Analysis of crop virtual water flow at dual scales in yellow river basin based on the SWAT model

Recently, water scarcity has been becoming increasingly severe, and the research of virtual water flow has offered a scientific foundation for effective water resource management. This study used a SWAT semi-distributed hydrological model, focusing on sub-basins and secondary water resource divisions to quantitatively assess crop virtual water flow in Yellow River Basin (YRB), along with its network structure and water saving benefits. From 2007 to 2020, crop virtual water flow increased by over 20% at both scales, with net outflow areas predominantly in the north and net inflow areas mainly in the south. High centrality areas were predominantly located in the upstream mid-section and the eastern and southern regions of the midstream. The middle reaches of the upper Yellow River Basin and the middle YRB consistently occupied central positions. Water saving benefits significantly improved, with the total water saving at the secondary water resource divisions scale increasing from 21.97×10⁸ to 46.92×10⁸ m³, and the water saving efficiency growing by 72%. Areas with positive water saving benefits accounted for approximately 70% of YRB, especially in the northeastern part of the middle reaches of the YRB, while negative water saving benefits were mostly found in the southern middle and lower reaches. In the future, enhancing the monitoring and evaluation of crop virtual water flow will be essential. Strategic planning of crop trade routes should integrate both scales, emphasizing the development of core network regions while fostering growth in peripheral areas to ensure network stability. Additionally, implementing water-saving technologies and adjusting crop planting structures are vital for sustainable water resource management in YRB.