National Coastal-Inland Flood Model for CLimate Change

The ongoing climate change poses many challenges to the planet of earth. Prime Minister Lee Hsien Loong sounded the clarion call for the country to tackle climate change in his National Day Rally speech in August 2019, calling it an existential threat for Singapore.

Sea level rise coupled with increased rainfall intensity associated with weather extremes will undoubtedly threaten low-lying areas in Singapore with more frequent and severe flooding, if coastal defence measures are not upgraded. A continuous line of coastal defence comprising adaptation measures, including both nature-based approaches and engineering solutions, is required to effectively protect Singapore. In spite of the uncertainties involved with the long-term climate projections, coastal adaptation work must start now given the long lead time and the huge costs required in developing and implementing new coastal infrastructures.

In 2019 the Building and Construction Authority (BCA) concluded the Coastal Adaptation Study (CAS), which divided Singapore into 8 hydraulically distinct Adaptation Planning Areas (APAs). The CAS also produced a preliminary coastal protection framework replete with proposed climate change adaptation pathways and measures, including cost estimates, to protect Singapore against higher sea levels. As Singapore forges ahead with the implementation phase of coastal protection, the assumptions and data used in the CAS need to be re-examined and the results be reviewed.

Recently, the Public Utilities Board (PUB) in Singapore has been designated as the National Coastal Protection Agency and charged to


  1. set out policies and institutional structures to achieve climate adaptation;

  2. develop state-of-the-art National Water Model; and

  3. develop coastal protection solutions relevant for land constrained Singapore.


To fulfil its mission in planning and designing adaptation measures against the evolving climate change, PUB intends to develop a National Water Model, which is accurate and robust and is capable of using the best available information to determine coastal protection design levels, and to assess the effectiveness of proposed measures against compound flood risks. The foundation of the National Water Model is an integrated inland rainfall-runoff and coastal inundation model at the national level. Taking into account the effects of extreme sea levels, storm surges, wind waves and rainfall during a future projected weather extreme, the model is expected to produce spatial and temporal distributions of inundation depth with desirable resolutions. The National Water Model will also have the capability of forecasting flood events from rainfall and tides for early warning system and for operational management.

National University of Singapore (NUS) in collaboration with Hydroinformatics Institute (H2i) proposes to develop such an integrated inland rainfall-runoff and coastal inundation model at the national level for PUB. The specific objectives of this proposed project are:


  1. Develop an integrated inland-coastal flooding model integrating physical processes of storm surge-tide, wave runup, and rainfall induced overland flows.

  2. Review and collect essential bathymetry and topography data, and develop central database and data management system to improve understanding of the changing coastal environment in Singapore.

  3. Conduct research on coastal hydrodynamics in Singapore water, and develop additional physics-based modules to complement the integrated coastal flooding models.

  4. Develop training materials and education programs for PUB staff on coastal and inland flood modelling.


Given the breadth of the input required for testing and implementing such an integrated model, the proposed project will require access and collaboration with government centres and agencies, such as Center for Climate Research Singapore (CCRS) for down-scaled climate projections; Meteorological Service Singapore (MSS) for operational weather forecasts to forecast operational surge levels and wave heights; Maritime and Port Authority (MPA) and Singapore Land Authority (SLA) to access geo-spatial data from the GeoSpace databases; and Urban Redevelopment Authority (URA)/Ministry of National Development (MND) for projected land outline/land-use changes.

This project has been funded by PUB.