Complex Adaptive Systems Approach To Simulate The Unified Water Regulation In River-Reservoir System

The unified water regulation plays an important role in ensuring the safety of water supply in China,implementing water allocation plan,implementing the strictest control over water resources and ecological restoration.With climate change and the evolution of water resources caused by human activity,new method is urgent needed to study the complex adaptability of water resources system.So focusing on the complex adaptability of water resources system,the complex adaptive system(CAS)are used to simulate the unified water regulation,especially for water demand forecasting,water supply scheduling and short-term reservoir operation.In addition,the South-to-North Water Transfer Project is taken as a case study to verify the effectiveness of the proposed model.The research is organized as the following four aspects:(1)Firstly,the complex adaptability of water resources system is analyzed,including the adaptability of the water demand based on the behavior of consumers,the adaptability of the stakeholders in the decision-making process of water supply scheduling and the adaptability between the reservoir operations in different time scale.Moreover,the adaptive mechanism in the water resources system is revealed through the induction of individual behavior characteristics and the construction of the feedback path with each other.(2)In order to describe the dynamic adaptive relationship between supply-side and demand-side in reservoir water supply system,an agent-based model(ABM)in which the manager of river basin and microcosmic water consumers are described as two kinds of agents is proposed to forecast the water demand of the system.In addition,the behavior of consumer agent is driven by the water saving intention which affected by the interaction with the manager agent through water supply strategy or total amount control according to the theory of planned behavior.So water demand is reduced with the decrease of inflow by the increase of water saving rate and water restrictions from the behavior of consumers during dry season,while water demand increases with the inflow through the agent cellular automata triggered by population growth and economic development of the river basin during wet season.(3)According to the adaptation in the decision-making process of water supply scheduling,the water administration managers in each region are generalized as agent and the water supply scheduling model based on interactive decision-making process is proposed to simulate the coordination and adaptation among each region manager agent and river basin organization agent.Moreover,a distributed optimization method is proposed to derive the annual water supply plan by balancing the individual optimal release of each region and the global constraints of the basin system.The centralized model which taking the river basin organization as the only decision-maker is a special case of the interactive decision model when the individual preference of each region is 0.In general,the water supply of the region with high priority derived from the interactive decision model is more compared with that from the centralized model,while the total water supply of the system derived from the two model are the same.However,severe water shortage may occur through the supply schedule derived from the interactive decision model because of the decision feedback from the region manager agent which always tends to the increase water supply according to their own benefits during serious dry season,which can be named as the shortsighted decision making.(4)In order to describe the adaptive relationship between the annual water supply scheduling and the short-term reservoir operation with long and short nesting framework and rolling decision-making,a two-period reservoir operation model based on the storage targets is proposed by taking the storage process in the annual water supply plan as the macro control variable and the Karush-Kuhn-Tucker(K-K-T)condition is used to derived the analytical hedging rule for water supply.The sensitivity analysis of storage target shows that when its value is set too low,the derived hedging rule cannot guide reservoir to store enough water before severe dry season,leading to unacceptable one period water shortage.On the other hand,the hedging rule with high storage target may cause unnecessary hedging,thus reducing the probability of water supply.In addition,the case study of Danjiangkou reservoir operation in the middle route of the South to North Water Transfer Project shows that the storage process of the annual water supply scheduling can be taken as storage targets to balance the benefits between the immediate release and the carryover storage,making the water allocation in the unified water regulation become more reasonable.In conclusion,the unified water regulation simulation model based on the complex adaptive system is proposed in which the behavior mechanism of different agent is revealed and the feedback path or adaptive relationships are established in the water resources system in this paper.The results of this research not only enrich the method of reservoir operation modeling,but also provide theoretical support for the practice of the unified water regulation.