Actual and perceived causes of flood risk: climate versus anthropogenic effects in a wet zone catchment in Sri Lanka

ABSTRACT

The Kalu Ganga Basin in Sri Lanka is generally flooded once a year. A network of low-lying lands acts as natural retention and storage that captures floodwater, minimizing damage. An increase in the flood frequency has been observed in recent years. It is commonly perceived that this increase is caused by a rise in the frequency and severity of ‘very wet’ precipitation events. We conclude that land-use changes may have played a larger role in generating floods.

KEYWORDS:

• Flood frequency
• extreme events
• land use
• urbanization
• flood retention
• Sri Lanka

Acknowledgements

The authors would like to acknowledge the support provided by Mr Nandana Mahakumara (independent consultant) and Upamali Surangika (IWMI) in carrying out the household survey, and the Sri Lanka Land Reclamation and Development Corporation for access to their database on reclamation permits. Thanks are also due to the Department of Meteorology, Sri Lanka, for the use of rainfall station data in the Ratnapura and Kalutara Districts.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by the International Water Management Institute as part of the CGIAR Research Programs on Climate Change Agriculture and Food Security and Water Land and Ecosystems.