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Revival of Innovative systems for reservoir operation and flood forecasting

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Most reservoirs in Sri Lanka are agriculture and hydropower dominated. Reservoir operators are often unwilling to acknowledge the flood detention capability of major reservoirs during the onset of monsoons. Deviating from the traditional priority for food production and hydropower development, it is time to reorient the operational approach of major reservoir operators under extreme events, where flood control becomes a vital function. While admitting that total elimination of flood impacts is not technically feasible, the impacts can be reduced by the efficient operation of reservoirs and effective early warning systems.

At the very outset, I would like to mention that the contents in this article are based on my personal experience in the Irrigation Department (ID), and there is no intention to disrespect their contributions during the most recent flood event. The objective is to improve the efficiency and the capability of the human resources available in the ID and other relevant institutions to better respond to future flood disasters.

Reservoir operation and flood forecasting

Reservoir management is an important aspect of water management, as water storage and release are crucial for managing floods and droughts. Several numerical models and guidelines have already been introduced to the ID and MASL during numerous training programs for reservoir management and forecasting of inflows.

This article highlights expectations of engineering professionals and discusses a framework for predicting reservoir inflows from its catchment by using the measured rainfall during the previous few days. Crucially, opening the reservoir gates must be timed to match the estimated inflow.

Similarly, rainfall-runoff relationships had been demonstrated and necessary training was provided to selected engineers during the past to make a quantitative (not qualitative) forecast of river water levels at downstream locations, based on the observed rainfall in the upstream catchment.

Already available information and technology

Furthermore, this article highlights the already available technology and addresses certain misinformation provided to the mass media by some professionals during recent discussions. These discrepancies are primarily related to the opening of reservoir gates and flood forecasting.

A. Assessing the 2025 Flood Magnitude

It is not logically sound to claim that the 2025 flood in the Kelani basin was the highest flood experienced historically. While, in terms of flood damage, it was probably the worst flood experienced due to rapid urbanisation in the lower Kelani basin. We have experienced many critical and dangerous floods in the past by hydraulic definition in the Kelani Ganga.

Historical water levels recorded at the Nagalagam Street gauge illustrate this point: (See Table)

In view of the above data, the highest water level recorded at the Nagalagam river gauge during the 2025 flood was 8.5 ft. This was a major flood, but not a critical or dangerous flood by definition.

B. Adherence to Reservoir Standing Orders

According to the standing orders of the ID, water levels in major reservoirs must be kept below the Full Supply Level (FSL) during the Northeast (NE) monsoon season (from October to March) until the end of December. According to my recollection, this operational height is 1.0m below the FSL. Therefore, maintaining a reservoir below the FSL during this period is not a new practice; it explicitly serves the dual purpose of dam safety and flood detention for the downstream areas.

C. Gate Operation Methodology

When a reservoir is reaching the FSL, the daily operation of gates is expected to be managed so that the inflow of water from the catchment rainfall is equal to the outflow through the spill gates (Inflow *  Outflow). The methodology for estimating both the catchment inflow and the gate outflow is based on very simple formulas, which have been previously taught to the technical officers and engineers engaged in field operations.

D. Advanced Forecasting Capabilities

Sophisticated numerical models for rainfall-runoff relationships are available and known to subject specialists of the ID through the training provided over the last 40 years. For major reservoirs, the engineers in charge of field operations could be trained to estimate daily inflows to the reservoirs, especially in cases where the simple formulas mentioned in section C are not adequate.

Design concept of reservoir flood gates

Regarding the provision of reservoir spill gates, one must be mindful of the underlying principles of probability. Major reservoir spillways are designed for very high return periods, such as 1,000 and 10,000 years. If the spillway gates are opened fully when a reservoir is at full capacity, this can produce an artificial flood of a very large magnitude. A flood of such magnitude cannot occur under natural conditions. Therefore, reservoir operators must be mindful in this regard to avoid any artificial flood creation.

In reality, reservoir spillways are often designed for the sole safety of the reservoir structure, often compromising the safety of the downstream population. This design concept was promoted by foreign funding agencies in recent times to safeguard their investment for dams. Consequently, the discharge capacities of these spill gates significantly exceed the natural carrying capacity of river downstream. This design criterion requires serious consideration by future designers and policymakers.

