Researchers suggest that humans need to enhance flood management strategies in response to the rise in 100-year floods.
By Chloe Baul, Courthouse News Service
Rivers are undergoing a dramatic transformation worldwide, with headwater streams swelling and downstream basins shrinking.
A comprehensive study published Thursday in Science has mapped 2.9 million rivers from 1984 to 2018, revealing significant changes in global river flow patterns and highlighting the evolving role of upstream rivers in flood dynamics.
Researchers Dongmei Feng and Colin Gleason from the University of Cincinnati developed the Global River Discharge Reanalysis dataset — a tool that combines satellite data with hydrologic models to track daily river flow from source to sea.
Their findings reveal that river flows have shifted significantly upstream across 29% of the global land surface. This change has resulted in a 42% increase in the frequency of 100-year floods and a 4.9% rise in erosional stream power in headwater regions.
I think the primary drivers are climate change and human regulations,” Feng said in an email. “We found consistent upstream shift patterns in global river flow, precipitation, and snow melt.”
The effects of these changes go beyond just how water flows, researchers say.
According to Feng, these shifts can disrupt critical ecological processes, affecting everything from fish migration to local economies dependent on river resources.
“River flow interacts with surrounding ecosystems by exchanging water, energy, nutrients, sediment, and other materials with the surrounding environment,” Feng said. “Changes in river dynamics affect the timing and availability of these materials.”
Additionally, the increase in 100-year floods — flood events with a 1% chance of occurring each year — in headwater regions is particularly concerning, as nearby human settlements often have less flood protection than those downstream.
“The increase in 100-year floods implies that flood management likely needs to be strengthened.” Feng said. “Human activities can impact the magnitude and timing of global river flow. And for regions where river flow has experienced significant changes, policy or infrastructure development should take these changes into account.”
According to Feng, areas like High Mountain Asia and the upstream Amazon are already considering infrastructure improvements to mitigate risks.
“I’m optimistic that with rapidly increasing resources, such as remote sensing earth observation techniques, we will have substantially improved capabilities to understand global rivers at scale,” Feng said. “And their interactions with the climate and human activity and will better predict their future trends.”
