Colombo’s Wetlands: IWMI”s Concerns and Explorations

Darshanie Ratnawalli, in Sunday Island, 4 February 2018, where the title runs “Understanding Colombo’s wetlands with IWMI


According to historians the very position of Kotte in the middle of a marsh attests to peril. It was to arrest peril emanating from the North that a city was built in the middle of a marsh. For what except the most dire necessity would induce anyone to locate a capital city in a marsh? Given any other choice what self-respecting feudal overlord would opt for a marsh as a location of a capital?

This is how K.M de Silva, Sri Lanka’s foremost historian describes the forces that led to the shift of the capital from its secure fastness in Gampola surrounded by mountains and rivers to the marshy Kotte. “After Vikramabahu, the kingdom of Gampola passed on to Bhuvanekabahu V who became king in 1371….The most important political development during his period of rule was that the Sinhalese kingdom freed itself from the grasp of the king of Jaffna. During the invasion of 1359, Mayarata and a number of Kandyan districts had passed into the hands of the Jaffna ruler. It was Alakesvara who assumed the leadership of the struggle against the Tamils by organizing action to free these areas from their domination. The first step in this campaign was the clearing of some marshlands near Colombo and the construction of the fortress of Sri Jayavardanapura.

“…The Jafna kingdom’s expansion southwards had been checked, but the Sinhalese had no reason to believe that this had been halted for good. On the contrary, they assumed that pressure from the north would persist. The capital of the Sinhalese kingdom was moved once more, this time from the mountains to the west coast near Colombo, where Nissanka Alagakkonara had built the fort of Jayavardhanapura (Kotte). Once again the shift of the capital was evidence of the continuing weakness of the Sinhalese kingdom, and once more the reasons for the move were essentially defensive: to protect the west coast with its rich cinnamon resources, which the Tamil kingdom was so anxious to gain control of.”- A History of Sri Lanka

This then was the historical process through which Sri Lanka’s capital city got its natural urban wetlands. Predictably the same process continued over the centuries has now become the story of how Sri Lanka’s capital city is losing its natural urban wetlands. For the nature of a capital city is to expand and for that to happen more and more land should be reclaimed from the marsh. Hence the prospect of dwindling wetlands.

“In the 80s we had about 60% of the land in Colombo under wetlands,” says Herath Manthrithilake, Head of Sri Lanka Development Initiative of the International Water Management Institute (IWMI), addressing a group of media personnel invited on a field visit of Colombo’s wetlands.


According to Manthrithilake, Colombo is “between two rivers, Kelaniya and Kalu. Those are like the flood plains. If you look at old maps, you can see a lot of wetlands around it. We called them marshy lands those days. And the trend was to reclaim them for development. That’s why the Sri Lanka Land Reclamation and Development Corporation (SLLR & DC) was formed. For low-lying land reclamation.”


IWMI calls wetlands, natural capital. Even though you’d expect some rivalry between IWMI and SLLR & DC, the former trying to conserve wetlands while the later has a mandate to reclaim them, the reality is that even SLLR & DC realized the repercussions of their development, Manthrithilake adds, because, “we need to preserve these natural wetlands. They are like lungs, purifying the air, purifying the water, absorbing the floodwaters. They are essential elements to have around the cities.”

Far from being at loggerheads with IWMI, SLLR & DC’s Deputy General Manager (Wetland Management) Dr. N.S. Wijayarathna, “is trying to promote Colombo as a wetland city and working with the Cabinet, Megapolis Ministry and a lot of other agencies to protect wetlands” says Manthrithilake.

“After Dutch times, in the Colombo city developed by the British, they reclaimed a lot of marshy lands. Because of that you can’t now see any wetlands around the Beira lake up to the BMICH. In old times, it was all wetlands, continuation of the Muthurajawela marshes. Now you are thinking of the Muthurajawela in the Wattala area, but Muthurajawela is continuing up to Bellanwila. Bellanwila marshes are the end of the Muthurajawela area.

“After independence, one division of the Irrigation department, the Low Lying Board was set up to reclaim land for the new city, that is the administrative capital of Colombo. And they reclaimed a lot of wetlands,” says Dr. Wijayarathna. Then they realised something of great hydrological significance.

“The Colombo city is not inundated by the Kelani river over-flow. The Harvard dam built in the old times protects the city from this sort of flooding. Instead the city is inundated by the storm overflow. 39% of the storm overflow is absorbed by Colombo’s wetlands.”

With that realisation came the sobering awareness that only around 20 Sq. Km of wetlands remain in the Colombo city. “Now we want to protect that 20 Sq. Km. Because otherwise, we will have to build up pump stations to protect our capital.”

