Features
The Salinity Barrier and Nilwala Floods: Clearing up Misconceptions
by Dr. R. Galappatti,
Chairman, Lanka Hydraulic Institute (LHI).
Introduction
Recent experience of high water levels in lower reaches of the Nilwala Ganga has been attributed by various parties to the construction of the Salinity Barrier in 2018-2022, 5.4 km upstream of the sea outfall. While it is understandable that the affected communities would blame the most recent construction in the river channel for this, many technically qualified persons have also subscribed to this view without either examining hydraulic computations or making any measurements at the barrier. We are concerned that ill-considered attempts are being made to interfere with the structural integrity of the barrier and endanger a major piece of water supply infrastructure.
The salinity barrier is designed to protect the water supply intakes from salinity intrusion and ensure an uninterrupted supply of drinking water to around 600,000 consumers by the year 2035, in the Matara and Hambantota districts, under the Matara Stage IV Water Supply Project of the National Water Supply & Drainage Board (NWSDB). The conceptual design of the barrier including its dimensions, levels and operating rules was carried out by Lanka Hydraulic Institute (LHI).
Regular review meetings were held at regional level by the NWSDB with participation of the Irrigation Department. The Central Engineering Consultancy Bureau (CECB), the EIA consultant, also participated, with full access to the details of the ongoing work at all stages of the study. Modifications were made to the study approach and the designs as required.
The hydraulic studies including design calculations were carried out and the main parameters of the barrier were determined and verified using physical and numerical model studies. This focused on the salinity barrier, particularly its flood impacts, and led to a positive EIA report after public consultations were completed. Detailed designs and construction of the barrier was carried out by a Korean Company (Kolon Samsung C&T) with Ceywater as the local design partner under a Design-Build contract.
The Salinity Barrier
The final design consists of providing a 5-bay gated type structure with vertical lifting gates and piers across the inner stream section 5.4 km upstream of the sea mouth, in the river reach between Thudawa Pump station and Navimana ferry crossing. The gates are 10m wide and 3.1m high with the gate sill fixed at –2.5 m MSL. Gate top at closed position is at +0.6 m MSL and the gate bottom in fully open position is to be at 5m MSL during high and normal flow conditions. This level is above the High Flood Level, as the top level of the flood bund is only around 4.3 m MSL.
Three of the five gates were to be made of two separate sections to allow the upper section to be lowered independently, to make it possible to lower the upstream pool level when necessary for irrigation water management at the request of the Irrigation Department. Sheet-pile cut-off walls were provided across the low-lying areas of the flood plain on either bank to prevent saline water bypassing the main structure during operation and to ensure that during dry weather the river flow is confined to the inner channel and not to overflow into the floodplain. In addition to these main features, gate operating structures, cut-off walls, access roads etc. were included in the design.
The barrier is in full conformity to the stipulations in the MOU signed between NWSDB and the Irrigation Department in March 2017, and the Irrigation Department granted approval for the NWSDB to implement the project.
Impacts of the Salinity Barrier
The increase in river water level during floods, and operating conditions and concerns of the stakeholders due the proposed structure, were the main considerations in determining optimal values for gate openings, gate sill levels and other parameters for the design.
The upstream flooding impact of the barrier design was computed using a numerical model and verified by carrying out a series of physical model tests at Lanka Hydraulic Institute (LHI). These were used to verify that the flow pattern around and downstream of the gated structure was satisfactory.
The water levels in the upstream river reach, with and without the barrier, were estimated for different flow conditions including floods up to 100 yr return period. The estimated anticipated water level rise just upstream of the Salinity Barrier was about 1 cm maximum during floods of 100 yr return period. There was a higher (4-7 cm) relative water level rise during bank full and low return period floods.
Backwater propagation lengths have been calculated and these anticipated water level rises were considered acceptable. It is relevant to note that, the acceptable head loss at the planned Kelani Ganga salinity barrier was fixed in the range 5 cm to 6 cm for a 100 yr flood.
As far as the flood impact of the cut-off wall is concerned, the impact will be negligible because this wall, with a top level of only 0.8 m MSL, will be well and truly submerged during a major flood. Further there is an allegation that debris might trap buildup from the river bed level to the sill level of gates, and exacerbate flooding. Even if debris are accumulated, its total hydraulic impact is still negligible. Further, fresh bathymetric survey conducted in Dec 2023 has even revealed that there is in fact no debris accreted upstream of the gate structure.
