Uma Oya Multi-Purpose Development Project


The Uma Oya Multi-Purpose Development Project (UOMDP) 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 in a 23 km long trans-basin diversion tunnels with an underground power station at Randeniya.


In May 2008 an agreement upon Uma Oya multipurpose project was signed by the presidents of Iran and Sri Lanka with a value of 525 million USD. According to this agreement the duration of the project was predicted to be 5 years and it has started from 2010.


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

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

Specific Characteristics

Main features of the project include two RCC dams and more than 20 km of tunnels to connect the created reservoirs with the underground power station and to release water to the downstream Alikota Ara River.

Project Specifications

Dam Type

Two RCC Dams

Dam Height Above Foundation (M)

Puhulpola Dam: 35            

 Dyraaba  Dam: 50

Dam Crest Length (M)


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)


Powerhouse Type


Powerhouse Dimensions (M)

Length: 70

Width: 17.90

Height: 23.30

Spillway Type

Free Overflow

Energy Dissipater Type

Flip Bucket & Plunge Pool

Installed Capacity

2 x 60

Annual Energy

290 GWh