Sri Lanka: Reality of the Uma Oya

The latest study of the Uma Oya basin was the trans-basin scheme prepared by SNC Lavalin Inc. (Canada) in 2000. This study was aimed at a comprehensive evaluation and assessment of the best scheme, from in-basin and trans-basin alternatives which have previously been studied.

by G.T. Dharmasena

( October 14, 2017, Colombo, Sri Lanka Guardian) Much has been reported about the Uma Oya debacle which has adversely impacted on the lives of people in Bandarwela in Badulla District. There are newspaper articles and TV debates, providing information on this, with either the present or previous government being blamed. Allegations are also levelled against officials of the Ministry of Irrigation, Mahaweli and the Environment Authority who were responsible for implementing this major engineering project. After evaluating these allegations, I thought it pertinent to provide some background information on the emergence of this project and slightly touch upon the current situation. Failure to provide vital material to the public could mislead the relevant officials and masses. Some of my concerns over this project were expressed at the beginning of implementation, in an article to Daily News on 29th of April 2008, coinciding with the foundation laying by former President Mahinda Rajapaksa and the Iranian President. The heading of the article was “Development of water resources of Uma Oya Basin ”

The Background

From the early planning stage of the Mahaweli Development Programme, several proposals for the development and utilization of water resources of the Uma Oya basin were made by United States Operations Mission (USOM) and the Canadian Hunting Survey Corporation (CHSC) as early as 1959. Later, UNDP/FAO Master Plan studies (1968/1969) for the accelerated Mahaweli programme proposed in basin development by the construction of Upper and Lower Uma Oya reservoirs, for hydro-power development.

In 1956, Lakshman Rajapaksa, MP for Hambantota (cousin of MR) was the Deputy Minister for Commerce and Trade under S.W.R.D Bandaranaike’s government, and he took the initiative to set up a cotton processing factory at Mirijjawila near Hambantota to encourage cotton cultivators in Hambantota and Monaragala. During this period cotton was a popular crop in the Eastern part of Hambantota and Monaragala, and cotton was cultivated under rain-fed conditions. This factory functioned satisfactorily and it started processing their home grown cotton. It was set on fire during the youth unrest in 1971 and became redundant.

Meanwhile, the Irrigation Department planned the Lunugamvehera Reservoir across Kirindi Oya in Hambantota District under ADB funding, with the objective of stabilizing the water storage in the existing Ellagala irrigation system with five tanks in Tissamaharama. In addition, cultivation of 8000 ha of irrigated cotton on new lands above Ellagala irrigation system was envisaged. The justification of cotton cultivation was mostly due to the ongoing practice of cultivation of rain fed cotton, which prevailed in Tanamalvila, Hambegamuwa and Hambantota areas. The availability of Reddish Brown (RB) soils in this area for such cultivation became an added advantage. Therefore, an ADB loan was obtained by the government for the construction of Lunugamvehera by giving the assurance for cotton cultivation under the new lands.

However, the original objective of irrigated cotton cultivation under the Lunugamvehera reservoir was forgotten soon after the construction of the reservoir, and the new irrigable area was converted to paddy cultivation. The shortage of water at Lunugamvehera arose as a result of changing the original cropping pattern from cotton to paddy, as paddy consumes very much more water in RB soil than cotton. Therefore, after completion of the reservoir project, the shortage of water at Lunugamvehera became a hot topic and the Irrigation Department was blamed for wrong planning. In view of this development, the Irrigation Department was thinking about various options to augment Lunugamvehera, including diversion of Menik Ganga and Uma Oya to Kirindi Oya.

In 1991, a pre-feasibility study of the Uma Oya Multi-Purpose Project (Trans basin option) was carried out by the Central Engineering Consultancy Bureau (CECB). In order to augment irrigation water supplies to Kirindi Oya basin, the CECB conceived a multi-purpose scheme for the development of the Uma Oya water resources as an alternative to the in-basin hydro-power development in the Mahaweli basin. According to this concept, water from Uma Oya would be diverted through a 24 km tunnel to the upper Kirindi Oya basin to augment the Kirindi Oya flows, and in the process generate a large block of electrical energy, utilizing a drop of about 600 m in a single stage.

Meanwhile, this issue of the Lunugamvehera water shortage was subsequently resolved successfully by the Irrigation Department, by diverting the Menik Ganga water to Kirindi Oya. For this purpose, the Irrigation Department constructed the Veheragala reservoir across Menik Ganga in 2006.Therefore, the diversion of Uma Oya to Kirindi Oya was never considered as a strategy by the Irrigation Department after the year 2000.

Hambantota Mega City

Then around the year 2000, development of Hambantota harbour, and airport at Weerawila were considered, with an objective of establishing an industrial city at Hambantota. This project was given serious consideration under the Southern Area Development Authority (SADA) during Chandrika’s government (1994-2005). The selected area of Hambantota for development is rich in land resources, but lacks in water resources. Therefore, finding water for industrial and domestic needs for these development activities became a priority. At this juncture, diversion of Uma Oya water to Kirindi Oya basin came to the stage again, and this time the objective was to provide industrial and domestic water for the Hambantota Mega city development.

The latest study of the Uma Oya basin was the trans-basin scheme prepared by SNC Lavalin Inc. (Canada) in 2000. This study was aimed at a comprehensive evaluation and assessment of the best scheme, from in-basin and trans-basin alternatives which have previously been studied. The consultant SNC-LAVALIN recommended the trans-basin diversion option to divert water to Kirindi Oya based on the conditions prevailing at that time. It was proposed to divert 192 mcm of water annually through a 23.2 km long tunnel to an underground power house at Randeniya on the right bank of Kirindi Oya. The installed capacity of the power house is 90 MW to produce 312 GWh of electrical energy. The total approximate cost of the project in year 2000 was Rs.16, 000 million.

