Role of Water Storage in River Rejuvenation & Sustaining E-flows
05.04.2016
R N Singh THDC INDIA LTD
TEHRI DAM & RESERVOIR
TEHRI DAM & RESERVOIR River Discharge : 30 to 7500 Cumec Design Flood : 15,540 Cumec Gross Storage : 3,540 MCM Live Storage : 2,615 MCM Mean Annual Run-off : 8,000 MCM Catchment Area : 7,299 sq km Snowbound Rainfed
: :
2,424 sq km 4,863 sq km
Annual rainfall : 1,016 to 2,630 mm Max. Flood Level : EL 835 m Full Reservoir Level : EL 830 m MDDL : EL 740 m
Tehri Power House (1,000 MW)
KOTESHWAR RESERVOIR (Located 22km downstream of Tehri Reservoir)
Downstream view of Koteshwar Dam
KOTESHWAR RESERVOIR (Located 22km downstream of Tehri Reservoir)
Gross Storage : 88.9 MCM Live Storage : 35 MCM Mean Annual Run-off : 8,000 MCM Catchment Area : 7,691 sq. km at dam site Snowbound
: 2,328 sq. km
Annual normal water flow Max. Flood Level : Full Reservoir Level : MDDL :
: 258.0 cumecs EL 615 m EL 612.5 m EL 598.5 m
TEHRI AND KOTESHWAR RESERVOIR TEHRI DAM ( STAGE-I)
TEHRI RESERVOIR
FRL. EL. 830.0 M MDDL. EL. 740.0 M
KOTESHWAR RESERVOIR FRL. EL. 612.5 M
~ 22 KM
MIN.LEVEL EL. 606 M
KOTESHWAR DAM
TEHRI RESERVOIR OPERATION ROLE OF TEHRI RESERVOIR Tehri HPC was conceived & designed to store surplus water of the river Bhagirathi during monsoon and releasing the same during the lean season as per the requirement of command area for drinking and irrigation purposes and to provide peaking support to grid by Tehri HPP & PSP . ROLE OF KOTESHWAR RESERVOIR The Koteshwar project is an integral part of Tehri HPC. The Koteshwar reservoir is to serve the purpose of reregulation of the flow released from the Tehri reservoir, in order to maintain uniform continuous flow d/s of Koteshwar.
TEHRI RESERVOIR OPERATION The hydrology year in the Central Himalaya starts from 21st June. Around this time the reservoir level is brought to its minimum level at EL 740.00 i.e. MDDL (Minimum draw down level below which no power generation can takes place) so that complete storage capacity remains available to store surplus water of monsoon. From 21st June to 31st October (monsoon period) water is allowed to fill in the reservoir. From 1st November to 20th June, stored water including the natural inflow is allowed to be released as per UPID requirement thus touching MDDL (EL 740m) around 20th June.
TEHRI RESERVOIR OPERATION Reservoir Operation DURING MONSOON Average Inflow & Outflow during monsoon are as below
2006 2007 2008 2009 2010 2011
Average Inflows Cumecs MCM 382.25 4392.47 429.73 4938.08 484.07 5562.58 312.77 3594.05 617.72 7098.32 598.82 6881.13
Average Outflow Cumecs MCM 306.12 3516.67 258.90 2975.10 318.25 3657.05 113.23 1301.18 426.73 4903.63 418.17 4805.31
2012
492.30
287.13
Sl.No.
Year
1 2 3 4 5 6 7
5657.07
3299.44
TEHRI RESERVOIR OPERATION Reservoir Operation DURING NON-MONSOON During lean months (1st Nov to 20th June), in addition to natural river inflow, water stored in the dam is also released. The annual schedule for release of water from 1st Nov to 20th June is prepared in mutual agreement with UPID. ●
Live storage corresponding FRL i.e EL 830 is 2615 MCM, which will allow average release around 130cumecs (4550cusecs) apart from releasing the natural inflow. In lean period.
TEHRI RESERVOIR OPERATION Reservoir Operation DURING NON-MONSOON â—?
â—?
During the lean months when river Bhagirathi inflow varies from 40 to 80 cumecs, it is augmented to make it 180 to 250 cumecs by releasing water from Tehri dam reservoir. Water released from Tehri dam not only revive river Bhagirathi but river Ganga also because overall flow of river Ganga also decreases considerably during the months of Dec, Jan & Feb. Availability of water in the river decreases to an extent, if not supported by Tehri dam reservoir, would covert into a nala in the farther plain areas.
TEHRI RESERVOIR OPERATION Reservoir Operation DURING NON MONSOON Average Inflow & Outflow during non-monsoon are as below
Sl.No.
