The inter-basin water transfer project is the final important method to realize the spatially optimized allocation of water resources. When an area can satisfy the natural and economic conditions for water transfer projects, the rational water transfer scale will be the most important and fundamental parameters for the project planning. Since this parameter should be determined on the basis of theeffective excavation potentials in intake areas, sufficient throttling and rational allocation and involves the overall optimization of various regulation measures in intake areas, the resolution to this research question was in wantof a series of comprehensive and effective quantitative technical methods bothin China and at abroad before 1990s.
Through in charge of the special research “Study on the Rational Allocation of Water Resources in Huang-Huai-Hai Basin” under the master plan of South-to-North Water TransferProject and based on the principle of "three firsts and then three lasts" determined by the State Council, the theory and methodology for the planning of the inter-basin water transfer project based on three-hierarchical of balances between supply and demand of water resources have been proposed toassist the decision-making and the basic parameter selection of the water diversion project. The first balance is between the current water supplyability and increase in water demand in an extensive sense, whose results reflecting the largest water quantity in short in the coming years which have different available water resources against the backdrop of no newly added input for managing water supply and demand. It is the fundamental platform of overall balance of the planning and regulation measures such as tapping new sources of supply and reducing consumption in certain areas. The second balance is between water resources supply and demand on the basis of the first balance and after full excavation in certain areas and strict water demand management, whose results reflecting the least water quantity in short which can be achieved incertain areas under non-conventional water conditions such as full exploitation of local water potentials and the adoption of the utmost water saving or consuming measures. The third balance, based on the second balance, is the balance between supply and demand after the unified allocation of water transferred from the outside and local water, whose results reflecting the regional balanced condition of supply and demand with the transferred water from the outside.
In accordance with the logical relations of increasing progressively, the method of three-hierarchical supply and demand balance describes from the quantitative viewpoint the water lacking state in certain areas under different situations. It is an integrated comprehensive platform for the balanced implementation of various regulation measures in certain areas and the planning of inter-basin water transfer projects through clarifying the contribution ratio of various regulation measures such as water-saving quantities, water exploitation potentials in local areas and non-conventional water utilization for relieving the water lacking situations in certain areas, and has achieved good implementation effects in the planning of South-to-North Water Transfer Project. At the expert examination meeting, the expert examination group including 7 academicians organized by the Ministry of Water Resources hold that "In accordance with the principle of "three firsts and three lasts", the gap between supply and demand drawn from the analysis on three hierarchies of extension, water conservation and pollution treatment and potentials exploitation, and inter-basin water transfer is credible. Proceeding from the rational allocation of water resources in Huang-huai-hai River basins and by analyzing and comparing different objectives and plans, water supply objectives and needed water transfer quantities have been proposed and the scale of the east, middle, west water transfer projects is basically rational." This research, enclosed in Appendix 6, along with the master plan of South-to-North Water Transfer Project has been reported to the State Council for approval, and won National Outstanding Award on Consulting Service Project in 2003.
Three-hierarchical balance method is not only well applied in the planning of South-to-North Water Transfer Project but also adopted by many other key inter-basin water transfer projects for their planning including the planning for water transfer project from Datong River to Huangshui River in Qinghai Province, planning for watertransfer project from Dianchi in Yunnan Province, planning for water transfer project from city cluster in the central part of Jilin Province, planning forwater transfer project from Yili River in the northern part of Xinjiang Uygur Autonomous Region to its southern region, and the planning for water transfer project from the Huaihe River to the northern part of Anhui Province, and soon. At present, three-hierarchical balance method has been incorporated into the technical outline and specifications of national integrated water resources planning, and has gradually become the universal method for domestic inter-basin water transfer project planning.
