Accurate digital elevation models (DEMs) created using airborne lidar have transformed regional flood modelling and forecasting. At continental and global scales, however, the best-available DEMs come from satellite images and are too crude for simulating flooding — and its related risks to public health, biogeochemical cycling and wetland ecology. We would like to see industry, governments and humanitarian agencies come together to support the development of a global DEM with higher resolution and accuracy.
Current global DEMs cannot resolve the detail of terrain features that control flooding. More-effective flood-hazard maps could be created by obtaining high-resolution stereo images from satellites, combined with the latest advances in flood modelling using supercomputers. By 2050, worldwide annual losses due to flooding are predicted to reach US$1 trillion (S. Hallegatte et al. Nature Clim. Change 3, 802–806; 2013). A global-scale DEM would have an enormous impact on finance (such as flood re-insurance), humanitarian services (such as disaster relief) and scientific research.
The advanced global DEM would use existing lidar data and stereo satellite images, and new lidar elevation data would be acquired on board disaster-relief aircraft or on drones deployed over flood plains. The operation costs would therefore be substantially cheaper than most satellite missions.