Optimization of Hydro-Power Potential of Samanalawewa Project

The Ceylon Electricity Board under the Ministry of Power & Energy commenced the construction of Samanalawewa Hydroelectric Project in early 1987. The aim of the project was to harness the hydro electric potential of the Walawe Ganga to produce about 430 million units of firm electrical energy per anum and to add 120 MW power to the national grid. The project consists of a rockfill dam with a crest length of about 530 m and a height of about 100m above the river bed level. Samanalawewa dam is located just downstream of the confluence point of Walawe Ganga and Belihul Oya, one of its main tributaries. The reservoir created by the dam has a total live storage capacity of 218 MCM and the dead storage is about 60 MCM. The U shaped reservoir spreads to a distance of 8km upstream along two limbs of the Walawe Ganga and Belihul Oya. The intake with the waterway system for the powerhouse is located about 6 km upstream of the dam. At this region, the reservoir and a secondary tributary of Walawe, Katupath Oya come nearest to each other and the level difference exceeds 400m. (Fig 1)