A recent study has identified how human construction has impacted the flow of some of the world’s largest rivers.
Researchers spent about 10 years mapping the 246 rivers longer than 621 miles where river flow was impeded by dams and other obstructions. The results showed that only 37% of rivers flow freely – the rest are dammed, channelized or heavily developed.
Free-flowing rivers support fish and other aquatic life, as well as wetland species and some inland fisheries. Without rivers carrying sediment to beaches or deltas, these areas could erode away.
Fifteen years ago, researchers found that about half of the world’s large rivers were affected, but now that number is up to 73% — nearly three quarters. Though the 246 rivers are a minority of all waterways, their volume accounts for 41% of the total volume of rivers, making them an important freshwater source.
Rivers have historically provided humans with food, water, transportation and a means of producing energy. Researchers have found that half the world’s rivers are obstructed in some way, thanks to human infrastructure.
Researchers on the study are advocating for awareness of river obstruction and calling for more strategic planning in future building projects.
“In a world of accelerating hydropower development and a shift to low-carbon economies, forward-looking system-scale approaches to energy and hydropower planning . . . are required to minimize loss of river functions,” the study reported.
Going forward, researchers advise maintaining the connectivity of large rivers in order to maintain their functionality.