 This study evaluated the performance of the newly available Sentinel-2A multispectral instrument, MSI, imagery for mapping water bodies. The study used the Normalized Difference Water Index, NDWI, at 10M resolution to sharpen the 20M SWR bands. The results showed that the proposed NDWI-based MNDWI image has better separability and is more effective for both classification level and boundary level final water maps than traditional approaches. This article was authored by Xiu Qingyang, ShanChan Zhao, Xiu Binqin, and others.