Year
Average Inflow
Average Outflow
Cumecs
MCM
Cumecs
MCM
1
2006-07
77.38
1551.02
131.84
2642.65
2
2007-08
95.56
1923.79
180.53
3634.24
3
2008-09
74.74
1497.51
184.91
3706.56
4
2009-10
67.06
1344.24
176.96
3547.07
5
2010-11
95.03
1904.77
202.33
4055.70
5
2011-12
75.94
1528.82
180.02
3624.03
6
2012-13
146.54
2937.46
224.01
4490.21
Average Monthly Flow Ratio River Ganga at Rishikesh Month
36 years (1970-2005) Pre Tehri flow (Cumec)
7 years (2006-12) Post Tehri flow (Cumec)
Post to Pre Tehri flow Ratio
June
897.2
731.7
0.8
July
2064.4
1678.7
0.8
Aug
2681.4
2369.7
0.9
Sep
1524.6
1609.5
1.1
Oct
500.0
603.7
1.2
Nov
275.7
353.4
1.3
Dec
198.2
270.3
1.4
Jan
168.8
254.9
1.5
Feb
164.7
290.4
1.8
March
195.6
338.7
1.7
April
257.1
406.2
1.6
May
419.9
502.4
1.2
TEHRI RESERVOIR OPERATION Reservoir Operation DURING NON-MONSOON The average flows during the lean period has been augmented during all the lean months (Nov-Apr) which reflects the special characteristics of storage type reservoir. It is worth mentioning that the minimum flow of Ganga river have been augmented by 1.2 times to 1.8 times at Rishikesh. The typical lean period (Nov-Apr) flow augmentation shows the way how this type of reservoir may increase the river flow during lean months of a year.
ROLE OF TEHRI DAM DURING FLOOD OF 2013 The water levels in Tehri dam were low at the start of the monsoon. This proved a critical factor in the dam retaining waters of an engorged Bhagirathi and preventing a 10-12 feet rise in the Ganga at Rishikesh that could have been ruinous for the town and its ashrams. Without Tehri dam, Rishkesh, Haridwar and parts of western UP would have been inundated. At Devprayag, the confluence of Bhagirathi and Alaknanda, the river level was 458.25 m at 11 am on June 16, the next day around the same time, the rise in water level was by 11 meters to 469.10 m. “It would have been a catastrophe downstream of Devprayag, in Rishikesh and Haridwar, if instead of 14,000 cusecs, 2,44,000 cusecs was added from Bhagirathi”
Actual observed inflow and outflow at Tehri during Floods of June 2013 8000
7534.56 7090.17
7000 D i s c h a r g e i n C u m e c s
6229.18 6000 5413.31 5000
4000
3639.24
3634.24 3186.38 2887.81
3000
3335.67 3037.1
3781.58 3781.58
4291.93 4104.46 3878.79
3292.06
3037.1 3037.1
2979.61 2862.12 2487.17
2439.96 2000
2112.22 2112.22 1924.75
1808.09
1174.84
957.51
1000 592.98 471.47 424.94 424.94 424.94 424.94 424.94 424.94 354.95 354.95 354.95 354.95 354.95 354.95 354.95 354.95 354.95 354.95 354.95 354.95 349.95 349.95 349.95 349.95 349.95 349.95 349.95 349.95 349.95 349.95 349.95 349.95 0
Date and Time Outflow from Tehri Reservoir (Cumecs)
Inflow Tehri (Cumecs)
Actual observed discharge of Ganga at Rishikesh and anticipated discharges after su 18000 15728.48 15284.09
16000 D i s c h a r g e i n C u m e c s
13923.16
14000
12357.39 12000 10000
11083.26
10736.08 9823.01 10048.67
9375.84 9200.87 9061.3
9236.28
8223.91 8548.87 8548.87 8048.94 7798.97 7086.56 7299.04 6241.68 6799.1 6549.13 6299.17 6299.17 5636.76 6124.19 5436.78 6000 5949.21 5774.24 5089.33 5599.26 5474.28 4607.72 4799.37 4169.45 4649.39 4419.42 4259.44 4179.45 4179.45 4000 3999.47 3949.48 3307.2 3749.5 3699.51 3589.53 34 3149.58 2522.72 2231.23 2699.64 2279.7 2000 2109.72 8000
8161.42 7463.74 7405.13 6946.58 6889.37 6535.94 6537.33
0
Date and Time Actual inflow at Rishikesh (Cumecs) Anticipated inflow at Rishikesh if actual inflows at Tehri superimposed with 10 hrs time lag (Cumecs)
Actual observed discharge of Ganga at Haridwar and anticipated discharges after su 24000 21519.2
22000
D i s c h a r g e i n C u m e c s
19771.79
20000
20331.39 18009.41
18000 16292.25 16000
15008.09 13938.48 13152.6 12925.07
14000 12000
12307.39 11948.59 11704.33 11189.99 11091.08
10000
14457.17 14339.59
13036.57 13007.97 12320.94 11251.33 11062.6
9939.35 9632.94 9166.47 9112.16 9023.11 8502.84
8000 6000
16139.82 15747.57 15420.42 15246.33 15144.79 14916.9
12909.05 12951.05 12088.49 12713.19 12320.94 12207.68 11722.49 11001.29 11483.44 11167.4 9691.6 10284.4 9909.44 9419.17 9651.32 8454.89 8939.06 8222.16 8004.32 7919.37 770
5450.5
4842.95 3688.82 4000 3445.79 2362.51 2000 2241 0
Date and Time Actual inflow at Haridwar ( Cusecs) Anticipated inflow at Haridwar if actual inflows at Tehri superimposed with 12 hrs time lag (Cusecs)
TEHRI RESERVOIR OPERATION ●
ADDITIONAL WATER FOR GANGA SNANS
Tehri reservoir provides additional water for Snans during Kumbh Mela, Magh Mela etc. ● Tehri reservoir played important role in Kumbh Mela 2010 & 2013. ● During Kumb Mela 2010 & 2013 Tehri reservoir released 200-250 Cumecs against the inflow of 40-50 Cumecs during Snan Days. ● Every year additional water is released from Tehri dam for Magh Mela in Jan & Feb. ●
Kumbh Snan
THANK YOU