Clean rivers and healthy aquatic life symbolize that the ecosystem is functioning well. The Ganga River has shown signs of rejuvenation and a significant improvement on many parameters, following the eight-week nationwide lockdown due to coronavirus pandemic. Since industrial units and commercial establishments were closed, water was not being lifted by them with a negligible discharge of industrial wastewater. It was observed that during the lockdown period most of the districts falling under the Ganga basin observed 60% excess rainfall than the normal, which led to increased discharge in the river, further contributing towards the dilution of pollutants. Further, data analysis of live storages in the Ganga Basin revealed that the storage during the beginning of the third phase of lockdown was almost double than the storage during the same period the previous year. Analysis of the storage data of the last ten years revealed that the storage till May 6, 2020 was 82.83% more than the average of the previous ten years, which meant that more water was available for the river during the lockdown period. The impact could be seen in terms of increased dissolved oxygen (DO) and reduced biological oxygen demand (BOD), Faecal coliform, Total coliform and nitrate (NO 3 -) concentration. A declining trend in nitrate concentration was observed in most of the locations due to limited industrial activities and reduction in agricultural run-off due to harvesting season. The gradual transformation in the quality of the water has given a sign of optimism from the point of restoration. Yet, it is believed that this improvement in water quality is ‘short-lived’ and quality would deteriorate once the normal industrial activities are resumed, indicating a strong influence of untreated commercial–industrial wastewater. The paper concludes that the river can be rejuvenated if issues of wastewater and adequate flow releases are addressed.

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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.

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