Analysis of the Taquari Megafan through radiometric indices

• Published in: Journal of South American earth sciences 2022-11, Vol.119, p.104034, Article 104034
• Main Authors: Pereira, Luciana Escalante, Lo, Edward Limin, Paranhos Filho, Antônio Conceição
• Format: Article
• Language: English
• Subjects: MNDWI; NDWI; Pantanal wetland; Radiometric indices
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2022.104034

The complex landscapes of tropical monsoonal lowlands make water resource estimates difficult, given sparsely distributed monitoring networks. Satellite radiometry has facilitated increased access to environmental data. Here, we use radiometric indices to analyze the Taquari megafan and identify features of the Pantanal subregions that characterize it. Recent periods of strong droughts and floods were selected in the region for statistical analysis using the following radiometric indices: NDWI-Gao, NDWI-McFeeters and MNDWI. The behavior of the NDWI-Gao showed that the Paiaguás and Nhecolândia subregions had similar vegetation moisture values in 2011 and 2012, but surprisingly, the two subregions did not attain maximum values of vegetation moisture higher than values in the Taquari subregion during severe flooding in 2011. The Paiaguás and Nhecolândia subregions were more correlated in terms of vegetation moisture than open water features. The MNDWI analysis of the Taquari subregion, however, revealed the highest levels of liquid water in the vegetation and the highest values for water bodies/courses. The permanently flooded state of the Taquari subregion may explain why the vegetation appears to be moister in the NDWI-Gao. The NDWI-Gao data were consistent for dry vegetation in 2020, recording values of −0.7, while other dry periods such as 2010 and 2013 recorded values of −0.4. The vegetation responded quickly to the alternation of drought/flood cycles, registering high values of liquid water content in the period 2011–2012 and reduced values in 2012–2013. •The choice of radiometric index affects the distinction of mapped water features.•MNDWI accurately identifies water bodies and channels.•NDWI-Gao was very responsive to alternating cycles of wetter and drier vegetation.•The vegetation that makes up the Taquari megafan is unevenly affected by drought.