Giri River is also famous as “Giri Ganga” and is an important river that feeds the Yamuna river. Giri River originates from the hills of Kotkhai and drains at the parts of Himachal in the southeastern areas. It flows through the district of Sirmaur and further merges with the Yamuna River. At this point, it divides the Sirmaur district into two equal parts which are the Cis-Giri and Trans-Giri regions and then they join Yamuna upstream of Paonta below Mokkampur. Giri is one of the important tributaries of the Yamuna River.
The major tributaries of the Giri River are Ashani which meets Giri close to Chail and Jalal which joins it at Dadhau. The Palar and Nait stream meets the river on its left bank.
The water of Giri River is channeled through the Nahan ridge to the Girinagar powerhouse and is released with gushing force into the river of Bata. The diversion project on the river houses 30 MW twin units for power supply to the districts. Also, Renukaji Dam Multi-Purpose Project is a storage project on the Giri river which is a tributary of the Yamuna at the Sirmour district of Himachal Pradesh.
Giri River originates from a small spring-fed by the waters of Shimla. After that, the water flow then turns to the southwest for a distance; further, it changes its course for a southeastern alignment. The upper course of this river has a deep gorge in a V-shape across a place called Nag Tibba.