“亚洲水塔”水压力缓解度的时空变化及其经济效益

Water provisioning in the Asian Water Tower (AWT) is crucial to meet the demand of economic development in basin countries, whereas both climate change and economic development are altering the balance of water supply and demand. Previous researches mostly focus on the problem of how the availability of upstream water resources affects downstream uses, but the benefits to economic development are yet addressed. On the basis of hydrological runoff data in the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), we developed an index representing the degree of water stress mitigation by the AWT, and established a production-oriented model using Adaptive Regional Input-Output (ARIO), for the evaluation of economic benefit and its relationship with the degree of water stress mitigation. The results show that the water stress mitigation index of basin countries exhibits dependency on geographical location, and the Central Asian countries display as a core area with higher mitigation index and temporal variation. Meanwhile, the overall economic benefit of the AWT to mitigate water stress reaches as high as 13.06% of Gross Domestic Product (GDP) of all basin countries. The benefit exhibits a significant spatial heterogeneity, with the beneficiary countries mainly concentrated in Central and South Asia, exceeding up to 80% of GDP, such as Bhutan, Nepal, Tajikistan and Kyrgyzstan. Importantly, the benefit not only depends on the degree of water stress mitigation, but also on economic structure, notably demonstrated by Bangladesh. Furthermore, the marginal economic benefit of water stress mitigation by the AWT increases with the degree of mitigation. This implies that the reduced water supply will have a much greater impact on the countries highly benefited from the AWT, especially in the low developing countries. The disparity between countries that benefit the most and least, respectively, can reach up to 2.63 times. As mentioned above, the low developing countries receive the greatest economic benefits when there is an increasing water supply of the AWT. Therefore, the greater significance of AWT is illustrated by its role, not only in mitigating water stress, but also in advancing economic development in the basin countries. In this regard, the basin countries are suggested to take joint actions, so as to safeguard the AWT, and establish a long-term comprehensive water resources management that takes into account the balance of supply and demand. This study can provide evidences for promoting sustainable development of the economic circles around the AWT, especially in low developing countries.