ABSTRACT Pantanal da Nhecolândia is one of the most well-preserved areas in the State of Mato Grosso do Sul. Located in the southern part of the Taquari River megafan, it is in tectonic contact with the fault escarpments of the Maracaju-Campo Grande plateaus to the east and with the fault escarpments of the Bodoquena plateau to the west, which continue to north. To the south and to the north, the limits are marked respectively by the lineaments of the Negro and Taquari Rivers. Nhecolândia is characterized by the existence of at least 17,631 lagoons, 17,050 (96.70 %) of which are of fresh water (baías) and 577 (3.3 %) of salty water (salinas). Studies based on (Landsat) satellite images and use of free software (QGIS, version 2.8.3) and GIS (Geographic Information Systems) revealed that the major axes of the lagoons are aligned along two directions, NE (62.49 %) and NW (37.51 %), with modes concentrated between N30-40E and N30-40W, suggesting in both cases the role played by tectonic control (neotectonics) in their formation. Evidences of fluvial origin are presented for these groups of lagoons, as well as for their tectonic alignment.

Resumo: A aplicação dos sensores remotos orbitais para identificação e delineamento de corpos d’água foi avaliado neste estudo. Para isto, foram utilizadas fotos aéreas como referência para obtenção de área de três corpos d’água em São Gabriel do Oeste, MS- Brasil, sendo analisados sete sensores comumente aplicados em estudos ambientais: ALOS-AVNIR; CBERS 2B-CCD; CBERS 2B-HRC; IRS P6-LISS3; LANDSAT-TM; LANDSAT-ETM+ e LANDSAT-OLI. As imagens foram analisadas com a banda do Infravermelho Próximo, além disso, técnicas de processamento digital foram aplicadas em alguns sensores. As técnicas de processamento digital utilizadas foram à fusão de imagens, a composição falsa-cor e a correção radiométrica (pré-processamento), sendo a fusão e a correção radiométrica aplicadas em três sensores. A composição colorida só não foi realizada no sensor HRC. Dos corpos d’água analisados, as imagens do sensor CCD foram as que apresentaram maior valor de imprecisão, chegando a um valor de 192% para o corpo d’água #3 na imagem CCD sem processamento digital. Considerando as propriedades da banda espectral infravermelho próximo, esperavam-se dados mais precisos das análises feitas com a mesma. Entretanto, as análises feitas em composição colorida obtiveram melhores percentuais de precisão do que as analisadas somente com a banda do infravermelho próximo.

Abstract: The application of orbital sensors to identify and delineate water bodies was evaluated in this study. Reference aerial photos were used to measure the surface area of three water bodies in São Gabriel do Oeste, MS, Brazil and assess seven sensors commonly used in environmental studies: ALOS-AVNIR, CBERS 2B-CCD, CBERS 2B-HRC, IRS P6-LISS3, LANDSAT-TM, LANDSAT-ETM+, and LANDSAT-OLI. The images were analyzed with the near infrared (NIR) band, and digital processing techniques including image fusion (spatial enhancement), false-color composition, and pre-processed radiometric correction were applied to some sensors. Image fusion and radiometric correction were applied to three sensors; only color composition was not conducted on the HRC sensor. In all water bodies analyzed, images from the CCD sensor showed the greatest values of imprecision, reaching 192% for Water Body #3 without digital processing. Considering the spectral properties of the NIR band, we expected more precise data from the analyses using this spectral range. However, color composite analyses obtained greater percent precision compared with analyses that only used the NIR band.