Long inundation period during present flood compared to previous floods
While it has been demonstrated that construction of the Salinity Barrier is not the cause of recent floods, it is nevertheless necessary to investigate why this long inundation of paddy lands occurred and determine what actions need to be taken to prevent or reduce the probability of a recurrence.
In this context it is necessary to examine what happened in May 2017 when there was an extreme flood event in this basin. The flood was caused by an extreme rainfall event of about three days duration that caused a sharp flood peak reaching a daily average water level of 4.32 m MSL at Thalagahagoda on the very next day. The water levels receded to normal levels within the next ten days while it took seven days to decrease to flood alert level (1.4 m MSL) at Thalagahagoda. The return period of this flood is said to be between 75 and 100 yr.
The duration of the long series of rainfall events that spread out over more than two months from Mid-September to end November 2023 is markedly different – both from the point of view of the basin and the time of the year when it took place. While the water level at Thalagahagoda peaked only at 2.92 m MSL in 2023, the level continued to stay above 1.7 m MSL (Minor flood level) for almost the entire period (Oct to mid of Nov).

Figure 3: Rainfall Pattern and Drawdown of Water Levels during Sep Oct 2023 Flood (06th Sep – 22nd Nov 2023)
The markedly different nature of this flood – including its extremely slow recession could only be explained by considering the retention (storage) of flood water on the flood plain which is divided into two on either side of the Nilwala flood bund. The area adjacent to the river will drain slowly into the river channel in the normal manner. The water collecting in the “protected area” must be pumped out at a few pumping stations located along the flood bund.
Duration of operation of these pumps is on record but their pumping rate is not known. An additional point to be considered is that the measured water level profile on the short river reach downstream of the barrier show a steeper slope indicating a more constricted channel from the railway bridge to the sea.
It is also important to note that the rainfall pattern in 2023 is unusual and unexpected, and that no usual rainfall runoff model could accurately interpret it. The models, in turn, must be more detailed, to include the flood plain storage and pumping rates to represent the flood routing performance of the system under such unusual rainfall patterns which might be a trend caused by climate change.
It must also be borne in mind that the Nilwala basin is not a stranger to flooding, though not so late in the year. The steep upper basin that descends suddenly into a largely flat coastal plain is characteristic of all large wet zone rivers in Sri Lanka.
Conclusions
The long-duration flooding experience in the Nilwala basin in 2023 has not been caused by the construction of the Salinity Barrier.A more detailed representation of the flood plains and pump operation is needed to quantify accurately the long recession of the flood plain
The marked change in rainfall patterns might be due to a climate change effect and this type of effect might also impact other river basins in the wet zone. This requires attention.
The ill- considered removal of the low cut-off wall across the lower floodplain should be restored to avoid possible shut down of water supply intakes in the next dry season.
Features
The challenge of being positive about SAARC
It was a few years back that a former President of Sri Lanka took it on himself to pronounce SAARC ‘dead’. Since then there have been other sections of Sri Lankan opinion that have joined the critics of SAARC and taken the solemn stance that SAARC has indeed died what may be called a natural death.
Their fatalism is understandable. SAARC has failed to meet at heads of government or state level for the past several years to take the SAARC process notably forward. Regional cooperation has more or less been only an appealing idea. No substantive concrete projects have taken off to make the idea a hard reality. ‘Inner paralysis’ seems to be SAARC’s lot. Hence the fatalism in these circles.
However, being one of the worst cash-strapped regions of the world and a teemingly populated one with people virtually left to their devices, what choices do the ‘SAARC Eight’ have other than to try their best to band together and continue with their cooperation efforts, however small they may be?
There is no escaping the mounting debt trap for many of these countries and bankrupt Sri Lanka is a glaring example, but ‘throwing in the towel’ and abandoning themselves entirely to the diktats of the strongest economies and their agencies will prove a ‘living death’ for many countries in the SAARC fold.
The gains may be meagre but giving-up on SAARC cooperation in full would prove self-defeating for the organization and South Asia. Right now, the collective intention ought to be to salvage what the region could from the tenuous cooperative efforts. Moreover, such initiatives could go some distance to generate a degree of goodwill among the Eight and help in sustaining a dialogue process.
Given this backdrop it proved ‘a stich in time’ for the Regional Centre for Strategic Studies (RCSS), Colombo, to recently host the SAARC Secretary General Ambassador Md. Golam Sarwar to a round table discussion on the unifying potential of SAARC and its future possibilities, besides other related issue areas.
