Kalabagh Dam

The Kalabagh Dam Project site is located 210 km downstream of Tarbela Dam and 26 km upstream of Jinnah Barrage on the River Indus. The project envisages the construction of 260 ft high rock-fill dam. With its maximum retention level at 915 ft., the dam will create a reservoir with usable storage of 6.1 MAF. The project has two spillways on the right bank for disposal of floodwater. In the event of the highest probable flood, these spillways will have a discharge capacity of over 2 million cusecs. On the left bank is the powerhouse, which will be connected to twelve conduits, each 36 feet in diameter, with an ultimate generation capacity of 3,600 MW. It may be noted that the average flow at Kalabagh is 89 MAF, made up of 72 percent from the Indus, 25 percent from the Kabul and 3 percent from the Soan. The live storage of 6.1 MAF will be only 7% of the average annual flow.

Initial Design:
The initially proposed design of Kalabagh Dam consisted of an earth fill dam of about 265 feet height above the average riverbed and 4,150 feet in length. The crest of the embankment was to be at an elevation of 945 ft and top width 50 feet. The auxiliary dam, situated between the sluiceway and the natural high ground on the right bank, was to be 4,900 feet long with a maximum height of about 100 feet. The design features of the auxiliary dam were to be similar to those of the main dam. The proposal included the construction of a sluiceway - diversion structure located on the right bank and provided outlet and diversion facilities. Provisions were made for 33 diversion vents, each 20 feet wide and 25 feet high, fitted with radial gates with a capacity of discharging 1.33 million cusecs when the reservoir were full at a water level of 925 feet. Depending upon the sluicing operation; the useful life of Kalabagh reservoir is almost unlimited. The maximum capacity of the storage was planned to be 9.375 MAF with a live
Storage of 7.771 MAF. The capacity at lowest water level was 1.604 MAF and
1.037 MAF at the sill of sluices. The level of full reservoir was to submerge 2,189 miles2 of land. Auxiliary gravity spillways were to-be-provided to discharge 1.4 million cusecs through 56 gates at 907 ft at sill level of spillway. The power facilities of the dam were to be similar to Tarbela and Mangla, having 8 power generating units, each with a power waterway and penstock of 36 ft internal diameter.

Key Facts:

Dam Type:	Earth fill
Height:	260 ft. (above riverbed)
Length:	11,000 feet
Area at retention level	164 miles2
Catchments Area:	110,500 miles2
Gross Storage Capacity:	7.9 MAF
Live Storage Capacity:	6.1 MAF
Dead Storage:	1.8 MAF
Retention Level:	915 ft amsl
Main Spillway Capacity:	1.07 million cusecs
Design Flood Discharge:	1.92 million cusecs
Hydropower Generation:	3,600 MW
Maximum Discharge:	1.2 million cusecs (in 1929)
Total Volume of Dam:	34 million yds3
Geology:	Beds of clay stone, silt stone and Sandstone

Refined Design:
The project was initially developed with somewhat differing design criteria. The refined criteria were introduced in the subsequent layout optimization studies to accommodate technical, social, economic and political issues.

The principal modifications were as follows:

1. The retention level was 925 ft, which has been reduced by 10 ft to 915 ft.
2. The probable maximum flood inflow was 3.5 million cusecs, which has been raised to 3.65 million cusecs.
3. One gated overflow spillway and one orifice spillway of approximately equal capacity were to be provided.
4. Four low-level outlets were initially provided, whereas, low-level outlets are provided now are also convertible conduits.
5. Four tunnels have been added for powerhouse enhancement. The initial installed plant capacity was 2,400 MW comprised of 8 units of 300 MW each whereas now 12 units may be installed to provide 3,600 MW.
6. The water retaining concrete structures, such as spillway headworks, would be designed and located so that they would not retain more than 160 ft head of water and would be founded on not less than 40 ft thick sandstone.
7. The dam would be an embankment dam with slopes of 1 on 2.5 generally.
8. No concrete structure should be built over the Kharjwan fault.
9. The power station would be sited so that large rebound movements due to deep excavations would be avoided, if possible.
10. The live storage capacity of the reservoir will now be 6.1 MAF with gross storage equal to 7.9 MAF, which were 7.77 and 9.37, respectively in the initial design.
11. The Orifice Spillway with crest elevation 40 feet below the minimum level of 825 will enable sluicing of silt-laden water of early floods and also help in the flushing of the sediment deposited in the narrow gorge of the reservoir.

