Satellites reveal hotspots of global river extent change

Rivers are among the most diverse, dynamic, and productive ecosystems on Earth. River flow regimes are constantly changing, but characterizing and understanding such changes have been challenging from a long-term and global perspective. By analyzing water extent variations observed from four-decade Landsat imagery, we here provide a global attribution of the recent changes in river regime to morphological dynamics (e.g., channel shifting and anabranching), expansion induced by new dams, and hydrological signals of widening and narrowing. Morphological dynamics prevailed in similar to 20% of the global river area. Booming reservoir constructions, mostly skewed in Asia and South America, contributed to similar to 32% of the river widening. The remaining hydrological signals were characterized by contrasting hotspots, including prominent river widening in alpine and pan-Arctic regions and narrowing in the arid/semi-arid continental interiors, driven by varying trends in climate forcing, cryospheric response to warming, and human water management. Our findings suggest that the recent river extent dynamics diverge based on hydroclimate and socio-economic conditions, and besides reflecting ongoing morphodynamical processes, river extent changes show close connections with external forcings, including climate change and anthropogenic interference. Rivers are among the most diverse, dynamic, and productive ecosystems on Earth. Here, using Landsat imagery, the authors provide a global attribution of the recent changes in river regime to morphological dynamics, dam-induced widening, and hydrological signals.

Automated summary

By analyzing Landsat imagery, the authors found that recent changes in river regime are attributed to morphological dynamics, dam-induced widening, and hydrological signals. Morphological dynamics dominate in approximately 20% of global river area. Reservoir constructions in Asia and South America contribute to about 32% of river widening. The remaining hydrological signals show contrasting patterns, with prominent river widening in alpine and pan-Arctic regions and narrowing in the arid/semi-arid continental interiors, driven by varying trends in climate forcing, cryospheric response to warming, and human water management.