Hydromorphological shifts in the Yamuna River: Post-barrage impacts and water management implications

ABSTRACT The study analyzes the hydromorphological impacts of barrage construction and operation on the Yamuna River over 25 years, employing the River Flow Health Index (RFHI). The RFHI methodology includes segregating flow data into different periods, identifying key parameters, assessing flow alterations, and developing an index from 0 to 1. Results indicate moderate alterations in the flow regime, with RFHI of 0.379 and 0.328 for different periods. Geomorphological analysis revealed variations in river sinuosity, peaking at 1.232 in 1999 before reducing to 1.206 by 2018, and braid-channel ratio decreasing from 1.864 in 1999 to 1.508 in 2018. Channel width narrowed in 1999 to 0.082 km and slightly expanded to 0.093 km by 2018. The channel area reduced from 6.418 km² in 1993 to 5.632 km² in 2018, with the bar area significantly decreasing and bar density dropping from 3.28 to 0.83, indicating changes in the channel belt. Construction phases showed increased fluvial bars and channel multiplicity and decreased channel area and width. Post-Hathnikund barrage, withdrawals during lean seasons left the channel dry, as seen in 2003, 2008, and 2013. These findings emphasize integrated river basin management to harmonize development with ecological impacts.