Flood Inundation Generation Mechanisms and Their Changes in 1953–2004 in Global Major River Basins

Abstract

Despite the serious threats posed by floods, the driving mechanisms of floods are still not well understood. Here we apply a physically based inundation model coupled with a river routing model (Model for Scale Adaptive River Transport (MOSART)) within the Energy Exascale Earth System Model (E3SM) framework to investigate flood inundation dynamics. After calibration using observed streamflow and satellite-derived flood extent, the model is used to simulate global flood inundation from 1953 to 2004. The mean date and seasonality of annual maximum flood, defined based on flood extent, exhibit significant regional differences across 16 major basins. Generally, soil moisture and monthly maximum daily rainfall (MMR) are the dominant drivers of flood in tropical basins while monthly maximum daily snowmelt (MMS) is the dominant driver in high-latitude basins. From 1953From -1982From to 1975From -2004 changes in flood generation mechanisms are found in some basins such as Amazon, Lena, Yenisey, and Kolyma. Analysis of the rainfall seasonality and water balance at grid scale reveals a stronger rainfall seasonality in the Amazon during the later period that increases the synchrony between extreme rainfall and wet soil. With high antecedent soil moisture coinciding with rainfall, MMR contributes more to flood in the later period. Fewer extreme rainfall events and increasing soil moisture reduced the contribution of MMR and increased the role of MMS in floods in the Lena and Yenisey basins, respectively. Lastly, increased soil moisture and frequency of large MMS reduced the contribution of the latter to floods in the Kolyma basin. Key Points: • Global flood inundation dynamics are simulated with a physically based inundation model coupled with a river routing model • Flood date, seasonality, and generation mechanisms show large spatial variability across 16 major river basins around the world • Rainfall importance to flood decreased in most rainfall-driven basins and snowmelt importance decreased at high latitudes in

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“…Zhou et al (2020) developed two‐way coupling between ELM and MOSART with water management to constrain the irrigation amount by water available in the streams and reservoirs. Mao et al (2019) evaluated a MOSART floodplain inundation parameterization (Luo et al, 2017) globally and studied flood generation mechanisms and their historical changes. The stream temperature, water management, and floodplain inundation modules, as well as the two‐way coupling of ELM and MOSART with irrigation and water management, are being integrated into E3SM v2 for enhanced capabilities to represent human‐Earth system interactions.…”

A review of freely accessible global datasets for the study of floods, droughts and their interactions with human societies

“…Sutanudjaja et al (), for instance, used global datasets of both environmental and human variables to setup a global hydrological‐water resources model. Mao et al () utilized datasets of observed streamflow and satellite‐derived inundation extents to simulate 50 years of flood extents in major river basins across the globe. de Graaf, Gleeson, van Beek, Sutanudjaja, and Bierkens () used data on climate and human water demand to setup and run a global surface water‐groundwater model, exploring the influence of groundwater pumping on environmental water flows.…”

“…Sutanudjaja et al (2018), for instance, used global datasets of both environmental and human variables to setup a global hydrological-water resources model. Mao et al (2019) demand to setup and run a global surface water-groundwater model, exploring the influence of groundwater pumping on environmental water flows. Lack of data on human behavior has been compensated in model parametrization by employing environmental data.…”

“…Sutanudjaja et al (2018), for instance, used global datasets of both environmental and human variables to setup a global hydrological-water resources model Mao et al (2019). utilized datasets of observed streamflow and satellite-derived inundation extents to simulate 50 years of flood extents in major river basins across the globe.…”

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“…In the past few decades, the proportion of flood disasters in global natural disasters has been rising [1]. A flood disaster is a comprehensive response of many driving processes, including meteorological forcing, basin morphology (altitude, slope), geological characteristics, and human activities [2][3][4].…”