Influence of Water-Sediment Regulation Scheme on Accretion and Erosion in a River Delta: a Case Study of the Yellow River Delta, China

The development of river deltas has considerable economic and ecological benefits; however, owing to sediment interception by dams, river deltas face the risk of shrinking, which is a major environmental challenge of the twenty-first century. The Yellow River contains the highest amount of sediment globally, and accretion and erosion are extremely active in its river delta. The water-sediment regulation scheme (WSRS) of the Yellow River have increased the frequency and unpredictability of the alternation of accretion and erosion areas in the river delta. We studied 25 satellite remote sensing images taken from 1999 to 2019. We used the mean high tide line to calculate the accretion and erosion of the Yellow River delta under different runoff and sediment transport scenarios. WSRS have effectively reversed the erosion of the Yellow River delta that had operated from 2002 to 2019. Runoff and sediment transport during the WSRS period are positively correlated, and both are negatively correlated with erosion area; correlations between variables during the non-WSRS period are not significant. During the WSRS, a sediment and runoff transport ratio greater than 10 kg/m(3) results in overall accretion, and a value lower than this results in erosion. In general, during the WSRS period, runoff, sediment transport, and the sediment-runoff ratio jointly control the changes in the accretion area of the river delta. Our research provides a scientific basis for the sustainable development of the Yellow River delta and WSRS scheduling for the Xiaolangdi Reservoir.