Exploring the ENSO Impact on Basin-Scale Floods Using Hydrological Simulations and TRMM Precipitation

El Nino-Southern Oscillation (ENSO) is an important driver of interannual climate variability with increasing attention for its impacts on water and flood management. The impact of ENSO on basin-scale floods during the TRMM period (1998-2013) is examined by using the streamflow outputs from the Dominant river Routing Integrated with VIC Environment model (DRIVE). Significant simultaneous correlations between flood indices and Nino 3.4 appear in many flood-prone river basins during peak flood months across both the tropics and midlatitudes especially for flood frequency and flood duration. Gauged by significant lag-correlations between floods and Nino 3.4, significant ENSO-leading-floods relations are found as well in many river basins in South America, south and southeastern Asia, and northern Africa. These ENSO-floods-relations can greatly enhance understanding of physical mechanisms relevant to the ENSO impact and may also improve the skills of basin-scale monthly-to-seasonal flood forecast, thus allowing for better preparedness and management of flood risks. Plain Language Summary As a naturally occurring phenomenon involving quasi-periodic variation of air pressure and sea surface temperature, the ENSO impacts global floods through its modulation of atmospheric circulations, weather, and precipitation. Previous studies on ENSO-floodsrelations are often limited in supporting practical flood disaster preparedness and risk analyses because of the lack of a complete reconstruction of past flood events likely due to scattered gauge-based streamflow data and/or coarse-resolution retrospective simulations. Here flood events at model grids and for individual river basins are identified using the outputs from the Dominant river Routing Integrated with VIC Environment model (DRIVE) with a high spatial resolution (0.125 degrees x 0.125 degrees) driven by the state-of-the-art satellite precipitation product TMPA. Simultaneous and lagged responses of basin-scale floods to ENSO are explored to provide an improved knowledge of the ENSO effect on global floods and a guidance for flood disaster planning and risk management for the regions consistently impacted by ENSO.