Abstract

Floods have caused severe environmental and social economic losses worldwide in human history, and are projected to exacerbate due to climate change. Many floods are caused by heavy rainfall with highly saturated soil, however, the relative importance of rainfall and antecedent soil moisture and how it changes from place to place has not been fully understood. Here we examined annual floods from more than 200 hydrological stations in the middle and lower Yangtze River basin. Our results indicate that the dominant factor of flood generation shifts from rainfall to antecedent soil moisture with the increase of watershed area. The ratio of the relative importance of antecedent soil moisture and daily rainfall (SPR) is positively correlated with topographic wetness index and has a negative correlation with the magnitude of annual floods. This linkage between watershed characteristics that are easy to measure and the dominant flood generation mechanism provides a quantitative method for flood control and early warnings in ungauged watersheds in the middle and lower Yangtze River basin.

Highlights

  • In this study we mainly focus on the impacts of antecedent soil moisture and rainfall on flood generation

  • Heavy rainfall on highly saturated soil was identified as the dominant flood generation mechanism across world (Berghuijs et al 2019; Wang et al 2021; Wasko et al 2020)

  • This study aims to further evaluate the relative importance of antecedent soil moisture and rainfall on floods generation and the controlling factors

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Summary

Introduction

Flooding is one of the most destructive and costly natural hazards in the world, resulting in considerable fatalities and property losses (Suresh et al, 2013). Numerous studies have been conducted to investigate the cause of floods across the world (Bloschl et al 2013; Munoz et al 2018; Zhang et al 2018). Many studies focused on examining the environmental and social characteristics that lead to specific catastrophic flood events (Bloschl et al 2013; Liu et al 2020; Zhang et al, 2018). Others concentrated on single locations, usually catchment outlets, to explore the influential factors of floods and the future trends (Brunner et al, 2016; Munoz et al 2018). Given the amount of data and time required, it is not practical to apply these detailed studies to hundreds of catchments to generate an overview of the flood generation mechanism at large scale

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