Then came another dose of conviction through a new project. “We got a grant from the World Bank and did a wetland management strategy for the whole city from 2015 to 2016. From that we realised that wetlands are not only giving flood retention benefits. They are giving so many other benefits to the city, to the people.

“The heat in the city is lowered by the wetlands. The carbon dioxide taken up by marshy areas is double the amount taken up by other areas. So wetlands take up twice as much carbon, heat and retain storm water. What are these? These are the stresses of the city. And you see the people walking and running along the foot paths built around the wetlands. So their stresses are also given to the wetlands.”

Dr. Wijayarathna then asks IWMI to calculate the monetary value of the services rendered by wetlands to Colombo. Barely an hour later, another resource person brought in by IWMI for the wetlands visit, quite independently of Dr. Wijayarathna  shows how such calculations could be done. This is Ms. Lucy Emerton, Environment Management Group, SOAS University of London. She talks to us inside a picturesque shack in the Diyasaru Park Thalawatugoda.

“I am going to talk about the services, the really important economic services that wetlands give because I am an economist. Mainly economists and urban planners are seen as the enemy of wetlands. What I want to do is to report on some good work done in bringing economics and urban planning for the good of wetlands. And how I want to do it is by valuing wetlands as urban infrastructure.

“Infrastructure is meant to be all of the equipment and facilities and services that people need to live and communicate and travel and get clean water and be protected against disasters and actually we need to start seeing wetlands as natural infrastructure. Infrastructure isn’t just pipes and bricks and roads. It’s actually also species and plants and hydrological systems.

“If you ask most people what are wetlands, they say they are a wet, smelly, unhealthy waste of space. And economists like me, well not like me hopefully, economists unlike me, would very much argue a wetland is an unproductive land. Particularly in the city, where land is at such a premium, you need to do something about it. And it would be much better to reclaim wetlands for more economic uses.”

She then tells us that the Diyasaru Park for instance can be reclaimed and houses built on it. They can be sold for a fortune. Or a shopping mall or a road can be built. That has been the dominant thinking.

“We need urban infrastructure and we need to get rid of wetlands and other natural areas that are wet and smelly and dirty and bringing diseases. But we know that is not the case. Wetlands actually save a great deal of money for the government and the city dwellers. The key challenge is how to flip perception from an unproductive space to valuable natural infrastructure that saves people money.”

Lucy Emerton then proceeds to illustrate with three case studies, how that perception fillip has been achieved and how city planners around the world and Sri Lanka have translated wetland benefits into currency values and actually preferred a wetland to a brand new spanking industrial zone for instance. But this is a story for the next instalment


If I travelled 500 years back in time from a spot inside the city of Colombo, where would I emerge, I used to wonder. Now I know the answer; in a marsh. In that particular sense, Colombo is indeed a wetland city, i.e it has a wetland past, having risen up on marshy land reclaimed for urban use over the last 500 years. It has a wetland present too, for as recently as the 1980s, 60% of Colombo could be designated as wetlands. The figure 60% was shared by Herath Manthrithilake, Head of the Sri Lanka programme of the International Water Management Institute (IWMI) at a round table briefing of media to commemorate World Wetlands Day on February 2. Currently, only 20% of the city area can be classified as wetlands, also according to Manthrithilake. This then is an overall loss of 40%, though according to an IWMI fact sheet, in some areas of the Colombo metropolitan region, the loss of wetland area since 1980s is as high as 60%. The question, does Colombo have a wetland future, assumes urgency in this backdrop.

At present according to Dr. N.S. Wijayarathna, Deputy General Manager (Wetland Management) of Sri Lanka Land Reclamation and Development Corporation (SLLR & DC), whom we also met at IWMI, 20 Sq. Km. of wetland remains to Colombo. This is 4,700 in acres according to the IWMI fact sheet. IWMI took some pains to convince the media that that these acres should be maintained as wetlands, not to satisfy environmentalists, but because it makes good economic sense. Perhaps in the wake of USA declaring its intention to leave the Paris agreement alleging incompatibility with America’s economic interests, IWMI couldn’t have chosen a wiser approach.

They brought in Lucy Emerton, an environmental economist, who showed a slide of a Sri Lankan wetland with a stash of rupee notes lurking under its surface and told the media gathering that Colombo wetlands should be preserved because they are natural urban infrastructure which provides services of economic value to the city.

