Global Assessment of SWOT River Discharge Representation at Channel Bifurcations

SWOT river discharge products rely on the SWOT River Database (SWORD), designed mainly for single‐thread channels. We assess how well SWORD represents ∼65,000 river bifurcations from the Global River Topology (GRIT) network. SWORD geographically intersects both downstream branches at 88.2% of bifurcations, but only 2.0% of these have distinct reach IDs per branch. At structurally usable bifurcations, summed branch discharge exceeds the upstream value by a median factor of 2.1 in every algorithm tested, and the closure error is independent of branch width asymmetry. A width‐based redistribution ( Q ∝ W 1.52 ) enforces closure by construction; at the Athabasca–Embarras bifurcation, when anchored to the upstream gauge discharge and using Landsat‐derived branch widths, the redistribution matches the gauged Embarras flow fraction ( Q EM / Q upstream ) within 0.004 whereas SoS V3 underestimates it by 0.089. Improved multi‐channel topology in SWORD‐like frameworks remains the longer‐term path to branch‐resolved discharge.