Undesirable gate openings

The public often asks a basic question regarding flood hazards in a river system with reservoirs: Why is flooding more prominent downstream of reservoirs compared to the period before they were built? This concern is justifiable based on the following incidents.

For instance, why do Magama in Tissamaharama face flood threats after the construction of the massive Kirindi Oya reservoir? Similarly, why does Ambalantota flood after the construction of Udawalawe Reservoir? Furthermore, why is Molkawa in the Kalutara District area getting flooded so often after the construction of Kukule reservoir?

These situations exist in several other river basins too. Engineers must therefore be mindful of the need to strictly control the operation of reservoir gates by their field staff. The actual field situation can sometimes deviate significantly from the theoretical technology discussed in air- conditioned rooms. Due to this potential discrepancy, it is necessary to examine whether gate operators are strictly adhering to the operational guidelines, as gate operation currently relies too much on the discretion of the operator at the site.

In 2003, there was severe flood damage below Kaudulla reservoir in Polonnaruwa. I was instructed to find out the reason for this flooding by the then Minister of Mahaweli & Irrigation. During my field inspection, I found that the daily rainfall in the area had not exceeded 100mm, yet the downstream flood damage was unbelievable. I was certain that 100mm of rainfall could not create a flood of that magnitude. Further examination suggested that this was not a natural flood, but was created by the excessive release of water from the radial gates of the Kaudulla reservoir. There are several other similar incidents and those are beyond the space available for this document.

Revival of Innovative systems

It may be surprising to note the high quality of real-time flood forecasts issued by the ID for the Kelani River in the late 1980s and early 1990s. This was achieved despite the lack of modern computational skills and advanced communication systems. At that time, for instance, mobile phones were non-existent. Forecasts were issued primarily via the Sri Lanka Broadcasting Corporation (SLBC )in news bulletins.

A few examples of flood warning issued during the past available in official records of the ID are given below:

Forecast issued at 6th June 1989 at 5.00 PM

“The water level at Nagalagam street river gauge was at 9 ft 0 inches at 5.0 PM. This is 1.0 ft above the major flood level. Water level is likely to rise further, but not likely to endanger the Kelani flood bund”.

Eng. NGR. De Silva, Director Irrigation

Forecast issued at 30th Oct 1991 at 6.00 PM

“The water level at Nagalagam street river gauge was at 3 ft 3 inches at 6.0 PM. The water level likely to rise further during the next 24 hours, but will not exceed 5.0 ft.”

Eng. K.Yoganathan, Director Irrigation

Forecast issued at 6th June 1993 at 10.00 AM:

“The water level at Nagalagam street river gauge was at 4 ft 6 inches last night. The water level will not go above 5.0 ft within the next 24 hours.”

Eng. K.Yoganathan, Director Irrigation

Forecast issued at 8th June 1993 at 9.00 AM:

“The water level at Nagalagam Street River gauge was at 4 ft 6 inches at 7.00 AM. The water level will remain above 4.0 ft for the next 12 hours and this level will go below 4.0 ft in the night.

The water level is not expected to rise within next 24 hours.”

Eng.WNM Boteju,Director of Irrigation

Conclusion

Had this technology been consistently and effectively adopted, we could have significantly reduced the number of deaths and mitigated the unprecedented damage to our national infrastructure. The critical question then arises: Why is this known, established flood forecasting technology, already demonstrated by Sri Lankan authorities, not being put into practice during recent disasters? I will leave the answer to this question for social scientists, administrators and politicians in Sri Lanka.



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Features

Acid test emerges for US-EU ties

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European Commission President Ursula von der Leyen

European Commission President Ursula von der Leyen addressing the World Economic Forum in Davos, Switzerland on Tuesday put forward the EU’s viewpoint on current questions in international politics with a clarity, coherence and eloquence that was noteworthy. Essentially, she aimed to leave no one in doubt that a ‘new form of European independence’ had emerged and that European solidarity was at a peak.

