Features
Raising of the Kotmale dam – misconceptions and facts
By Asoka Herath
BSc (Geology Hons); MSc (Engineering Geology), CEng.
Over the past few months, there has been considerable interests among not only geoscientists and engineers but also ordinary people in the potential risks faced by two of the major hydropower projects constructed in the central highlands, namely the Victoria and Kotmale projects. These projects have come into the limelight owing to some minor seismic tremors felt in the Victoria area, together with the recent announcement of the intention to raise the Kotmale dam. Alarm bells are ringing that seismic activity may jeopardize the integrity of the Victoria dam and the raising of Kotmale may result in dam failure. Should these dams fail, they will be the biggest manmade disasters our country has ever faced. This risk has prompted suggestions from the people higher up that we should seek advice from foreign experts.
Various opinions from the leading geoscientists of the country, regarding the causes and effects of this unusual activity were aired through the media recently. Some have attributed the seismic tremors to limestone quarrying in the Victoria reservoir area, some as the result of neo-tectonic movements of the central highlands, yet some others said they are reservoir-induced earthquakes. Those who are interested in the fundamentals of such activity may find the presentation in this link useful (https://www.youtube.com/watch?v=7huzvuU9TEI).
The intention of this article is to provide an insight into the geotechnical issues that influence the Kotmale Project, the risks, and to address some misconceptions people may have regarding the project. I take the liberty of writing on these issues as a person who has an in-depth knowledge of the Project by working from the site investigation phase through to construction completion, the later years as the Senior Engineering Geologist, leading the project geoscientist team.
The Project
Kotmale was meant to be the main upstream storage reservoir under the Mahaweli development scheme launched in the 1960s. It will regulate the Mahaweli waters, while providing a substantial energy component. The capacity of the reservoir will be more than doubled by the proposed raising of the dam, approximately by 30 m. The project was inaugurated in 1979 and funded by Sweden. Sir William Halcrow and Partners of UK (Halcrow) with Central Engineering Consultancy Bureau of Sri Lanka (CECB) was the design engineer and Skanska of Sweden was the contractor.
Geology of the Project Area
To understand the project risks, it is essential to understand the geology and structure of the project area. The area is underlain by Pre-Cambrian age metamorphic rocks comprising predominantly of two rock types, charnokite (gneiss) and crystalline limestone (dolomite or marble) with minor quartzites. The limestone is sandwiched between layers of charnokite gneiss.
The rock units are folded into a gentle anticlinorium (an arch like structure-convex shape) which has a slight plunge downstream. The axis of the anticline trends northwest and falls on the right abutment in the dam area. As such the dam foundation rocks have a slight inclination (15°-25°) downstream and into the abutments.
Charnokite is a very strong resistant rock, which does not breakdown easily while limestone deteriorates and erodes more easily. The initial site investigation drilling in the Kotmale valley found limestone thickness varied from 20 m to 130 m within the project area.
The limestone consists mainly of calcium carbonate (CaCO3) and partly magnesian carbonate (MgCO3). Carbonates dissolves in acidic water (acid rain) and forms solution cavities. These cavities have the potential to create leaks from the reservoirs.
Formation of the Kotmale Valley
The Kotmale valley is an amphitheatre-like valley reshaped by the erosional activity of the Kotmale Oya for millennia. It is approximately 5 km wide at the widest point, is surrounded by high rock cliffs up to 300 m high on both flanks, which converge at the Kadadora village; the site of the dam construction. The valley forming process was a combination of differential weathering and erosion of the underlying limestone unit, resulting in the collapse of overlying more resistant rock units. The basal slopes of the cliffs consist of accumulated debris of rocks and soil derived from the cliffs (termed as scree or talus). Historically these talus slopes were in perpetual slow motion (creep) towards the river. They were subjected to numerous landslides, typically during or after heavy rain events. Generally, the Kotmale valley was infamous for landslide activity.
History of Kotmale Project investigations
The location of the dam site had been selected for the seemingly favourable topography formed by the converging valley flanks. One of the first jobs assigned to me when I joined the CECB in 1978 as a young engineering geologist, was to map four exploratory tunnels driven into the abutments of the proposed dam and report the rock conditions. Our evaluation indicated the left abutment had very poor rock conditions not suitable for a dam foundation.
