Review of hydrology and spillway capacity of Simly Dam project

Simly Dam was built to supply drinking water to Islamabad, the Capital of Pakistan. During construction of the project, flood higher than the design flood was experienced. The hydrological data and design of existing spillway for safe passing of revised PMF was reviewed. the spillway capacity was found inadequate. It was decided to construct an auxiliary spillway on the saddle. Later on gates were installed on the existing service spillway to enhance the water supply from 24 MGD to 42 MGD. This paper describes the studies carried out to review the hydrology and spillway capacity of the project.