The unexpected global distribution of Earth’s sediment sources and sinks

Abstract Earth’s landscapes, geochemical cycles, and sedimentary record are shaped by the source-to-sink transport of sediment. Sediment is sourced in erosional landscapes under the influence of climate and tectonics, transported through net bypass zones that can obscure forcing signals, and deposited in sinks to build the sedimentary record. Despite the importance of source-to-sink sediment transport in Earth science, the relative abundance of these domains remains unquantified, and the extent to which Earth’s surface resembles classic conceptual models has not been tested. Here we produce a global database of Earth’s source-to-sink systems. Results show that Earth’s land area is mostly erosional (59%), with bypass (22%) and sink (19%) domains less common (18%, 6%, and 76%, respectively, including oceans and Antarctica). Higher elevations are likelier to be erosional, with the world’s lowlands and large rivers disproportionately depositional. Large parts of the world are not described by the source-to-sink model; these areas are mostly deserts or shields without substantial rivers or sediment transport. Even in areas that do resemble the classic textbook progression, systems show exceptional source-to-sink domain variability between catchments and down the world’s major rivers. While the source-to-sink paradigm remains useful, it cannot describe the sedimentologically inactive areas that make up much of the world.