Of all urban the eco systems, environmental economists find it easiest to sell wetlands to city planners, because they, wetlands not city planners, are so very versatile. According to a briefing note by a panel appointed by the RAMSAR Convention of 1971, the international convention on wetlands that Sri Lanka is a party to, of seven ecosystem types (street trees, lawns/parks, forests, cultivated land, wetlands, streams and lakes/sea), only wetlands deliver all six of the services assessed (air filtering, micro-climate regulation, noise reduction, rainwater drainage, sewage treatment and recreational or cultural values).

Lucy Emerton described to us how environmental economists tried to sell That Luang marsh to the Vientiane Municipal Council. “In Vientiane, the capital of Lao PDR, That Luang marsh, you can see running down by the Mekong river, occupies a large area of the city. What the economists and the city planners have decided is that the most economic use of That Luang marsh is to get rid of the natural wetland and swamp areas and actually create a large new housing development and shopping mall, largely financed with Chinese money. So a huge challenge here was to say how do we correct the balance sheet, how do we show that this reclamation would actually incur very large costs? The answer is That Luang marsh is actually vital for flood control in Vientiane, which suffers appalling floods every year and as climate change happens, these floods get worse and worse, and like many of the wetlands here [in Sri Lanka], That Luang marsh is actually essential flood buffer.

“It’s flood control infrastructure and it’s actually worth millions of dollars a year, just for the very small locality that lives around the marsh. Any development which converts it to a more economic land use will actually be incurring this cost on all the people who live around the wetland, and on their personal assets, public infrastructure, crops, health, income and traffic. And that has to be factored into the equation. Now in this case, this was actually a very nice story. Vientiane Municipal Council did take these figures and did start to think about them, and did say, maybe we need to take a much broader view of the wetland reclamation.

“Unfortunately, a lot of Chinese money came in and you know Vientiane, [very poor]. And that Luang housing development and shopping mall is in the process of being built.”

According to an IWMI fact sheet, “The Colombo wetlands play an important role in mitigating floods (with a capacity to store enough water to fill 27,000 Olympic-size swimming pools).” In that case, why is the city still periodically plagued by floods? Are Colombo wetlands punching below their weight, or to choose a more appropriate idiom, sponging below their capacity when flood waters hit? The obvious answer, which eluded me until the briefing by IWMI is that while wetlands have a spectacular capacity to store the flood water, they can’t exert magnetic force and attract flood waters unto themselves. Hence the need for efficient drainage systems to draw the flood waters from the residential areas to the wetlands.

It was such a drainage project conducted under the World Bank funded Metro Colombo Urban Development project that got Nadeera Rajapakse Rubaroe, Wetlands Ecologist involved in the Talangama tank as an environmental specialist, monitoring environmental aspects. It was essentially a project to try to reduce the flood risk in the Colombo city area.

She starts her story holding up a map depicting the Colombo wetland complex comprising the wetland units, Beddagna, Thalawathugoda (Diyasaru Park), Kimbulawela, Madiwela, Kolonnawa, Crow Island, Talangama Tank, and Beira Lake.

What Nadeera tells us in a very detailed way is that Talangama is a classic example of an urban wetland which serves more than one purpose. It provides water for paddy farming, facilitates flood water drainage to keep the city safe and serves as a wild life site, to which nature lovers and bird watchers gravitate, where nature studies are done and which the schools use as an outdoor laboratory for various wetland related studies.

Sometimes these various purposes conflict with each other and when that happens, the competing interests of the various stakeholders are not resolved based on the economic case method Lucy Emerton describes. For, there is no need to sell this wetland to the city planners of Colombo. Nobody will try to build a shopping mall or a housing estate by reclaiming the Talangama wetland. It’s already an environmentally protected area, legally declared by the Central Environmental Authority. They, therefore, have the luxury of sacrificing the economic interest to a considerable degree, to serve the eco system.

Talangama Tank is maintained by the Irrigation Department with the ostensible purpose of supplying water to the farming community for paddy cultivation. Yet in 1991, when the flood drainage scheme called the Madiwela East Diversion scheme was implemented to divert flood water away from the city into the Kelani river, they built a circular weir on the tank and conveyed the spill-over away from the Parliament lake. This weir or ‘pitawana’ was lower than the original, historical weir of the tank, resulting in some decrease in the capacity of the tank. This capacity loss, though it scuttled the irrigating ability of the tank, was in a good cause and no farmer would have grudged the new circular weir. Then things got worse. As the catchment area got urbanized and generated more runoff containing silt and other waste, the lake got shallower and shallower.

