Costs and benefits of river flood risk management at the global scale

Abstract:

Floods cause billions of dollars of economic damage each year, and this is expected to increase in the future due to socioeconomic development and climate change‎. To limit these losses, and to protect people and their livelihoods from flooding, adaptation in flood risk management systems is required that takes into account both current and future risk. Whilst several global scale flood risk models have now been developed to assess both current and future river flood risk, to date none of these include currently installed or future flood risk management measures, nor their costs and benefits. In this contribution, a new modelling framework is presented for assessing both the costs and benefits of flood risk management at the global scale, which employs a cascade of models to provide first-cut estimates of the costs and benefits of adaptation by means of hazard reduction through the construction of dikes.

The modeling framework is first used to assess what protection standards would be required in the future per state, in order to keep future flood risk constant at today’s levels, and the costs and benefits associated with such a strategy. In a second analysis, flood risk protection standards are calculated per state that optimize the net present value of adaptation. The potential usefulness and limitations of the results for practical applications are discussed, as well as key avenues for future developments. In particular, recent research has shown flood risk itself to be non-stationary, being influenced by oscillations in climate variability caused by phenomenon such as El Niño Southern Oscillation (ENSO). The results of the research will be discussed within the context of climate-driven ENSO variability.