Multi-objective synergy and competition relationship of water and sediment regulation of the Heishanxia reservoir in upstream of the Yellow River Basin

Heishanxia Reservoir, upstream of the Yellow River Basin. The complicated management of the Yellow River Basin stems primarily from an uncoordinated relationship between water and sediment. The un-built Heishanxia Reservoir has been designated as one of seven pivotal projects, and its regulating effect remains to be thoroughly studied. First, nine typical inflow water and sediment scenarios were constructed based on probability inference. Then, a multi-objective water and sediment regulation model of Heishanxia Reservoir was established with the objectives of maximum erosion quantity (EQ) of the channel, maximum ecological satisfaction rate (ESR), and maximum power generation (PG). Finally, the multi-dimensional regulating effect was revealed, and the synergy-competition relationships among EQ, ESR and PG were analyzed. The operation of Heishanxia can increase the discharge during the flood season in the downstream Ning-Meng Channel, and the average annual EQ is 0.19×10 8 t more than the current condition. Further, the ESR decreases slightly during the high-flow and normal-flow years and increases slightly during the low-flow years. The PG in the upper reaches of the Yellow River has increased by approximately 10 %. Among the three objectives, EQ and ESR, as well as EQ and PG, demonstrate a competitive relationship, whereas ESR and PG exhibit a synergistic relationship. Reservoir inflow plays a major role in the changes of synergy-competition relationship. • Generating nine typical inflow water and sediment scenarios based on the probability inference. • Establishing a multi-objective water and sediment regulation model of Heishanxia Reservoir. • Revealing the multi-dimensional benefit and the synergy-competition relationships among objectives.