Quantifying Anthropogenic Interventions in Yamuna River Through River Flow Health Index and Geomorphic Analysis

The study deals with the flow alterations and planform adjustments due to the construction and operation of barrages in Yamuna River, India. The flow alterations are quantified using the River Flow Health Index on a 0–1 scale. The planform adjustments are analyzed using satellite-generated geomorphic maps. Results show that the magnitude and variability of flows are the most altered components during the construction phase. During post operation of Hathnikund barrages, the variability of flows associated with water withdrawal is the most altered component. Downstream of the barrage displayed an increase in fluvial bars and channel multiplicity and a decrease in channel area and width due to erratic construction activities, restricting floodplain connectivity. However, the river tends to return to the previous altered state during the post-Hathnikund barrage period. Withdrawal from the Hathnikund barrage to meet the water demand has left the channel dry during the year's lean season (2003, 2008, and 2013). Maintaining a minimum flow of 10m 3 /s during the lean season as ordered by the National Green Tribunal, India has reduced the channel belt in the Yamuna River (2018). These findings may help re-implement reservoir operating policies reducing downstream hydrological modifications, and aid in developing the river basin development plans.