FLOOD & DRAINAGE MANAGEMENT

Background of the Project

The Metro Colombo Drainage Basin, which is about 105 km2 in size, is probably the most noteworthy drainage basin in SriLanka since it covers the administrative and commercial capital of the country. This basin consists of areas such as Kotte, Battaramulla, Rajagiriya, Madiwela, Dehiwala and about 75% of the area of Colombo Municipal Council. This basin has a number of sea outlets as well as river outlets. The 2010 November flood is the latest extreme event that affected this area. The “Metro Colombo Urban Development Project” (MCUDP) which is funded by World Bank was initiated in year 2012, with the aim of flood mitigation in this area. It has been identified that the present outfall capacity of the system is not enough for such an extreme event and filling of existing storage areas aggravates the condition. Therefore, a number of outfalls are proposed under MCUDP, while preserving the existing flood retention areas. Preliminary designs of the major interventions under MCUDP have already been completed by end of 2014. Detailed designs of major projects which were identified have also been completed and the implementation are is in progress for most of the sub projects.

Objective of the Project

To reduce the physical and socio economic impacts of flooding in the Metro Colombo Region.

The project was launched in July 2012.

Sri Lanka Land Development Corporation (SLLDC) and Colombo Municipal Council (CMC) are the two implementing agencies who are responsible for design and implementation supervision works.

SLLDC focuses on the primary canal system and overall drainage management in the basin (Macro Drainage Component), while CMC is concerned with the urban drainage management in the area (Micro Drainage Component)