Uma Oya diversion to Kirindi Oya:

After receiving the report from the consultant, SNC-Lavalin Inc. then government (2002-2004) wanted to make a decision regarding this proposed new diversion route, as it was originally planned to Randenigala reservoir according to the Mahaweli Master Plan. A meeting was held at the Power and Energy Ministry around 2003 headed by the Minister of Power and Energy and at least 7 or 8 Cabinet Ministers were present, and the Ambassador of Japan. At that meeting an agreement was reached to proceed with the investigation of Uma Oya diversion to Kirindi Oya for the purpose of meeting the industrial and domestic water to Hambantota. However, the Ambassador for Japan raised a question on water availability and requested to look into the varying flow figures provided by different consultants. Then a committee was appointed with Prof. KKW. Perera, then Chairman of the CEB, myself and some others and we were instructed to review the water availability and provide a report within a week.

After reviewing the available data by this committee, it was revealed that the availability of water is very much less than the estimates made by previous consultants, and therefore, our report was not encouraging. However, the expected report of our committee within a week was never tabled due to some reason, and the official process of project implementation by diverting water from the Uma Oya to Kirindi Oya was continued.

Cost and benefits:

Based on the current official figures, cost of construction is estimated at US $ 530 million and the expected benefit from the project is estimated at 290 GWh annually. It is expected to divert 167.0 mcm of water annually from Uma Oya through 120 MW power plants. The total length of the tunnel from Puhulpola to Wellawaya is 22.7 km. In addition to the power generation, it is planned to irrigate 4500 ha of new lands and 1500 ha of existing lands for rice cultivation in Wellawaya area. The original objective of supplying water for Hambantota industrial development and domestic water is now forgotten.

This cost excludes the resettlement and compensation to be paid to the victims of the project and this amount is yet to be estimated.

Current debacle at Uma Oya:

The current debacle is the damage to the environment as a result of lowering the ground water table due to the construction of the trans-basin tunnel. This leads to the interruption of the domestic water supply and geo-technical issues related to settlement of foundations of buildings, landslides etc. Some politicians, foreign experts and researchers are raising their finger towards the CEA and the Environment Impact Assessment (EIA) already carried out.There may be lapses in the EIA report, but this debacle has nothing to do with the environmental studies. Because, technical issues that one would anticipate during a tunnel construction cannot be clearly identified during an EIA study in advance. However, it is the responsibility of engineers to rectify those issues while construction is progressing. This requires adequate previous experience in tunnel construction in different geological conditions, as problems cannot be foreseen before actual drilling.

According to a Sri Lankan tunnelling expert working in UK, “Tunnels are much more environmentally friendly than most surface schemes where flora, fauna and human habitation can have adverse effects upon them which require serious physical mitigation. No environmental study is able to establish the crack pattern and the solidity of underground rock formations. If at all, such perdition could be made only by the experts who are thoroughly involved with tunnel design and construction. These issues will only come to light during the construction and the TBM should be so designed to be able to investigate the rock formations forward of the excavation face, inject grout, and stabilise the rock before boring through it, and then install the tunnel lining and the grout seal.”

Further, according to the expert, “The rock here in the Badulla region is not granite. It is a mixture of sandstone and limestone, and hence amenable to be bored using a TBM. However, as I said before, they should have made provision for forward probing and sealing cracks to avoid the leakage of water and reducing the water table of the ground above, which was the cause of the cracking in the buildings constructed with shallow foundations on weak soil. Apparently there are no specific building regulations in Sri Lanka and these buildings on shallow foundations tend to crack with the slightest of movement in the underlying soil”.


The most of the people who write articles and appear in TV debates have absolutely no idea of tunnelling, and very few people, if any, in Sri Lanka have any experience on Tunnel Boring Machines (TBM). The whole thing has been hijacked by some political elements to promote their ideology among the poor uneducated people in the Uva province, without giving room for someone with some expertise to explain the facts and the reasons behind this debacle. Most of the discussions are a pathetic display of ignorance by the “educated class”.

Superficially depletion of the ground water table and foundation settlement of a large number of houses and cracks are the critical issues at the moment. As explained by experts, provision has to be made for forward probing and sealing cracks to avoid the leakage of water and reducing the lowering of the ground water table after drilling.

According to the physical progress of the project at the moment, there is no possibility to turn back, as 70% of the work has been completed. Therefore, we have to go forward while rectifying the defects irrespective of the cost and economic viability.

Regarding the proposal for a fresh EIA, it is a matter of further wasting time and money. One of the issues related to an EIA study of this nature of work is whether we have experienced expertise in hydro-geology (not geo-hydrology) in Sri Lanka. The countless issues cannot be simply attributed to general Geography or Geology.

However, the crux of the issue at Uma Oya is the availability of water for diversion. There are more than 700 minor irrigation schemes above Puhulpola and Dyraaba reservoirs, and only the remaining water after diverting for upstream irrigation is available for diversion to Kirindi Oya.This concern can be seen only during the operation of the project after completion. Our concerns in this respect were highlighted in detail by the writer in the article published in the Daily News on the day of laying the foundation by the then President on 29th April 2008.

( The writer is the Former Director General of Irrigation)

Author: Sri Lanka Guardian

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