Derivation Of The Optimality Conditions For Water Supply Operation Rules Of Multi-reservoir System

With the implement of the most stringent water resource management and the construction of large reservoirs in series and in waterscale scale, the problem of reservoir system operation has transforming from "individual reservoir, independent operation" to "multi-reservoir, coordinated operation". In order to permit the coordinated operation of multi-reservoir operation and overcome the limitations of the traditional methodology for single reservoir operation that can not meet the complexity of most multi-reservoir system, it is necessary to propose a new system analysis theories and techniques for the operation of multi-reservoir system. Taking the parallel reservoir system and the inter-basin water transfer-supply project as real-world examples, the purpose of this dissertation is to derive the optimal operating policies for multi-reservoir system and devise the efficient algorithm on the basis of the two-period model. The dissertation comprises three parts.Firstly, the general optimality conditions of the commonly used operating policies, defined in terms of system-wide release rules and individual reservoir storage balancing functions, are derived from a two-period model for the operation of parallel reservoir system with joint demand. Following that, the applicable water availability for the commonly used operating policies is given, and the main factors to determine the priority for the water supply operation of individual reservoir are specified. Using the optimality conditions of the two-period model, an algorithm for solving a numerical model is proposed and applied to simulating the performance of a real-world parallel reservoir system in Liaoning province of northeast China-Biliu River reservoir and Yingna River reservoir. Compared to the performance of the commonly used policies, some advantages of the proposed algorithm are illustrated. Most notably, less water shortage occurrence and higher water supply reliability are obtained.Secondly, analytical operation rules, including the hedging rule to determine system release from reservoirs in parallel, the parametric rule to specify the target storage in each reservoir and the proposed operation rules to distribute the system release, are derived by considering balance between beneficial release and carryover storage value among reservoirs in parallel. The commonly used operating policies quantified in terms of hedging rule and parametric rule, are found to be a special case of the newly derived rules. Moreover, numerical results show that the proposed new operation rules are reasonable and effective, and the operation performance is improved than that of the commonly used operating policies.Thirdly, a new water transfer triggering mechanism is proposed for multi-reservoir system to divert water from abundant to scarce regions in an inter-basin water transfer-supply project. In the new triggering mechanism, several water transfer rule curves of the donor reservoir are set for each recipient reservoir respectively, since the diversion amount is derived as a positive function of the water availability of donor reservoir and negative function of the water availability of the recipient reservoir from the two-period model. In order to verify the applicability of the new triggering mechanism, an inter-basin water transfer-supply project in China is employed as a case study. The results indicate that water diversion decisions of the proposed triggering mechanism are more comprehensive than the decisions of other water transfer triggering mechanisms when recipient reservoirs require water transferred from donor reservoir at the same time.This dissertation extends the two-period model from single reservoir operation to multiple reservoir operation problems. Based on the model, the optimality conditions for the operating policies of parallel reservoir system and the water transfer triggering mechanism for inter-basin water transfer-supply project are derived. In addition, an algorithm for solving a two-period operation problem of parallel reservoir system is proposed. The achievements of this research not only advance theory analysis of optimal operation for the multi-reservoir system, but also provide technical support for practical operation of large hydraulic projects.