In 1979, to evaluate the landslide risk to the project, Halcrow carried out a landslide survey of the project area. This survey was done due to the frequent landslide activity in the Kothmale area, and its similarities to the Vajont Dam disaster that occurred in Italy in 1963, which wiped out several downstream towns resulting about 2500 deaths.
This study identified the left abutment as a settled block (subsided en mass); limestone solution the likely cause. It strongly recommended to move the damsite downstream and monitor the impressive cliffs on the left flank of the valley for potential movements.
Evaluation by a panel of experts
As these findings were major issues impacting the viability of the Project, the Mahaweli Authority of Sri Lanka as the owner of the project, in early 1980 engaged a panel of foreign experts who were the leaders in the fields of rock and soil mechanics, to evaluate the potential issues and provide recommendations. This panel endorsed the relocation of the damsite.
Subsequently, the dam axis was moved approximately 200 m downstream from the original location.
Nature and distribution of the limestone
At the new location, the limestone was at a much greater depth below the dam foundation compared to the original site as shown in Figure 1. Even so, solution cavities were observed in the contact zone and within the limestone itself identified by drilling and close circuit television (CCTV) inspections carried out in the drillholes. Our best estimate indicated small cavities, however a drillhole represents only a small area, therefore the existence of larger cavities could not be ruled out.
Leakage through cavernous limestone is widespread from the reservoirs built in our hill country. The Samanalawewa Project is the best example where significant leakage had been occurring through a cavernous limestone under the right abutment since the impoundment, which could not be sealed.
Continuity of the Kotmale limestone
Investigations were carried out to establish the continuity of the Kotmale limestone to downstream areas in view of potential leakage which were inconclusive. The recent geological map for the Kandy-Nuwara-Eliya districts (GSMB), I am convinced that the Kotmale limestone continues to Gampola-Atabage Valley and further to the Victoria Reservoir as a major rock unit. The limestone quarrying in the Victoria Reservoir area occurs in the same unit, which caused the recent furore about seismic events allegedly caused by blasting. Whilst I do not believe there is (or will be) significant leakage from Kotmale Reservoir, future raising of the dam may enhance leakage if it exists which needs evaluation.
Water tightness of the dam foundation
To eliminate the risk of water leakage through the limestone under the dam foundation, it was extensively grouted from a grouting gallery constructed below the dam level (see Figure 1). Generally, the grout intakes were low. Nevertheless, few holes required significant amounts of grout before they could be sealed. Subsequent water pressure testing indicated the limestone unit was properly sealed and the foundation was watertight.
Monitoring of the cliffs and other landslides
During the initial impoundment, the cliffs were inspected by walkover surveys and by periodic monitoring with geodetic surveying. Movements of any significance, precursor of an impending major failure were not recorded during the early years after construction.
Reservoir Induced Seismicity (RIS)
One important consideration in the construction of large reservoirs is the potential for reservoir induced seismicity (RIS). RIS is the incidence of earthquakes triggered due to the impoundment of water behind a dam. A simplistic explanation is that reservoirs trigger earth tremors due to the load of water which could activate otherwise dormant faults, the energy released causing earth tremors.
Halcrow decided to investigate the risk of movement of some major structures present in the Kotmale reservoir area upon impoundment, which could potentially induce seismic events. Consequently, a micro-seismic monitoring network (MSMN) consisting of four monitoring stations was established around Kotmale project in 1981. The monitoring program was managed by the CECB and continued until the early 90s.
Published data (Fernando & Kulasinghe 1985) show that the maximum event recorded at Kotmale during the first two and half years of monitoring, was an event of 2.25 magnitude (Richter Scale), located far away from the project area. The monitoring led to the conclusion that the potential for RIS at Kotmale was extremely low or non-existent. However, in view of the recent seismic events recorded around Victoria, it will be prudent to revisit the monitoring records from the Kotmale network, presumably archived by the CECB.
