Role of Storage in River Rejuvenation & Sustaining E-flow By Vinay Kumar Chief Engineer, Central Water Commission &N.N.Rai Director, Hydrology (NE) Central Water Commission

Key issues  17% of World’s population, 4% of renewable water resource, 2.5% land area  India is already under water stressed conditions (per capita availability is less than 1700 m 3 /per person per year)  Most of the basins in western part and peninsular India already water scarce (per capita availability is less than 1000 m 3 per person per year)  Over-exploitation of groundwater resources, leading to rivers getting dry in lean season.

Spatial variation of rainfall in India mm Average1,170 Max.11,000Mawsynram Meghalaya Min.100Western Rajasthan Precipitation during June to September 3000 BCM (75%)

Temporal variation of rainfall in India

Storage as % of annual water availability

Basin wise availability and live storage

Ganga Basin Issues

Flow Availability and diversion from Upper Ganga Canal

Flow availability and diversion from Hathanikund barrage

Pre and Post Tehri Flow Pattern at RishikeshMonth Post and pre Tehri Flow ratio Jun0.8 Jul0.8 Aug0.9 Dec1.4 Jan1.5 Feb1.8 March1.7

Moderation of Flood at Hardwar during June 2013 Flood event of Uttarakhand

Important flow statistics at Rishikesh PeriodAvailable flow (BCM) Available flow as % of annual Diversion (BCM) Surplus (BCM) Annual May-Oct Jun-Oct Jul-Sep Nov-Apr By storage of 2.5 to 3 BCM of monsoon water and consequent release during non monsoon months, flow can be augmented to its natural condition during the non-monsoon months

Important flow statistics at Hathanikund Month Availability (MCM) Diversion(MCM)Surplus(MCM) Jun Jul Aug Sep Oct-May About 2 BCM storage of monsoon water in Renuka, Kisau and Lakhwar will ensure about 3400 cusec surplus flow availability at Hathanikund during Oct to May, while at present in most of the non-monsoon 10 daily the natural flow is less than 3000 cusec

Off Channel Storage CWC was been asked to make a pilot study on storing flood water in a meaningful way, in peninsular India and another in Ganga Basin. CWC was been asked to make a pilot study on storing flood water in a meaningful way, in peninsular India and another in Ganga Basin. Accordingly, a pilot study has been carried out for Diverting the Flood Water of river Ganga near Kanpur city and storing it in a Single/ Interconnected Chain of Tanks during the flood period. Accordingly, a pilot study has been carried out for Diverting the Flood Water of river Ganga near Kanpur city and storing it in a Single/ Interconnected Chain of Tanks during the flood period. Such stored water can be utilized for irrigation as well as rejuvenating Ganga in lean season. Diversion of flood water can also provide flood protection in downstream areas. Such stored water can be utilized for irrigation as well as rejuvenating Ganga in lean season. Diversion of flood water can also provide flood protection in downstream areas.

Study area In the study it has been proposed to construct a diversion structure upstream of Kanpur city and storing the flood water in a single / chain of reservoirs and releasing the same into Ganga at Shazadpur around 170 km downstream of proposed Barrage at Kanpur In the study it has been proposed to construct a diversion structure upstream of Kanpur city and storing the flood water in a single / chain of reservoirs and releasing the same into Ganga at Shazadpur around 170 km downstream of proposed Barrage at Kanpur The study area of reach between Kanpur and Allahabad is selected from the point of view of poor water quality in the reach during lean season. The study area of reach between Kanpur and Allahabad is selected from the point of view of poor water quality in the reach during lean season. The catchment area of Ganga upto Kanpur city is about sqkm. The catchment area of Ganga upto Kanpur city is about sqkm. Average annual rainfall of Ganga basin up to Allahabad is about 1069 mm and almost 89% (i.e. 950 mm) of it occurs during monsoon period (June- October). Average annual rainfall of Ganga basin up to Allahabad is about 1069 mm and almost 89% (i.e. 950 mm) of it occurs during monsoon period (June- October).

Flow Pattern of Ganga at KanpurYear Monsoon Flows (BCM) Annual Flows (BCM) Monsoon Flows as Percentage of Annual Flows Average Flow Year ( ) % Maximum Flow Year ( ) % Minimum Flow Year ( ) %

Quantification of divertible water The study initiated with an idea of constructing a diversion structure on Ganga upstream of Kanpur city for diverting the flood water during the monsoon season The study initiated with an idea of constructing a diversion structure on Ganga upstream of Kanpur city for diverting the flood water during the monsoon season The quantity of divertible flood water through diversion structure at Kanpur basically depends on the monsoon discharge above which the flood water planned to be diverted (Q limit ), storing capacity of the reservoir behind the proposed hydraulic structure and canal carrying capacity. The quantity of divertible flood water through diversion structure at Kanpur basically depends on the monsoon discharge above which the flood water planned to be diverted (Q limit ), storing capacity of the reservoir behind the proposed hydraulic structure and canal carrying capacity.