Held on June 24th and moderated by RCSS Executive Director and former ambassador Ravinatha Aryasinha, the forum brought together a vibrant, wide ranging audience comprising academicians, diplomats, senior public servants, civil society activists and many others. Following the presentation by Ambassador Golam Sarwar titled, ‘Reigniting SAARC: Achievements, Challenges and the Way Ahead’, a lively Q&A followed.
The above forum could be described as an act of lighting the proverbial ‘candle’ rather than ‘cursing the darkness.’ It surely is a ‘darkness’ that could be seen as daunting considering that the region’s pivotal powers, India and Pakistan, are failing to act in a spirit of accord but are engaged in bitter finger-pointing on a number of questions of vital importance to SAARC.
On the other hand, what is the rest of the region doing to bring the above sides together? It is disappointing that to date the rest of SAARC has failed to launch a major diplomatic drive to bring peace between the feuding regional heavyweights. It needs to act without delay and establish its earnestness and this effort would need to prove SAARC’s staying power in the unfolding months and even years.
In assessing SAARC’s seeming failure local opinion in particular has failed to factor in what could be described as weak leadership. Since Sheikh Mujibur Rahman of Bangladesh, the founding father of SAARC, the region has failed to produce a visionary leader who could advance the SAARC cause with charisma and drive.
Among other reasons, weak leadership accounts considerably for the faltering and stuttering status, as it were, of SAARC. Badly needed are leaders who could go the extra mile, think less of narrow national interests and work diligently towards the collective well being of the region but SAARC’s millions of ordinary people have been made to wait in vain for leaders of such stature. Instead, they have been burdened with politicians who seem to be relishing the apparently moribund state of SAARC.
Looking back, it could be said that it was the dynamic leadership factor that led to the launching of the Non-Aligned Movement and for its sustenance for a few decades. True, it could be seen in some quarters that NAM is no more, but as in the case of SAARC, the former too has been unfortunate to be burdened over the years with politicians who lack the vision and drive to unflaggingly advance the fortunes of the South. NAM and SAARC lack the dynamism and vision of leaders of the stature of Jawaharlal Nehru, for example, to give them the required guidance and intellectual depth.
The reasons are complex for there not being among us currently political leaders with the vision and the steadfast commitment to advance the legitimate interests of the South. However, it could be stated with conviction that the majority of Southern leaders have too easily caved in to the demands of the global North and its financial agencies.
These leaders have failed to see, for instance, that the largely market economy oriented Northern governments would not view with favour a centrist economic model that attaches priority to the interests of the dis-empowered publics of the South. This realization ought to have dawned on the current government in Sri Lanka, for instance, some while ago but it has no choice but to abide by IMF dictates since economic survival at present is unthinkable without the latter’s succour.
Accordingly for SAARC this should be the time for some soul-searching. Priority needs to be attached to ending the feuding between India and Pakistan since at present the material fortunes of the region hinge largely on these regional giants giving peaceful relations among them a try. This is no easy challenge to meet but some daring, visionary diplomacy needs to take hold among the rest of SAARC.
There is some sense in SAARC bringing the peoples of the region together through programs that address their best collective interests. A meeting of minds among SAARC nations could enable SAARC and its agencies to build a region-wide people’s movement for progressive political and economic change that could in turn lead to the region’s political leaders sensitizing themselves more to the neglected needs of their publics.
However, the time is ‘now’ for the initiation of these progressive changes and the voice of SAARC well wishers would need to drown out those of their critics.
Features
OPA seminar examines Sri Lanka’s economic recovery, resilience and growth pathways
A seminar, “Sri Lanka’s Economic Crossroads: Navigating Recovery, Resilience and Growth” was recently held by the Organisation of Professional Associations of Sri Lanka (OPA) at the OPA Auditorium, bringing together economists, OPA members, and professionals from diverse fields for an insightful discussion on Sri Lanka’s economic recovery and future growth prospects.
The event was held under the patronage of Jayantha Gallehewa, President of the OPA, and was jointly organised by the National Issues Committee (NIC) and the Seminars, Workshops and Programmes Committee of the OPA. The event reaffirmed the organisation’s commitment to advancing professional excellence, fostering insightful intellectual engagement, facilitating interdisciplinary knowledge exchange and creating a constructive platform for informed dialogue on issues of national importance.
