Pakistan, bestowed with vast water reservoir and favourable dam sites. The first major dam (Warsak) was completed in 1960. This was followed by other dams; such as Baran Dam, Tanda Dam, but the real breakthrough in this field occurred upon the launching of Indus Basin Replacement Plan. This plan included construction of two large dams; namely, Mangla Dam and Tarbela Dam.

In view of the key role of these dams in the economy of the country and huge loss to the life and property associated with their failure, concern was felt for the proper arrangement to safeguard their safety during operation. Accordingly, in the light of practice of safety monitoring system followed by US Corps of Engineers and other developed world countries, Dams Monitoring Organization (DMO) was first established in WAPDA in August, 1973. Later on it was renamed as Dams Safety Organization (DSO).

Functions

Most of the high dams in Pakistan lie above thickly populated areas and rich agricultural lands. Failure of any such dam could spell a disaster and irreparable loss of life and property. In order to minimize the chances of such failures, systematic monitoring of their performance has been considered imperative. Dams Safety Organization (DSO) is responsible for implementation of this programmed monitoring for completed dams with WAPDA namely; Mangla Dam, Tarbela Dam, Warsak Dam, Khanpur Dam, Hub Dam and Chashma Barrage.

The dam safety programme consists of Three Tiers. The First Tier monitoring is carried out by the operation and maintenance (O&M) staff of the project. This consists of observing the responses of the vast network of instruments embedded in the various structures. The data collected thus is compiled and analyzed to identify the areas of abnormal behavior and to devise measures for immediate action.

The Second Tier monitoring is carried out by DSO. It is done by keeping a constant watch on the flow of instrument response data of the project structures through Tier One, analyzing it using the latest interpretation techniques, locating the areas of abnormal behavior and suggesting short term and long term solutions. DSO also undertakes annual inspections to see the physical condition of the works and to make on site appraisal of performance data. At the end of the inspection, a comprehensive report is issued commenting upon the physical condition of the works, abnormalities observed, their likely causes and possible solutions, its experts also visit projects, whenever any abnormal situation is reported, to study the phenomenon in situ and suggest corrective measures. In summary DSO's functions under Second Tier are as below:

• Carrying out annual inspection and issuance of inspection report, identifying physical inadequacies, erratic performances, possible causes and the corrective measures.
• Compilation, tabulation and interpretation of performance data of project structures and issue biannual safety evaluation reports.
• Paying site visits to study, diagnose and prescribe problems of emergent natures.

The Third Tier monitoring implies Periodic Inspections which are undertaken at an interval of 2 to 5 years, depending upon the hazard valued and age of the dam. This is supposed to be carried out by a team whose members have no direct concern with O&M of the project and may be drawn from, within and outside WAPDA. Periodic Inspection reports are comprehensive documents reviewing the health of the structures, identifying the areas of concern and suggesting short term and long term corrective measures.

DSO has so far carried out 89 Annual Inspections and arranged 22 Periodic Inspections of various projects. DSO renders performance monitoring and safety inspection services to federal and provincial dams of the country whenever asked for by any agency. Twenty (20) small dams of Punjab Government were inspected and advised rendered. Simly Dam of Capital Development Authority is being regularly monitored and inspected by DSO.