These comments emerge against the backdrop of speculation in some international quarters that the Post-World War Two global political and economic order is unraveling. For example, if there was a general tacit presumption that US- Western European ties in particular were more or less rock-solid, that proposition apparently could no longer be taken for granted.

For instance, while US President Donald Trump is on record that he would bring Greenland under US administrative control even by using force against any opposition, if necessary, the EU Commission President was forthright that the EU stood for Greenland’s continued sovereignty and independence.

In fact at the time of writing, small military contingents from France, Germany, Sweden, Norway and the Netherlands are reportedly already in Greenland’s capital of Nook for what are described as limited reconnaissance operations. Such moves acquire added importance in view of a further comment by von der Leyen to the effect that the EU would be acting ‘in full solidarity with Greenland and Denmark’; the latter being the current governing entity of Greenland.

It is also of note that the EU Commission President went on to say that the ‘EU has an unwavering commitment to UK’s independence.’ The immediate backdrop to this observation was a UK decision to hand over administrative control over the strategically important Indian Ocean island of Diego Garcia to Mauritius in the face of opposition by the Trump administration. That is, European unity in the face of present controversial moves by the US with regard to Greenland and other matters of contention is an unshakable ‘given’.

It is probably the fact that some prominent EU members, who also hold membership of NATO, are firmly behind the EU in its current stand-offs with the US that is prompting the view that the Post-World War Two order is beginning to unravel. This is, however, a matter for the future. It will be in the interests of the contending quarters concerned and probably the world to ensure that the present tensions do not degenerate into an armed confrontation which would have implications for world peace.

However, it is quite some time since the Post-World War Two order began to face challenges. Observers need to take their minds back to the Balkan crisis and the subsequent US invasions of Afghanistan and Iraq in the immediate Post-Cold War years, for example, to trace the basic historic contours of how the challenges emerged. In the above developments the seeds of global ‘disorder’ were sown.

Such ‘disorder’ was further aggravated by the Russian invasion of Ukraine four years ago. Now it may seem that the world is reaping the proverbial whirlwind. It is relevant to also note that the EU Commission President was on record as pledging to extend material and financial support to Ukraine in its travails.

Currently, the international law and order situation is such that sections of the world cannot be faulted for seeing the Post World War Two international order as relentlessly unraveling, as it were. It will be in the interests of all concerned for negotiated solutions to be found to these global tangles. In fact von der Leyen has committed the EU to finding diplomatic solutions to the issues at hand, including the US-inspired tariff-related squabbles.

Given the apparent helplessness of the UN system, a pre-World War Two situation seems to be unfolding, with those states wielding the most armed might trying to mould international power relations in their favour. In the lead-up to the Second World War, the Hitlerian regime in Germany invaded unopposed one Eastern European country after another as the League of Nations stood idly by. World War Two was the result of the Allied Powers finally jerking themselves out of their complacency and taking on Germany and its allies in a full-blown world war.

However, unlike in the late thirties of the last century, the seeming number one aggressor, which is the US this time around, is not going unchallenged. The EU which has within its fold the foremost of Western democracies has done well to indicate to the US that its power games in Europe are not going unmonitored and unchecked. If the US’ designs to take control of Greenland and Denmark, for instance, are not defeated the world could very well be having on its hands, sooner rather than later, a pre-World War Two type situation.

Ironically, it is the ‘World’s Mightiest Democracy’ which is today allowing itself to be seen as the prime aggressor in the present round of global tensions. In the current confrontations, democratic opinion the world over is obliged to back the EU, since it has emerged as the principal opponent of the US, which is allowing itself to be seen as a fascist power.

Hopefully sane counsel would prevail among the chief antagonists in the present standoff growing, once again, out of uncontainable territorial ambitions. The EU is obliged to lead from the front in resolving the current crisis by diplomatic means since a region-wide armed conflict, for instance, could lead to unbearable ill-consequences for the world.

It does not follow that the UN has no role to play currently. Given the existing power realities within the UN Security Council, the UN cannot be faulted for coming to be seen as helpless in the face of the present tensions. However, it will need to continue with and build on its worldwide development activities since the global South in particular needs them very badly.

