the water quality periodically by field measurements is uneconomical. With recent and planned launches of satellites with improved spectral and spatial resolution sensors, greater application of remote sensing techniques to assess and monitor water quality parameters are possible. Multispectral or Hyperspectral images from the remote sensing satellites can be used for assessment of spatial and temporal variation in water quality. Chemical parameters like suspended chlorophyll, suspended minerals, colored dissolved organic carbon, secchi depth and turbidity can be derived. The paper attempts to give a conceptual idea of developing a water quality assessment model for a particular satellite sensor. Optical properties of the water and its spectral response pattern in various wavelength regions for different type of pollutants are to be determined. Water sampling should be carried at some fixed points and the spectral reflectances of the same locations are obtained through ground truth radiometer. Quality parameters of the collected samples will be analyzed experimentally to find the pollutant levels. Relationship between the pollutant levels and its spectral response in various wavelength regions will be established. Multispectral or Hyperspectral data obtained from the satellite will be corrected for atmospheric corrections and the same will be calibrated with the radiometric values obtained from the ground truth radiometer.