Flood control in Colombo:

SLLRC’s mission nearing completion

by Ranil Wijayapala

The severe floods that hit the greater Colombo areas in May and November 2010 were an eye opener for many in Colombo. It brought to mind the badly maintained canals and drainage systems in the commercial capital Colombo and the administrative capital Sri Jayawardhanapura, Kotte.

Members of Parliament had to wade through the waters of the Diyawanna as it inundated all the access roads to the legislature covering the ground floor of parliament building fully on November 11. It became a matter of grave concern for the authorities to think afresh, to find short-term, medium-term and long-term solutions to the flooding in Colombo and suburbs.

It was the Land Reclamation and Development Corporation (SLLRC) which was listed under the Ministry of Defence, in the Cabinet reshuffle following the 2010 general election, that took the lead along with other relevant agencies to think of a solution to this problem.

A Chartered Architect Harshan de Silva who was appointed Chairman of the SLLRDC in May 2010, was the one who had to lead the fight against floods in Colombo. The process was in itself a war to control floods as it affected the lives of the poorest of the poor living in shanties and the richest of the rich living in mansions.

Dredging in progress

It was a long and arduous process to rectify the ills in the drainage system the canals and sub canals.

The main canal system in the Colombo basin had six outfalls to drain the water collected in the Dehiwela, Wellawatta, St. Sebestian’s, Kolonnawa Ela canals into the sea. It was through the outfalls at Dehiwela, Wellawatte and the Beira Lake that the Galle Face green and MacCalum Road and Colombo Port connected those canals directly into the Indian ocean.

The outfalls at Mutuwal, Nagalagam Street and Ambatale connected the canals in Colombo North to the Kelani River.

“We had to see the quantity of water flowing through these outfalls. The entire canal system had not been dredged in one run for years,” de Silva said.

One major problem we faced was that there was no allocation of funds for the dredging of the entire canal system in one run by the treasury.

When the treasury allocates funds they give a limited amount of money and with that money the SLLRC can dredge only a segment of a canal.

They used to dredge parts of each canal according to the allocation of funds but not the entire thing at once.

“That was something which I thought which we lack. If we take the entire canal system - 1 Metre Mean Sea Level you have to do dredging of the entire canal network. If you do the dredging only in one part of a canal it is useless.

You have to dredge the whole canal at once”, de Silva said.

The SLLRC studied the root causes for the flooding and the Defence Secretary, Gotabhaya Rajapaksa formed a Task Force under the Chairmanship of SLLRC Chairman Harshan de Silva to look into the matter on priority basis.

The Coast Conservation Department, Irrigation Department, Land Reclamation and Development Corporation, Urban Development Authority, Forest Department, Wild Life Department and all Local Authorities were members of this task force and they met every week to discuss the issue.

“After about two months we found 44 locations which have to be addressed and we had to address them pretty soon,” he said.

To address the immediate issue we did a survey at Devi Balika Junction, D.S. Senanayake Junction and Colombo University where there were no canals or rivers, places that were inundated due to flash floods.

“It was due to various technical issues that these areas went under water and some of them went into the short-term and medium-term slots,” he said.

To address the immediate issues the SLLRC worked with the Colombo Municipal Council. Its Special Commissioner Omar Kamil and Commissioner Badrani Jayawardene did a great job with all other organisations and institutions came up to address the 44 issues.

To control floods around Devi Balika Vidyalaya a peripheral drain was constructed in Manning Town and Health grounds.

“Now we are looking at penetrating the Castle Hospital and we have to connect that drain into the Heen Ela that goes behind the Golf grounds” de Siva said.

The floods close to Devi Balika Vidyalaya stalled traffic along Parliament drive and beyond Malabe town creating transport problems and other issues.

“Like this project the SLLRC along with other agencies had to address many isolated places where flash floods were reported. We had to address them under the short-term and medium-term projects, he said.

The SLLRC managed to complete the short-term projects during May to December 2010.

When addressing those issues the SLLRC had to face certain restrictions with regard to manpower, financial issues, fuel allocation and the supervision and monitoring of the work. It was the Defence Secretary Gotabhaya Rajapaksa who helped resolve those issues.

“I got about 500 personnel from the Sri Lanka Navy to work on the canals.

The Sri Lanka Air Force helped me to do the surveillance and monitoring on air. The Army also helped providing us with security and the Police assisted us to go ahead with our work. That I think was a big way forward for us,” he said.

To dredge the entire canal network the SLLRC needed a lot of machines. The Corporation machines which were idle for years were repaired and barges were welded by the Navy along with the workers of the SLLRC.

A huge amount of money for the entire project was allocated from the Defence Ministry budget.

