Water quality monitoring in estuarine waters using the landsat thematic mapper

Abstract

Due to the impacts of rural and urban development on southwestern Australian estuaries, and the general isolation of these water bodies, there is a need to develop water quality monitoring systems that are both repetitive and cost-effective. The literature suggests that Landsat Thematic Mapper (TM) has spectral and spatial characteristics that are suited to monitoring small coastal water bodies. This study examined the potential for the satellitebased TM sensor to serve as a regular monitoring tool. Atmospherically corrected TM digital data acquired on four dates over summer 1990 / 91 and concurrent field measurements collected at the time of the satellite overpass over the Peel-Harvey Estuarine System (32° 30'S lat. 115° 40'E long.) were used to obtain multitemporal, empirical algorithms for predicting pigment concentration, Secchi disk depth (SDD), and salinity. Highly significant, predictive algorithms were developed for these parameters. It is concluded that Landsat TM has the resolution and accuracy to be a potentially very useful monitoring tool. However, cloud cover and delays in data acquisition seriously diminish its usefulness for monitoring on anything less than a seasonal basis. Laboratory-based radiometric studies also indicated that Landsat TM was unlikely to be useful in determining the taxonomic composition of phytoplankton blooms in coastal waters.