This is especially dangerous if a lack of changes in moderate events gives us a false sense of security when, in fact, extreme flood events will become increasingly likely and potentially cause more extensive damage. — Manuela Brunner, Postdoctoral Researcher at NCAR
This is especially dangerous if a lack of changes in moderate events gives us a false sense of security when, in fact, extreme flood events will become increasingly likely and potentially cause more extensive damage. — Manuela Brunner, Postdoctoral Researcher at NCAR
Flooding patterns expected to change with future warming
Climate change will significantly alter future patterns of flooding, according to a new study. Although future increases in moderate storms won't necessarily lead to more runoff in many regions, extreme storms will generate more devastating and frequent flooding.

At the same time that warmer temperatures will cause the atmosphere to release more moisture, they will dry out soils and enable the land to absorb more rain and snowmelt.

As a result, the water from moderate cloudbursts can seep into the ground instead of inundating the landscape. But the drenching precipitation from extreme storms, which are becoming more frequent with climate change, will saturate the soil and cause increases in flooding, according to advanced computer simulations by the research team.

"It may seem counterintuitive, but climate change can lead to both reduced flooding for moderate rainfall and increased flooding for extreme rainfall," said the study's lead author, Manuela Brunner. "This is especially dangerous if a lack of changes in moderate events gives us a false sense of security when, in fact, extreme flood events will become increasingly likely and potentially cause more extensive damage."


... Major deluges, such as the torrential rains that caused devastating flooding in western Europe this summer, have heightened concerns about the impacts of a changing climate. But streamflow observations across much of the world have provided mixed evidence regarding the response of flooding to increasingly intense downpours.

... "Flooding is not just about precipitation. It's also about snow and soil and other catchment characteristics," Brunner said. "It's important to understand that you can't just apply the same change factor to every kind of flood event."

The study did not look at urban settings in which paved surfaces are largely impermeable and lead to a relatively direct relationship between increasing precipitation and flooding. But its findings are relevant to regions in the world with temperate climates and hydrological systems that are driven by precipitation or snowmelt.

"Antecedent conditions such as soil moisture are important in modulating moderate events," Brunner said. "The hydrologic response to precipitation varies, and we need to understand these variations in order to strengthen society's resilience to floods."
Read the full article: https://www.sciencedaily.com/releases/2021/09/210901142707.htm