Energy Crisis: Causes and Solutions

Construction of Bhasha Dam, if built, will take a decade or more which will only replace the dwindling capacity of Tarbela and Mangla Dams and not add to the capacity; a fallacy being projected. One of the answers is in the construction of Akhori Dam. Building of Akhori Dam could be partial answer as this project will store about 8.6 billion cubic meters (Seven million acre feet) surplus Indus River water that is spilled after filling Tarbela reservoir.

The reservoir is proposed to be developed by constructing dams across a valley near Akhori village. The valley is situated between Attock and Fatehjang, on the left bank of the Haro River, about 40 km west of Islamabad and 35 km south of Tarbela Dam. The intake structure will be designed for supplying water from Tarbela to Akhori reservoir and it will be constructed on the southern periphery of Tarbela reservoir.The intake will function as an additional spillway of Tarbela that will release the water into the conveyance channel for delivering to and storing in Akhori reservoir. The invert or sill of the intake structure will be at the same level as the crest of two existing spillways of Tarbela. Apart from storing water for agriculture, it has the capacity to generate electricity as well as the design of hydropower station shall tie together the hydro energy of the stored water before it is released from Akhori reservoir into the Haro River.Then the released water will join the Indus River downstream of Ghazi Barotha hydropower station. Also, sedimentation problem is believed to be less as the raised intake sill can divert to Akhori reservoir sediment free water that is near the top surface of the full Tarbela reservoir.

Diamer Bhasha Dam Project will be undertaken in the first phase. Detailed engineering design of the dam and allied structures is complete and tender documents are ready. Process of prequalification of contractors has started and contract for project implementation through five lots is in advertising phase. The project is located on Indus River, about 315 km upstream of Tarbela Dam, 165 km downstream of the Northern Areas’ capital Gilgit and 40 km downstream of Chilas.

The proposed dam would have a maximum height of 272 m, and impound a reservoir of about 8.1million acre feet (MAF), with live storage of more than 6.4 MAF. Mean annual discharge of Indus River at the site is 50 MAF. Thus the dam will impound 15 per cent of the annual river flow. The dam project would cover an area of 110 km2 and extend 100 km upstream of the dam site up to Raikot Bridge on Karakoram Highway (KKH). The dam is located at the boundary of Khyber Pakhtoonkhwa (KP) and Northern Areas (NA) in such a way that the right abutment and the right Power House is in NA while the left bank of the dam and the left Power House is in KP. WAPDA offices and Colony, including that of the consultants will be in the Thor Nullah Valley in NA while the contractor’s camp and fabrication yard and workshop will be in KP. Fearing that this project might actually go through, India in all its treachery put in complaints to the international forums that its construction may be stopped as the area falls in their purview of Greater Kashmir.

Dasu hydropower project is a run of river scheme, seven km upstream of Dasu village on Indus River, 69 km downstream of Diamer Bhasha Dam and 345 km from Islamabad. Its salient features are that it will be constructed on river Indus with electricity generation capacity of 4230 MW and annual energy of 21,300 GWh. It will be roller compacted concrete dam with 233 m above bed rock and with gross storage capacity of 1.15 MAF. A joint venture of two foreign companies, Colence and MWH with Nespak and ACE as local firms signed agreement on June 15, 2006, for consultancy job.Feasibility study was completed in February 2009. Pre-qualification documents were received in April 2009 and the bids have been submitted by the short listed firms at the time of writing this report. Detailed design is to be awarded this year. The chances of this dam being built are brighter as it is run-of-the-river project without a reservoir.More space is needed for discussing other feasible projects namely: Munda Dam Project, Tarbela 4th Extension, Kohala Hydropower Project, Bunji Hydropower Project, Kurram Tangi Dam Multipurpose Project, Keyal Khwar Hydropower Project, Golen Gol Hydropower Project, Lower Spat Gah Hydropower Project, Lower Palas Valley Hydropower Project, Thakot Hydropower Project, Pattan Hydropower Project, Phandar Hydropower Project, Basho Hydropower Project, Lawi Hydropower Project, Harpo Hydropower Project, Yulbo Hydropower Project, Suki Kinari Hydropower Project and Matiltan Hydropower Project as per Wapda Plans. These shall be discussed in our subsequent discourses. It is, therefore, proposed to conclude this submission on the need for saving Tarbela Dam.

Need for saving Tarbela

Tarbela Dam supports irrigated agriculture by supplying its stored water for irrigation. It also supplies 3,478MW cheap and inflation proof hydropower to Pakistan’s power grid. A loss of storage capacity of Tarbela results in a corresponding decline in wheat, rice, cotton, sugar cane and other agricultural outputs. In fact, Tarbela is a very important and strategic resource which must be protected at any cost. The storage capacity of Tarbela reservoir, however, is depleting at a rate of 100,000 to 120,000 acre feet per year because it is accumulating 150 to 200 million tonnes sediment inflow of the Indus annually. The following sketch shows the magnitude of the accumulated sediment in Tarbela reservoir and the corresponding loss of the useful storage capacity. The depletion of Tarbela reservoir is one of the reasons for the recent water shortage and the consequent power and food shortages.

The trapped sediment has now reached a point where its outflow through power tunnels one to three is increasing and is damaging cooling water system, pressure relief valves and other similar parts of power plant. It is difficult to understand why unmitigated sedimentation of Tarbela was allowed. Probably WAPDA must have assumed that new, large water reservoirs would have been built at regular intervals for replacing the aging reservoirs. Or WAPDA assumed that trapping the sediment in Tarbela was beneficial because it would maximize the hydropower output, prevent erosion of water outlets and reduce O&M cost of Tarbela plus other downstream irrigation works.

Now in the light of impact of reduced water storage on national economy it is obvious that unmitigated sedimentation is going to inflict bigger damage than the assumed benefits. All the viable options like dredging for removing the trapped sediment from Tarbela reservoir are expensive. If this option is adopted, one could build another reservoir in that cost. It is essential that further unmitigated sedimentation should be prevented; otherwise Tarbela will become a run of river project, like Warsak, by 2025. Unfortunately WAPDA has no plausible plan for mitigating the sedimentation except trapping the sediment in the future Bhasha reservoir, which is wrong for three reasons.

First, the construction of new water storages on the Indus River is uncertain, because it involves the complex social, environmental, political and other issues. Second, it is not prudent to stop sedimentation of Tarbela by depleting the storage of more costly Bhasha.

Third it is not certain that Bhasha dam can be completed before Tarbela reservoir becomes a run of river project. A policy of inactivity must be replaced with immediate action for preventing further depletion of Tarbela reservoir. For this purpose WAPDA had commissioned many studies from which an appropriate solution for mitigating the sedimentation may be possible. Alternatively WAPDA should make arrangements to manage the impact of increasing sediment outflow through all tunnels.

For this purpose first the outlet control structure of Tunnel-3 should be reconnected with the tunnel for emergency operation. Second, new hydropower plants should be installed on Tunnels-4 and 5 so that optimum power can be generated from Tarbela when some tunnels will have to be closed for repairing the damages caused by sediment outflow. Third, O&M budget of Tarbela Dam project should be increased so that damaged hydraulic surfaces can be repaired regularly.