Potential risks from future raising
The Kotmale project infrastructure, were designed and constructed for future raising. Theraised dam simply achieves the original vision of the project, as the main upstream storage reservoir and increases power output.
In my opinion the geotechnical risks arising from the raising of the Kotmale dam are as follows:
= The raised water level in the reservoir will fully inundate the scree slopes and reach the base of the left bank cliffs with potential to create major landslides. Cliff monitoring should be re-established using modern methods such as satellite based synthetic aperture radar interferometry (inSAR).
= There is potential for leakage through the limestone with raised water levels. All evidence suggests the limestone under the dam was properly sealed. Leakage from the reservoir flanks cannot be prevented, which is not a fatal flaw to the project. Requirement for abutment sealing should be revisited.
= It will be useful to re-establish the monitoring program of stream gauging in the Gampola-Atabage valley to investigate if any leakage will occur from Kotmale to Atabage valley. This should be initiated before the dam raising.
= All evidence points to reservoir induced seismicity is a non-issue for Kotmale Project.
Finally, I strongly advocate the raising of the dam for the following reasons:
= The original project infrastructure was developed with the intention of future raising.
= There are potential risks but not fatal flaws to the viability of the Project. These risks can be mitigated.
= People were evacuated from their ancestral lands going under the reservoir and if the project is not completed as originally intended, then this relocation of people was without merit and a grave injustice to them.
= The country unnecessarily lost approximately 30 MW of power for more than 35 years.
The potential risks with the raising of the Kotmale dam discussed here need to be evaluated, and if the need arise, they should be mitigated and managed using local expertise. In my opinion, what Sri Lanka lacks is good project managers vital in successful implementation of projects of such enormous national importance. In hindsight, the Kotmale reservoir should have been built to the full capacity at the first instance.
(The author currently works as a Principal Geotechnical Engineer with AMC Consultants Pty Ltd, Perth, Australia, and can be contacted at hma1904@gmail.com).
Features
Combining local resources,traditional knowledge and science to build a food-secure Sri Lanka
World Food Day 2026: Innovating today for a better food future
by Dr. Kaushalya Wijayasekara
What will be on the Sri Lankan dinner table ten years from now? Will our children be able to get nutritious food at a price their families can afford? Will farmers be able to grow enough despite changing weather and rising costs? And how much of the food we produce will actually reach the consumer, instead of being lost or wasted along the way?
These questions can’t wait. A farmer faces unpredictable weather. A family faces rising food costs. Fruit goes unsold after a good harvest. Some children do not get enough nutrition. The future of food is tied to the future of Sri Lanka itself.
World Food Day 2026 is a chance to look beyond the immediate problems and ask whether we can build a food system that feeds our people well, gives farmers better opportunities, protects the environment and makes better use of what we already have. The answer can be yes, but we will have to think differently.
We are not starting from zero. Sri Lanka has diverse crops, fisheries, traditional food knowledge, indigenous varieties, research institutions, universities and a young generation able to create new solutions. What we need is to bring these together and act. Producing more will not secure our food future on its own. It will depend on how intelligently we produce, process, preserve, distribute and consume food.
Making more of what we already have
Innovation does not always mean inventing something new. Often it means finding better uses for the resources we have.
Sri Lanka grows traditional rice varieties, kurakkan, green gram, cowpea, jackfruit, breadfruit, cassava, sweet potato, coconut and palmyrah. All of them have great potential for modern, nutritious, value-added foods. Jackfruit and breadfruit can be made into flour and other convenient products. Traditional rice varieties can go into new foods that suit changing consumer needs. Palmyrah, with its strong cultural heritage, can create new income through better processing, packaging, quality assurance and market development.
The aim is to connect our traditional food knowledge with modern consumer needs and technology, while keeping our food heritage.
Stop wasting the food we produce
Reducing food loss and waste should be a major priority. Seasonal fruits such as mango, banana, papaya and pineapple can be lost in large quantities when production exceeds demand or when storage, transport and processing facilities are inadequate. With suitable technology, these fruits can become dried products, pulps, powders, beverages and other shelf-stable foods.
