Remote Sensing of Discharge Ratios at River Channel Bifurcations

Abstract River channel bifurcations are crucial for distributing water and sediment on floodplains and deltas, but estimating discharge ratios between branches remains challenging. Using satellite imagery and in‐situ discharge data, we demonstrate that bifurcate channel widths can estimate discharge ratios at 23 of 27 bifurcations in 11 rivers worldwide, with good accuracy ( R 2 = 0.80) in 26 of 33 measurements. An empirical width‐discharge equation derived from 5,740 United States Geological Survey gauging stations further improves accuracy ( R 2 = 0.82). For best results, branch widths should be measured within one channel width of the bifurcation. The method is ineffective in cases influenced by tributaries, avulsion, or multiple branches. We conclude that channel width is effective for estimating discharge ratios, especially when paired with an empirical width‐discharge equation, potentially enhancing river discharge estimates from the Surface Water and Ocean Topography satellite mission, which currently lacks flow partitioning capabilities for bifurcations.