 The paper proposes a novel approach to generate a 10-meter resolution modified Normalized Difference Water Index, MNDWI, from Sentinel, two images with a 20-meter resolution shortwave infrared, SWR, band. The authors compare the performance of four pan-sharpening algorithms, namely principal component analysis, PCA, intensity hue saturation, IHS, high-pass filter, HPF, and Atru's wavelet transform, ATWT. They find that the ATWT algorithm produces the best results when it comes to the accuracy of the sharpened images and the map level accuracy of the resultant water body maps. This article was authored by Yundu, Ehang Zhang, Feng Ling, and others.