Agricultural and fisheries by-products are resources too. They could be turned into food ingredients, animal feed, bio-based products and other useful materials, which would move us toward a more circular food economy.
Technology alone is not enough. We need stronger local processing facilities, cold storage, efficient transport, collection centres and market information systems, especially close to where food is produced. Cutting food loss raises the value of what our farmers and fishers already produce.
Nutrition and food safety come first
Food security means more than having enough food. People also need food that is safe and nutritious.
Sri Lanka can develop affordable, nutritious foods from local pulses, grains, vegetables, fruits and fish. Children and other vulnerable groups should get particular attention. Schoolchildren in particular deserve a focus: safe, nutritious, locally sourced products for school feeding programs would support child nutrition, local farmers and domestic food industries at the same time.
Food safety must stay at the centre of food innovation. Good hygiene, quality control, laboratory testing, traceability and appropriate food safety systems are what make new products safe as well as attractive and nutritious.
A food system that can cope with climate change
Climate change is already affecting agricultural production, water availability, crop yields and food prices. We need food systems that can handle changing conditions. That means climate-resilient crops, efficient water use, soil and water conservation, better storage and resource-efficient food processing.
Traditional knowledge matters here. Generations of Sri Lankan farmers have developed practices suited to local climates and ecosystems. Combining that experience with modern science can give us solutions that fit local conditions and are sustainable. Technology alone will not build the future of food. Science, experience and local knowledge together can.
Give young people a bigger role
Sri Lanka’s universities have an important part to play in shaping our food future. Young people should be encouraged to identify real problems in the food system and work on practical solutions in areas such as food waste, sustainable packaging, nutrition, food safety, modernising traditional foods and digital technologies.
A good research project should not always end as a research paper. Where appropriate, research should be supported to move on to products, technologies, enterprises and community solutions. That needs stronger partnerships between universities and industry, along with mentoring, research funding, business support and market connections. If young researchers and entrepreneurs can turn their ideas into viable food innovations, both consumers and producers will benefit.
A pathway designed for Sri Lanka
We do not need to copy food-system models from other countries. We can build a pathway that suits our own resources, culture and needs. It would bring together local resources, traditional knowledge, scientific research, appropriate technology and entrepreneurship, with farmers, fishers, universities, research institutions, food industries, entrepreneurs and policymakers working side by side.
The goal goes beyond selling raw materials. We need to create more value, reduce waste, improve nutrition, generate jobs and strengthen rural livelihoods. This matters especially for small and medium-scale food enterprises, which can drive local economic development when they get the right technical, financial and market support.
The choices we make today
The food future will not create itself. It will be shaped by what we grow, what we research, what we process, what we consume and what we choose not to waste.
So, the question for World Food Day 2026 is this: what can we do today so that every Sri Lankan has safe, nutritious, affordable and sustainable food tomorrow?
The answers are already around us, in our farms, fisheries, food businesses, universities, laboratories and communities. We have the resources, the traditional knowledge, the scientific expertise and talented young people. What we need now is to connect them and act.
A better food future begins with the choices we make today.
Dr. Kaushalya Wijayasekara
Senior Lecturer, Department of Biosystems Technology, Faculty of Technology, University of Ruhuna
Features
20th Anniversary of Digampathana blast – the day Sri Lanka Navy cried
By Admiral Ravindra C Wijegunaratne
WV, RWP and Bar, RSP, VSV, USP, NI (M) (Pakistan), ndc, psn, Bsc
(Hons) (War Studies) (Karachi) MPhil (Madras)
Former Navy Commander and Former Chief of Defence Staff
Former Chairman, Trincomalee Petroleum Terminals Ltd
Former Managing Director Ceylon Petroleum Corporation
Former High Commissioner to Pakistan
The Digampathana suicide truck attack on 16th October 2006 remains the deadliest single strike in Sri Lanka Navy history, leaving scars that time cannot erase.
