Uma Oya

Largest basin to basin water transport in Sri Lanka which was inaugurated by the president of Sri Lanka

The Uma Oya Multi-Purpose Development Project is located 200 km east of Colombo Uva Province of Sri Lanka. It consists of the construction of two dams across two main tributaries of Uma Oya at Welimada and Dyraba and a 23 km long trans-basin diversion tunnel with an underground power station at Randeniya.
Dam Type Two RCC Dams
Dam Height above Foundation (m)
  • Puhulpola Dam: 35
  • Dyraaba Dam: 50
Dam Crest Length (m) 1550
Total Reservoir Volume (MCM)
  • Puhulpola Dam: 0.97
  • Dyraaba Dam: 0.634
Diversion Culvert Length (m)
  • Puhulpola Dam: 30
  • Dyraaba Dam: 40
Mean Annual Discharge (MCM) 218
Powerhouse Type Underground
Dimensions (m)
  • Length: 70
  • Width: 17.90
  • Height: 23.30
Spillway Type Free Overflow
Energy Dissipater Type Flip Bucket & Plunge Pool
Installed Capacity MW 2 x 60
Annual Energy 290 GWh


The main objectives of Uma Oya Multi-Purpose Development Project are as follows:

  • Generation of hydropower
  • Irrigation of farmlands
  • Supplying drinking water
  • Supplying industrialwater
  • Supplying water for the second International Airport in Hambanthota, the Industrial Zone of Hambanthota, the Hambanthota Harbor and the Oil Refinery