Introduction

Hydrological extremes, in the form of droughts and floods, have impacts on a wide range of sectors including water availability, food security, and energy production, among others. Given continuing large impacts of droughts and floods and the expectation for significant regional changes projected in the future, there is an urgent need to provide estimates of past events and their future risk, globally. However, current estimates of hydrological extremes are not robust and accurate enough, due to lack of long-term data records, standardized methods for event identification, geographical inconsistencies and data uncertainties. To tackle these challenges, we develop the first Global Drought and Flood Catalogue (GDFC) [He et al., 2020] for 1950-2016 by merging the latest in situ and remote-sensing datasets with state-of-the-art land surface and hydrodynamic modeling to provide a continuous and consistent estimate of the terrestrial water cycle and its extremes. This GDFC also includes an unprecedented level of detailed analysis of drought and large-scale flood events using a multivariate risk assessment framework, which incorporates regional spatial-temporal characteristics (i.e., duration, spatial extent, severity) and global hazard maps for different return periods. This catalogue forms a basis for analyzing the changing risk of droughts and floods and can underscore national and international climate change assessments and provide a key reference for climate change studies and climate model evaluations.