The UN needs to strive in the latter directions more than ever before since multi-billionaires are now in the seats of power in the principle state of the global North, the US. As the charity Oxfam has pointed out, such financially all-powerful persons and allied institutions are multiplying virtually incalculably. It follows from these realities that the poor of the world would suffer continuous neglect. The UN would need to redouble its efforts to help these needy sections before widespread poverty leads to hemispheric discontent.

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Features

Brighten up your skin …

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Hi! This week I’ve come up with tips to brighten up your skin.

* Turmeric and Yoghurt Face Pack:

You will need 01 teaspoon of turmeric powder and 02 tablespoons of fresh yoghurt.

Mix the turmeric and yoghurt into a smooth paste and apply evenly on clean skin. Leave it for 15–20 minutes and then rinse with lukewarm water

Benefits:

Reduces pigmentation, brightens dull skin and fights acne-causing bacteria.

* Lemon and Honey Glow Pack:

Mix 01teaspoon lemon juice and 01 tablespoon honey and apply it gently to the face. Leave for 10–15 minutes and then wash off with cool water.

Benefits:

Lightens dark spots, improves skin tone and deeply moisturises. By the way, use only 01–02 times a week and avoid sun exposure after use.

* Aloe Vera Gel Treatment:

All you need is fresh aloe vera gel which you can extract from an aloe leaf. Apply a thin layer, before bedtime, leave it overnight, and then wash face in the morning.

Benefits:

Repairs damaged skin, lightens pigmentation and adds natural glow.

* Rice Flour and Milk Scrub:

You will need 01 tablespoon rice flour and 02 tablespoons fresh milk.

Mix the rice flour and milk into a thick paste and then massage gently in circular motions. Leave for 10 minutes and then rinse with water.

Benefits:

Removes dead skin cells, improves complexion, and smoothens skin.

* Tomato Pulp Mask:

Apply the tomato pulp directly, leave for 15 minutes, and then rinse with cool water

Benefits:

Controls excess oil, reduces tan, and brightens skin naturally.

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Features

Shooting for the stars …

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That’s precisely what 25-year-old Hansana Balasuriya has in mind – shooting for the stars – when she was selected to represent Sri Lanka on the international stage at Miss Intercontinental 2025, in Sahl Hasheesh, Egypt.

The grand finale is next Thursday, 29th January, and Hansana is all geared up to make her presence felt in a big way.

Her journey is a testament to her fearless spirit and multifaceted talents … yes, her life is a whirlwind of passion, purpose, and pageantry.

Raised in a family of water babies (Director of The Deep End and Glory Swim Shop), Hansana’s love affair with swimming began in childhood and then she branched out to master the “art of 8 limbs” as a Muay Thai fighter, nailed Karate and Kickboxing (3-time black belt holder), and even threw herself into athletics (literally!), especially throwing events, and netball, as well.

A proud Bishop’s College alumna, Hansana’s leadership skills also shone bright as Senior Choir Leader.

She earned a BA (Hons) in Business Administration from Esoft Metropolitan University, and then the world became her playground.

Before long, modelling and pageantry also came into her scene.

She says she took to part-time modelling, as a hobby, and that led to pageants, grabbing 2nd Runner-up titles at Miss Nature Queen and Miss World Sri Lanka 2025.

When she’s not ruling the stage, or pool, Hansana’s belting tunes with Soul Sounds, Sri Lanka’s largest female ensemble.

What’s more, her artistry extends to drawing, and she loves hitting the open road for long drives, she says.

This water warrior is also on a mission – as Founder of Wave of Safety,

Hansana happens to be the youngest Executive Committee Member of the Sri Lanka Aquatic Sports Union (SLASU) and, as founder of Wave of Safety, she’s spreading water safety awareness and saving lives.

Today is Hansana’s ninth day in Egypt and the itinerary for today, says National Director for Sri Lanka, Brian Kerkoven, is ‘Jeep Safari and Sunset at the Desert.’

And … the all-important day at Miss Intercontinental 2025 is next Thursday, 29th January.

Well, good luck to Hansana.

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