Alterations in hydrological connectivity patterns drove spatiotemporal variations in riverine carbon emissions

Baiyangdian Basin, and Jinsha River Basin, China. Variations in river hydrological connectivity influence carbon cycling, yet the regulatory mechanisms remain unclear. This study integrates field experiment, carbon flux simulation, and model construction to assess how hydrological connectivity affects riverine carbon emissions. ( i ) Disruption of longitudinal hydrological connectivity increased CO 2 emissions from dry channels compared to flowing channels, whereas CH 4 emissions showed the opposite trend. ( ii ) Floodplain released more CO 2 and CH 4 than riverbed. ( iii ) Enhanced vertical groundwater recharge stimulated carbon emissions, with CO 2 and CH 4 fluxes being greater in high baseflow areas. ( iv ) Reservoir CO 2 emissions were higher during the dry season than those during the wet season, particularly in shallow areas, while CH 4 emissions showed an inverse pattern. ( v ) Under actual scenarios, the expansion of dry channels resulted in higher CO 2 emissions but lower CH 4 emissions than natural scenarios. And ( vi ) discharge was positively correlated with CO 2 emissions, with the Jinsha River Basin exhibiting greater sensitivity of CO 2 emissions to discharge variations than the Baiyangdian Basin. This study offers insights for watershed management and emission mitigation. • Hydrological connectivity significantly influenced riverine carbon emissions. • Perennial and non-perennial rivers exhibit distinct carbon emission patterns. • Higher river discharge promote riverine CO 2 emissions. • Large river systems showed higher sensitivity of CO 2 emissions to discharge.