It was a seemingly ordinary Monday morning on 16 October 2006, but the calm of that day would soon be shattered in a way none of us could have imagined. As the Commandant of the Naval and Maritime Academy and Flag Officer Commanding Naval Fleet at Trincomalee, I was aware that a number of my cadets were travelling that morning, part of a convoy of fifteen buses carrying naval personnel from Trincomalee, Colombo, and other bases, heading toward Dambulla to rendezvous with another group. The convoy also included trucks and escort vehicles, a routine movement planned and coordinated with the army to ensure the roads were clear. The morning started quietly. Some personnel greeted friends, handed over their weapons, or strolled to a nearby tea shop. It all seemed so ordinary—too ordinary for what would come next.

Sri Lanka Navy sunk LTTE Ships carrying arms, ammunition and warlike materials thousand miles away from Sri Lanka in Indian Ocean in September and October 2007.
By late morning, both convoys had reached the small ground at Digampathana, near the Sigiriya junction, and personnel mingled briefly, unaware that a carefully orchestrated act of terror was waiting. Then, suddenly, an empty half-truck veered directly into the convoy. It exploded with a ferocity I can still recall as if it were yesterday. Nuts, bolts, and high explosives tore through the air. Pandemonium erupted instantly. I later learned that 107 of our naval personnel were killed on the spot and another 153 critically injured. The scene was indescribable—bodies scattered, vehicles mangled, personal effects strewn across the ground. I remember later hearing that the head of the suicide bomber was recovered more than 100 meters away from the blast, a grim testament to the sheer force of the explosion.
I was in my office at the Naval and Maritime Academy when my mobile phone rang. A young midshipman from the 21st intake called, his voice trembling: “Sir, there was a huge explosion at the convoy point! Many are dead … my batch mate Wijesundara is among them.” I immediately jumped into my jeep with my escort Chief Petty Officer and driver and rushed to Digampathana, relying on every ounce of my driving skill to reach the scene. The journey, which usually took little more than an hour, felt endless that day, each passing mile weighed down by dread.
When I arrived, I was confronted with a sight that no training can prepare you for. The injured were being rushed to Dambulla Hospital, where doctors and nurses worked tirelessly, improvising in ways that saved lives despite the overwhelming chaos. I went back to the site after visiting the hospital. The remains of our naval personnel were scattered across the ground, and someone had begun collecting weapons and protective gear. I immediately contacted Surgeon Rear Admiral Nico Jayasekara and received his instructions: collect all body parts in separate bags and transport them to the Trincomalee Naval Hospital mortuary. This gruesome work had to be done with care and dignity, and it filled the icebox in my vehicle. Through DNA testing initiated by Rear Admiral Nico, we were able to identify every naval personnel lost that day, bringing some closure to grieving families.
The Navy Commander at the time, Vice Admiral Wasantha Karannagoda, was devastated. I had worked closely with him and knew how deeply he cared for his men. He ensured that the fallen were honoured with full ceremonial naval funerals at Welisara Naval Base, attended by families and comrades. Sixty-seven funerals were conducted in a single day—a number that still haunts me.
The Digampathana attack remains the largest single loss of naval life in our history. It was a day of sorrow, but also a day that reinforced our resolve. The tragedy galvanized the Navy to target the LTTE Sea Tiger wing with renewed determination and reshaped our maritime operations forever. Every time I think of that day, I remember not just the lives lost, but the courage, professionalism, and dedication of those who survived, those who treated the injured, and those who ensured the fallen were honored properly. May the souls of our naval hero’s rest in peace, their sacrifice guiding us and inspiring generations of naval personnel to come.
Features
‘Murder at Whitby Abbey’
Tales of Mystery and Suspense – 24
I was intrigued by the title of a book I found in a book drop at the condominium of a friend, Murder at Whitby Abbey, and I brought it home with me though I will not be able to return it in the near future. It was described on the cover page as ‘a standout in the crowded medieval mystery field’, though I fear I do not know of other books in this field, apart from the Cadfael series, which I have dealt with earlier.
