(A) Sardar Sarovar Reservoir
The Full Reservoir Level (FRL) of the Sardar Sarovar Dam is fixed at RL 138.68 metres (455 feet). The Maximum Water Level is 140.21 metres (460 feet.) while minimum draw down level is 110.64 metres (363 feet.). The normal tail water level is 25.91 metres (85 feet.).
The gross storage capacity of the reservoir is 0.95 M. ha.m. (7.7 MAF) while live storage capacity is 0.58 M.ha.m. (4.75 MAF). The dead storage capacity below minimum draw down level is 0.37 M. ha. m. (2.97 MAF). The reservoir would occupy an area of 37,000 ha. and would have a linear stretch of 214 kilometer of water and an average width of 1.77 kilometer.
The submergence at Full Reservoir Level (FRL) is 37,690 ha. (86,088 acres), which comprises 11,279 ha. agricultural land, 13,542 ha. forests and 12,869 ha. river bed and waste land. In all 245 villages of the three states viz. 193 Villages of Madhya Pradesh, 33 villages of Maharashtra and 19 villages of Gujarat are affected. Only 3 villages of Gujarat are fully affected, while the remaining 16 villages are partly affected. In Madhya Pradesh, out of 193 villages, more than 10% agricultural land will be submerged only in 79 villages, in 89 villages less than 10% agricultural land or only houses will be submerged under FRL, due to back water of 1 in 100 years flood. In 25 villages, only Government waste land will be submerged.
(B) Sardar Sarovar Dam
A concrete gravity dam, 1210 meters (3970 feet) in length and with a maximum height of 163 meters above the deepest foundation level, is under construction across river Narmada.
The dam will be the third highest concrete dam (163 meters) in India, the first two being Bhakra (226 metres) in Himachal Pradesh and Lakhwar (192 meters) in Uttar Pradesh. In terms of the volume of concrete involved for gravity dams, this dam will be ranking as the second largest in the world with an aggregate volume of 6.82 million cu.m. The first is Grand Coule Dam in USA with a total volume of 8.0 million cu.m. This dam with its spillway discharging capacity of 85,000 cumecs (30.00 lac), will be the third in the world, Gazenba (1.13 lac cumecs) in China and Tucurri (1.0 lac cumecs) in Brazil being the first two.
For chute spillway Radial gates, 7 in number and size 60' x 60' and for service spillway, 23 Radial gates of size 60' x 55' are to be provided to negotiate the design flood. 10 number of temporary construction sluices, each of size 2.15 m x 2.75 m. are provided in the boby of the spillway at RL 18 m. Another set of 4 permanent river sluices are provided at RL 53.0 m. The lower sluices were closed in February, 1994.
The design of the dam allows for a horizontal seismic coefficient of 0.125g and it also covers an additional risk due to reservoir induced seism city. Most sophisticated seismological instruments for monitoring and evaluation of the stresses in the body of the dam as well as the effect on the periphery of the reservoir are under installation.
(C) Hydro Power
There are two power houses for the Sardar Sarovar Project (SSP). Power benefits are shared among Madhya Pradesh, Maharashtra and Gujarat in the ratio of 57:27:16 respectively.
(i) River Bed Power House
The RBPH is an under ground power house stationed on the right bank of the river located about 165 meters downstream of the dam. It has six number of Francis type reversible turbine generators each of 200 MW installed capacity. The T.G. Sets are supplied by M/S Sumitomo Corporation, Japan and M/S BHEL. These units can operate at minimum reservoir water level of 110.64 meters. These six units have been commissioned in a phase manner during Feb-05 to June-06. The generation of energy depends upon inflow of water from upstream projects and need of water for irrigation in Gujarat.
(ii) Canal Head Power House
The CHPH is a surface power station in a saddle dam on right bank of the reservoir having total installed capacity of 250 MW (5 x 50 MW). These five units have been commissioned in a phased manner during Aug-04 to Dec-04. These units can be operated with minimum reservoir water level of 110.18 meters.
The CHPH is being operated in consultation and as per advice of NCA/WREB based on irrigation requirement of Gujarat/Rajasthan and availability of water in reservoir and release from upstream project of Madhya Pradesh.
The energy generated from both the power houses is to be evacuated through 400 KV level through interconnecting transformers at GIS, situated in RBPH switch yard. The 400 KV Switchyard is indoor type having Gas Insulated Switch Gear and Bus bars. The energy is transmitted to party states i.e. Gujarat, Maharashtra and Madhya Pradesh in the proportion of 16:27:57 respectively through 400 KV double circuit transmission lines, namely SSP-Kasor, SSP-Asoj, SSP-Dhule and SSP-Nagda respectively. All the transmission lines are commissioned and charged.
The operation and maintenance of SSP power complex and transmission lines is being done by Gujarat State Electricity Company Limited (GSECL), for which O&M agreement between SSNNL and GSECL has been signed.
(iiI) Small/Mini/Micro Hydro Power Projects
The Development of Small/Mini/Micro Hydro Power Projects on Sabarmati escape NMC chainage 229 km & Narmada Dam Godbole Gate at Kevadia Colony is not feasible due to following reasons:
- At the ultimate stage of project development, there will not be surplus water to the released through such Escapes and data of past can not be considered for future projection in such cases. A guaranteed/assured discharge through Escapes, power generation can not be predicted and therefore its economic viability is questionable.
