Hydrological Modeling for Flood Risk Management and Mitigation Efforts in the Rhine River Basin

Abstract

Urban flooding is a global issue that affects millions of people every year. It is the most frequent natural hazard to affect large cities, and causes numerous damages to personal property, city infrastructure, and in some cases loss of life. In July of 2021, western Germany was greatly impacted by urban flooding; from the 14 to 15th of July, more than 180 lives were lost due to intense rainfall and flooding, with more than 40,000 people affected. In this work the flooding of 2021 was modeled within the Upper Rhine River basin using the LISFLOOD-OS hydrological model, to conduct a flood-risk analysis in one of the most impacted states during the flooding even, Rhineland Pfalz. Further, the calibrated model was run with higher levels of precipitation to determine possible risks associated with a future flooding event in the same region. To calculate flood-risk, flood depth-damage functions were implemented on simulation outputs to determine flood-risk. Reliability of the flood-risk analysis was done by comparing Copernicus monitored flood extent data from the flooding event against the flood-risk classification map. Results show that the flooding event of 2021 could be modeled with reasonable discharge levels compared to observations from the Mainz gauging station, producing a KGE score of 0.438; further, land use classes which received the highest damage values in both the simulated flooding event of 2021 and in the future flooding event scenario were agricultural and residential areas. High-risk areas from the flood simulation of 2021 fell within Copernicus monitored flood extent areas, highlighting the potential of this methodology to be applied to future flood-risk management practices.