Full-stream erosion in the lower Yellow River: Feasibility, sustainability and opportunity

The issue of how to achieve removal of recently accumulated sediment is one of the largest unresolved puzzles in China's lower Yellow River. In this work, the feasibility and sustainability of achieving full-stream erosion in the lower Yellow River based on a water-sediment regulation scheme (WSRS) have been comprehensively investi-gated. The results indicate that the erosion-deposition state of the lower Yellow River is controlled by the incom-ing flow discharge level and the corresponding sediment concentration. The year 1987 is identified as an abrupt change point for streamflow in Xiaolangdi station. The relationships between channel erosion or deposition and the sediment concentration of the incoming discharge are constructed for the periods 1960-1987 and 1988-2017. Based on a constrained optimization approach, a sediment concentration lower than 19.96 kg/m(3) in the discharge from Xiaolangdi Reservoir is determined to be the critical controlling condition for achieving full-stream erosion in the lower Yellow River under the average discharge level observed during 1960-1987; however, it is challenging to achieve full-stream erosion under the average discharge level of 1988-2017. Al-though this erosion status could potentially be achieved through continued implementation of the WSRS, its sus-tainability is restricted by the declining storage capacity of Xiaolangdi Reservoir, decreasing water discharge levels and riverbed coarsening in the Yellow River. It is necessary to design cross-basin collaboration measures for the upper, middle and lower Yellow River to achieve sustainable sediment reduction and healthy develop-ment of the Yellow River basin as a whole. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the feasibility and sustainability of achieving full-stream erosion in the lower Yellow River based on a water-sediment regulation scheme. The critical condition for achieving full-stream erosion is determined to be a sediment concentration lower than 19.96 kg/m³ in the discharge from Xiaolangdi Reservoir. However, challenges arise due to declining storage capacity, decreasing water discharge levels, and riverbed coarsening, pointing to the need for cross-basin collaboration measures for sustainable sediment reduction and healthy development of the Yellow River basin.