Abstract
Floods are a natural hazard that affect communities worldwide, but to date the vast majority of flood hazard research and mapping has been undertaken by wealthy developed nations. As populations and economies have grown across the developing world, so too has demand from governments, businesses, and NGOs for modeled flood hazard data in these data‐scarce regions. We identify six key challenges faced when developing a flood hazard model that can be applied globally and present a framework methodology that leverages recent cross‐disciplinary advances to tackle each challenge. The model produces return period flood hazard maps at ∼90 m resolution for the whole terrestrial land surface between 56°S and 60°N, and results are validated against high‐resolution government flood hazard data sets from the UK and Canada. The global model is shown to capture between two thirds and three quarters of the area determined to be at risk in the benchmark data without generating excessive false positive predictions. When aggregated to ∼1 km, mean absolute error in flooded fraction falls to ∼5%. The full complexity global model contains an automatically parameterized subgrid channel network, and comparison to both a simplified 2‐D only variant and an independently developed pan‐European model shows the explicit inclusion of channels to be a critical contributor to improved model performance. While careful processing of existing global terrain data sets enables reasonable model performance in urban areas, adoption of forthcoming next‐generation global terrain data sets will offer the best prospect for a step‐change improvement in model performance.
Highlights
The repeated occurrence of high-profile flood events (e.g., Australia and Thailand in 2011; central Europe in 2013; and India and Pakistan in 2014) has resulted in sustained public, commercial, political, and scientific interest in flooding
The total runtime for a typical 108 3 108 equates to approximately 2000 h on a single core of a 3.2 GHz Intel i7 processor, the exact value for each tile varies according to several factors, including percentage land surface, climate, and hydrograph durations on the largest rivers in the tile
Validation of a flood hazard map is challenging as such data do not attempt to describe any single real event but instead attempt to describe the areas affected by all events of a certain magnitude
Summary
The repeated occurrence of high-profile flood events (e.g., Australia and Thailand in 2011; central Europe in 2013; and India and Pakistan in 2014) has resulted in sustained public, commercial, political, and scientific interest in flooding. Scenario-based simulations using climate models do indicate the possibility of increasing future flood risk in many regions due to climate change, there is considerable variability between models and scenarios [Arnell and Gosling, 2014]. This prospect is of particular concern to international humanitarian and development organizations such as the World Bank and the UN World Food Programme, as well as to the global (re)insurance market. Recent losses have proven significant: household losses resulting from the summer 2007 floods in the UK reached £2.5 billion, with business losses accounting for a further £1 billion [Chatterton et al, 2010]. Estimates of the total economic losses from the Australian and Thailand events of 2011 range between USD 2.8–6.1 billion and USD 30–40 billion, respectively [Munich Re, 2012; Swiss Re, 2012]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
