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 m3/per person per year) Most of the basins in western part and peninsular India already
water scarce (per capita availability is less than 1000 m3 per person per year) Over-exploitation of groundwater resources, leading to rivers
getting dry in lean season.
Spatial variation of rainfall in India
mm Average
1,170
Max.
11,000 Mawsynram Meghalaya
Min.
100
Western Rajasthan
Precipitation during June to September 3000 BCM (75%)
Post Monsoon (Oct-Dec)
Monsoon (Jun-Sep)
Pre Monsoon (MarMay
Winter Monsoon (Jan-Feb)
Rainfall in mm
Temporal variation of rainfall in India 1000 900 800 700 600 500 400 300 200 100 0
0 urray Darling Basin
Colorado Basin
Ganga Basin
India
S Africa
China
Spain
Turkey
USA
Brazil
Australia
Russia
Storage as % of annual water availability 440
400
360
320
280
240
200
160
120
80
40
0
Bangladesh/Myanmar)
WFR (Tadri-KK)
WFR (Tapi-Tadri)
Tapi
Narmada
Water Availability
utch, Saurashtra, Luni)
Mahi
Sabarmati
Subernrekha
Brahmani-Baitarni
Mahanadi
EFR (Pennar-KK)
EFR up to Pennar
Pennar
500
Cauvery
Krishna
Godavari
Barak +
Brahmaputra
Ganga
Indus
BCM
Basin wise availability and live storage 600
Live Storage
400
300
200
100
Ganga Basin Issues
Flow Availability and diversion from Upper Ganga Canal 3000 2800 2600 2400 2200 2000 1800 1600 Discharge (cumec) 1400 1200 1000 800 600 400 200 0
Avg flow
Avg diversion
Flow availability and diversion from Hathanikund barrage 900
Avg flow
800
Avg diversion
700 600 500 Discharge (m3/s) 400 300 200 100 0 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Pre and Post Tehri Flow Pattern at Rishikesh 3000 2800 2600 2400
Month
2200
Discharge (m3/s) 2000
Post and pre Tehri Flow ratio
Jun
0.8
Jul
0.8
1400
Aug
0.9
1200
Dec
1.4
1000
Jan
1.5
800
Feb
1.8
March
1.7
1800 1600
600 400 200 0
Moderation of Flood at Hardwar during June 2013 Flood event of Uttarakhand
Important flow statistics at Rishikesh Period
Available flow (BCM)
Available flow as % of annual
Diversion (BCM)
Surplus (BCM)
Annual
23.70
100.00
6.89
16.81
May-Oct
19.98
84.30
4.19
15.79
Jun-Oct
18.84
79.48
3.54
15.30
Jul-Sep
15.34
64.71
2.33
13.01
Nov-Apr
3.72
15.70
2.70
1.02
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
Jun Jul Aug Sep Oct-May
Availability (MCM)
Diversion (MCM)
Surplus (MCM)
711.40
344.77
366.63
1287.50
893.96
393.55
2223.86
1135.73
1088.13
1787.19
619.13
1168.06
2398.01
2082.58
315.44
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. 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.
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 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 87650 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).
Flow Pattern of Ganga at Kanpur Year
Monsoon Flows (BCM)
Annual Flows (BCM)
Monsoon Flows as Percentage of Annual Flows
Average Flow Year (1986-87)
25.65
28.60
89.70%
Maximum Flow Year (1978-79)
48.29
54.00
89.40%
Minimum Flow Year (1987-88)
7.30
8.20
89.02%
Quantification of divertible water ď‚— 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 ď‚— 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 (Qlimit), 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 Qlimit was fixed
at 2000 m3/sec. Around 10.15 BCM flood water can be diverted in an average year from Ganga without considering limitations of conveying capacity of the canal into account.
With Qlimit fixed at 2000 m3/sec the Divertible Flood water with different canal
capacities results :
Canal capacity (M3/Sec) 500
Divertible flood water in an Average Year (BCM) 2.20
1000
4.09
Considering the existing canal capacities in India as well as general topography of the
area, canal with a carrying capacity of 1000 m3/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
WRIS land cover/ land use statistics for a stretch of 20 km width on either side of river Ganga between Kanpur and Allahabad S.No.
Land use
Class
1 2 3 4 5 6 7 8
Built-Up
Urban Rural Mining Crop Land Fallow Plantation Deciduous River / Stream /Canals
9 10 11 12 13 14 15
Agriculture Forest Water Bodies
Wasteland
Area (km2) 381.00 202.43 1.68 6934.23 795.68 538.09 9.07 455.76
Water Bodies Inland Wetland
27.70 151
Barren Rocky Gullied / Ravinous Land
9.88 92.45
Salt Affected Land Sandy Area
681.23 58.09
Scrub Land Total Area
935.15 11273.24
Findings 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 km2 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
Brahmaputra basin
Rainfall Pattern in Brahmaputra basin
Live Storage in proposed projects Sub basin
Project
Present Live Storage (MCM)
Total
Flood moderation requirement
Subansiri
Subansiri lower
645 at FRL 120 between FRL and MWL)
3.002 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
1764.3
1.764 BCM
0.56 BCM
Lohit
Demwe lower
171.4
1.61 BCM
Demwe upper
37.4
0.633 BCM
Hutong-II
278
Kalai-II
30.4
Kalai-I
116
Siang upper stg-1
1032
9.2 BCM
Siang upper stg-2
750
1.782 BCM
Siang
From above storage it will be possible to achieve effective flood moderation and nonmonsoon 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 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
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
Role of storage in river rejuvenation and Environmental flow releases in Murray Darling basin Australia Average annual surface runoff - 32.5 BCM including 0.95 BCM transferred from
Snowy river
Existing surface water live storage - 34.5 BCM (106 % of average annual surface
runoff)
Environment flow releases before 2009 -0.87 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)
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) 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 Glen Canyon Dam (Lake Powell) - 26.2 million acre-feet (32.3 BCM) Flaming Gorge Reservoir – 3.8 million acre-feet (4.67 BCM) Navajo Reservoir -1.71 million acre-feet (2.11 BCM) Hoover Dam (Lake Mead) - 28.54 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
Conclusion ď‚— 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
Thank You