Modified normalised difference water index
MNDWI = (G - MIR ) / (G + MIR)
The MNDWI is derived from the NDWI defined by Mcfeeters (1996) by the use of middle infrared instead of near-infrared (Xu, 2006). Water bodies are better delineated by a more efficient discrimination between open surface water and dry surfaces.
References: Xu, H. Q., 2006. Modification of normalised difference water index (NDWI) to enhance open water features in remotely sensed imagery. International Journal of Remote Sensing 27, 3025-3033