Impact of river channelization and riverfront development on fluvial habitat: evidence from Gomti River, a tributary of Ganges, India

Riverfront development is one of the important pervasive modifiers of river morphology and processes affecting river corridors, floodplains and associated riparian zones. The Irrigation and Water Resources Department of Government of Uttar Pradesh, India’s most populous state, undertook an ambitious project of riverfront development during April 2015 to March 2017 in the capital city of Lucknow on Gomti River, a meandering perennial tributary of Ganges which is fed by rainfall and groundwater. Under this project, straightening and shortening of the river channel was done by controlling its width, shape and riverbed through constructing a heavily reinforced diaphragm wall on both banks on an 8.1 km stretch. River floodplain width was restricted to 240 m out of 450 m and clear waterway to 100–125 m from existing 250 m to reclaim about 200 ha of land upstream and downstream of Gomti barrage in the city. This paper assesses the loss of river processes and ecosystems under changed hydraulic regimes post riverfront development project. We observed eight types of habitat in the undisturbed segments of the Gomti River, while only two major habitat types were present in the channelized segments. The paper argues that, due to heavy channel engineering led riverfront development and other related morphometric changes, there would be decline in freshwater species and water quality, lowering of groundwater tables in the city reach, resulting from diminishing base flow and flooding of the downstream areas. The river is fed by rainfall and groundwater, maintaining variable flow regimes with a very lean flow during the summer season. The reduction in flow, in the absence of water augmentation measures, will further impact the minimum environmental flows required to maintain the healthy ecosystems in the river broadening the area of ecological disturbances. This study can provide valuable insights for future projects on riverfront development and restoration measures in India and elsewhere.