Tarbela, world's largest earth and rock-filled dam with 85 years life is key factor in self-sufficiency in food and accelerating the pace of national economic development.
Tarbela completed in 1974 under historic Indus Basin Settlement Plan, has greatly enhanced the agriculture and industrial potential of the country lending major support to the country's economy.
Sedimentation to the extent of 2.521 million acre feet (MAF) in Tarbela reservoir since its operation has reduced the reservoir's gross capacity from 11.620 MPF to 7.3 MAF at present.
Billions of units of electricity energy generated at Tarbela Power Station so far have reduced the gap between supply and demand and also saved huge amount of foreign exchange which otherwise had to be spent on thermal power generation and keeping overall tariff down.
A total of about Rs 123 billion have been recorded in terms of direct benefits from water releases and power generation during the last 24 years of its operation.
Initially Tarbela Dam project was designed to have a useful life of 55 years, however, measurement of actual deposition in the reservoir during the last 25 years of its operation indicate that sediment influx has been on the lower side and it is anticipated that with careful operation in future, its storage life can be enhanced to some 85 years.
The live storage capacity of reservoir has reduced from (original) 9.68 MAF (million acre feet) to 7.3 MAF at present.
With the yearly cycle of reservoir operation, the delta formation is continuously reworked and moved down stream coming closer to the dam. On an average rate, the pivot point of delta has been advancing at half a mile per year and the pivot point is 9 miles upstream dam site at present.
The yearly hydrographic surveys reveal that about 200 feet deep sediment deposits have accumulated up to 30 miles upstream the dam.
Wapda while meeting the water requirements for Rabi and Kharif crops also fully ensure safety of the structure of the project which is paramount.