Simulation of population size and economic scale supportable by the Yellow River’s available freshwater in 2030 under multiple scenarios

The Yellow River plays a crucial role in China’s socioeconomic development and ecological security. The amount of freshwater available for allocation to the nine provinces of the Yellow River basin (YRB) is expected to be 39.485 billion m3 in 2030, for a projected population of 0.13094 billion people. This study aimed to simulate the sustainable population size and economic scale attainable with the Yellow River’s restricted freshwater supply. We forecasted population size and economic scale under various scenarios using a water resource carrying capacity (WRCC) prediction model. Further, the most likely scenarios—high, moderate, and low development—were analyzed based on historical trends. The results showed that by 2030, the available freshwater could support population sizes of 0.16, 0.152, and 0.147 billion under the high-, moderate-, and low-development scenarios, respectively, all of which are greater than 0.13094 billion. Moreover, economic scales of CNY17.5 trillion ($2.52 trillion), CNY15.01 trillion ($2.18 trillion), and CNY13.2 trillion ($1.91 trillion) could be supported under the high-, moderate-, and low-development scenarios, respectively. This study’s contributions are that (1) using population size and economic scale to characterize WRCC overcomes the limitation of measuring WRCC with a dimensionless index; (2) quantifying WRCC overcomes the flaws of single-trend measurement; and (3) the scenarios paint a clear picture of the YRB’s future water security and socioeconomic development. Our findings could help steer the direction of future water-, population-, and economy-related policymaking.