Effect of terraces and check dams on sediment connectivity in a catchment on the Loess Plateau, China

Sediment connectivity describes the potential linkages between sediment sources and sinks and provides a useful framework for identifying priority areas for sediment control. However, how soil and water conservation measures reshape catchment topography and geomorphic processes, and thereby influence sediment connectivity, remains insufficiently understood. This study quantifies spatial variations in sediment connectivity induced by terraces and check dams in a representative small catchment on the Loess Plateau. We used the landscape evolution model (LAPSUS) to simulate erosion–deposition patterns and applied a spatial autocorrelation index, the bivariate local Moran's I, to characterize the spatial relationship between erosion intensity and sediment connectivity. The results indicate that: (i) compared with the no-measure scenario, sediment connectivity was reduced by 19.55%, 4.82%, and 31.99% under terrace-only, check-dam-only, and combined scenarios, respectively; (ii) terraces reduced slope erosion areas by 33.44%, whereas check dams increased channel deposition areas by 90%, leading to distinct erosion–deposition patterns; and (iii) sediment export was primarily controlled by highly connected areas. High erosion–high connectivity (HE–HC) zones and low erosion–high connectivity (LE–HC) zones emerged as critical regions driving sediment loss and should be prioritized for targeted management interventions. By integrating sediment connectivity analysis with scenario-based landscape evolution modelling, this study quantitatively elucidates how terraces and check dams reorganize erosion–deposition processes and sediment transfer pathways, providing scientific support for more targeted and effective soil and water conservation planning in erosive catchments on the Loess Plateau and in regions with similar geomorphic settings.