Quantification of divertible water-contd.. Based on the stage discharge curve and non monsoon flow pattern the Q limit was fixed at 2000 m 3 /sec. Around BCM flood water can be diverted in an average year from Ganga without considering limitations of conveying capacity of the canal into account. Based on the stage discharge curve and non monsoon flow pattern the Q limit was fixed at 2000 m 3 /sec. Around BCM flood water can be diverted in an average year from Ganga without considering limitations of conveying capacity of the canal into account. With Q limit fixed at 2000 m 3 /sec the Divertible Flood water with different canal capacities results : With Q limit fixed at 2000 m 3 /sec the Divertible Flood water with different canal capacities results : Considering the existing canal capacities in India as well as general topography of the area, canal with a carrying capacity of 1000 m 3 /sec is assumed for further analysis. Considering the existing canal capacities in India as well as general topography of the area, canal with a carrying capacity of 1000 m 3 /sec is assumed for further analysis. Approximate surface area of pond /reservoir with a depth of 4 m to accommodate 4.00 BCM works out 1000 sq km which is very huge in comparison with land availability in the area Approximate surface area of pond /reservoir with a depth of 4 m to accommodate 4.00 BCM works out 1000 sq km which is very huge in comparison with land availability in the area Canal capacity (M 3 /Sec) Divertible flood water in an Average Year (BCM)

S.No. Land use Class Area (km 2 ) 1Built-UpUrban Rural Mining1.68 4Agriculture Crop Land Fallow Plantation ForestDeciduous Water Bodies River / Stream /Canals Water Bodies Inland Wetland Wasteland Barren Rocky Gullied / Ravinous Land Salt Affected Land Sandy Area Scrub Land Total Area WRIS land cover/ land use statistics for a stretch of 20 km width on either side of river Ganga between Kanpur and Allahabad

For 170 km length between Kanpur and Shahjadpur width required will be about 5.8 km and for 4 m depth 4 BCM can be stored – 220 cumec By converting such 151 km 2 inland wetland area into ponds with a depth of 4 m could lead to storing of water to the tune of 600 MCM – 33 cumec (Nov-May) From the land use statistics the tanks area approximately is 27.7 sq km. Considering the depth of such ponds to be approximately 4 m, the tanks’ storing capacity works out to 111 MCM – 6 cumec Findings

Brahmaputra basin

Rainfall Pattern in Brahmaputra basin

Live Storage in proposed projects Sub basinProjectPresent Live Storage (MCM) TotalFlood moderation requirement Subansiri Subansiri lower 645 at FRL 120 between FRL and MWL) BCM 1.91 BCM Kamala 1060 between (447m-470 m) Subansiri upper 745 at FRL 460 m 432 between 460 m and 470 m Dibang Dibang MLP BCM 0.56 BCM Lohit Demwe lower BCM 1.61 BCM Demwe upper 37.4 Hutong-II278 Kalai-II30.4 Kalai-I116 Siang Siang upper stg BCM 9.2 BCM Siang upper stg From above storage it will be possible to achieve effective flood moderation and non- monsoon flow security in Brahmaputra in event of any diversion by China

Murray Darling basin, Australia Basin area of Murray Darling Basin is 10,56,000 sq.km (14% of total area of Australia) Basin area of Murray Darling Basin is 10,56,000 sq.km (14% of total area of Australia) Basin generates 39% of the national income derived from agricultural production, contributing 53% of Australian cereals grown for grain, 95% of oranges and 54% of apples Basin generates 39% of the national income derived from agricultural production, contributing 53% of Australian cereals grown for grain, 95% of oranges and 54% of apples Basin supports 28% of the nation’s cattle herd, 45% of sheep and 62% of pigs Basin supports 28% of the nation’s cattle herd, 45% of sheep and 62% of pigs The basin is home to a large number of different plants and animals including: 35 endangered species of birds, 16 species of endangered mammals, over 35 different native fish species, over 30,000 wetlands The basin is home to a large number of different plants and animals including: 35 endangered species of birds, 16 species of endangered mammals, over 35 different native fish species, over 30,000 wetlands The twenty-three river catchments in the Basin Basin

Role of storage in river rejuvenation and Environmental flow releases in Murray Darling basin Australia Average annual surface runoff BCM including 0.95 BCM transferred from Snowy river Average annual surface runoff BCM including 0.95 BCM transferred from Snowy river Existing surface water live storage BCM (106 % of average annual surface runoff) Existing surface water live storage BCM (106 % of average annual surface runoff) Environment flow releases before BCM (2.68% of mean annual flow) Environment flow releases before BCM (2.68% of mean annual flow) Total Environment flow release target to be achieved by year 2019 – 3.62 BCM (11.14% of mean annual flow) Total Environment flow release target to be achieved by year 2019 – 3.62 BCM (11.14% of mean annual flow)

Colorado river basin The Colorado runs 1,450 mi (2,330 km) from the Rocky mountains to the Gulf of California, draining parts of seven U.S. states and two Mexican states. From 1906 to 2007 average annual flow of the basin – 15 million acre feet (18.5 BCM) From 1906 to 2007 average annual flow of the basin – 15 million acre feet (18.5 BCM) 90% of the stream flow generated in upper basin, in the states Colorado, Wyoming, Utah, New Mexico and some of Arizona 90% of the stream flow generated in upper basin, in the states Colorado, Wyoming, Utah, New Mexico and some of Arizona Total storage – About 60 million acre feet (74 BCM) which is 4 times of average annual flow Total storage – About 60 million acre feet (74 BCM) which is 4 times of average annual flow  Glen Canyon Dam (Lake Powell) million acre-feet (32.3 BCM)  Flaming Gorge Reservoir – 3.8 million acre-feet (4.67 BCM)  Navajo Reservoir million acre-feet (2.11 BCM)  Hoover Dam (Lake Mead) million acre-feet (35.2 BCM) EF release from Morelos dam– 195 MCM (1.05% of average annual flow) out of which 135 MCM as pulse flow and 60 MCM as base flow EF release from Morelos dam– 195 MCM (1.05% of average annual flow) out of which 135 MCM as pulse flow and 60 MCM as base flow

Conclusion Considering the spatial and temporal in rainfall and consumptive uses, storage of monsoon water at key locations could play an important role in river rejuvenation and sustaining the environmental flow without adversely affecting the consumptive water needs of the country Considering the spatial and temporal in rainfall and consumptive uses, storage of monsoon water at key locations could play an important role in river rejuvenation and sustaining the environmental flow without adversely affecting the consumptive water needs of the country

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