Analysis of Environmental and Atmospheric Influences in the Use of SAR and Optical Imagery from Sentinel-1, Landsat-8, and Sentinel-2 in the Operational Monitoring of Reservoir Water Level

In this work, we aim to evaluate the feasibility and operational limitations of using Sentinel-1 synthetic aperture radar (SAR) data monitor water levels in Poço da Cruz reservoir from September 2016–September 2020, semi-arid region northeast Brazil. To segment water/non-water features, SAR backscattering thresholding was carried out via graphical interpretation backscatter coefficient histograms. addition, surrounding environmental effects on polarization thresholds were investigated by applying wavelet analysis, Landsat-8 Sentinel-2 normalized difference index (NDWI) modified (MNDWI) used compare discuss results. The assessment observed estimated showed that (i) accuracy equivalent NDWI/Landsat-8; (ii) optical image outperformed inlet branches, where complexity features is higher; (iii) VV VH polarization. results confirm images can be suitable for monitoring, offering a similar multispectral indices. threshold variations strongly correlated vegetation (NDVI), soil moisture depletion zone, prior precipitation quantities, which as proxy predict cross-polarization (VH) co-polarization (VV) thresholds. Our findings may improve algorithms designed automate extraction data, either isolation or combined with images.