17. Preliminary Assessment and Attempt to Maintain Minimum Ecological Flows in Upper and Middle Ganga River

The impact of releasing additional water from Tehri Dam (114 m³/s), and subsequent releases downstream barrages at Bhimgoda, Bijnor, Ramganga feeder canal (from Kalagarh Dam on Ramganga River), and Narora Barrage (71 m³/s) particularly during Kumbh bath festival for cultural/spiritual/ecological reasons during lean flow months (December–March) to augment river flows at Har ki Pauri (Hardwar) and at Sangam (Allahabad before confluence of Ganga with Yamuna River) at the cost of irrigation water seems to be unattractive due to negative water balance during non-monsoon period between Hardwar downstream catchment and Allahabad. The better option to raise water level at Sangam appears to be closing of lift pump canals situated between Kanpur and Raebareli (34 m³/s) and escaping Sharda Sahayak canal water (11 m³/s) from Bhadri escape into the Ganga River 40 km upstream of Allahabad. The other option may be construction of barrages at suitable places – Chhatnag (d/s Sangam nose, Allahabad), Kalakankar (Pratapgarh), and Bhitaura (Fatehpur) – to augment 64 m³/s water at 75 % dependability to maintain water depth 1.2 m at Sangam. Dredging of the active channel may provide adequate depth of water for bathing and navigation.

The combined effect of low flow and discharge of polluting effluent into the Ganga has caused severe deterioration in the quality of water, sediment, and aquatic biodiversity in the river. But the Ganges’ pollution and low flow issues are two entirely different things. Similarly, trade-off between food security and river ecological services has to be decided on objectives of the society. The preliminary assessment of environmental flows (EFs) for the Upper Ganga basin by WWF-India (2012 assessment of environmental flows for the Upper Ganga Basin, HSBC Water Programe) at Kaudiyala (rafting site 30 km u/s Rishikesh), Kachla bridge (d/s Narora), and Bithoor (u/s Kanpur Lav Kush barrage) suggests 72 %, 45 %, and 47 % MAR natural, respectively, using building block methodology (BBM). This study further needs refinement based on actual flow regimes.