ESTIMATING THE SUSPENDED SEDIMENT CONCENTRATION IN THE UPPER PARANÁ RIVER USING LANDSAT 5 DATA: DATA RETRIEVAL ON A LARGE TEMPORAL SCALE AND ANALYSIS OF THE EFFECTS OF DAMMING

Resumo

The suspended sediment concentration SSC of the Upper Paraná River (Brazil) was strongly affected by the Porto Primavera Dam, but assessing the effects of the dam is complicated by the absence of a series of continuous SSC data. This paper aims to produce satellite estimates of SSC for the Upper Paraná River to partially address the temporal gaps in the existing SSC database and to evaluate the effects of the dam on this variable. For this aim, a total of 164 Landsat TM-5 images were processed: 29 for model generation, supported by SSC data from in situ gauging stations, and 135 for SSC retrieval. By using surface reflectance values, three models were obtained: (A) for water dominated by inorganic particles, (B) for clear waters (mixed spectral response of inorganic particles and phytoplankton) and (C) for very clear water conditions. The mean and variance of the SSC was 24.2 and 15.82 mg/l, respectively, before the construction of the Porto Primavera dam and 4.91 and 3.7 mg/l, respectively, after the completion of the dam. Additionally, the Porto Primavera dam modified the seasonal SSC pattern of the Upper Paraná River