Safety inspections of Chashma Barrage

Chashma Barrage is one of the six barrages constructed under Indus Basin Project and is the highest of all the barrages in Pakistan. It was built to re-regulate the discharges downstream of Tarbela Dam. A series of annual and periodic inspections has been carried out at Chashma since 1978 to assess its structural safety. The barrage used to be closed annually during the last week of December for inspection and repair of downstream glacis, stilling basin, concrete blocks and stone apron. Upstream components of barrage remained under water since first filling in 1971 ans were never inspected before 1997. This paper deals with the salient problems of the barrage as inferred from the inspection history. It also summarizes the annual inspection of 1997 when reservoir was depleted for about one month to repair the sill beam, paint the upstream sides of the gates and to repair the seals of gates.