Impacts of Cascading Check Dams on Sediment Yield in the Middle Yellow River Basin: Insights from 50 Years of Grid-cell-level Simulation

Abstract. Check dams, globally built for controlling soil erosion, form complex cascading systems that pose significant challenges for assessing spatiotemporal dynamics of sediment yield (SY) at large basin scale. This study proposed an integrative framework combining dynamic sediment trapping efficiency of cascading check dams with the Revised Universal Soil Loss Equation (RUSLE), index of connectivity (IC), and sediment delivery ratio (SDR). This model was applied to evaluate grid-cell-based distribution of SY and sediment trapped by check dams during 1970–2020 in the middle Yellow River Basin (with over 47000 check dams). The Nash-Sutcliffe efficiency of proposed model increased to 0.71 compared to model ignoring sediment trapping of check dams (0.59). Check dams reduced the multi-year average SY by 50.01 % in dam-controlled areas. Totally 3.84 × 10⁹ t of sediment was trapped over the 50 years, constituting 41.49 % of designed storage capacity. The sediment reduction contribution by check dams (SRC_dam) exhibited considerable spatial heterogeneity, ranging from 73.9 % to 0.9 % among sub-basins, and the proportion of accumulated sediment to storage capacity of check dams (SAR_dam) varied from 78.1 % to 1.1 %. The SRC_dam increased linearly with check dam density and the share of area they controlled, whereas SAR_dam increased logarithmically with SY from upstream of the check dams (P < 0.001). A trade-off between SRC_dam and SAR_dam in some sub-basins indicates that the number of check dams in these basins is insufficient or overmuch. This study provides a practical and data-efficient method for assessing sediment trapping and reduction by cascading check dam systems in large basins, offering valuable insights for improving soil and water conservation strategies in erosion-prone regions.