The panel of speakers comprised Dr. Harsha Aturupane, Lead Economist and Programme Leader for Human Development at the World Bank for Sri Lanka and the Maldives; Dr. Achinthya Koswatta, Senior Lecturer in Economics at the Open University of Sri Lanka, and Anushan Kapilan, Lead Economist at Verité Research.
In his welcome address, the President of the OPA emphasised that Sri Lanka was at a critical juncture in its economic recovery journey where sustained reforms, effective implementation, and collective national commitment are essential to achieving long-term stability, resilience and inclusive growth. He noted that the country had experienced one of the most severe economic crises in its history with the economy contracting by 7.8 percent in 2022 and a further 11.5 percent in 2023, resulting in significant economic and social challenges.
Delivering his introductory remarks Bhanu Wijeyaratne, Vice President of the OPA and Chairman of the National Issues Committee, underscored the need to move beyond short-term economic stabilisation towards a comprehensive agenda of structural transformation. He observed that the economic crisis had revealed deep-rooted weaknesses within the economy, including persistent fiscal pressures, rising public debt, foreign exchange limitations, and insufficient diversification of the export base. He stressed that addressing these challenges through strategic reforms, institutional strengthening and long-term economic planning would be essential to establishing a more resilient and competitive economy.
While acknowledging recent positive developments, including improved inflation management, tourism recovery and signs of economic stabilisation, Wijeyaratne stressed the need to advance reforms aimed at strengthening fiscal discipline, enhancing productivity, improving competitiveness, developing human capital and reinforcing governance and institutional effectiveness.
He further highlighted the important role of professionals, businesses, academia and other stakeholders in contributing to evidence-based dialogue and supporting Sri Lanka’s journey towards a resilient, inclusive and sustainable economic future.
Delivering the keynote presentation, Dr. Harsha Aturupane provided a comprehensive assessment of Sri Lanka’s economic prospects within the broader context of global economic transformation. He argued that Sri Lanka functioned as a small open economy whose performance is significantly influenced by developments in the global marketplace. External factors could not be controlled, and the country must strengthen its domestic capacity and resilience to respond effectively to international economic shifts, he noted.
Tracing the evolution of global economic systems, Dr. Aturupane highlighted the transition from ideological divisions between state-controlled and market-oriented economies towards increasingly pragmatic approaches focused on growth, competitiveness and development. He noted that Sri Lanka’s own economic journey reflects a similar evolution, with contemporary policy debates now centred on practical solutions for sustainable economic progress.
The presentation also examined the transformative impact of globalisation. Dr. Aturupane observed that global economic integration had enabled several East Asian economies, including South Korea, Singapore, Taiwan and Hong Kong, to achieve remarkable economic advancement through export-led growth strategies. Sri Lanka similarly benefited from this process through the expansion of its apparel industry and increased integration into global value chains.
Turning to Sri Lanka’s recovery programme, Dr. Aturupane emphasised that the ongoing stabilisation process should be viewed as a national programme supported by the International Monetary Fund rather than solely as an IMF initiative. He observed that strong worker remittances, improved tourism earnings, enhanced government revenue mobilisation and prudent import management have contributed significantly to economic stabilisation.
Despite this progress, he cautioned that rebuilding foreign exchange reserves and meeting future debt obligations remain major challenges. He underscored the need to strengthen export performance, attract investment and generate sustainable foreign exchange earnings to ensure long-term economic resilience.
The discussion also focused on monetary stability, inflation management and exchange-rate policy. Dr. Aturupane stressed that maintaining price stability was fundamental to sustainable growth and household welfare, while sound monetary policy remains essential for preserving economic confidence.
Looking beyond stabilisation, he argued that Sri Lanka must transition towards a broader economic transformation agenda. Sustainable growth, he noted, will depend on expanding productive capacity through investment, technological advancement, innovation, skills development and structural reforms.
Among the key constraints identified was the high cost of energy, which continues to affect competitiveness and investment attractiveness. Dr. Aturupane emphasised the importance of improving efficiency and affordability within the energy sector to enhance Sri Lanka’s business environment.
He further highlighted the social dimensions of the crisis, noting the rise in poverty and economic vulnerability among households. Strengthening social protection systems and ensuring inclusive growth, he argued, must remain central components of the national development agenda.
