Sectoral and Regional Allocation of Initial Water Rights of Reservoirs: A Two-Dimensional Method Based on Matter-Element Extension Theory

As an important surface water source, the rational water rights allocation of reservoirs plays a crucial role in alleviating the contradiction between water supply and demand in surrounding areas. However, the theoretical framework for water rights allocation mostly focuses on the watershed scale, which is different from water rights allocation of reservoirs. Research on the water rights allocation of reservoirs is relatively scarce and still at a preliminary stage. Therefore, this study developed a two-dimensional method for sectoral and regional allocation of initial water rights of a reservoir, which was applied to Nishan Reservoir in northern China. The reservoir’s utilizable storage capacity, total initial water rights, and water rights of various sectors were determined using the water balance principle and chronological method. Subsequently, based on the constructed system of indices and assessment criteria for the regional allocation of initial water rights, an allocation model for the reservoirs’ initial water rights was established using the matter-element extension theory to subdivide the sectoral water rights allocations into regional initial water rights allocations. The results show that the total initial water rights of Nishan Reservoir are 20.64 million m3, with the water rights allocations for agricultural irrigation, industry/domestic use, and ecological needs at 4.24, 10.4, and 6.00 million m3, respectively. The 6.00 million m3 allocation for ecological water use is solely managed by the prefecture-level administration of Jining City. The remaining allocations of the reservoir’s initial water rights are 9.67 million m3 for Qufu City, 1.63 million m3 for Sishui County, and 3.34 million m3 for Zoucheng City. This allocation scheme has been accepted by all stakeholders of the Nishan Reservoir’s water rights. The method proposed in this study can provide support for the construction of a reservoir water rights allocation system. However, it has a limitation in that it fails to consider the robustness of the allocation scheme and the dynamic adjustment mechanism under future variable conditions, such as extreme hydrological scenarios and changes in water demand. This serves as a direction for future research.