Precipitation, landscape pattern and sediment connectivity differ in their effects on runoff and sediment transport

Four major sub-basins of Yangtze River, China Precipitation , landscape pattern and sediment connectivity significantly influence hydrological processes within a basin. However, the large-scale impacts of landscape patterns and sediment connectivity on watershed runoff and sediment transport remain poorly understood. This study focuses on the runoff and sediment changes in the four sub-watersheds of the Yangtze River from 2001 to 2022 and their comprehensive response to precipitation, landscape pattern and sediment connectivity, to elucidate the mechanisms through which climate and land use changes affect hydrological processes. Our findings showed that precipitation and landscape pattern predominantly affects basin runoff, whereas sediment connectivity primarily influences sediment yield. Precipitation and landscape pattern accounted for 70.6 % of the variation in runoff, while precipitation, landscape pattern, sediment connectivity, and runoff jointly explained 43.2 % of the variation in sediment yield. Among the observed variables, the mean patch fractal dimension (FRAC_MN) contributed the most to the landscape pattern, precipitation erosivity contributed the most to the precipitation factor, and the maximum value of the sediment connectivity index (ICmax) contributed the most to sediment connectivity factor. • Precipitation and landscape pattern control runoff in Yangtze sub-basins. • Sediment transport is dominated by sediment connectivity. • Landscape pattern affects sediment yield indirectly via runoff. • Framework transferable to other large basins for water-sediment assessment.