Water quality assessment with simultaneous Landsat-5 TM data at Guanabara Bay, Rio de Janeiro, Brazil

Abstract

This study aims at determining relationships between water quality parameters and digital data from the Landsat-5 Thematic Mapper (TM). The study area was the Guanabara Bay, in Rio de Janeiro, Brazil. Water samples were collected on two dates, coincident with Landsat passages, and when different tide conditions were present at the Bay. TM Bands 1, 2, 3, 4, and 6, band ratios 1 3 and 2 3 , and principal component analysis of TM Bands 1–4 were compared with in situ measurements and laboratory analysis of water samples. Some water quality parameters were very well correlated with the digital remotely sensed data, especially during high tide: for instance, iron and manganese concentrations in total suspended solids; salinity and Secchi depth; temperature and Secchi depth; temperature and total suspended solids; total suspended solids and Bands 4 and 6; Secchi depth and Bands 4 and 6; temperature and Band 6. Lower correlation coefficients, although also significant, were found for the low tide condition. No correlation was found with chlorophyll-a concentrations. TM data were shown to be adequate to analyze temperature, Secchi depth, total suspended solids, and iron and manganese contents in the total suspended solids for the polluted estuary area studied.