The River Servalar, a main tributary of Tambarabarani joins
the main river at a running distance of 22-km. The diversion weir marks
the confluence of Servalar and Tambaraparani.
A diversion weir was constructed just below the confluence of Servalar. The weir has a storage capacity of 49 M.cft. The Powerhouse, just below functions with a gross head of 91 m and a capacity 4 x 7 MW.
The Servalar Reservoir is across Servalar River. This is also a Masonry Gravity Dam of 450 m long and 53 m high. The reservoir has a storage capacity of 1,225 Mcft. The Power House at the reservoir will have an installed capacity of 20 MW. The Papanasam and Servalar reservoirs are interconnected by, a tunnel of 10,886 feet long.
The tailrace water from Papanasam Power House joins the main river Tambarabarani and it serves the wetlands on both sides enroute before it confluences with Gulf of Mannar. Many tributaries join the river course in the plains both on the right and left flanks.