Eduardo Felix Justiniano, Edimilson Rodrigues Santos Junior, Breno Malheiros de Melo, Gustavo Paixão Menezes, Rúbia Gomes Morato, Marcel Fantin, Julio Cesar Pedrassoli, Marcos Roberto Martines, Fernando Shinji Kawakubo

This paper proposes a modification of MNDWI called Rescaled Water Index (RWI), aiming to enhance the delineation and performance of water body mapping in urban areas using satellite imagery. To evaluate the effectiveness of the proposed index, we compare its performance in mapping water surfaces (WSs) in different cities in South America with the results obtained by other well-known water indices in the literature (namely, NDWI, MNDWI, AWEIsh, and AWEInsh). We utilized images from the Sentinel satellites (2A and 2B), all acquired in June 2021, focusing on cities located south of the Tropic of Capricorn to obtain images with the highest incidence of shading, whose spectral response complicates the mapping of WSs without commission errors. In this scenario, the present study revealed that selecting the best single index for mapping all WSs is an arduous task, as their performances varied across the analyzed locations. Overall, the performance of the indices, evaluated by partial receiver operating characteristic curve (pROC) analysis and non-water misclassification point restrictions, revealed quite close but different results, especially considering RWI, NDWI, and MNDWI. In the six areas analyzed, RWI outperformed in three. Additionally, when considering the results for all the cities, RWI outperformed in all the analyses. Such results, therefore, are interpreted as an essential contribution to water body mapping, considering its practical applications in environmental monitoring and water resource management in urbanized areas.