“People may ask why we need this much of money for the defence budget since there is no war. Now this is the types of work the Ministry of Defence is doing,” he said.

The process of dredging was monitored. “For all these machines we had Navy personnel monitoring fuel consumption, meters and the manpower. Nothing went astray. My audit team and engineers were there and in addition the Navy also monitored the process very accurately,” he said.

“In six months we managed to dredge the entire canal system. There were ups and downs due to the November rains but we made adjustments. The entire thing is done and we are now doing some rectifications,” he said.

Though the SLLRC found the dredging of the canal network a difficult task the maintenance of these dredged canals is a much more difficult task. Specially in the areas like Colombo North it is a very difficult task as people living there have used these canals as garbage dumping yards.

“A Sense of awareness, a sense of gratitude and responsibility was nil among that community and their attitude was a problem. That was why we had to dredge the St. Sebestian canal again before the ICC World Cup matches,” he added.

Forces personnel had to be deployed on full time basis in Colombo North to maintain cleanliness of the canals since it was difficult to maintain the canals there. The SLLRC had to relocate some shanty dwellers who had encroached the reservations of these canals.

“Despite these problems the short-term plan of dredging the main canal system is quite a success,” he said.

The dredging of secondary or sub canals which lead to the main canals was begun early this year. “Those are even tougher to handle. They are located in between shanties. We are working on it,” he said.

As short-term projects are in the process of completion medium-term plans to control floods in the Colombo basin was begun. This was the toughest job for the SLLRC as it had to tackle the most powerful who had encroached into the retention areas of the Colombo basin at this stage.

Canal reservations were invaded by poor shanty dwellers the rich and the powerful (either politically backed or underworld backed).

“In the Colombo basin, according to the 1991 survey, we had 1500 acres for retention areas. Now it is about 800 to 900 acres.

Basically all these were filled by high powered people,” he said.

Due to filling of these retention areas the retention capacity in the Colombo basin is reduced.

At the medium-level, whatever the retention areas we lost we have to regain. “A huge amount of retention areas are lost. But we can compensate for it,” he said.

“We have to rectify this problem. We won’t be able to get back the 1,500 acres lost. This is where engineering comes into play. If we can create retention lakes in the upper catchment areas, then the entire volume can be held upstream. What happens is that all the water gets flushed and comes to the low lying areas if there are no retention areas,” he said.

In the Colombo basin whatever is below + 2 metres MSL is considered low lying. The canals will take upto + 2 metres MSL.

“We are half the capacity in retention areas. We have to artificially create retention areas to hold these waters, by keeping gates to send them through the canals when flood waters recede. That is why we began the medium-term plan because we thought that cleaning the main canals won’t do the entire thing,” de Silva said.

Construction of retention tanks near the Peliyagoda fish market: Rampalawatta: Thalawathugoda and Waters Edge, were begun end last year. Construction now in progress.

Some of them are 20 acres in extent and will hold about 100,000 cubic metres.The dredging of the banks of the Diyawanna Oya at Battaramulla is also a part of this project.

Apart form the ongoing projects to have retention tanks a few other retention tanks will also be constructed in the upper stream of Diyawanna oya in Thalangama North and Thalangama South.

“We have already done the East diversion through Thalangama tank upto Ambatale via Arangala and Kaduwela. That helped reduced the water coming to the Colombo basin to the Diyawanna and diverts towards the East,” he said.

“As a long-term solution to the floods in Colombo basin, we are looking at a South diversion to divert the water collected in Diyawanna to the Bolgoda Lake through Weras Ganga and it will have to be done in the future,” he said.

The Weras Ganga project will help reduce the floods in places like Rattanapitiya, Attidiya, Bellanwila areas. “We are doing the technical evaluation and once the funds come through a Chinese soft loan the project will be implemented.

The final solution to the Colombo basin floods will come when the pump houses and gates are restored. “Where we can control the floods naturally we have done so. Then we have to come out with the pump houses,” he said.

These pump houses located at Gothatuwa, Nagalagam Street, MacCalum Street and at Mudun Ela are not in order. They have to be repaired to control floods. “We have requested a loan from the World Bank. Once we get the funds from the WB we will be able to rectify the long-term solutions also,” he said.

The other long-term solution is the restoration of Beira Lake by stopping sewer into it.

“We have come a long way and have to go further forward. By the end of 2011 we will be able to complete the short-term and medium-term plans to concentrate on the long-term and the maintenance of the work that we have already done, he said.

Weras Ganaga South diversion will be completed by 2014 or 2015 the latest.

“With the completion of all these projects I am not saying that there won’t be flooding.

Floods will happen in a way that doesn’t harm the day-to-day work of the people. If we can achieve this our, vision and mission is achieved,” he said.