Delineation of Water Bodies Using Vegetation and Water Indices

Mapping the water surface is a significant aspect of identifying the extension or shrinkage of any water body. It is a beneficial technique for a region, experiencing gradual river shifting, erosion, or frequent flood events. Climate change often causes excessive rainfall or drought conditions in a riverine region, significantly impacting water over-spilling or shrinkage and sedimentation of a river. The spatio-temporal study of delineation and mapping of water surface area helps to determine the pattern of change of a water body, analyze the trend of shifting of a river course, and estimate the change in the proportion of water surface area. All these kinds of assessments are helpful in analyzing the inundated area of a flood prone region. This study aims to delineate water bodies of Lakhimpur district of Assam using Geographic Information System (GIS) and remote sensing over a temporal scale of twenty years from 2001 to 2021. Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) are used in this study to map and estimate the changes and extension of water bodies of the region. It is observed that there is an increase of 16.75% in water bodies in the district from 2001 to 2021