Protecting Colombo from future floods

Protecting Colombo from future floods

Climate Adaptation

In May 2016, Colombo, the capital of Sri Lanka, was hit by the worst floods since 1989.The reduction in the storage capacity of valuable wetlands, illegal settlements and a failing sewage system were all major factors that contributed to the intensity of the floods.The amount of water passing through the Kelani River, which borders the city centre to the northeast, reached the second-highest level in 35 years. In combination with the neap tide, the result was the most devastating flood in nearly three decades. In the district of Colombo alone, 185,000 people were affected and there were three fatalities.

We are helping the government of Sri Lanka in the 'Metro Colombo Urban Development Project' by estimating the likelihood of future floods and devising a strategy to reduce the associated risks. The project has two main objectives. Firstly, the mapping out of the current and future flood risk in the Colombo Metropolitan Region. Secondly, with future land use in Colombo in mind, collaboration with a range of stakeholders to develop a strategy that reduces the risk of floods.

Protecting Colombo from future floods

We are using a detailed hydrodynamic model of the Metro Colombo region to map out the risk of flooding. These data will be combined with an economic analysis of major infrastructure to produce an estimate of the potential economic damage of floods of different kinds and sizes. In addition, we are going to enhance the capacity of local people to interpret and assess this kind of risk information and to include the information in plans for the future development of the urban area. We have organised a range of courses and workshops about these topics. Finally, we are creating a publicly accessible website (GeoNode FRA4CMR) with a database of all GIS information from this project on flood risk management.

The project is a good example of how Deltares maps out flood risks in urban areas. A unique feature of this study is that we quantified the vulnerability of people, infrastructure and buildings, as well as the potential damage down to the level of individual streets.
Hans Gehrels
Deltares expert sustainable cities
This project is an important step not only in reducing the current flood risk but also in providing useful input for future large-scale urban megapolis development interventions that will be undertaken by the government.
Mr. Suresh
Project Director, Metro Colombo Urban Development Project
The project is a good opportunity to both improve the modelling capacities at SLLRDC and to develop a risk assessment and loss estimation model for different flood events.
Mevr. Thushari
Deputy Project Director, Metro Colombo Urban Development Project

For this project Deltares has collaborated with the following partners:

  • Asian Disaster Preparedness Center
  • Central Engineering Consultancy Bureau of Sri Lanka
  • The World Bank

Want to know more about this project?

Hans Gehrels
Expert sustainable cities