Quantifying water supply–demand relationship and spatial flow in Qinghai–Xizang Plateau: Case study of Lhasa River Basin

• Beneficiary areas of water supply services increased from 2005 to 2020. • There is a mismatch between water supply and demand services in Lhasa River Basin. • The predicted total water supply amount in 2030 decreases compared to 2020. • Industrial water is predicted to take up the largest proportion of water demand in 2030. • Reasonable water resource management is important to the ecosystem’s sustainability. The Qinghai–Xizang Plateau is a primary water supply region in Asia. The Lhasa River Basin is the political, economic, and cultural core area and main cultivation area of Qinghai–Xizang Plateau and is considered ecologically fragile. With uneven spatial and temporal distribution of water resources, mismatched supply and demand may accentuate differences in distribution and affect the security of regional water resources. This study employed system dynamics (SD) to measure the supply and demand of water supply services and analyzed the correlation between supply and beneficiary areas by evaluating the supply and demand overlap. Moreover, the 2030 supply–demand relationship was predicted, the pattern of sustainable development of the basin is discussed, and optimization suggestions are proposed. The range of water supply service beneficiary areas in the Lhasa River Basin shows an increasing trend from 2005 to 2020. The spatial distribution of water supply in 2030 is predicted to be the same as that in 2020, while the total amount of water supply is expected to decrease. By 2030, the largest proportion of water demand will be industry, followed by agriculture, forestry, and animal husbandry. Overall, there is a mismatch between water supply and demand services in the Lhasa River Basin, and it is essential to develop a reasonable water resource management and allocation policy as well as an optimized ecological management strategy for the basin through integrated planning. Here, we provide suggestions for the sustainable development and ecological environmental protection of the Lhasa River Basin.