Índice de Água por Diferença Normalizada para o monitoramento de seca em açudes no semiárido do Nordeste Brasileiro

Abstract

The drought phenomenon can be considered a natural disaster whose occurrence is historical in the Northeast region of Brazil. The Normalized Difference Moisture Indices or Water Indices search for remote sensing processes, which are tools to delimit surface water bodies that can highly contribute to water management by optimize planning and alleviate water scarcity disturbances. These indices are based on the premise that the ratio between the difference and the sum of bands, with high and low spectral water responses, provides objectivity and dynamism in surveys of water bodies' surfaces. The purpose of the study is to present and evaluate the performance of water indices; to delimit, map, and monitor water bodies during a period of prolonged drought, so contributing to a more efficient management of water resources. They were adjusted as the reflectance of natural targets. A Normalized Difference Water Indices were proposed, compared to indices in the literature, and were calculated as weir areas monitored by the Water Resources Management Company (COGERH) during a prolonged drought that lasted from 2013 to 2018. The study illustrated the severity of the drought extended over the analyzed period and takes advantage of the fact that the integration of Coastal-Aerosol and green spectral bands, as well as near-infrared and short wave infrared, which can represent a significant improvement in the mapping of water bodies.