- 1st October 2020
- Posted by: Emilia Gates
- Category: Projects
Client: Asian Development Bank Partner: Landell Mills Location: Indonesia
Like many countries in Asia, the risk of flooding in Indonesia is now so great that no one flood risk management measure (e.g. flood walls) will provide the level of resilience required to manage risk now and in the future. Managing flood risk appropriately will require a range of integrated measures including hard defences, nature-based solutions and other non-structural interventions (e.g. flood warning, emergency planning, development planning). While the concept of Integrated Flood Risk Management (IFRM) is now well established, designing effective schemes that consider risk at catchment scales – which is essential in order to account for integrated processes – has been a challenge due to data and modelling limitations. Making sound investment decisions at a national level is equally challenging because the spatial distribution of the costs and benefit of different flood risk management options is unknown.
Working with Landell Mills, this project involved the development of a highly innovative, catastrophe-modelling based approach to identify the spatial distribution of flood risk in Indonesia and to explore the impact of different combinations of flood risk measures on key metrics such as annual average losses, people and property affected. Our FLY technology was used to provide a probabilistic estimate of average annual losses based on our library of 30m global flood maps (GFM), combined with high resolution population density information, census data and vulnerability curves. The risk was disaggregated at a range of scales including sub-district, district and river basins. A set of opportunity maps for four categories of IFRM – property level protection, dykes/embankments, nature-based solutions (runoff interception, floodplain connection, riparian planting) and flood warning – were also developed and used in combination with adjustments to the risk calculation to estimate the relative benefits. The outputs were built into an on-line mapping App called NIRA (National Integrated Risk Analytics), which visualizes the data produced and allows a user to explore the potential costs and benefits of different combinations of measures.
By using NIRA, it was possible to identify those districts/regions in Indonesia that are at greatest risk of flooding. More importantly, it is a powerful tool that is being used to identify those districts where there are the greatest opportunities with respect to IFRM and nature-based solutions. While data and analytics at this scale does not provide detailed solutions, the tool is now being used to help guide and prioritise an “investment-decision roadmap”, steering investment decisions and technical studies that will have the best chance of impact. NIRA can be used to weigh-up combinations of measures that would provide the equivalent level of risk reduction to traditional approaches, whilst providing greater co-benefits.
Want to know more?
Funding for this work is provided by the Urban Climate Change Resilience Trust Fund. This fund supports cities by improving urban planning, designing climate resilient infrastructure and investing in projects and people. The Rockefeller Foundation and the governments of Switzerland and the United Kingdom support the fund.