Increasing water demand compounded by climate variability has put immense pressure on freshwater resources, and on water security, thus threatening sustainable water management all around the world. Understanding the spatio-temporal variability of water security can, therefore, play a pivotal role in sustainable management of freshwater resources. One of the various methods used for analyzing the spatio-temporal variability of freshwater resources and water security is, classifying the freshwater resources into blue and green water and estimating water scarcity. Using this approach, the objective of this study is to analyze the water security situation of the Grand River Watershed (GRW), using the Soil and Water Assessment Tool (SWAT) under present (1950-2015) and future scenario (2035-2099). It was observed that freshwater resources followed the pattern of weather variables like precipitation and temperature. Blue water scarcity was found to be high in urban areas and green water scarcity reached its peak in agricultural areas.