Global Scale Analysis on the Geomorphology of Rivers and Channel Belts

Rivers are fundamental geomorphic features on the Earth's surface and have an important role in controlling human habitat, climate, ecosystems, and the hydrological cycle. However, only recently has the surface area of rivers globally been quantified, and there remains a significant knowledge gap in understanding the distribution of river types, the extent of channel belt deposits and their morphology. Yet it is these factors that ultimately control the behavior of river systems and the ecosystems and human livelihoods that depend on those rivers. Here we develop a novel machine learning method to recognize the patterns of different river channels and their deposits to classify their morphology. Our results quantify, for the first time, that the global observable extent of river channel belts covers an area of 30.5 x 105 km2, which equates to roughly the known size of lakes or 7 times larger than the extent of river channels. Of those channel belts, nearly 77% of the surface area are classified as meandering with the remainder defined by a more braided morphology. Furthermore, we quantify the hydrological, physio-climatic and tectonic controls governing the geomorphology of rivers globally. It is hoped that the new Global River Morphology (GRM) map and database may provide new insights into predicting the intensity and behavior of future floods, improve analysis of biogeochemical cycles and aid in water resource management.