ed as
Novo, Evlyn
Table 2 — Proportion of Pixels classified in the different water type classes.
Selected River Sections Background Black Water Clear Water White Water
(^) (7) (70) (6)
100m | 258m | 100m | 258m | 100m | 258m | 100m | 258m
Santo António do Icá 86.88 85.47 - - 0.42 0.35 12.70 14.18
Mamiá 66.64 54.21 - 4.79 11.67 12.00 21.69 29.00
Manaus 44.10 43.43 13.99 15.59 2.38 7.64 39.53 33.34
Madeira 51.58 50.39 6.79 6.20 2.77 4.66 39.45 38.16
Trombetas 67.42 47.93 - 10.53 9.17 14.63 23.41 26.91
Tapajós 28.68 32.13 2.25 4.80 35.23 30.45 33.84 32.60
Xingu 43.51 47.7 15.91 17.50 15.33 17.50 25.24 21.85
Reaches dominated by larger rivers of white water were not deeply affected by changes in resolution. Those are the
cases of Santo Antônio do Iça, where classification results differ at about 15 %. At the Manaus reach, the change in
resolution affected the discrimination between clear water and white water pixels. White water pixels were classified as
clear water probably as an artifact from the adopted resampling scheme.
Results in Table 2 show that in most of the reaches the White Water pixels are coherently classified at both spatial
resolutions. They differ in less than 10% except for Mamiä reach where there is a 25% difference between the
resolutions.
Based on the preliminary results one can support the use of WFI/CBERS images for mapping water types at the
Amazon River basin. The accuracy of the results must be better assessed because they will vary according to the
complexity of the reaches under study.
CONCLUSIONS
The experiment allows to conclude that the 258 m spatial resolution of the WFI/CBERS data is not a strong limitation
to map the water pathways from the river to the floodplain. Although the resolution affects the discrimination between
the three water types at certain reaches, they do not affect the mapping of White Water, allowing the detection of water
path from the white water rivers to the floodplain.
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