Another critical challenge identified was Sri Lanka’s demographic transition. With an ageing population, outward migration and evolving labour market dynamics, the country is increasingly confronting labour shortages in several sectors. Dr. Aturupane suggested that greater automation, increased labour-force participation and strategic workforce planning would be necessary to address these emerging realities.
Concluding his presentation, he emphasised the need to improve governance, strengthen institutions, enhance competitiveness and create an enabling environment for private sector investment. Sri Lanka’s future success, he noted, will depend on its ability to move decisively beyond crisis management towards a development model founded on resilience, innovation, productivity and inclusive growth.
Dr. Achinthya Koswatta reiterated the importance of policy consistency and predictability in fostering investment and industrial development. She observed that frequent policy changes create uncertainty and discourage long-term investment decisions, whereas stable and coherent policy frameworks build confidence and support sustainable economic transformation.
Meanwhile, Anushan Kapilan highlighted the substantial progress achieved in restoring macroeconomic stability following the recent crisis. He noted significant improvements in fiscal performance, including increased government revenue, reduced reliance on debt financing and a historically low fiscal deficit.
He further observed that public debt levels are declining faster than anticipated, economic growth has exceeded expectations and inflation has been brought under control more rapidly than forecast. Nevertheless, he cautioned that the recovery remains uneven, particularly within the industrial sector and that many households have yet to experience a meaningful improvement in living standards.
The seminar was expertly coordinated by Eng. Chamil Edirimuni, Vice President of the OPA and Chairman of the Seminars, Workshops and Programmes Committee, while the technical moderation and interactive discussion session were facilitated by Bhanu Wijeyaratne, Vice President of the OPA and Chairman of the National Issues Committee.
The event was attended by Tisara De Silva, President-Elect of the OPA, Eng. Ravi Rupasinghe, General Secretary, Past Presidents, members of the Executive Council, representatives of the General Forum and professionals representing a wide range of disciplines.
The seminar concluded with a vibrant exchange of ideas and perspectives, reaffirming the importance of evidence-based policy dialogue, institutional collaboration and collective national commitment in advancing Sri Lanka’s economic recovery, resilience and sustainable growth.
Features
Her roots run deep in Sri Lanka
Yes, for UK-based presenter and artiste Samantha Kay, home is where the heart – and the roots – are. And her roots run deep in Sri Lanka.
In an exclusive interview with The Island, Samantha says “I’m proud to be Sri Lankan. My mum is from Kandy and my dad is from Colombo, so Sri Lanka has always held a very special place in my heart.
“Whenever I visit Sri Lanka, I love spending time on the beautiful south coast, especially Hikkaduwa and Mirissa. It’s somewhere I always feel connected to my roots and completely at peace.”
Now living in Bournemouth, on the south coast of England, where, she says, she is lucky to be close to some of the UK’s most beautiful beaches, including the iconic Sandbanks, Samantha has built a career that refuses to fit into one box.
She is a radio presenter, podcast host, singer-songwriter, personal trainer and life coach.
“I genuinely love the variety because every role allows me to connect with people and, hopefully, make a positive difference in someone’s day.”
Of course, music has taken her far.
One of her proudest achievements, she says, was releasing a song with 90s music icon Angie Brown, which reached No. 9 in the UK Club Charts.
She also reached the final stages of The X Factor and performed at Wembley Stadium in front of thousands.
Beyond music, Samantha competed in bikini bodybuilding across the UK, winning several titles. “It taught me discipline, resilience and self-belief,” she recalls.
Today, her focus is on radio, podcasting and coaching women. Her podcast encourages people to live life on their own terms rather than feeling pressured to follow society’s expectations.
Says Samantha: “Whether someone is single, changing careers, travelling solo or simply trying to find their purpose, I want them to know that it’s never too late to create a life that feels authentic. If you’ve ever felt like you don’t fit into the box, maybe you were never meant to.”
Samantha Kay also spent a year in Dubai, performing at five-star hotels, including FIVE, and coaching at the iconic outdoor gym on Palm Jumeirah.
“I taught strength and conditioning classes, and hosted wellness retreats, combining my passion for music, health and inspiring others.”
However, with family matters calling her back to the UK, she made the choice to return. “Family comes first,” she says.
Looking ahead, Samantha plans to grow her radio and podcast work, release more music, and expand her wellness retreats.
“My biggest passion is helping people, especially women, build confidence and believe in themselves,” she says.
“Wherever my career takes me, I hope to continue inspiring others to live with courage, kindness and authenticity, while never forgetting my Sri Lankan roots.”
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