Future Plan:
The Kalabagh reservoir (according to the existing design) will extend 92 miles upstream reaching 10 miles upstream of the confluence of Kabul-Indus. The Kalabagh storage, at a 915 ft elevation, would pose no flood risk to Nowshera, which is located at an elevation of 938 ft. Neither would it effect the operation of Mardan SCARP, the outfall elevation of which is 958.7 ft. It is estimated that the project will submerge 35,000 acres of land. Of this, 27,500 acres will remain submerged and shall have to be acquired permanently. This area would cover 24,500 acres in the Punjab and 3,000 acres in the NWFP.

Project’s Benefits:
Kalabagh Dam would enable additional and improved irrigation supplies to all
Provinces, within a short period. All other identified sites for dams have a
Much longer gestation period, in the absence of initial studies. The initial installation will generate 11,400 million Kwh of energy annually. As a consequence of conjunctive operation, it will enable enhancement of 600 MW of peaking capability and additional 336 million Kwh of annual generation at Tarbela.

Kalabagh Dam will augment irrigation supplies, hydropower and alleviate floods. Additionally, indirect benefits like more industrial and food production, employment and agricultural boost will accrue. The project will have a useful economic life of over 50 years, without requiring any major replacement of machines and E&M equipment. The project will pay back its investment cost in a period of less than 10 years, as projected project annual benefits are US$ 628.18 Million and the project financial cost is US$ 6002 Million (inclusive of interest and escalations) at 1998 price level.

On the basis of the project benefits accruing over a period of 50 years and
Investment cost for its construction, the proposed project shows an Economic
Internal Rate of Return (EIRR) of about 12% with a B.C. Ratio of 1.05:1 at 12%
Discount rate

LAND ACQUISITION AND RESETTLEMENT ISSUE

Based on a 1999 estimate, the total population to be relocated because of the project is 120,000. Of this, 78,000 persons will have to be relocated from the Punjab and 42,500 from NWFP. The project includes compensation for all Affectees for their properties, which include land, trees, buildings and other Structures at market price in compliance with the Land Acquisition Act. It is proposed to offer alternative land with minimum 12.5 acres to the land owning families. This would require about 74,000 acres of irrigated land. Another major incentive provided for the Affectees in the case of this dam, not previously offered for such a project in Pakistan, would be to fully compensate the farmers for the land on the reservoir periphery, above normal conservation level of 915 feet that could be flooded once in five years. This land would remain the property of the original owners for cultivation, with the undertaking that they would not claim any damages to crops for occasional flooding. The comprehensive resettlement package proposed for Kalabagh is both, more innovative and attractive than those adopted for Mangla and Tarbela Dams. The basic objective is that the Affectees should find themselves in a better socio-economic environment.
According to the plan, non-agriculturist Affectees would be trained in various trades in the Training Institutes to be established in the Model Villages. These measures will provide the Affectees with maximum job opportunities, where They would also be able to invest their compensation money, thus giving them an assured means of livelihood for future. By dropping the retention level from 925 ft to 915 ft, the area to be affected by the envisaged reservoir has been reduced from 159,700 acres to about 134,500 acres. This includes 74% un-cultivable land in both the provinces. Of this, 95,800 acres falls in the Punjab and remaining 38,700 acres in the NWFP. The project estimate provides for Rs. 5,731 million as the cost of land acquisition, resettlement and relocation works at June 1991 prices.