Historical and future changes in  global flood magnitude – evidence from a model-observation investigation

This study presents a comprehensive investigation of historical and future changes in flood hazard based on a solid evaluation of model performance. Using a comprehensive streamflow database of more than 30,000 gauges across the globe, the study shows that most models possess a moderate capacity in reproducing the characteristics of trends in floods, including the mean, the standard deviation, the percentage of locations showing significant trends and the spatial association of trends.

blue-ocean-rain-1298688The projected trends under RCP6.0 greenhouse gas concentration scenario highlight a high level of change in individual regions, with up to 35% of cells showing a statistically significant trend (increase or decrease). Importantly, the observed streamflow database under-samples the percentage of high-risk locations by more than an order of magnitude (0.9% compared to 11.7%).

This finding indicates a highly uncertain future for both flood-prone communities and decision-makers in the context of climate change.

Paper: Do, H. X. and Zhao, F. and Westra, S. and Leonard, M. and Gudmundsson, L. and Chang, J. and Ciais, P. and Gerten, D. and Gosling, S. N. and Schmied, H. M. and Stacke, T. and Stanislas, B. J. E. and Wada, Y. (2019). Historical and future changes in global flood magnitude – evidence from a model-observation investigation. Hydrology and Earth System Sciences Discussions. 10.5194/hess-2019-388