Saving the Megapolis from floods: Rs 39.8 billion for 8 projects

Compiled by Chandani Jayatilleke

New projects have been approved and existing ones accelerated, to double the storm water discharge capacity of the canal and tunnel network in and around the Colombo metropolitan region, envisaged as the new 'Megapolis', to protect the island's export manufacturing hub from the worst floods expected once in 50 years.

An aerial view of the Container Yard in Orugodawatte submerged during the recent floods

The move comes in the wake of the unprecedented floods along the Kelani River, triggered by a severe tropical storm in mid-May, which also caused landslides in the hill country, killing several people, forcing thousands more from their homes and causing much damage to infrastructure and business, particularly tea exports. The National Insurance Trust Fund (NITF), the government re-insurer, estimates claims from the disaster to around Rs15.5 billion.

The government has decided on a holistic policy to prevent, control and manage floods in the Western Province, in early July, approving Rs. 8.2 billion for 2016 to implement eight projects under the Storm Water Drainage Improvement Plan of the Ministry of Megapolis and Western Development.

According to the cabinet proposal, the Colombo Metropolitan Area (CMA) is the most important industrial, commercial and administrative centre in the country. A major share of the country's export oriented manufacturing takes place in the Western Province, in which the CMA is the engine of growth. The Western Province contributes more than 50% to the GDP and about 80% of industrial value addition, although it accounts for only 5.7% of the country's geographic area. The Western Province is, therefore, crucial for achieving the country's long-term development plans in economic growth and social well-being. In order to facilitate the transformation of Western Province to a Megapolis of international standards, the government has to address numerous critical problems that have for long been obstructing economic and physical urban regeneration of the city.

The Region of the Megapolis encompasses the entire Western Province, from the Ma-Oya basin in the North to the Bentota Ganga basin in the South. A major portion of the country's economic activities and population is concentrated in this region within the Attanagalu Oya, Kalu Oya, Kelani River, Weras Ganga and Kalu Ganga basins. Of the total extent forming the Western Region, 91 km (2.5%) is occupied by inland water bodies. Of the 103 river basins in Sri Lanka, 36 are major river basins and 5 such major river basins, namely Kalu Ganga, Kelani River, Attanagalu Oya, Ma-Oya and Bentara Ganga are located in the Western Region.

Holistic manner

The experience of the November 2010 flooding in the Western Province clearly showed the urgent need to integrate and bring together unique institutional capabilities, improvement of existing technological infrastructure and professional development, to minimize flood risk in a holistic manner. In this respect, a number of drainage improvements were identified to cover a substantial extent of the Western Region.

Some of the interventions have been initiated through the Metro Colombo Urban Development Project (MCUDP) financed by World Bank to increase the storm water discharge capacities to the sea, and are under implementation stage at a total approximate cost of USD 160 million. Under this investment, two micro tunnels at Torrington and Mutwal, a pumping station at St. Sebastian North Gates at Nagalagam Street and improvements to Madiwela East Diversion Scheme have been earmarked, to increase discharge capacity. With all interventions identified, the discharge capacity will be increased by 100%, enabling flood safety for a 1 in 50-year flood in Colombo. A major part of improvements is ready for implementation under the MCUDP, utilizing World Bank funding.

The second major investment is the Weras Ganga Storm Water Drainage and Environment Improvement Project, to address flooding in the Weras Ganga catchment. It is an ongoing project, with 30% zones completed.

Apart from the MCUDP and Weras Ganga Project, a few major integrated measures have been identified to address the flooding problems outside Metro Colombo, such as Kolonnawa and Moratuwa-Ratmalana, which are vulnerable to flooding.

Under the Gampaha District drainage improvement, master plans are being prepared for Kalu Oya catchment and Attanagalu Oya catchment, and other isolated areas prone to flooding. Flood prone areas in the Kalutara District are also being identified and prioritized under this project.

Proposal

With the experience of flooding in May 2016, an urgent need for the implementation of the remaining proposals on a priority basis was felt. Of the remaining proposals, Madiwela South Diversion is vital for the reduction of flood risk to the Metro Colombo region in general, and Parliament area in particular. It has been identified as the most effective proposal for flood reduction in the conceptual stage of MCUDP; and the targeted flood safety for a 1 in 50-year flood in Colombo could be achieved only with the implementation of this proposal.

Apart from this, the implementation of the Kolonnawa Pumping Station and the Ambatale Pumping Station have also been identified as major interventions to increase the discharge capacity of the Colombo area.

The government has decided to effectively implement the priority improvements identified for flood reduction in Colombo through the above mention projects.

The Laugfs Gas Plant under water in Orugodawatte