The rate of climate disruption caused by human activities is higher now than it was 2,000 years ago. The planet’s temperature has increased, especially in the previous 35 years, according to data collected by satellites that circle it. The changing climate affects the hydrology of the river systems across the world. This chapter looks at how the hydrology of the Bhagirathi River basin—which is composed of the two major watersheds of Bhilangana and Bhagirathi, which come from the Gangotri and Khatling glaciers, respectively—is affected by differences in temperature and precipitation brought on by climate change. The Tehri Dam, a national landmark is located in the study area. Any change in the hydrology of the area would impact the discharge from the dam which would inturn impact the power generated. The Cartosat Digital Elevation Model (CartoDEM) from the BHUVAN site is used in the study to demarcate the Bhagirathi river basin. Daily temperature data from the Atmospheric Infrared Sounder (AIRS) and daily rainfall data from the Tropical Rain Monitoring Mission (TRMM) GIOVANNI station are used to calibrate and evaluate the hydrological modeling software HEC-HMS. At the dam reservoir location, measured intake and outflow statistics are provided by Tehri Hydro Development Corporation (THDC). Under RCP 2.6, 4.5, 6.0 and 8.5, csiro_mk3_6_0 model is used for research on climate change in this chapter. The discharge values for csiro_mk3_6_0 model increases during the end of the century (2040–99) under different RCP’s. These results indicate an increase in discharge along with increaseed extreame rainfall and non-rainfall events.