Water Quality Analysis by Digital Chromaticity Mapping of Landsat Data

Abstract

SUMMARYDigital chromaticity analysis of LANDSAT CCT (computer compatible tapes) data with the IMAGE-100 system is a rapid and convenient method for investigating water quality. The chromaticity transformation involves ratio normalization by total radiance, which enhances and facilitates water colour monitoring and analysis. Radiance noise of equal proportions in all bands is removed by the chromaticity transformation, and residual chromatic effects of other noise are easily perceived on a chromaticity diagram. Chromaticity loci have been defined for pure water, suspended solids, chlorophyll, bathymetry, dry vs. wet sand, snow, ice, air pollution, haze, and clouds of variable thickness. A correlation coefficient of r = 0.96 (p < 0.001) has been obtained, after graphical adjustment for varying atmospheric conditions, for multi-date sampling of suspended solids in the Minas Basin, Nova Scotia. A practical LANDSAT IMAGE-100 chromaticity analysis system for water quality monitoring at relatively low cost can now be developed.