Floods and droughts have increased significantly in the United States and Canada over the past century, according to a Dartmouth College study.
The new study analyzed records from 1910, which confirm the impact of recent changes in rainfall on river systems.
Floods and droughts are extremely expensive and life-threatening events. It is very important that humanity has ways to assess the likelihood of such an event.
According to research work, the number of such extreme events has increased in recent years. Scientists have combined data on 541 rivers in the United States and Canada in 15 hydrological regions, collected according to seasonal characteristics: frequent or rare floods, tropical storms, rains, melting snow. This grouping made it possible to more identify trends towards various extreme events on an annual and seasonal basis.
According to the study, in regions that were prone to more frequent floods and droughts, their number has doubled in frequency compared to the period 1950-1969. The increase in flooding occurred despite a decrease in snow cover caused by lower winter temperatures.
While floods were more site-specific, droughts were widespread in the identified regions.