The Potential Risk of Flooding

Two recent studies have illustrated that more people may be exposed to flooding than currently predicted The first study, completed by the University of Bristol, examined flood patterns of rivers. The results showed that a staggering 41 million Americans were at risk for river flooding, compared to the currently estimated 13 million people.

What makes the University of Bristol study unique is that it is based on a new high resolution model, which maps the entire continental United States, compared to the current model which only maps 60% of the US. Additionally, the high resolution model allowed researchers to predict flooding from small streams at a high level of accuracy. In addition, the new model is more accurate in estimating where people currently live, as well as where they may live in the future.

Oliver Wing, the lead researcher on the study, was surprised by the number of people exposed to flooding. This is concerning to researchers since most people aren’t aware of their risk. Furthermore, people continue to build in and develop potential flood areas. The new study shows that 41 million Americans are at risk for flooding from rivers currently. By 2050, it is estimated that more than 60 million Americans could experience a 100 year flood. Keep in mind that because of climate change, so-called “100 year floods” are likely to occur more often.

This massive exposure illustrates the need to plan ahead to minimize risk.The average cost of flooding in the United States is $10 billion annually. Not to mention, the National Flood Insurance Program is currently $24.6 billion in debt. One example of planning would be to add more flood tolerant parks and flood plains. These areas can prevent flooding in nearby communities, improve water quality, and provide habitats for wildlife. Moreover, now that we have a more detailed idea of where flooding could occur, it’s important to stop building in those places.

The second study illustrated the increased risk of flooding in urban areas. Completed by engineers at the University of New South Wales, the initial purpose was to examine how rising temperatures, due to climate change, may alter the flow of rivers. The research was based on data from the Global Historical Climatology Network and included 5,300 river monitoring sites and 43,000 rainfall stations across 160 countries.

Once the data was gathered, it became evident that river flow had shifted so that cities have more flooding while rural areas stay drier. These results were partially expected from researchers since warmer air can store more water, thus making rainfall more intense. What wasn’t as expected is how dry the country side is compared to cities.

It turns out that this can also be explained by the rising air temperatures. Warmer air means that there will be quicker evaporation of moisture in the soil. Thus, while rainfall is more intense, moisture evaporates quicker and the soil dries out before the next rainfall. This makes it challenging to keep livestock and vegetation alive. On the other hand, urban areas have limited areas of soil to absorb rainfall. If they experience intense rainfall, it will be dependent on the city infrastructure to prevent flooding.

The higher risk of flooding in cities was not apparent in model simulations but was quite clear once actual data was used. Unfortunately, more people are migrating to cities, which may need to increase their flood preparedness. For instance, California is able to thrive and avoid intense flooding, thanks to extensive work by civil engineers.

It is evident from these studies that many areas will experience an increased risk of flooding in the future. People may need to exercise caution when building near rivers plus, cities may need to add extra protection against flooding. The good news is that now people can be aware of potentially dangerous situations.

University of Bristol. "Flood risk from American rivers is greatly underestimated." ScienceDaily. ScienceDaily, 28 February 2018. .
University of New South Wales. "Urban floods intensifying, countryside drying up: An exhaustive global analysis of rainfall and rivers shows signs of a radical shift in streamflow patterns, with more intense flooding in cities and smaller catchments coupled with a drier countryside." ScienceDaily. ScienceDaily, 14 August 2017. .