The book, by Cassandra Clark, is set during the reign of Richard II and has as a backdrop his precarious position, which led to his being replaced, and murdered, by his cousin Henry, who reigned as Henry IV. It is a gloomy book, the action taking place in the twelve days of Christmas leading up to the Epiphany. And the gloom is pervasive, even though this is supposed to be a time of festivity, with mummers performing, and many of those in the guest house where the heroine stays going to town to enjoy themselves, with much drinking and much music, which also fills the guesthouse.
The heroine Hildegarde is a nun, sent to try to acquire a relic being sold by Whitby Abbey, though this was also a penance set by the Abbot of the monastery that governed her abbess because she had had sex with a man. Soon after she and her companions reach the Abbey set high on a cliff, she finds that there are other bidders, and soon suspects that the hierarchy, not perhaps the Abbot who seems a weakling, but his rapacious bursar, is determined to make money, and not above creating false relics to sell to several aspirants.
After Hildegarde and her Cistercian companions – Whitby is a Benedictine Foundation – two monks, Gregory and Egbert, and a young priest Mark, reach the abbey, they find that Aelwyn, a monk they had met on their way to the guesthouse had died. This was in the apple store, and they realize, when they find the surplices of novices stuffed into the air vents, that he had been left to suffocate in the overwhelming scent of apples.
The Cistercians are asked to look into the death, perhaps because they are likely to get no cooperation from the Abbey folk, but perhaps because those in charge are keen to know what happened. And the infirmarer, an old monk, suggests Hildegarde talk to a man called Edred who worked for the bursar, and had been a friend of Aelwyn’s. But Edred too is killed, before he can keep an appointment he had made with Hildegarde, drowned in a pool near the farmhouse of the Abbey.
Meanwhile tensions arise between the fisherfolk and the abbey for the bursar wants to charge them for using the beach that technically belongs to the abbey to dry their fish and their nets. This leads to physical battles, when the guards used by the abbey, under the command it seems of the bursar whose determination to make money is not resisted by the abbot and the prior, try to storm the area where the fishermen live.
Hildegard finds out more about what had happened through two youngsters, one of whom Torold is the son of Aelwyn by a woman who worked as a prostitute for a cartel, and with whom Mark fell in love. The other works on the farm and had seen Edred meet someone near the pool, after which that someone left the place by himself. And the boy had also found in the pool a sort of dagger with the seal of the abbey.
He and his dog, and Torold who follows her, rescue Hildegarde from a man at arms who has waylaid her and tries to rape her earlier. Escaping into the abbey she was nearly been raped then by the bursar, but she managed to escape, in the process setting fire to him and the muniments room, which led, when he was rescued, to the discovery of a box with the money he said had been stolen, blame being cast on both Aelwyn and Edred.
Matters come to a head when the fisherfolk try to storm the abbey, being resisted by the men at arms stationed on the towers. But then Hildegarde realizes that behind the murders was the bursar’s clerk, whom she pursued to the cathedral. There is great drama then as she escapes from him when he tries to kill her, and then from the man at arms who had tried to both rape and kill her, but they both fall from the scaffolding she had climbed, the latter coming from a tower where he had been stationed.
Both of them think they run the rapacity of the abbey, the latter claiming to work for the nobles opposed to Richard, who is presented throughout the book as devoted to his subjects, not to power or money. But though the villains die, the bursar continues, having got over the hysteria the fire had caused and his acknowledgment then of guilt – and though the abbot and the prior seem less vicious, whether they will be able to assert themselves is questionable.
Before the climax, when the others in the guesthouse were leaving, Hildegarde found that two of them were in possession of the relic, for which they seem to have paid well. Hildegarde herself had made a derisory offer, but before she leaves the abbot gives her the relic, perhaps in gratitude for what she and her fellow Cistercians had discovered, the abbey having made as much money as it needed and more from the gullible other buyers.
Mark’s inamorata is saved from the stews because she moves in with Edred’s widow whom the bursar had thrown out of the rooms he occupied when her husband was found dead. Hildegarde had paid for lodgings, in a house run by the man who ran the brothels, but he had a kindly side and was going to finance them to make nets for the fishermen.
So, the Cistercians set off for their home as swiftly as they can to get there on the day of the Epiphany, having stopped en route to pray for King Richard whose birthday it was.
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