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Application of Side Scan sonar technology and Isotope Techniques to confirm reservoir leakage - Samanalawewa Reservoir


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Application of Side Scan sonar technology and Isotope Techniques to confirm the reservoir leakage ingress of the Samanalawewa Reservoir

Date and Time

04 April 2013 - 17:30-19:00


Colombo 1, Sri Lanka - icon_popup  (See map)


Joint Event.
Contact Eng. Rukmal Jayasinghe - Hony. Secretary (0777751343) for more information.

About this event

The Samanalawewa reservoir on the Walawe river of Sri Lanka was built during the period 1986 to 1991. It is formed by a 100m high embankment dam and is the main element of the 120MW Samanalawewa Hydroelectric project. The dam is built in an area of complex geology, showing Karstic characteristics. Indications of a possible water leak through the right bank were surfaced when poor geological conditions were encountered during construction of the dam.  During the initial trial impoundment, the reservoir started to leak from its right bank with the reservoir partially filled, and impoundment was suspended. 

Attempts were made twice to remedy the leakage firstly with a 100m-deep, 1300m long grout curtain and then secondly with a clay blanket constructed over the suspected ingress zones. However both attempts could not stop the leakage. Although the second attempt did help to reduce groundwater pressure in the right bank.  The reservoir is presently operating with a continuous leakage of about 2000 litres per second.  

An analysis conducted on the right bank ground water level behaviour indicated that the possible leakage ingress areas are lying towards the right abutment of the dam. Later in 2011 a field exercise engaging Radio Isotopes was conducted to verify the above findings. The study confirmed the existence of inlets in the said area. Then again early this year underwater side sonar scanning of the suspected area was conducted to verify the findings further. The side sonar survey indicated images of anomalies in the ground profile which are considered to be the leakage inlets in the area identified.


17.30 - 19.00 Hrs


LKR 1,500/- for Non Members

Additional information

The lecture commences at 5.30 pm. Refreshments will be served after the lecture. Non-members will be charged at Rs.1,500/= per head.

Registration information

Online Registration -


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