Research shows that the large water reservoirs act as an extensive evaporative surface and increase the surface temperature in area with low humidity. Because the large dams have a negative long term impacts on the local climates, it is necessary that, further studies are performed in positioning of these dams before the construction in semi-arid climates. Remote sensing is a powerful tool in temporal studies of macro and micro climates. Generally, TVDI index examines the relationship between vegetation and surface temperature of region, which reflects the degree of drought. Our Objective in this research is to investigate the role of Baft reservoir dam on local climate and the dryness of this area using Landsat series of satellite images. The result of this study confirmed the negative impacts of large dams in semi-arid climates and represents an increase of drought index around the Baft reservoir dam.