Simulation of erosion in the braided reach of the Lower Yellow River from 2000 to 2022

Since the impoundment and water-sediment regulation operations of the Xiaolangdi Reservoir, the riverbed in the braided reach of the lower Yellow River has experienced continuous erosion, with significant declines in sediment transport and erosion efficiency. A critical research focus is the development of an accurate computational method for adjusting sediment transport and erosion efficiency during ongoing erosion of this reach. To address the impact of measurement errors in observed sediment transport rates on riverbed erosion-deposition calculations, this study utilized observed data from the Huayuankou intake station and modeled the sediment transport rate at the Gaocun outlet station to partially correct measurement errors at Gaocun. A sediment transport rate lag response model was established, incorporating the riverbed’s delayed response and the sediment mass balance method, combined with the power-law function formula for sediment transport calculations in the lower Yellow River. This model was applied to simulate the adjustment process of sediment transport and erosion efficiency during continuous erosion from 2000 to 2022. The results demonstrated that the model performed well in simulating the changes in sediment transport rate and cumulative erosion-deposition at the Gaocun outlet station before and after the Xiaolangdi Reservoir’s operations, with determination coefficients (R²) of 0.936 and 0.908, Nash-Sutcliffe efficiency coefficients (f_NSE) of 0.93 and 0.85, and relative errors (E_RE) of −0.03 and −0.08, respectively. The simulation of erosion efficiency adjustments during continuous erosion showed a better match with the measured trend using the cross-sectional method compared to the results calculated by the measured sediment mass balance method. This indicates that the model can effectively reduce the impact of measurement errors in observed sediment transport rates at Gaocun to some extent.