- Godbole Gate essentially is a device to discharge surplus water back to the River and not to the Head Regulator of the canal. This arrangement under ideal normal conditions will not be functional and any investment made on such contingent would not guarantee the investor any dependable return.
- The Godbole Gate will not be operated all time, but the quantum will also be determined by levels in the ponds and would continue to fluctuate with water level in Pond no. 3 & 4. this would also seriously affect power generation as quantum and velocity of water vary greatly. Hydro Power requires a definite discharge and velocity.
Hence investment made on such contingent arrangement would not guarantee the investor and dependable return.
(D) Main Canal
Narmada Main Canal is a contour canal. It is the biggest lined irrigation canal in the world. It is about 458.318 km. long up to Gujarat -Rajasthan border. The canal extends further in the state of Rajasthan to irrigate areas in Barmer and Jhalore districts of Rajasthan. The Main Canal is lined with plain cement concrete to minimise seepage losses to attain higher velocity and to control the water logging in future. The lining work is carried out with the mechanized pavers. Such a large scale paving of concrete lining is done for the first time in India.
The Main Canal in its journey has to negotiate several water streams, rivers, roads, railways etc. This is possible by constructing appropriate structure on the canal. In all, there are 634 structures on the Narmada Main Canal. Narmada Main Canal as on today is completed up to 458 Km. and water has been flowing throught it right upto the state of Rajasthan.
Features of Narmada Main Canal:
- Full supply level (F.S.L.) at H.R. 91.44 m (300 ft)
- Length up to Gujarat - Rajasthan border 458.318 Km
- Base width in head reach 73.10 m
- Full supply depth (F.S.D.) in head reach 7.60 m
- Design discharge capacity
- In head reach 1133 cusecs
- At Gujarat Rajasthan border 74.55 cusecs
Statement showing total number of structures on Narmada Main Canal
|Reach in Km.
||0 to 144.5
||144.5 to 263.265
||263.265 to 356.422
||356.422 to 388.164
||388.164 to 458.318
|Total Number of Structures
|Canal Crossing + Super Passage
(E) Canal Distribution Systems and their Operations
Number of Branches 38 Nos.
Length of Distribution System Network 74626 Km.
Culturable Command Area 18.45 Lakh Ha.
Water for irrigation will be conveyed to 8 ha. Blocks through a 74626 km. network of conveyance and distribution system consisting of branch canals, distributaries, minors and sub-minors. There will be 38 branch canals off-taking from main canal, out of whichMiyagam, Vadodara, Saurashtra and Kachchh branch canals will be the major branches having a capacity of more than 75 cumecs (2650 cusecs). The distribution system would cover culturable command area of 18.45 lakh ha. (45.57 lakh acres) spread over in 3112 villages in 73 talukas of 15 districts of Gujarat. The branch canals and the distribution system network up to 8 ha. Block will be lined.
The Canal Systems up to the village levels (called village Service Area) will be operated by the Central Authority i.e. Sardar Sarovar Narmada Nigam Ltd. Below the village levels, the systems will be fully operated by the organizations of farmers to be explicitly formed for the purpose. With the system affixed annual water allowance pre-decided and pre declared for various parts of the command area, is easy to convert this water allowance into numbers of actual watering that the farmers would get from the system at the village levels. For example, on an average about 6 to 7 annual watering can be made available to the farmer’s Associations at village levels. It is the need-based privilege of the farmers associations to plan what number of watering that they would like to avail in the Kharif (monsoon) season and what number of watering they would like to use in the non-monsoon (winter)season. They would take decisions on the basis of rainfall an its distribution. Once the farmers make their schedules, it would be easy to aggregate these at the level of distributaries and branches of the systems.
(F) Command Area Development
Sardar Sarovar (Narmada) Project (SSP covers Culturable Command Area (CCA) of 18.45 lac ha within Gujarat. With extensive studies on the subject, detailed elaborate and micro level plan has been evolved to deal with the development of SSP command. Entire command area is divided into 13 agro climatic zones and each zone is further subdivided in to irrigation and drainage blocks ranging from 4000 to 10,000 ha. Involvement of farmers in the construction activities and there after for irrigation management is aimed at to ensure efficient user friendly uses. The system below the VSA outlets will be managed by the Water Users' Associations (WUAs) based on Participatory Irrigation Management (PIM).
One of the unique feature is that the Irrigation Water in the command area of SSP would be delivered to farmer's groups (Water Users Association (WUA) and not to individual farmers. It would be for the farmers groups to manage distribution within their block called village service Area (VSA). The corollary to this management is that the minors, subminors and field channels will be owned and looked after by these WUAs.
Involvement of farmers/NGOs in the construction of micro level canal network system would ensure 'owners' amongst the beneficiary farmers.
The another important feature is the volumetric supply of water instead of conventional area approach. The micro level canal systems with appropriate structures are being designed and constructed to ensure timely and equitable distribution of water. This would guard against the most commonly observed problem of overuse of water by initial command blocks, leaving less supplies to the tail enders.
To ensure efficient water uses, the evaluation would be based on delta basis. Water intense crops would be discouraged.
Micro irrigation system like drip and sprinkler would be encouraged for efficient water uses.
An interesting as well as innovative feature of the SSP's irrigation plan is to supplement canal water supply by conjunctive use of ground water. This would augment total water availability and stretch the irrigation benefit to more area. It will also prevent water logging by regarding excess ground water and thereby protecting command against water logging and soil salinity.