Mapping the existing water reservoirs in the Negro River Watershed, Rio Grande do Sul, Brazil in 2014
ISBN 978-85-88783-11-9
Authors
1Schafer, A.; 2Branco, V.; 3Lucas, E.; 4Richa, C.
1FEDERAL UNIVERSITY OF PAMPA Email: alexandro.schafer@unipampa.edu.br
2FEDERAL UNIVERSITY OF PAMPA Email: viviantabranco@gmail.com
3FEDERAL UNIVERSITY OF PAMPA Email: evertonlucas1990@hotmail.com
4FEDERAL UNIVERSITY OF PAMPA Email: cesarhuegel@live.com
Abstract
The Negro River watershed in Brazilian territory extends approximately 3.007km², covering partially the municipalities of Aceguá, Bage, Candiota, Don Pedrito and Hulha Negra. Among the problems in the Negro River watershed, the lack of water is most prominent. Thus, the understanding and prediction of the watershed hydrology is of high importance. In the process of calibration and application of a hydrological model, it is important to verify the existence and location of water reservoirs, which can influence the water balance and, consequently, the results generated by the model. This study presents the mapping and quantification of existing water reservoirs in the Negro River watershed in Rio Grande do Sul, Brazil, covering the areas detailed above. For this study, we used remote sensing images (orbit / point 223/082), obtained by an OLI sensor of Landsat 8 in September 2014, and aggregated with supervised classification techniques. With the aim of verifying the influence of algorithms of image classification in the detection of the reservoirs, the following methods of supervised classification were applied: minimum distance, Mahalanobis distance and maximum likelihood. The results were analyzed qualitatively and quantitatively. The method of maximum likelihood showed the strongest results, obtaining a Kappa index of 0.9956. The classified image from this method was post-classified to eliminate interference between categories. Finally, the resulting post-classified image was vectored and the area of each reservoir was calculated. As a result, 264 reservoirs were mapped, which occupy an area of 82,234Km², and which comprise 2.73% of the total area of Negro River watershed.
Keywords
water reservoir; Negro river watershed; remote sensing