The Ponmudi Dam is a concrete gravity dam built across the Panniyar river which is a tributary of Periyar river at Konnathady panchayath of Konnathadi village in Idukki district of Kerala, India. The dam was constructed in 1963 as a part of a hydroelectric project. Construction was led by E.U.Philipose, Superintending Engineer, Kerala State Electricity Board. It has a length of 288.80 m. The hydropower component of the dam has an installed capacity of 30 MW with firm power of 17 MW, generating 158 GWh annually. Taluks through which the river flow are Udumbanchola, Devikulam, Kothamangalam, Muvattupuzha, Kunnathunadu, Aluva, Kodungalloor and Paravur.

Location

The dam, located near Munnar on the Panniar river in the Periyar river valley in Kerala, is part of the basin of the West flowing rivers of the Tadri to Kanyakumari. The nearest city is Udumbanchola. Mattupetty to Ponmudi dam is a distance of 39 km.

Features

The Ponmudi dam is a masonry gravity dam of 59 m height with a total length of 294 m. At the Full Reservoir Level, the gross storage capacity of the reservoir is 51540000 m3 and live storage is 47400000 m3. The dam has a total volumetric content of 181000 m3. The dam is located in Seismic Zone-III. The reservoir water spread area or submergence area is 2.79 m2. The spillway is designed for a design discharge of 1416.03 m3 per second. The flood discharge is routed through a spillway which is fitted with three radial gates, each 10.9728 x. The stored water is diverted through a tunnel of 3066 m for power generation creating a head of 220 m.

Hydro power development

The water stored in the reservoir is utilized for power generation by diverting the flows through a 3066 m tunnel followed by two lines of penstock pipes each with a diameter of 1.7 m and a length of 762 m. The two penstock pipe lines are designed to carry a discharge of 17.88 m3 per second. The power station located at Panniyar is provided with installation of 30 MW comprising two units, each of 15 MW capacity Francis turbines. The firm power generation is 17 MW and the annual power generated is 158 GWh. The first unit was commissioned on 29 December 1963 and the second unit on 26 January 1964. The units were renovated in 2001 and 2003.

Major disaster

In a major disaster at the project site, which occurred 17 September 2007, one of the penstock valves burst causing the death of 7 people, destroying 15 houses, and damaging 150 acre of crops. The reason attributed to the pipe burst is the loosening of the flange bolt connection. The damaged valve was rectified in July 2009.