Revealing Climate Change’s Impact: Mapping Future Floods to Identify Vulnerable Communities.

Worldwide, flood disasters are expected to become more frequent and more severe with climate change. But what does that mean for your local community? A detailed understanding of local risks is crucial to being able to adapt to these changes and effectively mitigate flood risks in a changing climate.

In a study recently published in Hydrology and Earth System SciencesA research team from the University of Tokyo’s Institute of Industrial Sciences reported the most effective approach for creating future flood risk maps using two different methods combined with climate change simulations and comparing the results with historical flood risk maps.

“To simulate worldwide flooding, we used a large-scale watershed-based floodplain (CaMa-Flood) model, which is an efficient model used to represent channel flow and floodplain inundation. We used runoff data to create flood hazard maps, and reduce the simulated scale,” explains the author. Principal Yuki Kimura “River Water Levels to 100 Meter Accuracy Elevation Maps”.

The researchers then created three types of flood risk maps: historical maps based on recorded runoff data, and two maps based on future flood depths. Future flood depths were estimated by two different methods: the runoff-corrected method and the research method. They differ mainly in the way they process data and calculate future flood depths. The future risk maps generated using these two methods were then compared with historical risk maps and with each other.

To understand the differences between the results of these two methods, the researchers chose two test cases to examine in more detail: the basins of the Chi-Mun River, a tributary of the Mekong River in Southeast Asia, and the Amazon River in South America. . The maps generated by both methods successfully predicted the increased flood risk in the Chemun River basin. However, the runoff-correction method appears to have risk discrepancies in the Amazon River basin compared to climate model projections. On the basis of further analysis of the two methods and their results, it was found that the research method is more reliable and superior to the runoff correction method for future hazard map construction.

According to the results of the research method, about 1.86 billion people currently live in areas where the flood magnitude in future simulations has exceeded the flood magnitude with a return period of 100 years historically. “Our risk assessment also indicates that the traditional approach using historical risk maps rather than future simulation maps leads to an underestimation of the affected population by about 200 million people globally,” says lead study author Dai Yamazaki.

These findings highlight the importance of developing high-resolution future hazard maps for estimating local climate change risks. With the new approach and the valuable data provided by the research team, high-resolution future risk maps can be created to more accurately estimate flood risks due to climate change, which will help us better prepare for the disasters that come with climate change.