“With the silting up process there was also an alien plant that came and found ideal conditions here – the pond apple, which is actually a big problem in all the wetlands in the Western Province. So there was much capacity lost and there were constant requests from the farming community to restore some of the irrigation volume here,” Nadeera explains.

So was their request facilitated? Not wholly. The rights of the alien invasive plant, an officially declared weed in Australia, but which it was felt, had become naturalised in the Talangama tank, providing habitats to certain birds that had started to roost in the forest like groves of pond apple were considered. They were found to deserve consideration on a 50-50 basis with the farming community and only 50% of the proposed area of the lake was allowed to be dredged. “The proposal was to dredge this entire area, estimated to be about eight and half acres. But environmentally we could not agree to that because this is a system that had become naturalised. There are lots of habitats in it.”

Our discussion near the circular weir of the Talangama tank actually heated up due to the pond apple issue. An agricultural research officer invited by IWMI, who actually grew up in the area and has a strong stake in the irrigational capacity, speaks bitterly against the whimsical caprice of the environmental organizations in not allowing the pond apple to be cleared to increase the capacity of the tank.

“I know very well that four or five years ago, they tried to clear the pond apple in the tank. But then some lawyer in the neighbourhood blocked it using their higher contacts. It is alien to Sri Lanka and spreads so fast and it represses vegetation natural to the environment. You can’t even make a mammoty handle with the wood of pond apple”.

One of the journalists asks if there are any species that depend specifically and particularly on pond apple and neither the ecologist Nadeera Rajapakse Rubaroe, zoologist Dr. Priyanie Amerasinghe or the environment lawyer Sanjeev de Silva can give a definite answer. They will only say that pond apple has become naturalised in the system and sweeping changes to an ecosystem, like attempting to clear pond apple completely, could be dangerous. Dr. Priyani soothingly suggests progressive eradication, which the agricultural research officer firmly refutes, saying due to pond apple’s fast rate of reproduction, progressive elimination is not an option. Meanwhile, Sanjeev starts explaining that pond apple eradication may decrease the eco system’s ability to entertain the same numbers of birds that it is currently hosting in pond apple grooves. “And we don’t know the impact the eradication will have on other species such as the fishing cat. As an environmental lawyer I advocate the precautionary principle.”

“But it’s basically a weed right?” I ask puzzled. “It’s an invasive species,” Dr. Priyani replies aiming for ecological political correctness.

Pond apple has been classified by the Australian Government as a Weed of National Significance (WONS), due to its troublesome and invasive alien nature. Because it suppresses natural vegetation of the ecosystem, its eradication is supposed to lead to regeneration of native vegetation without any need for human intervention. Frankly, none of the environmentalists or ecologists with us seems very knowledgeable about these specific traits of pond apple. “So have the environmental organizations descended now to defending a weed?” I ask.

“That’s not the correct perception. You cannot say it’s just a weed, because it’s now a habitat for animals,” Dr. Priyani says almost chidingly. “Don’t term it in that way, that we are defending a weed. It’s a system. It’s trying to understand the system and trying to balance the demands of the system in the best possible way,” Nadeera too speaks up. Perhaps, they should try to study the Australian example more, which is especially relevant as Australia seems to be the only other significant example of a country, besides Sri Lanka where pond apple has encroached as an alien species. Even though I can’t help seeing these expert environmentalists’ attachment to pond apple as unrealistic and fanciful, on wetlands as a whole their message is strong and impactful.

“Talangama is one wetland. But it’s representative of the entire wetland complex in Colombo structurally. One thing that really needs to come up, is this concept of wise use. This wetland is doing things that we see and feel as well as things we are not conscious of. These are called eco system services. It’s treating the water quality. All the waste that’s coming from the catchment, it’s purifying. It’s preventing floods, providing habitats, sequestering carbon and helping climate change mitigation. It’s a source of food – fish, rice. All these wetlands are performing so many services to the city that we can’t afford to lose even an inch more. This part of the Colombo wetlands, they tried to assess for the services provided to the city. It’s in millions of rupees per year. If the city were to provide these services artificially, it would cost the city that much.

Sanjeeva says, “Fishing cat is one of the wild cats of Sri Lanka. To be able to see it in a capital city of a country is a big deal. There are not many cities in the world which can boast this. We also have the fresh water otter, a European otter in Colombo. It’s incredible. What’s missing in the story is neither government nor private sector has taken it up as an opportunity to promote tourism. Tourists spend very little time in Colombo. We are not a great shopping capital. Our culture is elsewhere. For the tourist to stay an extra night in the city means a lot of extra income generated and there will be opportunities for local residents to serve as guides. This is the story we want to bring to the public through you.” (Concluded)




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