Impacts of Spatial Resolution on the Capture of Global River Fluxes and Variability Through Remote Sensing

Satellite observations of Earth’s river networks offer a valuable perspective on global hydrologic dynamics. The spatial resolution and revisit patterns of remote sensing observations represent a key control on the fraction of global rivers that can be sensed, and thus the total river fluxes and storages that can be resolved. While it is expected that satellite observations with improved spatial resolution would capture a more comprehensive view of global river processes, the functional relationship between observing resolution and the resulting representation of river dynamics remains unknown. In this study, we assess how the spatial resolution of observations affects a satellite’s ability to observe key components of the global river water cycle using state-of-the-art hydrologic simulations. As expected, we find that increase spatial resolution has a positive influence on the degree to which global river fluxes and storages are captured. If remote sensing observations are made at a spatial resolution representing the current state of technological capabilities, we show that approximately 83% of global river discharge to the ocean and 91% of total river storage could be observed. Our findings can also serve as an easily applicable and transferable tool to aid in balancing scientific gain with technological constraints during the planning of river-observing satellite missions.