Study on Water and Sediment Regulation in Middle and Lower Reaches of the Yellow River under Changing Environment

The water and sediment regulation systems in the middle and lower reaches of the Yellow River has played a significant role in the flood control and silting reduction. The current operations of the backbone projects of flood and sediment regulation systems in the middle reaches of the Yellow River are summarized, and the responses of scour and deposition in such reservoirs and lower reaches to water and sediment regulation are studied. The future trend of change in scour and fill in the lower reaches of the Yellow River is predicted and then it is proposed that under a scenario of 800 million tons of sediment into the Yellow River in the future, the capacity of Xiaolangdi Reservoir will be depleted in 2030, and in the next 50 years the annual average deposition volume in the lower reaches will reach 200 million tons; under a scenario of 600 million tons of sediment in the future, Xiaolangdi Reservoir will be depleted in 2036, and the annual average deposition volume in the lower reaches will reach 130 million tons; under a scenario of 300 million tons of sediment in the future, Xiaolangdi Reservoir will be depleted in 2057, and the annual average deposition volume in the lower reaches will reach 33 million tons. Considering the need to coordinate restoration of the capacity of Xiaolangdi Reservoir and the reduction of deposition in the lower reaches, the water and sediment regulation systems in the Yellow River should be further improved in the future.