River flooding poses a threat to life and property, causing substantial damage annually. Scientists believe that global warming is contributing to an increase in “extreme” flooding occurrences in river systems. Extreme floods involve a larger volume of water flowing through the river, making them challenging to predict compared to historical floods. As a result, researchers are exploring new methods to forecast the likelihood of extreme flooding in river systems.
A team of scientists from Germany, Norway, and the US conducted a study on over 100 river basins in the US and Germany that had recently experienced significant flooding to determine if such events could be predicted. Traditionally, rainfall measurements have been used to forecast major floods, but they provide limited lead time between rainfall and flooding. Therefore, researchers hypothesized that factors like the physical structure of a river basin and local climatic conditions could offer better predictive insights into flood-prone rivers.
The researchers noted that river systems often witness small floods with predictable growth rates, but extreme floods can escalate rapidly and unpredictably due to factors like flood watershed and volume increases. They found that rivers with well-defined flood divides and larger flood divide volumes tend to experience more extreme flood events. By calculating flood divide volumes and other basin characteristics, researchers assessed the likelihood of extreme flooding in different river systems.
By defining characteristics like the Water Level Graph Recession Index (HRE) and Variable Daily Flow Coefficient (COVDF), researchers analyzed the physical structure and wetness of river basins to predict flood discharges. Based on their study of over 2,500 river basins in the US and Germany, they found that the values of HRE and COVDF accurately predicted distinct flood diversions in those river systems. These characteristics can help forecast extreme flooding and identify flood hazard risks in rivers.
The researchers emphasized the importance of studying the relationship between physical river structure, wetness, and flood divides in rivers of varying sizes to enhance the accuracy of extreme flood predictions. While their findings are based on medium-sized river basins, future research should investigate these relationships in larger and smaller rivers to improve flood forecasting across all river types.
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Source: sciworthy.com
